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TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time-domain Field (2024)
Journal Article
O’Brien, R., Jansen, R. A., Grogin, N. A., Cohen, S. H., Smith, B. M., Silver, R. M., …Acharya, T. (2024). TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time-domain Field. Astrophysical Journal Supplement, 272(1), Article 19. https://doi.org/10.3847/1538-4365/ad3948

The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14′ diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the groun... Read More about TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time-domain Field.

AGN STORM 2. V. Anomalous Behavior of the C iv Light Curve of Mrk 817 (2024)
Journal Article
Homayouni, Y., Kriss, G. A., De Rosa, G., Plesha, R., Cackett, E. M., Goad, M. R., …Zu, Y. (2024). AGN STORM 2. V. Anomalous Behavior of the C iv Light Curve of Mrk 817. Astrophysical Journal, 963(2), Article 123. https://doi.org/10.3847/1538-4357/ad1be4

An intensive reverberation mapping campaign of the Seyfert 1 galaxy Mrk 817 using the Cosmic Origins Spectrograph on the Hubble Space Telescope revealed significant variations in the response of broad UV emission lines to fluctuations in the continuu... Read More about AGN STORM 2. V. Anomalous Behavior of the C iv Light Curve of Mrk 817.

Deconvolution of JWST/MIRI Images: Applications to an Active Galactic Nucleus Model and GATOS Observations of NGC 5728 (2024)
Journal Article
Leist, M. T., Packham, C., Rosario, D. J. V., Hope, D. A., Alonso-Herrero, A., Hicks, E. K. S., …Shimizu, T. (2024). Deconvolution of JWST/MIRI Images: Applications to an Active Galactic Nucleus Model and GATOS Observations of NGC 5728. Astronomical Journal, 167(3), Article 96. https://doi.org/10.3847/1538-3881/ad1886

The superb image quality, stability, and sensitivity of JWST permit deconvolution techniques to be pursued with a fidelity unavailable to ground-based observations. We present an assessment of several deconvolution approaches to improve image quality... Read More about Deconvolution of JWST/MIRI Images: Applications to an Active Galactic Nucleus Model and GATOS Observations of NGC 5728.

The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei (2023)
Journal Article
García-Bernete, I., Alonso-Herrero, A., Rigopoulou, D., Pereira-Santaella, M., Shimizu, T., Davies, R., …Ward, M. J. (2024). The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei. Astronomy & Astrophysics, 681, Article L7. https://doi.org/10.1051/0004-6361/202348266

We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type 1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption bands with the level of nuclear obscuration traced by X-rays. This study is the first to use subarc... Read More about The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei.

Breakthrough results in astrobiology: is ‘high risk’ research needed? (2023)
Journal Article
Jeancolas, C., Gillen, C., McMahon, S., Ward, M., & Vickers, P. J. (2023). Breakthrough results in astrobiology: is ‘high risk’ research needed?. International Journal of Astrobiology, https://doi.org/10.1017/s1473550423000241

Astrobiology is a scientific endeavour involving great uncertainties. This could justify intellectual risk-taking associated with research that significantly deviates from the mainstream, to explore new avenues. However, little is known regarding the... Read More about Breakthrough results in astrobiology: is ‘high risk’ research needed?.

Wavelength dependences of the optical/UV and X-ray luminosity correlations of quasars (2023)
Journal Article
Ward, M., Done, C., Jin, C., Lusso, E., & Middei, R. (2024). Wavelength dependences of the optical/UV and X-ray luminosity correlations of quasars. Monthly Notices of the Royal Astronomical Society, 527(1), 356–373. https://doi.org/10.1093/mnras/stad3193

The interband correlations between optical/ultraviolet (UV) and X-ray luminosities of active galactic nuclei (AGNs) are important for understanding the disc–coronal connection, as well as using AGN as standard candles for cosmology. It is convention... Read More about Wavelength dependences of the optical/UV and X-ray luminosity correlations of quasars.

Delayed appearance and evolution of coronal lines in the TDE AT2019qiz (2023)
Journal Article
Short, P., Lawrence, A., Nicholl, M., Ward, M., Reynolds, T. M., Mattila, S., …Wevers, T. (2023). Delayed appearance and evolution of coronal lines in the TDE AT2019qiz. Monthly Notices of the Royal Astronomical Society, 525(1), 1568-1587. https://doi.org/10.1093/mnras/stad2270

Tidal disruption events (TDEs) occur when a star gets torn apart by a supermassive black hole as it crosses its tidal radius. We present late-time optical and X-ray observations of the nuclear transient AT2019qiz, which showed the typical signs of an... Read More about Delayed appearance and evolution of coronal lines in the TDE AT2019qiz.

MIDIS: Strong (Hβ+[O iii]) and Hα Emitters at Redshift z ≃ 7–8 Unveiled with JWST NIRCam and MIRI Imaging in the Hubble eXtreme Deep Field (2023)
Journal Article
Rinaldi, P., Caputi, K. I., Costantin, L., Gillman, S., Iani, E., Pérez-González, P. G., …Kokorev, V. (2023). MIDIS: Strong (Hβ+[O iii]) and Hα Emitters at Redshift z ≃ 7–8 Unveiled with JWST NIRCam and MIRI Imaging in the Hubble eXtreme Deep Field. Astrophysical Journal, 952(2), Article 143. https://doi.org/10.3847/1538-4357/acdc27

We make use of JWST medium-band and broadband NIRCam imaging, along with ultradeep MIRI 5.6 μm imaging, in the Hubble eXtreme Deep Field to identify prominent line emitters at z ≃ 7–8. Out of a total of 58 galaxies at z ≃ 7–8, we find 18 robust candi... Read More about MIDIS: Strong (Hβ+[O iii]) and Hα Emitters at Redshift z ≃ 7–8 Unveiled with JWST NIRCam and MIRI Imaging in the Hubble eXtreme Deep Field.

Life beyond 30: Probing the −20 < M UV < −17 Luminosity Function at 8 < z < 13 with the NIRCam Parallel Field of the MIRI Deep Survey (2023)
Journal Article
Pérez-González, P. G., Costantin, L., Langeroodi, D., Rinaldi, P., Annunziatella, M., Ilbert, O., …María Mérida, R. (2023). Life beyond 30: Probing the −20 < M UV < −17 Luminosity Function at 8 < z < 13 with the NIRCam Parallel Field of the MIRI Deep Survey. Astrophysical Journal Letters, 951:L1(1), 1-14. https://doi.org/10.3847/2041-8213/acd9d0

We present the ultraviolet luminosity function and an estimate of the cosmic star formation rate density at 8 < z < 13 derived from deep NIRCam observations taken in parallel with the MIRI Deep Survey of the Hubble Ultra Deep Field (HUDF), NIRCam cov... Read More about Life beyond 30: Probing the −20 < M UV < −17 Luminosity Function at 8 < z < 13 with the NIRCam Parallel Field of the MIRI Deep Survey.

The SOUX AGN sample: optical/UV/X-ray SEDs and the nature of the disc (2023)
Journal Article
Mitchell, J. A. J., Done, C., Ward, M. J., Kynoch, D., Hagen, S., Lusso, E., & Landt, H. (2023). The SOUX AGN sample: optical/UV/X-ray SEDs and the nature of the disc. Monthly Notices of the Royal Astronomical Society, 524(2), 1796-1825. https://doi.org/10.1093/mnras/stad1830

We use the SOUX sample of ∼700 active galactic nucleus (AGN) to form average optical-ultraviolet (UV)-X-rays spectral energy distributions (SEDs) on a two-dimensional (2D) grid of MBH and L2500. We compare these with the predictions of a new AGN SED... Read More about The SOUX AGN sample: optical/UV/X-ray SEDs and the nature of the disc.

AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope* (2023)
Journal Article
Homayouni, Y., De Rosa, G., Plesha, R., Kriss, G. A., Barth, A. J., Cackett, E. M., …Zu, Y. (2023). AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope*. Astrophysical Journal, 948(2), Article 85. https://doi.org/10.3847/1538-4357/acc45a

We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk 817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultraviolet obs... Read More about AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope*.

MIRI/JWST observations reveal an extremely obscured starburst in the z = 6.9 system SPT0311-58 (2023)
Journal Article
Álvarez-Márquez, J., Crespo Gómez, A., Colina, L., Neeleman, M., Walter, F., Labiano, A., …Waelkens, C. (2023). MIRI/JWST observations reveal an extremely obscured starburst in the z = 6.9 system SPT0311-58. Astronomy & Astrophysics, 671, Article A105. https://doi.org/10.1051/0004-6361/202245400

Luminous infrared starbursts in the early Universe are thought to be the progenitors of massive quiescent galaxies identified at redshifts 2–4. Using the Mid-IRfrared Instrument (MIRI) on board the James Webb Space Telescope (JWST), we present mid-in... Read More about MIRI/JWST observations reveal an extremely obscured starburst in the z = 6.9 system SPT0311-58.

A Complex Dust Morphology in the High-luminosity AGN Mrk 876 (2023)
Journal Article
Landt, H., Mitchell, J. A., Ward, M. J., Mercatoris, P., Pott, J., Horne, K., …Winkler, H. (2023). A Complex Dust Morphology in the High-luminosity AGN Mrk 876. Astrophysical Journal, 945(1), Article 62. https://doi.org/10.3847/1538-4357/acb92d

Recent models for the inner structures of active galactic nuclei (AGNs) advocate the presence of a radiatively accelerated dusty outflow launched from the outer regions of the accretion disk. Here, we present the first near-IR variable (rms) spectrum... Read More about A Complex Dust Morphology in the High-luminosity AGN Mrk 876.

The SOUX AGN sample: SDSS–XMM-Newton optical, ultraviolet, and X-ray selected active galactic nuclei spanning a wide range of parameter space – sample definition (2023)
Journal Article
Kynoch, D., Mitchell, J. A. J., Ward, M. J., Done, C., Lusso, E., & Landt, H. (2023). The SOUX AGN sample: SDSS–XMM-Newton optical, ultraviolet, and X-ray selected active galactic nuclei spanning a wide range of parameter space – sample definition. Monthly Notices of the Royal Astronomical Society, 520(2), 2781-2805. https://doi.org/10.1093/mnras/stad221

We assemble a sample of 696 type 1 active galactic nuclei (AGN) up to a redshift of z = 2.5, all of which have an SDSS spectrum containing at least one broad emission line (H α, H β, or Mg II) and an XMM-Newton X-ray spectrum containing at least 250... Read More about The SOUX AGN sample: SDSS–XMM-Newton optical, ultraviolet, and X-ray selected active galactic nuclei spanning a wide range of parameter space – sample definition.

The long-term broad-line responsivity in MKN 110 (2022)
Journal Article
Homan, D., Lawrence, A., Ward, M., Bruce, A., Landt, H., MacLeod, C., …Peterson, B. M. (2023). The long-term broad-line responsivity in MKN 110. Monthly Notices of the Royal Astronomical Society, 519(2), 1745-1763. https://doi.org/10.1093/mnras/stac3571

We examine the long-term history of the optical spectrum of the extremely variable Active Galactic Nucleus (AGN) MKN 110. By combining various archival data with new data, we cover an unprecedented long period of ∼30 yr (1987–2019). We find that the... Read More about The long-term broad-line responsivity in MKN 110.

Torus and polar dust dependence on active galactic nucleus properties (2022)
Journal Article
García-Bernete, I., González-Martín, O., Ramos Almeida, C., Alonso-Herrero, A., Martínez-Paredes, M., Ward, M. J., …Esparza-Arredondo, D. (2022). Torus and polar dust dependence on active galactic nucleus properties. Astronomy & Astrophysics, 667, 1-43. https://doi.org/10.1051/0004-6361/202244230

We present a statistical analysis of the properties of the obscuring material around active galactic nuclei (AGN). This study represents the first of its kind for an ultra-hard X-ray (14–195 keV; Swift/BAT), volume-limited (DL <  40 Mpc) sample of 24... Read More about Torus and polar dust dependence on active galactic nucleus properties.

Launching the VASCO Citizen Science Project (2022)
Journal Article
Villarroel, B., Pelckmans, K., Solano, E., Laaksoharju, M., Souza, A., Dom, O. N., …Ward, M. J. (2022). Launching the VASCO Citizen Science Project. Universe, 8(11), Article 561. https://doi.org/10.3390/universe8110561

The Vanishing & Appearing Sources during a Century of Observations (VASCO) project investigates astronomical surveys spanning a time interval of 70 years, searching for unusual and exotic transients. We present herein the VASCO Citizen Science Projec... Read More about Launching the VASCO Citizen Science Project.

A high angular resolution view of the PAH emission in Seyfert galaxies using JWST/MRS data (2022)
Journal Article
García-Bernete, I., Rigopoulou, D., Alonso-Herrero, A., Donnan, F., Roche, P., Pereira-Santaella, M., …Packham, C. (2022). A high angular resolution view of the PAH emission in Seyfert galaxies using JWST/MRS data. Astronomy & Astrophysics, 666, Article L5. https://doi.org/10.1051/0004-6361/202244806

Polycyclic aromatic hydrocarbons (PAHs) are carbon-based molecules that are ubiquitous in a variety of astrophysical objects and environments. In this work we use JWST/MIRI MRS spectroscopy of three Seyferts to compare their nuclear PAH emission with... Read More about A high angular resolution view of the PAH emission in Seyfert galaxies using JWST/MRS data.

Detection of an unidentified soft X-ray emission feature in NGC 5548 (2022)
Journal Article
Gu, L., Mao, J., Kaastra, J. S., Mehdipour, M., Pinto, C., Grafton-Waters, S., …Ward, M. (2022). Detection of an unidentified soft X-ray emission feature in NGC 5548. Astronomy & Astrophysics, 665, Article A93. https://doi.org/10.1051/0004-6361/202244075

Context. NGC 5548 is an X-ray bright Seyfert 1 active galaxy. It exhibits a variety of spectroscopic features in the soft X-ray band, in particular including the absorption by the active galactic nucleus (AGN) outflows of a broad range of ionization... Read More about Detection of an unidentified soft X-ray emission feature in NGC 5548.

Multiple locations of near-infrared coronal lines in NGC 5548 (2022)
Journal Article
Kynoch, D., Landt, H., Dehghanian, M., Ward, M. J., & Ferland, G. J. (2022). Multiple locations of near-infrared coronal lines in NGC 5548. Monthly Notices of the Royal Astronomical Society, 516(3), https://doi.org/10.1093/mnras/stac2443

We present the first intensive study of the variability of the near-infrared coronal lines in an active galactic nucleus (AGN). We use data from a 1-yr-long spectroscopic monitoring campaign with roughly weekly cadence on NGC 5548 to study the variab... Read More about Multiple locations of near-infrared coronal lines in NGC 5548.

Multiwavelength campaign on the Super-Eddington NLS1 RX J0134.2-4258 – I. Peculiar X-ray spectra and variability (2022)
Journal Article
Jin, C., Done, C., Ward, M., Panessa, F., Liu, B., & Liu, H. (2022). Multiwavelength campaign on the Super-Eddington NLS1 RX J0134.2-4258 – I. Peculiar X-ray spectra and variability. Monthly Notices of the Royal Astronomical Society, 512(4), 5642-5656. https://doi.org/10.1093/mnras/stac827

We have conducted a new long-term multiwavelength campaign on one of the most super-Eddington narrow-line Seyfert 1s (NLS1s) known, namely RX J0134.2-4258. In this first paper, we report deep simultaneous X-ray observations performed by XMM–Newton an... Read More about Multiwavelength campaign on the Super-Eddington NLS1 RX J0134.2-4258 – I. Peculiar X-ray spectra and variability.

A glint in the eye: Photographic plate archive searches for non-terrestrial artefacts (2022)
Journal Article
Villarroel, B., Mattsson, L., Guergouri, H., Solano, E., Geier, S., Dom, O. N., & Ward, M. J. (2022). A glint in the eye: Photographic plate archive searches for non-terrestrial artefacts. Acta Astronautica, 194, 106-113. https://doi.org/10.1016/j.actaastro.2022.01.039

In this paper, we present a simple strategy to identify Non-Terrestrial artefacts [NTAs; Haqq-Misra and Kopparapu (2012)] in or near geosynchronous Earth orbits (GEOs). We show that even the small pieces of reflective debris in orbit around the Earth... Read More about A glint in the eye: Photographic plate archive searches for non-terrestrial artefacts.

X-ray intraday variability and power spectral density profiles of the blazar 3C 273 with XMM–Newton during 2000–2021 (2022)
Journal Article
Pavana Gowtami, G., Gaur, H., Gupta, A. C., Wiita, P. J., Liao, M., & Ward, M. (2022). X-ray intraday variability and power spectral density profiles of the blazar 3C 273 with XMM–Newton during 2000–2021. Monthly Notices of the Royal Astronomical Society, 511(2), 3101-3112. https://doi.org/10.1093/mnras/stac286

We present X-ray intraday variability and power spectral density (PSD) analyses of the longest 23 pointed XMM–Newton observations of the blazar 3C 273 that were taken during 2000–2021. These good time intervals contain between 5 and 24.6 h of data. V... Read More about X-ray intraday variability and power spectral density profiles of the blazar 3C 273 with XMM–Newton during 2000–2021.

LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: exploring the origin of nuclear radio emission in active and inactive galaxies through the [O iii] – radio connection (2021)
Journal Article
Baldi, R., Williams, D., Beswick, R., McHardy, I., Dullo, B., Knapen, J., …Ward, M. (2021). LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: exploring the origin of nuclear radio emission in active and inactive galaxies through the [O iii] – radio connection. Monthly Notices of the Royal Astronomical Society, 508(2), 2019-2038. https://doi.org/10.1093/mnras/stab2613

What determines the nuclear radio emission in local galaxies? To address this question, we combine optical [O III] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1.5-GHz data, from the LeMMINGs survey, of a statist... Read More about LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: exploring the origin of nuclear radio emission in active and inactive galaxies through the [O iii] – radio connection.

The NuSTAR extragalactic survey of the James Webb Space Telescope North Ecliptic Pole time-domain field (2021)
Journal Article
Zhao, X., Civano, F., Fornasini, F., Alexander, D., Cappelluti, N., Chen, C., …Windhorst, R. (2021). The NuSTAR extragalactic survey of the James Webb Space Telescope North Ecliptic Pole time-domain field. Monthly Notices of the Royal Astronomical Society, 508(4), 5176-5195. https://doi.org/10.1093/mnras/stab2885

We present the NuSTAR extragalactic survey of the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field. The survey covers a ∼0.16 deg2 area with a total exposure of 681 ks acquired in a total of nine observations from three e... Read More about The NuSTAR extragalactic survey of the James Webb Space Telescope North Ecliptic Pole time-domain field.

Hubble Space Telescope [O iii] emission-line kinematics in two nearby QSO2s: a case for X-ray feedback (2021)
Journal Article
Trindade Falcão, A., Kraemer, S., Fischer, T., Crenshaw, D., Revalski, M., Schmitt, H., …Ward, M. (2021). Hubble Space Telescope [O iii] emission-line kinematics in two nearby QSO2s: a case for X-ray feedback. Monthly Notices of the Royal Astronomical Society, 505(2), 3054-3069. https://doi.org/10.1093/mnras/stab1549

We present a dynamical study of the narrow-line regions in two nearby type 2 quasars (QSO2s). We construct dynamical models based on detailed photoionization models of the emission-line gas, including the effects of internal dust, to apply to observa... Read More about Hubble Space Telescope [O iii] emission-line kinematics in two nearby QSO2s: a case for X-ray feedback.

On the multiwavelength variability of Mrk 110: two components acting at different time-scales (2021)
Journal Article
Vincentelli, F., McHardy, I., Cackett, E., Barth, A., Horne, K., Goad, M., …Williams, D. (2021). On the multiwavelength variability of Mrk 110: two components acting at different time-scales. Monthly Notices of the Royal Astronomical Society, 504(3), 4337-4353. https://doi.org/10.1093/mnras/stab1033

We present the first intensive continuum reverberation mapping study of the high accretion-rate Seyfert galaxy Mrk 110. The source was monitored almost daily for more than 200 d with the Swift X-ray and ultraviolet (UV)/optical telescopes, supported... Read More about On the multiwavelength variability of Mrk 110: two components acting at different time-scales.

Re-observing the NLS1 galaxy RE J1034+396 – II. New insights on the soft X-ray excess, QPO, and the analogy with GRS 1915+105 (2020)
Journal Article
Jin, C., Done, C., & Ward, M. (2021). Re-observing the NLS1 galaxy RE J1034+396 – II. New insights on the soft X-ray excess, QPO, and the analogy with GRS 1915+105. Monthly Notices of the Royal Astronomical Society, 500(2), 2475-2495. https://doi.org/10.1093/mnras/staa3386

The active galactic nucleus (AGN) RE J1034+396 displays the most significant X-ray quasi-periodic oscillation (QPO) detected so far. We perform a detailed spectral-timing analysis of our recent simultaneous XMM–Newton, NuSTAR, and Swift observations.... Read More about Re-observing the NLS1 galaxy RE J1034+396 – II. New insights on the soft X-ray excess, QPO, and the analogy with GRS 1915+105.

Broad He i 1.08-µm absorption from the obscurer in the active galaxy NGC 5548 (2020)
Journal Article
Wildy, C., Landt, H., Ward, M. J., Czerny, B., & Kynoch, D. (2021). Broad He i 1.08-µm absorption from the obscurer in the active galaxy NGC 5548. Monthly Notices of the Royal Astronomical Society: Letters, 500(2), 2063-2075. https://doi.org/10.1093/mnras/staa3301

The nucleus of the active galaxy NGC 5548 was the target of two intensive spectroscopic monitoring campaigns at X-ray, ultraviolet (UV), and optical frequencies in 2013/2014. These campaigns detected the presence of a massive obscuration event. In 20... Read More about Broad He i 1.08-µm absorption from the obscurer in the active galaxy NGC 5548.

Geometry of the X-ray source 1H 0707–495 (2020)
Journal Article
Szanecki, M., Niedźwiecki, A., Done, C., Klepczarek, Ł., Lubiński, P., & Mizumoto, M. (2020). Geometry of the X-ray source 1H 0707–495. Astronomy & Astrophysics, 641, Article A89. https://doi.org/10.1051/0004-6361/202038303

Aims. We investigate the constraints on the size and location of the X-ray source in 1H 0707–495 determined from the shape of the relativistically smeared reflection from the accretion disc. Methods. We developed a new code to model an extended X-ray... Read More about Geometry of the X-ray source 1H 0707–495.

Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance (2020)
Journal Article
Ward, M., Done, C., & Jin, C. (2020). Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance. Monthly Notices of the Royal Astronomical Society, 495(4), 3538-3550. https://doi.org/10.1093/mnras/staa1356

RE J1034+396 is a narrow-line Seyfert 1 galaxy (NLS1) in which the first significant X-ray quasi-periodic oscillation (QPO) in an active galactic nucleus (AGN) was observed in 2007. We report the detection of this QPO in a recent XMM–Newton observati... Read More about Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance.

State-of-the-art AGN SEDs for Photoionization Models: BLR Predictions Confront the Observations (2020)
Journal Article
Ward, M. J., Landt, H., Jin, C., Done, C., & Ferland, G. J. (2020). State-of-the-art AGN SEDs for Photoionization Models: BLR Predictions Confront the Observations. Monthly Notices of the Royal Astronomical Society, 494(4), 5917-5922. https://doi.org/10.1093/mnras/staa1207

The great power offered by photoionization models of Active Galactic Nuclei (AGN) emission line regions has long been mitigated by the fact that very little is known about the spectral energy distribution (SED) between the Lyman limit, where interven... Read More about State-of-the-art AGN SEDs for Photoionization Models: BLR Predictions Confront the Observations.

The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a “Missing Star” (2020)
Journal Article
Villarroel, B., Soodla, J., Comerón, S., Mattsson, L., Pelckmans, K., López-Corredoira, M., …Ward, M. J. (2020). The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a “Missing Star”. Astronomical Journal, 159(1), Article 8. https://doi.org/10.3847/1538-3881/ab570f

In this paper we report the current status of a new research program. The primary goal of the "Vanishing and Appearing Sources during a Century of Observations" project is to search for vanishing and appearing sources using existing survey data to fi... Read More about The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a “Missing Star”.

The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548 (2019)
Journal Article
Landt, H., Ward, M., Kynoch, D., Packham, C., Ferland, G., Lawrence, A., …Winkler, H. (2019). The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548. Monthly Notices of the Royal Astronomical Society, 489(2), 1572-1589. https://doi.org/10.1093/mnras/stz2212

We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision... Read More about The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548.

The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy PKS J1222+0413 (2019)
Journal Article
Kynoch, D., Landt, H., Ward, M. J., Done, C., Boisson, C., Baloković, M., …Myserlis, I. (2019). The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy PKS J1222+0413. Monthly Notices of the Royal Astronomical Society, 487(1), 181-197. https://doi.org/10.1093/mnras/stz1193

We present a multi-frequency study of PKS J1222+0413 (4C +04.42), currently the highest redshift γ-ray emitting narrow-line Seyfert 1 (γ-NLS1). We assemble a broad spectral energy distribution (SED) including previously unpublished datasets: X-ray da... Read More about The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy PKS J1222+0413.

Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies (2019)
Journal Article
García-Bernete, I., Ramos Almeida, C., Alonso-Herrero, A., Ward, M., Acosta-Pulido, J., Pereira-Santaella, M., …Fuller, L. (2019). Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies. Monthly Notices of the Royal Astronomical Society, 486(4), 4917-4935. https://doi.org/10.1093/mnras/stz1003

We characterize for the first time the torus properties of an ultra-hard X-ray (14–195 keV) volume-limited (DL < 40 Mpc) sample of 24 Seyfert (Sy) galaxies (BCS40 sample). The sample was selected from the Swift/BAT nine-month catalogue.We use high an... Read More about Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies.

The ‘Big Dipper’: the nature of the extreme variability of the AGN SDSS J2232−0806 (2019)
Journal Article
Kynoch, D., Ward, M. J., Lawrence, A., Bruce, A. G., Landt, H., & MacLeod, C. L. (2019). The ‘Big Dipper’: the nature of the extreme variability of the AGN SDSS J2232−0806. Monthly Notices of the Royal Astronomical Society, 485(2), 2573-2588. https://doi.org/10.1093/mnras/stz517

SDSS J2232−0806 (the ‘Big Dipper’) has been identified as a ‘slow-blue nuclear hypervariable’: a galaxy with no previously known active nucleus, blue colours, and large-amplitude brightness evolution occurring on a time-scale of years. Subsequent obs... Read More about The ‘Big Dipper’: the nature of the extreme variability of the AGN SDSS J2232−0806.

Resolving the Nuclear Obscuring Disk in the Compton-thick Seyfert Galaxy NGC 5643 with ALMA (2018)
Journal Article
Alonso-Herrero, A., Pereira-Santaella, M., García-Burillo, S., Davies, R., Combes, F., Asmus, D., …Ward, M. (2018). Resolving the Nuclear Obscuring Disk in the Compton-thick Seyfert Galaxy NGC 5643 with ALMA. Astrophysical Journal, 859(2), Article 144. https://doi.org/10.3847/1538-4357/aabe30

We present ALMA Band 6 12CO(2–1) line and rest-frame 232 GHz continuum observations of the nearby Compton-thick Seyfert galaxy NGC 5643 with angular resolutions 0farcs11–0farcs26 (9–21 pc). The CO(2–1) integrated line map reveals emission from the nu... Read More about Resolving the Nuclear Obscuring Disk in the Compton-thick Seyfert Galaxy NGC 5643 with ALMA.

Hubble Space Telescope Observations of Extended [O iii]λ 5007 Emission in Nearby QSO2s: New Constraints on AGN Host Galaxy Interaction (2018)
Journal Article
Fischer, T. C., Kraemer, S., Schmitt, H., Micchi, L. L., Crenshaw, D., Revalski, M., …Ward, M. (2018). Hubble Space Telescope Observations of Extended [O iii]λ 5007 Emission in Nearby QSO2s: New Constraints on AGN Host Galaxy Interaction. Astrophysical Journal, 856(2), Article 102. https://doi.org/10.3847/1538-4357/aab03e

We present a Hubble Space Telescope survey of extended [O iii] λ5007 emission for a sample of 12 nearby (z < 0.12), luminous Type 2 quasars (QSO2s), which we use to measure the extent and kinematics of their AGN-ionized gas. We find that the size of... Read More about Hubble Space Telescope Observations of Extended [O iii]λ 5007 Emission in Nearby QSO2s: New Constraints on AGN Host Galaxy Interaction.

The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342 (2017)
Journal Article
Kynoch, D., Landt, H., Ward, M. J., Done, C., Gardner, E., Boisson, C., …Pereira Santaella, M. (2018). The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342. Monthly Notices of the Royal Astronomical Society, 475(1), 404-423. https://doi.org/10.1093/mnras/stx3161

The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of γ-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum radio... Read More about The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342.

The broad-band SEDs of four ‘hypervariable’ AGN (2017)
Journal Article
Collinson, J. S., Ward, M. J., Lawrence, A., Bruce, A., MacLeod, C. L., Elvis, M., …Done, C. (2018). The broad-band SEDs of four ‘hypervariable’ AGN. Monthly Notices of the Royal Astronomical Society, 474(3), 3565-3575. https://doi.org/10.1093/mnras/stx2992

We present an optical-to-X-ray spectral analysis of four ‘hypervariable’ AGN (HVAs) discovered by comparing Pan-STARRS data to that from the Sloan Digital Sky Survey over a 10 yr baseline (Lawrence et al.). There is some evidence that these objects a... Read More about The broad-band SEDs of four ‘hypervariable’ AGN.

A population of highly energetic transient events in the centres of active galaxies (2017)
Journal Article
Kankare, E., Kotak, R., Mattila, S., Lundqvist, P., Ward, M., Fraser, M., …Waters, C. (2017). A population of highly energetic transient events in the centres of active galaxies. Nature Astronomy, 1(12), 865-871. https://doi.org/10.1038/s41550-017-0290-2

Recent all-sky surveys have led to the discovery of new types of transients. These include stars disrupted by the central supermassive black hole, and supernovae that are 10–100 times more energetic than typical ones. However, the nature of even more... Read More about A population of highly energetic transient events in the centres of active galaxies.

Determining the torus covering factors for a sample of type 1 AGN in the local Universe (2017)
Journal Article
Ezhikode, S. H., Gandhi, P., Done, C., Ward, M., Dewangan, G. C., Misra, R., & Philip, N. S. (2017). Determining the torus covering factors for a sample of type 1 AGN in the local Universe. Monthly Notices of the Royal Astronomical Society, 472(3), 3492-3511. https://doi.org/10.1093/mnras/stx2160

In the unified scheme of active galactic nuclei, a dusty torus absorbs and then reprocesses a fraction of the intrinsic luminosity which is emitted at longer wavelengths. Thus, subject to radiative transfer corrections, the fraction of the sky covere... Read More about Determining the torus covering factors for a sample of type 1 AGN in the local Universe.

Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow (2017)
Journal Article
Jin, C., Done, C., Ward, M., & Gardner, E. (2017). Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow. Monthly Notices of the Royal Astronomical Society, 471(1), 706-721. https://doi.org/10.1093/mnras/stx1634

We present a detailed multiwavelength study of an unobscured, highly super-Eddington Type-1 QSO RX J0439.6-5311. We combine the latest XMM–Newton observation with all archival data from infrared to hard X-rays. The optical spectrum is very similar to... Read More about Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow.

The infrared to X-ray correlation spectra of unobscured type 1 active galactic nuclei (2017)
Journal Article
García-Bernete, I., Ramos Almeida, C., Landt, H., Ward, M., Baloković, M., & Acosta-Pulido, J. (2017). The infrared to X-ray correlation spectra of unobscured type 1 active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 469(1), 110-126. https://doi.org/10.1093/mnras/stx795

We use new X-ray data obtained with the Nuclear Spectroscopic Telescope Array (NuSTAR), near-infrared (NIR) fluxes and mid-infrared (MIR) spectra of a sample of 24 unobscured type 1 active galactic nuclei (AGN) to study the correlation between variou... Read More about The infrared to X-ray correlation spectra of unobscured type 1 active galactic nuclei.

Spectral analysis of four ‘hypervariable’ AGN: a micro-needle in the haystack? (2017)
Journal Article
Bruce, A., Lawrence, A., MacLeod, C., Elvis, M., Ward, M., Collinson, J., …Waters, C. (2017). Spectral analysis of four ‘hypervariable’ AGN: a micro-needle in the haystack?. Monthly Notices of the Royal Astronomical Society, 467(2), 1259-1280. https://doi.org/10.1093/mnras/stx168

We analyse four extreme active galactic nuclei (AGN) transients to explore the possibility that they are caused by rare, high-amplitude microlensing events. These previously unknown type-I AGN are located in the redshift range 0.6–1.1 and show change... Read More about Spectral analysis of four ‘hypervariable’ AGN: a micro-needle in the haystack?.

Reaching the peak of the quasar spectral energy distribution – II. Exploring the accretion disc, dusty torus and host galaxy (2016)
Journal Article
Collinson, J., Ward, M., Landt, H., Done, C., Elvis, M., & McDowell, J. (2017). Reaching the peak of the quasar spectral energy distribution – II. Exploring the accretion disc, dusty torus and host galaxy. Monthly Notices of the Royal Astronomical Society, 465(1), 358-382. https://doi.org/10.1093/mnras/stw2666

We continue our study of the spectral energy distributions (SEDs) of 11 active galactic nuclei (AGN) at 1.5 < z < 2.2, with optical–near-infrared (NIR) spectra, X-ray data and mid-IR photometry. In a previous paper, we presented the observations and... Read More about Reaching the peak of the quasar spectral energy distribution – II. Exploring the accretion disc, dusty torus and host galaxy.

On the black hole mass of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342 (2016)
Journal Article
Landt, H., Ward, M., Baloković, M., Kynoch, D., Storchi-Bergmann, T., Boisson, C., …Stern, D. (2017). On the black hole mass of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342. Monthly Notices of the Royal Astronomical Society, 464(3), 2565-2576. https://doi.org/10.1093/mnras/stw2447

Narrow-line Seyfert 1 galaxies have been identified by the Fermi Gamma-Ray Space Telescope as a rare class of γ-ray emitting active galactic nuclei. The lowest redshift candidate among them is the source 1H 0323+342. Here we present quasi-simultaneou... Read More about On the black hole mass of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342.

TeV γ-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0 with H.E.S.S (2014)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2014). TeV γ-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0 with H.E.S.S. Monthly Notices of the Royal Astronomical Society, 441(1), 790-799. https://doi.org/10.1093/mnras/stu459

The non-thermal nature of the X-ray emission from the shell-type supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0 is an indication of intense particle acceleration in the shock fronts of both objects. This suggests that the SNRs are prime candidates... Read More about TeV γ-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0 with H.E.S.S.

Search for TeV Gamma-ray emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S (2014)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2014). Search for TeV Gamma-ray emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S. Astronomy & Astrophysics, 565, Article A16. https://doi.org/10.1051/0004-6361/201322984

The long gamma-ray burst (GRB) 100621A, at the time the brightest X-ray transient ever detected by Swift-XRT in the 0.3–10 keV range, has been observed with the H.E.S.S. imaging air Cherenkov telescope array, sensitive to gamma radiation in the very-... Read More about Search for TeV Gamma-ray emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S.

HESS J1640-465 - an exceptionally luminous TeV γ-ray supernova remnant (2014)
Journal Article
Abramowski, A., Aharonian, F., Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2014). HESS J1640-465 - an exceptionally luminous TeV γ-ray supernova remnant. Monthly Notices of the Royal Astronomical Society, 439(3), 2828-2836. https://doi.org/10.1093/mnras/stu139

The results of follow-up observations of the TeV γ-ray source HESS J1640−465 from 2004 to 2011 with the High Energy Stereoscopic System (HESS) are reported in this work. The spectrum is well described by an exponential cut-off power law with photon i... Read More about HESS J1640-465 - an exceptionally luminous TeV γ-ray supernova remnant.

Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011 (2014)
Journal Article
Collaboration, H., Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Zechlin, H. (2014). Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011. Astronomy & Astrophysics, 564, Article A9. https://doi.org/10.1051/0004-6361/201322897

Context. About 40% of the observation time of the High Energy Stereoscopic System (H.E.S.S.) is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy (VHE, E > 100 GeV) sourc... Read More about Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011.

Revealing the Location and Structure of the Accretion Disk Wind in PDS 456 (2014)
Journal Article
Gofford, J., Reeves, J., Braito, V., Nardini, E., Costa, M., Matzeu, G., …Miller, L. (2014). Revealing the Location and Structure of the Accretion Disk Wind in PDS 456. Astrophysical Journal, 784(1), Article 77. https://doi.org/10.1088/0004-637x/784/1/77

We present evidence for the rapid variability of the high-velocity iron K-shell absorption in the nearby (z = 0.184) quasar PDS 456. From a recent long Suzaku observation in 2013 (~1 Ms effective duration), we find that the equivalent width of iron K... Read More about Revealing the Location and Structure of the Accretion Disk Wind in PDS 456.

Constraints on the outer radius of the broad emission line region of active galactic nuclei (2014)
Journal Article
Landt, H., Ward, M., Elvis, M., & Karovska, M. (2014). Constraints on the outer radius of the broad emission line region of active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 439(1), 1051-1062. https://doi.org/10.1093/mnras/stu031

Here we present observational evidence that the broad emission line region (BELR) of active galactic nuclei (AGN) generally has an outer boundary. This was already clear for sources with an obvious transition between the broad and narrow components o... Read More about Constraints on the outer radius of the broad emission line region of active galactic nuclei.

HESS J1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays (2014)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2014). HESS J1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays. Astronomy & Astrophysics, 562, Article A40. https://doi.org/10.1051/0004-6361/201322914

Composite supernova remnants (SNRs) constitute a small subclass of the remnants of massive stellar explosions where non-thermal radiation is observed from both the expanding shell-like shock front and from a pulsar wind nebula (PWN) located inside of... Read More about HESS J1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays.

H.E.S.S. observations of the Crab during its March 2013 GeV gamma- ray flare (2014)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2014). H.E.S.S. observations of the Crab during its March 2013 GeV gamma- ray flare. Astronomy & Astrophysics, 562, Article L4. https://doi.org/10.1051/0004-6361/201323013

Context. On March 4, 2013 the Fermi-LAT and AGILE reported a flare from the direction of the Crab nebula in which the high-energy (HE; E > 100 MeV) flux was six times above its quiescent level. Simultaneous observations in other energy bands give us... Read More about H.E.S.S. observations of the Crab during its March 2013 GeV gamma- ray flare.

Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT (2014)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Anton, G., …Malyshev, D. (2014). Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT. Astronomy & Astrophysics, 562, Article A145. https://doi.org/10.1051/0004-6361/201322510

Context. Very-high-energy (VHE; E > 100 GeV) γ-ray emission from blazars inevitably gives rise to electron-positron pair production through the interaction of these γ-rays with the extragalactic background light (EBL). Depending on the magnetic field... Read More about Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT.

Long-term TeV and X-Ray Observations of the Gamma-Ray Binary HESS J0632+057 (2014)
Journal Article
Aliu, E., Archambault, S., Aune, T., Behera, B., Beilicke, M., Benbow, W., …Zechlin, H. (2014). Long-term TeV and X-Ray Observations of the Gamma-Ray Binary HESS J0632+057. Astrophysical Journal, 780(2), Article 168. https://doi.org/10.1088/0004-637x/780/2/168

HESS J0632+057 is the only gamma-ray binary known so far whose position in the sky allows observations with ground-based observatories in both the northern and southern hemispheres. Here we report on long-term observations of HESS J0632+057 conducted... Read More about Long-term TeV and X-Ray Observations of the Gamma-Ray Binary HESS J0632+057.

Variability of the High-velocity Outflow in the Quasar PDS 456 (2014)
Journal Article
Reeves, J., Braito, V., Gofford, J., Sim, S., Behar, E., Costa, M., …Ward, M. (2014). Variability of the High-velocity Outflow in the Quasar PDS 456. Astrophysical Journal, 780(1), Article 45. https://doi.org/10.1088/0004-637x/780/1/45

We present a comparison of two Suzaku X-ray observations of the nearby (z = 0.184), luminous (L bol ~ 1047 erg s–1) type I quasar, PDS 456. A new 125 ks Suzaku observation in 2011 caught the quasar during a period of low X-ray flux and with a hard X-... Read More about Variability of the High-velocity Outflow in the Quasar PDS 456.

A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026 (2013)
Journal Article
Jin, C., Done, C., Middleton, M., & Ward, M. (2013). A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026. Monthly Notices of the Royal Astronomical Society, 436(4), 3173-3185. https://doi.org/10.1093/mnras/stt1801

We explore the origin of the strong soft X-ray excess in narrow-line Seyfert 1 galaxies using spectral-timing information from a 120 ks XMM–Newton observation of PG 1244+026. Spectral fitting alone cannot distinguish between a true additional soft X-... Read More about A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026.

Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Zechlin, H. (2013). Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S. Astronomy & Astrophysics, 559, Article A136. https://doi.org/10.1051/0004-6361/201321639

The active galactic nucleus PKS 0301−243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV 100 GeV) by the High Energy Stereoscopic System (H.E.S.S.) from observations between September 2009 and De... Read More about Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S.

Constraints on axionlike particles with H.E.S.S. from the irregularity of the PKS 2155-304 energy spectrum (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Collaboration, H. (2013). Constraints on axionlike particles with H.E.S.S. from the irregularity of the PKS 2155-304 energy spectrum. Physical Review D, 88(10), Article 102003. https://doi.org/10.1103/physrevd.88.102003

Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model of particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent magnetic fields, the existence of... Read More about Constraints on axionlike particles with H.E.S.S. from the irregularity of the PKS 2155-304 energy spectrum.

HESS and Fermi-LAT discovery of γ-rays from the blazar 1ES 1312−423 (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Angüner, E., Anton, G., …Kadler, M. (2013). HESS and Fermi-LAT discovery of γ-rays from the blazar 1ES 1312−423. Monthly Notices of the Royal Astronomical Society, 434(3), 1889-1901. https://doi.org/10.1093/mnras/stt1081

A deep observation campaign carried out by the High Energy Stereoscopic System (HESS) on Centaurus A enabled the discovery of γ-rays from the blazar 1ES 1312−423, 2° away from the radio galaxy. With a differential flux at 1 TeV of ϕ(1 TeV) = (1.9 ± 0... Read More about HESS and Fermi-LAT discovery of γ-rays from the blazar 1ES 1312−423.

A new way to measure supermassive black hole spin in accretion disc-dominated Active Galaxies (2013)
Journal Article
Done, C., Jin, C., Middleton, M., & Ward, M. (2013). A new way to measure supermassive black hole spin in accretion disc-dominated Active Galaxies. Monthly Notices of the Royal Astronomical Society, 1955-1963. https://doi.org/10.1093/mnras/stt1138

We show that disc continuum fitting can be used to constrain black hole spin in a subclass of narrow-line Seyfert 1 (NLS1) active galactic nuclei as their low mass and high mass accretion rate means that the disc peaks at energies just below the soft... Read More about A new way to measure supermassive black hole spin in accretion disc-dominated Active Galaxies.

H.E.S.S. discovery of VHE γ-rays from the quasar PKS 1510−089 (2013)
Journal Article
H.E.S.S. Collaboration Abramowski, A. A., F. Aharonian, F. A., A.G. Anton, G. B., S. Balzer, A. B., A. Becherini, Y. B. T., J. Behera, B. B., …S., H. (2013). H.E.S.S. discovery of VHE γ-rays from the quasar PKS 1510−089. Astronomy & Astrophysics, 554, Article A107. https://doi.org/10.1051/0004-6361/201321135

The quasar PKS 1510−089 (z = 0.361) was observed with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes during high states in the optical and GeV bands, to search for very high energy (VHE, defined as E ≥ 0.1 TeV) emission. VHE γ-rays we... Read More about H.E.S.S. discovery of VHE γ-rays from the quasar PKS 1510−089.

Discovery of high and very high-energy emission from the BL Lacertae object SHBL J001355.9-185406 (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Angüner, E., Anton, G., …Zechlin, H. (2013). Discovery of high and very high-energy emission from the BL Lacertae object SHBL J001355.9-185406. Astronomy & Astrophysics, 554, Article A72. https://doi.org/10.1051/0004-6361/201220996

The detection of the high-frequency peaked BL Lac object (HBL) SHBL J001355.9–185406 (z = 0.095) at high (HE; 100 MeV < E < 300 GeV) and very high-energy (VHE; E > 100 GeV) with the Fermi Large Area Telescope (LAT) and the High Energy Stereoscopic Sy... Read More about Discovery of high and very high-energy emission from the BL Lacertae object SHBL J001355.9-185406.

A near-infrared relationship for estimating black hole masses in active galactic nuclei (2013)
Journal Article
Landt, H., Ward, M., Peterson, B., Bentz, M., Elvis, M., Korista, K., & Karovska, M. (2013). A near-infrared relationship for estimating black hole masses in active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 432(1), 113-126. https://doi.org/10.1093/mnras/stt421

Black hole masses for samples of active galactic nuclei (AGN) are currently estimated from single-epoch optical spectra using scaling relations anchored in reverberation mapping results. In particular, the two quantities needed for calculating black... Read More about A near-infrared relationship for estimating black hole masses in active galactic nuclei.

Discovery of TeV γ-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift (2013)
Journal Article
Collaboration, H., Abramowski, A., Acero, F., Akhperjanian, A., Anton, G., Balenderan, S., …Pelat, D. (2013). Discovery of TeV γ-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift. Astronomy & Astrophysics, 552, Article A118. https://doi.org/10.1051/0004-6361/201321108

Very high-energy γ-ray emission from PKS 0447−439 was detected with the H.E.S.S. Cherenkov telescope array in December 2009. This blazar is one of the brightest extragalactic objects in the Fermi bright source list and has a hard spectrum in the MeV... Read More about Discovery of TeV γ-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift.

H.E.S.S. observations of the binary system PSR B1259-63/LS 2883 around the 2010/2011 periastron passage (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Anton, G., Balenderan, S., …Zechlin, H. (2013). H.E.S.S. observations of the binary system PSR B1259-63/LS 2883 around the 2010/2011 periastron passage. Astronomy & Astrophysics, 551, Article A94. https://doi.org/10.1051/0004-6361/201220612

Aims. We present very high energy (VHE; E > 100 GeV) data from the γ-ray binary system PSR B1259-63/LS 2883 taken around its periastron passage on 15th of December 2010 with the High Energy Stereoscopic System (H.E.S.S.) of Cherenkov Telescopes. We a... Read More about H.E.S.S. observations of the binary system PSR B1259-63/LS 2883 around the 2010/2011 periastron passage.

Search for very-high-energy γ-ray emission from Galactic globular clusters with H.E.S.S (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Anton, G., Balenderan, S., …Zechlin, H. (2013). Search for very-high-energy γ-ray emission from Galactic globular clusters with H.E.S.S. Astronomy & Astrophysics, 551, Article A26. https://doi.org/10.1051/0004-6361/201220719

Context. Globular clusters (GCs) are established emitters of high-energy (HE, 100 MeV < E < 100 GeV) γ-ray radiation which could originate from the cumulative emission of the numerous millisecond pulsars (msPSRs) in the clusters’ cores or from invers... Read More about Search for very-high-energy γ-ray emission from Galactic globular clusters with H.E.S.S.

Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei (2013)
Journal Article
Videla, L., Lira, P., Andrews, H., Alonso-Herrero, A., Alexander, D., & Ward, M. (2013). Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei. Astrophysical Journal Supplement, 204(2), https://doi.org/10.1088/0067-0049/204/2/23

We present near- and mid-IR observations of a sample of Seyfert II galaxies drawn from the 12 μm Galaxy sample. The sample was observed in the J, H, K, L, M and N bands. Galaxy surface brightness profiles are modeled using nuclear, bulge, bar (when n... Read More about Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei.

Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Anton, G., Balenderan, S., …Zechlin, H. (2013). Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S. Astronomy & Astrophysics, 550, Article A4. https://doi.org/10.1051/0004-6361/201220355

The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the measurement of the imprint of the EBL opacity to γ-rays on th... Read More about Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S.

Search for Photon-Linelike Signatures from Dark Matter Annihilations with H.E.S.S (2013)
Journal Article
Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A., Anton, G., Balenderan, S., …Zechlin, H. (2013). Search for Photon-Linelike Signatures from Dark Matter Annihilations with H.E.S.S. Physical Review Letters, 110(4), Article 041301. https://doi.org/10.1103/physrevlett.110.041301

Gamma-ray line signatures can be expected in the very-high-energy (Eγ>100  GeV) domain due to self-annihilation or decay of dark matter (DM) particles in space. Such a signal would be readily distinguishable from astrophysical γ-ray sources that in m... Read More about Search for Photon-Linelike Signatures from Dark Matter Annihilations with H.E.S.S.

A combined optical and X-ray study of unobscured type 1 active galactic nuclei - I. Optical spectra and spectral energy distribution modelling (2012)
Journal Article
Jin, C., Ward, M., Done, C., & Gelbord, J. (2012). A combined optical and X-ray study of unobscured type 1 active galactic nuclei - I. Optical spectra and spectral energy distribution modelling. Monthly Notices of the Royal Astronomical Society, 420(3), 1825-1847. https://doi.org/10.1111/j.1365-2966.2011.19805.x

We present modelling and interpretation of the continuum and emission lines for a sample of 51 unobscured type 1 active galactic nuclei (AGNs). All of these AGNs have high-quality spectra from both XMM–Newton and the Sloan Digital Sky Survey. We exte... Read More about A combined optical and X-ray study of unobscured type 1 active galactic nuclei - I. Optical spectra and spectral energy distribution modelling.

The near-infrared broad emission line region of active galactic nuclei – II. The 1-μm continuum (2011)
Journal Article
Landt, H., Martin, E., Ward, M., Bentz, M., Korista, K., & Karovska, M. (2011). The near-infrared broad emission line region of active galactic nuclei – II. The 1-μm continuum. Monthly Notices of the Royal Astronomical Society, 414(1), 218-240. https://doi.org/10.1111/j.1365-2966.2011.18383.x

We use quasi-simultaneous near-infrared (near-IR) and optical spectroscopy from four observing runs to study the continuum around 1 μm in 23 well-known broad emission line active galactic nuclei (AGN). We show that, after correcting the optical spect... Read More about The near-infrared broad emission line region of active galactic nuclei – II. The 1-μm continuum.

Detection of extended very-high-energy gamma-ray emission towards the young stellar cluster Westerlund 2 (2007)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2007). Detection of extended very-high-energy gamma-ray emission towards the young stellar cluster Westerlund 2. Astronomy & Astrophysics, 467(3), 1075-1080. https://doi.org/10.1051/0004-6361%3A20066950

Aims. Results from $\gamma$-ray observations by the HESS telescope array in the direction of the young stellar cluster Westerlund 2 are presented. Methods. Stereoscopic imaging of Cherenkov light emission of $\gamma$-ray induced showers in the atmosp... Read More about Detection of extended very-high-energy gamma-ray emission towards the young stellar cluster Westerlund 2.

Constraints on accretion in ultraluminous X-ray sources from Spitzer IRS observations of NGC 4485/4490: Infrared diagnostic diagrams (2007)
Journal Article
Vazquez, G., Hornschemeier, A., Colbert, E., Roberts, T., Ward, M., & Malhotra, S. (2007). Constraints on accretion in ultraluminous X-ray sources from Spitzer IRS observations of NGC 4485/4490: Infrared diagnostic diagrams. Astrophysical Journal Letters, 658(1), L21-L24. https://doi.org/10.1086/513423

Constraining the astrophysical nature of ultraluminous X-ray (ULX) sources, which have X-ray luminosities exceeding 1039 ergs s1, has been elusive due to the optical faintness of any counterparts. With high spectral resolution observations in the ∼10... Read More about Constraints on accretion in ultraluminous X-ray sources from Spitzer IRS observations of NGC 4485/4490: Infrared diagnostic diagrams.

Fast variability of tera-electron volt gamma rays from the radio galaxy M87 (2006)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). Fast variability of tera-electron volt gamma rays from the radio galaxy M87. Science, 314(5804), 1424-1427. https://doi.org/10.1126/science.1134408

The detection of fast variations of the tera–electron volt (TeV) (1012 eV) -ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply... Read More about Fast variability of tera-electron volt gamma rays from the radio galaxy M87.

Observations of the crab nebula with HESS (2006)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). Observations of the crab nebula with HESS. Astronomy & Astrophysics, 457(3), 899-915

Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1. (2006)
Journal Article
Roberts, T., Kilgard, R., Warwick, R., Goad, M., & Ward, M. (2006). Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 371(4), 1877-1890. https://doi.org/10.1111/j.1365-2966.2006.10821.x

We report the results of a two-month campaign conducted with the Chandra X-ray observatory to monitor the ultraluminous X-ray source (ULX) NGC 5204 X-1. This was composed of a 50-ks observation, followed by ten 5-ks follow-ups spaced initially at ∼3,... Read More about Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1..

Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS (2006)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS. Astronomy & Astrophysics, 456(1), 245-251. https://doi.org/10.1051/0004-6361%3A20065511

Aims.Search for Very High Energy $\gamma$-ray emission in the Kookaburra complex through observations with the HESS array. Methods.Stereoscopic imaging of Cherenkov light emission of the $\gamma$-ray showers in the atmosphere is used for the reconstr... Read More about Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS.

Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes (2006)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes. Astronomy & Astrophysics, 455(2), 461-466. https://doi.org/10.1051/0004-6361%3A20054732

The extreme synchrotron BL Lac object H 2356-309, located at a redshift of z = 0.165, was observed from June to December 2004 with a total exposure of $\approx$40 h live-time with the HESS (High Energy Stereoscopic System) array of atmospheric-Cheren... Read More about Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes.

First detection of a VHE gamma-ray spectral maximum from a cosmicsource: HESS discovery of the Vela X nebula (2006)
Journal Article
Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Ward, M. (2006). First detection of a VHE gamma-ray spectral maximum from a cosmicsource: HESS discovery of the Vela X nebula. Astronomy & Astrophysics, 448(2), L43-L47. https://doi.org/10.1051/0004-6361%3A200600014

The Vela supernova remnant (SNR) is a complex region containing a number of sources of non-thermal radiation. The inner section of this SNR, within 2 degrees of the pulsar PSR B0833-45 , has been observed by the HESS $\gamma$-ray atmospheric Cherenko... Read More about First detection of a VHE gamma-ray spectral maximum from a cosmicsource: HESS discovery of the Vela X nebula.

An XMM-Newton view of M101 - II. Global X-ray source properties. (2005)
Journal Article
Jenkins, L., Roberts, T., Warwick, R., Kilgard, R., & Ward, M. (2005). An XMM-Newton view of M101 - II. Global X-ray source properties. Monthly Notices of the Royal Astronomical Society, 357(2), 401-419. https://doi.org/10.1111/j.1365-2966.2005.08645.x

We present the global X-ray properties of the point source population in the grand-design spiral galaxy M101, as seen with XMM–Newton. 108 X-ray sources are detected within the D25 ellipse of M101, of which ∼24 are estimated to be background galaxies... Read More about An XMM-Newton view of M101 - II. Global X-ray source properties..

A new description of the X-ray spectra of ULXs (2004)
Journal Article
Roberts, T., Warwick, R., Stobbart, A., Goad, M., Ward, M., Kilgard, R., & Jenkins, L. (2004). A new description of the X-ray spectra of ULXs. Bulletin of the American Astronomical Society, 8,

An XMM-Newton view of the luminous X-ray source population of M101. (2004)
Journal Article
Jenkins, L., Roberts, T., Warwick, R., Kilgard, R., & Ward, M. (2004). An XMM-Newton view of the luminous X-ray source population of M101. Memorie Della Società Astronomica Italiana, 75(3),

We present the first results of an XMM n EPIC observation of the luminous X-ray source population in the face-on supergiant spiral galaxy M101. We have studied the X-ray spectral and temporal properties of the most luminous sources in M101 at the tim... Read More about An XMM-Newton view of the luminous X-ray source population of M101..

The Swift gamma-ray burst mission (2004)
Journal Article
Gehrels, N., Chincarini, G., Giommi, P., Mason, K., Nousek, J., Wells, A., …Zhang, W. (2004). The Swift gamma-ray burst mission. Astrophysical Journal, 611(2),

High-resolution imaging of the He II λ4686 emission line nebula associated with the ultraluminous X-ray source in Holmberg II (2004)
Journal Article
Kaaret, P., Ward, M., & Zezas, A. (2004). High-resolution imaging of the He II λ4686 emission line nebula associated with the ultraluminous X-ray source in Holmberg II. Monthly Notices of the Royal Astronomical Society, 351(3), L83-L88. https://doi.org/10.1111/j.1365-2966.2004.08020.x

We present Hubble Space Telescope images of the He iii region surrounding the bright X-ray source in the dwarf irregular galaxy Holmberg II. Using Chandra, we find a position for the X-ray source of (J2000) with an uncertainty of 0.6 arcsec. We ident... Read More about High-resolution imaging of the He II λ4686 emission line nebula associated with the ultraluminous X-ray source in Holmberg II.

Chandra observations of five ultraluminous X-ray sources in nearby galaxies (2004)
Journal Article
Roberts, T., Warwick, R., Ward, M., & Goad, M. (2004). Chandra observations of five ultraluminous X-ray sources in nearby galaxies. Monthly Notices of the Royal Astronomical Society, 349(4), 1193-1210. https://doi.org/10.1111/j.1365-2966.2004.07626.x

We report the results of a programme of dual-epoch Chandra ACIS-S observations of five ultraluminous X-ray sources (ULXs) in nearby spiral galaxies. All five ULXs are detected as unresolved, point-like X-ray sources by Chandra, though two have faded... Read More about Chandra observations of five ultraluminous X-ray sources in nearby galaxies.

An XMM-Newton view of M101 - I. The luminous X-ray source population. (2004)
Journal Article
Jenkins, L., Roberts, T., Warwick, R., Kilgard, R., & Ward, M. (2004). An XMM-Newton view of M101 - I. The luminous X-ray source population. Monthly Notices of the Royal Astronomical Society, 349(2), 404-424. https://doi.org/10.1111/j.1365-2966.2004.07546.x

We present the first results of an XMM–Newton EPIC observation of the luminous X-ray source population in the face-on supergiant spiral galaxy M101. We have studied the spectral and temporal properties of the 14 most luminous sources, all of which ha... Read More about An XMM-Newton view of M101 - I. The luminous X-ray source population..

The Collimated Wind in NGC 253 (2003)
Journal Article
Sugai, H., Davies, R., & Ward, M. (2003). The Collimated Wind in NGC 253. Astrophysical Journal, 584, L9-L12

A massive x-ray outflow from the quasar PDS 456 (2003)
Journal Article
Reeves, J., O'Brien, P., & Ward, M. (2003). A massive x-ray outflow from the quasar PDS 456. Astrophysical Journal Letters, 593(2), L65-L68. https://doi.org/10.1086/378218

We report on XMM-Newton spectroscopic observations of the luminous radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, whi... Read More about A massive x-ray outflow from the quasar PDS 456.

The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1 (2003)
Journal Article
Roberts, T., Goad, M., Ward, M., & Warwick, R. (2003). The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1. Monthly Notices of the Royal Astronomical Society, 342(3), 709-714. https://doi.org/10.1046/j.1365-8711.2003.06593.x

We report the results of an observation of a large-diameter (110 pc) supernova remnant (SNR) found to encircle the position of the ultraluminous X-ray source (ULX) IC 342 X-1. The inferred initial energy input to the SNR is at least 2-3 times greater... Read More about The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1.

A Chandra Survey of Nearby Spiral Galaxies (2002)
Journal Article
Kilgard, R., Krauss, M., Prestwich, A., Kaaret, P., Garcia, M., Zezas, A., …Roberts, T. (2002). A Chandra Survey of Nearby Spiral Galaxies. Bulletin of the American Astronomical Society, 34, 1121-

A Chandra observation of the interacting pair of galaxies NGC 4485/4490 (2002)
Journal Article
Roberts, T., Warwick, R., Ward, M., & Murray, S. (2002). A Chandra observation of the interacting pair of galaxies NGC 4485/4490. Monthly Notices of the Royal Astronomical Society, 337(2), 677-692. https://doi.org/10.1046/j.1365-8711.2002.05950.x

We report the results of a 20-ks Chandra ACIS-S observation of the galaxy pair NGC 4485/4490. This is an interacting system containing a late-type spiral with an enhanced star formation rate (NGC 4490), and an irregular companion that possesses a dis... Read More about A Chandra observation of the interacting pair of galaxies NGC 4485/4490.

Chandra observations of the luminous infrared galaxy NGC 3256 (2002)
Journal Article
Lira, P., Ward, M., Zezas, A., Alonso-Herrero, A., & Ueno, S. (2002). Chandra observations of the luminous infrared galaxy NGC 3256. Monthly Notices of the Royal Astronomical Society, 330(2), 259-278. https://doi.org/10.1046/j.1365-8711.2002.05014.x

We present a detailed analysis of high-resolution Chandra observations of the merger system NGC 3256, the most infrared-luminous galaxy in the nearby universe. The X-ray data show that several discrete sources embedded in complex diffuse emission con... Read More about Chandra observations of the luminous infrared galaxy NGC 3256.

An X-ray/optical study of IXOs (2001)
Journal Article
Roberts, T., Goad, M., Ward, M., Warwick, R., O'Brien, P., Lira, P., & Hands, A. (2001). An X-ray/optical study of IXOs. Bulletin of the American Astronomical Society, 33, 858-

Identifying X-ray Sources in Bulge and Disk Galaxies (2001)
Journal Article
Prestwich, A., Kilgard, R., Krauss, M., Kaaret, P., Zezas, A., McDowell, J., …Trinchieri, G. (2001). Identifying X-ray Sources in Bulge and Disk Galaxies. Bulletin of the American Astronomical Society, 33, 1338-

The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1 (2001)
Journal Article
Roberts, T., Goad, M., Ward, M., Warwick, R., O'Brien, P., Lira, P., & Hands, A. (2001). The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 325(2), L7-L11. https://doi.org/10.1046/j.1365-8711.2001.04659.x

We report the identification of a possible optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. New Chandra data show that the X-ray source is point-like, with a luminosity of 5.2×10^39 erg/s (0.5-8 keV). It displays medium- and long... Read More about The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1.

Ultraluminous x-ray sources in external galaxies (2001)
Journal Article
King, A., Davies, M., Ward, M., Fabbiano, G., & Elvis, M. (2001). Ultraluminous x-ray sources in external galaxies. Astrophysical Journal Letters, 552(2), L109-L112. https://doi.org/10.1086/320343

We investigate models for the class of ultraluminous nonnuclear X-ray sources (i.e., ultraluminous compact X-ray sources [ULXs]) seen in a number of galaxies and probably associated with star-forming regions. Models in which the X-ray emission is ass... Read More about Ultraluminous x-ray sources in external galaxies.

PDS 456: an extreme accretion rate quasar? (2000)
Journal Article
Reeves, J., O'Brien, P., Vaughan, S., Law-Green, D., Ward, M., Simpson, C., …Edelson, R. (2000). PDS 456: an extreme accretion rate quasar?. Monthly Notices of the Royal Astronomical Society, 312, L17-L21

Fabry-Perot imaging of NGC 6090 in H₂ emission (2000)
Journal Article
Sugai, H., Davies, R., Ishii, M., & Ward, M. (2000). Fabry-Perot imaging of NGC 6090 in H₂ emission. Monthly Notices of the Royal Astronomical Society, 317, 447-452

BeppoSAX observations of luminous IRAS galaxies. (2000)
Journal Article
Ueno, S., Ward, M., O'Brien, P., Stirpe, G., & Matt, G. (2000). BeppoSAX observations of luminous IRAS galaxies. Advances in Space Research, 25(3-4), 823-826. https://doi.org/10.1016/s0273-1177%2899%2900848-0

We have obtained hard X-ray spectra of four luminous IRAS galaxies, which were selected on the basis of their optical polarized broad lines. We have found prominent Fe K line emission from IRAS 20210+1121, suggesting that its observed X-ray continuum... Read More about BeppoSAX observations of luminous IRAS galaxies..

Near- and mid-infrared imaging polarimetry of NGC 1068 (1999)
Journal Article
Lumsden, S., Moore, T., Smith, C., Fujiyoshi, T., Bland-Hawthorn, J., & Ward, M. (1999). Near- and mid-infrared imaging polarimetry of NGC 1068. Monthly Notices of the Royal Astronomical Society, 303, 209-220

The BeppoSAX observation of IRAS 20210+1121 (1999)
Journal Article
Ueno, S., Ward, M., O'Brien, P., Stirpe, G., & Matt, G. (1999). The BeppoSAX observation of IRAS 20210+1121. Nuclear Physics B - Proceedings Supplements, 69(1-3), 554-557. https://doi.org/10.1016/s0920-5632%2898%2900287-4

We have obtained a hard X-ray spectrum of the ultraluminous infrared galaxy IRAS 20210+1121 (z = 0.056), whose optical spectrum is that of a Seyfert 2. The most significant feature is a strong Fe K line at 6.7 (6.5–7.0) keV in the rest-frame with equ... Read More about The BeppoSAX observation of IRAS 20210+1121.

The obscured BLR in the radio galaxy 3C 234 (1998)
Journal Article
Young, S., Hough, J., Axon, D., Fabian, A., & Ward, M. (1998). The obscured BLR in the radio galaxy 3C 234. Monthly Notices of the Royal Astronomical Society, 294, 478-

Excitation of the Extended Gas in NGC 1068 (1997)
Journal Article
Nazarova, L., O'Brien, P., Ward, M., & Gondhalekar, P. (1997). Excitation of the Extended Gas in NGC 1068. Astrophysics and Space Science, 248, 121-126

Optical colour maps of Seyfert galaxies (1997)
Journal Article
Kotilainen, J., & Ward, M. (1997). Optical colour maps of Seyfert galaxies. Astronomy and astrophysics. Supplement series, 121, 77-94

Polarimetry and modelling of narrow-line active galaxies (1996)
Journal Article
Young, S., Hough, J., Efstathiou, A., Wills, B., Bailey, J., Ward, M., & Axon, D. (1996). Polarimetry and modelling of narrow-line active galaxies. Monthly Notices of the Royal Astronomical Society, 281, 1206-1242

The Extended Narrow Line Region in Mkn79 (1996)
Journal Article
Nazarova, L., O'Brien, P., & Ward, M. (1996). The Extended Narrow Line Region in Mkn79. Memorie Della Società Astronomica Italiana, 67, 1005-

Near-infrared and millimetre polarimetry of CEN A (1996)
Journal Article
Packham, C., Hough, J., Young, S., Chrysostomou, A., Bailey, J., Axon, D., & Ward, M. (1996). Near-infrared and millimetre polarimetry of CEN A. Monthly Notices of the Royal Astronomical Society, 278, 406-416

Spatially resolved spectropolarimetry of the galaxy NGC 1068 (1995)
Journal Article
Inglis, M., Young, S., Hough, J., Gledhill, T., Axon, D., Bailey, J., & Ward, M. (1995). Spatially resolved spectropolarimetry of the galaxy NGC 1068. Monthly Notices of the Royal Astronomical Society, 275, 398-416

Imaging the Collimating Structures in Seyfert Galaxies (1995)
Journal Article
Simpson, C., Wilson, A., Ward, M., Alonso-Herrero, A., Mulchaey, ,., & S., J. (1995). Imaging the Collimating Structures in Seyfert Galaxies. Bulletin of the American Astronomical Society, 27, 1321-

The Host Galaxies of SEYFERT-1 Nuclei (1994)
Journal Article
Kotilainen, J., & Ward, M. (1994). The Host Galaxies of SEYFERT-1 Nuclei. Monthly Notices of the Royal Astronomical Society, 266, 953-

The extended narrow line region of NGC 4151 (1994)
Journal Article
Robinson, A., Vila-Vilaro, B., Axon, D., Perez, E., Wagner, S., Baum, S., …Ward, M. (1994). The extended narrow line region of NGC 4151. Astronomy and Astrophysics, 291, 351-391

Infrared Spectroscopy of High-Redshift Quasars (1994)
Journal Article
Baker, A., Carswell, R., Bailey, J., Espey, B., Smith, M., & Ward, M. (1994). Infrared Spectroscopy of High-Redshift Quasars. Monthly Notices of the Royal Astronomical Society, 270, 575-

The U.K. Deep and Medium Surveys with ROSAT - N-Log Relation (1994)
Journal Article
Branduardi Raymont, G., Mason, K., Warwick, R., Carrera, F., Graffagnino, V., Mittaz, J., …Rowan-Robinson, M. (1994). The U.K. Deep and Medium Surveys with ROSAT - N-Log Relation. Monthly Notices of the Royal Astronomical Society, 270, 947-

The obscuration to the nucleus of IC 5063. (1994)
Journal Article
Simpson, C., Ward, M., & Kotilainen, J. (1994). The obscuration to the nucleus of IC 5063. Monthly Notices of the Royal Astronomical Society, 271, 250-256

A ROSAT observation of NGC 5548 (1993)
Journal Article
Nandra, K., Fabian, A., George, I., Branduardi-Raymont, G., Lawrence, A., Mason, K., …Warwick, R. (1993). A ROSAT observation of NGC 5548. Monthly Notices of the Royal Astronomical Society, 260, 504-512

Optical spectroscopy of southern radio galaxies (1993)
Journal Article
Simpson, C., Clements, D., Rawlings, S., & Ward, M. (1993). Optical spectroscopy of southern radio galaxies. Monthly Notices of the Royal Astronomical Society, 262, 889-892

FAST on the WHT. (1991)
Journal Article
Clegg, R., Ward, M., Blietz, M., Cameron, M., Drapatz, S., Genzel, R., …van der Werf, P. (1991). FAST on the WHT

The Buried Quasar in Cygnus A (1991)
Journal Article
Wilson, A., Ward, M., Blanco, P., & Nishida, M. (1991). The Buried Quasar in Cygnus A. Bulletin of the American Astronomical Society, 23, 928-

Infrared Variability of Active Nuclei (1991)
Book Chapter
Ward, M. (1991). Infrared Variability of Active Nuclei. In W. J. Duschl, S. J. Wagner, & M. Camenzind (Eds.), Variability of Active Galaxies: Proceedings of a Workshop of the Sonderforschungsbereich 328 Held at Heidelberg, Germany 3–5 September 1990 (235-). Springer Verlag. https://doi.org/10.1007/bfb0030065

An optical and near-infrared polarization survey of Seyfert and broad-line radio galaxies. I - Statistical properties. II - The wavelength dependence of polarization (1990)
Journal Article
Brindle, C., Hough, J., Bailey, J., Axon, D., Ward, M., Sparks, W., & McLean, I. (1990). An optical and near-infrared polarization survey of Seyfert and broad-line radio galaxies. I - Statistical properties. II - The wavelength dependence of polarization. Monthly Notices of the Royal Astronomical Society, 244, 577-618

Simultaneous multifrequency observations of the Seyfert 1 galaxy NGC 4051 - Constant optical-infrared emission observed during large-amplitude X-ray variability (1990)
Journal Article
Done, C., Ward, M., Fabian, A., Kunieda, H., Tsuruta, S., Lawrence, A., …Wamsteker, W. (1990). Simultaneous multifrequency observations of the Seyfert 1 galaxy NGC 4051 - Constant optical-infrared emission observed during large-amplitude X-ray variability. Monthly Notices of the Royal Astronomical Society, 243, 713-720

The jets of 3C120 (1989)
Journal Article
Axon, D. J., Pedlar, A., Unger, S., Meurs, E., Whittle, ,., & M., D. (1989). The jets of 3C120. Nature, 341, 631-633

Anisotropic Ionising Continuum Emission in AGN / Active Galactic Nuclei (1989)
Book Chapter
Meurs, E., Unger, S., Pedlar, A., Axon, D., Whittle, M., & Ward, M. (1989). Anisotropic Ionising Continuum Emission in AGN / Active Galactic Nuclei. In L. Maraschi, T. Maccacaro, & M. Ulrich (Eds.), BL Lac Objects: Proceedings of a Workshop Held in Como, Italy, September 20–23, 1988 (193-). Springer Verlag

The polarization of NGC 1068 (1988)
Journal Article
Bailey, J., Axon, D., Hough, J., Ward, M., McLean, I., & Heathcote, S. (1988). The polarization of NGC 1068. Monthly Notices of the Royal Astronomical Society, 234, 899-917

A tale of two Seyferts (1987)
Journal Article
Ward, M. (1987). A tale of two Seyferts. Observatory, 107, 268-269

The Deep X-ray Survey in Pavo: Optical Identifications (1986)
Journal Article
Griffiths, R., Brissenden, R., Hewitt, P., Murray, S., Tuohy, I., & Ward, M. (1986). The Deep X-ray Survey in Pavo: Optical Identifications. Bulletin of the American Astronomical Society, 18, 1046-

The 0.3 to 100 Micron Continua of Type 1 Seyferts (1985)
Journal Article
Ward, M., Elvis, M., Fabbiano, G., Carleton, N., Willner, S., & Lawrence, A. (1985). The 0.3 to 100 Micron Continua of Type 1 Seyferts. Bulletin of the American Astronomical Society, 17, 869-

EXOSAT observations of a strong soft X-ray excess in MKN 841 (1985)
Journal Article
Arnaud, K., Branduardi-Raymont, G., Culhane, J., Fabian, A., Hazard, C., McGlynn, T., …J., M. (1985). EXOSAT observations of a strong soft X-ray excess in MKN 841. Monthly Notices of the Royal Astronomical Society, 217, 105-113

JHKL photometry of the nuclei of normal spiral galaxies (1984)
Journal Article
Willner, S., Fabbiano, G., Elvis, M., Ward, M., Longmore, A., & Lawrence, A. (1984). JHKL photometry of the nuclei of normal spiral galaxies. Publications of the Astronomical Society of the Pacific, 96, 143-147

The Velocity Field in the Active Galaxy NGC 7582 (1984)
Journal Article
Morris, S., Ward, M., Whittle, M., Wilson, A., & Taylor, K. (1984). The Velocity Field in the Active Galaxy NGC 7582. Bulletin of the American Astronomical Society, 16, 916-

The Fe(9+) region in active galactic nuclei (1984)
Journal Article
Penston, M., Fosbury, R., Boksenberg, A., Ward, M., & Wilson, A. (1984). The Fe(9+) region in active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 208, 347-364

a 0729+103 (1982)
Journal Article
McHardy, I., Pye, J., Fairall, A., Warner, B., Allen, S., Cropper, M., & Ward, M. (1982). a 0729+103

The variable infrared source near HH100 (1982)
Journal Article
Axon, D., Allen, D., Bailey, J., Hough, J., Ward, M., & Jameson, R. (1982). The variable infrared source near HH100. Monthly Notices of the Royal Astronomical Society, 200, 239-245

The 1979 outburst of U Scorpii (1981)
Journal Article
Barlow, M., Brodie, J., Brunt, C., Hanes, D., Hill, P., Mayo, S., …Willis, A. (1981). The 1979 outburst of U Scorpii. Monthly Notices of the Royal Astronomical Society, 195, 61-78

X-ray emission from active galaxies (1981)
Journal Article
Hayes, M., Bell Burnell, S., Culhane, J., Barr, P., Sanford, P., Ward, M., & Ives, J. (1981). X-ray emission from active galaxies. Space Science Reviews, 30, 39-45

The eclipsing AM Herculis star 2A 0311-227 (1981)
Journal Article
Allen, D., Wright, A., & Ward, M. (1981). The eclipsing AM Herculis star 2A 0311-227. Monthly Notices of the Royal Astronomical Society, 195, 155-164

Observations and models of H2242-035 (1981)
Journal Article
Hassall, B., Pringle, J., Ward, M., Whelan, J., Mayo, S., Echevarria, J., …Hyland, A. (1981). Observations and models of H2242-035. Monthly Notices of the Royal Astronomical Society, 197, 275-286

The variability of 3C 390.3 (1980)
Journal Article
Barr, P., Pollard, G., Sanford, P., Ives, J., Ward, M., Hine, R., …Lloyd, C. (1980). The variability of 3C 390.3. Monthly Notices of the Royal Astronomical Society, 193, 549-562

2A 0311-227 (1979)
Journal Article
Ward, M., Allen, D., Smith, M., & Wright, A. (1979). 2A 0311-227

Infrared observations of this x-ray emitting, AM Her-like star (IAUC 3326) were made with the Anglo-Australian Telescope by M. J. Ward, Institute of Astronomy, Cambridge; and D. A. Allen, M. G. Smith and A. E. Wright, Anglo-Australian Observatory. Fl... Read More about 2A 0311-227.

Identification of Sources in the 3A Catalogue. (1978)
Journal Article
Lawrence, A., McHardy, I., Elvis, M., Ricketts, M., & Ward, M. (1978). Identification of Sources in the 3A Catalogue. Bulletin of the American Astronomical Society, 10, 500-

Supernova in IC 5201 (1978)
Journal Article
Ward, M., Blades, J., & Griffiths, R. (1978). Supernova in IC 5201

Seyfert galaxies as X-ray sources (1978)
Journal Article
Elvis, M., Maccacaro, T., Wilson, A., Ward, M., Penston, M., Fosbury, R., & Perola, G. (1978). Seyfert galaxies as X-ray sources. Monthly Notices of the Royal Astronomical Society, 183, 129-157

NGC 7213 (1978)
Journal Article
Allen, D., Smith, M., Wright, A., Ward, M., & Wilson, A. (1978). NGC 7213

Spectroscopic observations of the X-ray nova A0620-00 (1977)
Journal Article
Whelan, J., Allen, D., Danziger, I., Fosbury, R., Murdin, P., Penston, M., …Ward, M. (1977). Spectroscopic observations of the X-ray nova A0620-00. Monthly Notices of the Royal Astronomical Society, 180, 657-673

New Active Galaxy Identifications of 2A X-ray Sources. (1977)
Journal Article
Ward, M., Wilson, A., Penston, M., Tritton, K., Elvis, M., & Maccacaro, T. (1977). New Active Galaxy Identifications of 2A X-ray Sources. Bulletin of the American Astronomical Society, 9, 558-

NGC 3783 - A possible X-ray emitting Seyfert galaxy (1976)
Journal Article
Cooke, B., Elvis, M., Ward, M., Fosbury, R., Penston, M., & Maccacaro, T. (1976). NGC 3783 - A possible X-ray emitting Seyfert galaxy. Monthly Notices of the Royal Astronomical Society, 177, 121P-125P