Professor Paula Chadwick's Outputs (216)

Characterisation and testing of CHEC-M—A camera prototype for the small-sized telescopes of the Cherenkov telescope array (2018)
Journal Article
Zorn, J., White, R., Watson, J., Armstrong, T., Balzer, A., Barcelo, M., …Zink, A. (2018). Characterisation and testing of CHEC-M—A camera prototype for the small-sized telescopes of the Cherenkov telescope array. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 904, 44-63. https://doi.org/10.1016/j.nima.2018.06.078

The Compact High Energy Camera (CHEC) is a camera design for the Small-Sized Telescopes (SSTs; 4 m diameter mirror) of the Cherenkov Telescope Array (CTA). The SSTs are focused on very-high-energy -ray detection via atmospheric Cherenkov light detect... Read More about Characterisation and testing of CHEC-M—A camera prototype for the small-sized telescopes of the Cherenkov telescope array.

Artificial guide stars for adaptive optics using unmanned aerial vehicles (2018)
Journal Article
Basden, A., Brown, A. M., Chadwick, P., Clark, P., & Massey, R. (2018). Artificial guide stars for adaptive optics using unmanned aerial vehicles. Monthly Notices of the Royal Astronomical Society, 477(2), 2209-2219. https://doi.org/10.1093/mnras/sty790

Astronomical adaptive optics systems are used to increase effective telescope resolution. However, they cannot be used to observe the whole sky since one or more natural guide stars of sufficient brightness must be found within the telescope field of... Read More about Artificial guide stars for adaptive optics using unmanned aerial vehicles.

Fermi-LAT high-z active galactic nuclei and the extragalactic background light (2017)
Journal Article
Armstrong, T., Brown, A. M., & Chadwick, P. M. (2017). Fermi-LAT high-z active galactic nuclei and the extragalactic background light. Monthly Notices of the Royal Astronomical Society, 470(4), 4089-4098. https://doi.org/10.1093/mnras/stx1309

Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good understand... Read More about Fermi-LAT high-z active galactic nuclei and the extragalactic background light.

A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations (2017)
Journal Article
Abdalla, H., Abramowski, A., Aharonian, F., Benkhali, F. A., Akhperjanian, A., Angüner, E., …Żywucka, N. (2017). A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations. Astronomy & Astrophysics, 612, Article A10. https://doi.org/10.1051/0004-6361/201527773

Context. Microquasars are potential γ-ray emitters. Indications of transient episodes of γ-ray emission were recently reported in at least two systems: Cyg X-1 and Cyg X-3. The identification of additional γ-ray-emitting microquasars is required to b... Read More about A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations.

Discovery of a new extragalactic population of energetic particles (2017)
Journal Article
Brown, A. M., Bœhm, C., Graham, J., Lacroix, T., Chadwick, P., & Silk, J. (2017). Discovery of a new extragalactic population of energetic particles. Physical Review D, 95(6), Article 063018. https://doi.org/10.1103/physrevd.95.063018

The GCT camera for the Cherenkov Telescope Array (2016)
Journal Article
Lapington, J., Abchiche, A., Allan, D., Amans, J., Armstrong, T., Balzer, A., …Zorn, J. (2017). The GCT camera for the Cherenkov Telescope Array. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 876, 1-4. https://doi.org/10.1016/j.nima.2016.12.010

The Gamma Cherenkov Telescope (GCT) is one of the designs proposed for the Small Sized Telescope (SST) section of the Cherenkov Telescope Array (CTA). The GCT uses dual-mirror optics, resulting in a compact telescope with good image quality and a lar... Read More about The GCT camera for the Cherenkov Telescope Array.

Gamma-ray Novae: Rare or Nearby? (2016)
Journal Article
Morris, P., Cotter, G., Brown, A., & Chadwick, P. (2017). Gamma-ray Novae: Rare or Nearby?. Monthly Notices of the Royal Astronomical Society, 465(1), 1218-1226. https://doi.org/10.1093/mnras/stw2776

Classical novae were revealed as a surprise source of γ-rays in Fermi Large Area Telescope (LAT) observations. During the first 8 yr since the LAT was launched, 6 novae in total have been detected to >5σ in γ-rays, in contrast to the 69 discovered op... Read More about Gamma-ray Novae: Rare or Nearby?.

Feasibility study of airborne calibration of the Cherenkov Telescope Array (2016)
Presentation / Conference Contribution
Brown, A., Chadwick, P., Frizzelle, M., Gaug, M., Clark, P., Graham, J., & Armstrong, T. (2016, July). Feasibility study of airborne calibration of the Cherenkov Telescope Array. Presented at Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series

The GCT camera for the Cherenkov Telescope Array (2016)
Presentation / Conference Contribution
Brown, A., Abchiche, A., Allan, D., Amans, J.-P., Armstrong, T., Balzer, A., Berge, D., Boisson, C., Bousquet, J.-J., Bryan, M., Buchholtz, G., Chadwick, P., Costantini, H., Cotter, G., Daniel, M., De Franco, A., de Frondat, F., Dournaux, J.-L., Dumas, D., Fasola, G., …Zorn, J. (2023, June). The GCT camera for the Cherenkov Telescope Array. Presented at SPIE Astronomical Telescopes + Instrumentation, Edinburgh, United Kingdom

The Gamma-ray Cherenkov Telescope (GCT) is proposed for the Small-Sized Telescope component of the Cherenkov Telescope Array (CTA). GCT's dual-mirror Schwarzschild-Couder (SC) optical system allows the use of a compact camera with small form-factor p... Read More about The GCT camera for the Cherenkov Telescope Array.

Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild–Couder telescope prototype for the Cherenkov Telescope Array (2016)
Journal Article
Dournaux, J., De Franco, A., Laporte, P., White, R., Greenshaw, T., Sol, H., …Zink, A. (2017). Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild–Couder telescope prototype for the Cherenkov Telescope Array. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 845, 355-358. https://doi.org/10.1016/j.nima.2016.05.059

The Cherenkov Telescope Array (CTA) consortium aims to build the next-generation ground-based very-high-energy gamma-ray observatory. The array will feature different sizes of telescopes allowing it to cover a wide gamma-ray energy band from about 20... Read More about Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild–Couder telescope prototype for the Cherenkov Telescope Array.

Localizing the γ-ray emission region during the 2014 June outburst of 3C 454.3 (2016)
Journal Article
Coogan, R. T., Brown, A. M., & Chadwick, P. M. (2016). Localizing the γ-ray emission region during the 2014 June outburst of 3C 454.3. Monthly Notices of the Royal Astronomical Society, 458(1), 354-365. https://doi.org/10.1093/mnras/stw199

In 2014 May–July, the flat spectrum radio quasar 3C 454.3 exhibited strong flaring behaviour. Observations with the Large Area Telescope detector on-board the Fermi Gamma-ray Space Telescope captured the γ-ray flux at energies 0.1 ≤ Eγ ≤ 300 GeV incr... Read More about Localizing the γ-ray emission region during the 2014 June outburst of 3C 454.3.

The detection of Fermi AGN above 100 GeV using clustering analysis (2015)
Journal Article
Armstrong, T., Brown, A. M., Chadwick, P., & Nolan, S. (2015). The detection of Fermi AGN above 100 GeV using clustering analysis. Monthly Notices of the Royal Astronomical Society, 452(3), 3159-3166. https://doi.org/10.1093/mnras/stv1398

The density-based clustering algorithm DBSCAN has been applied to the Fermi Large Area Telescope (LAT) data set of Eγ ≥ 100 GeV events with |b| > 10°, in order to search for new very high energy (VHE) γ-ray sources. The clustering analysis returned 4... Read More about The detection of Fermi AGN above 100 GeV using clustering analysis.

γ-ray observations of extraterrestrial neutrino track events (2015)
Journal Article
Brown, A. M., Adams, J., & Chadwick, P. M. (2015). γ-ray observations of extraterrestrial neutrino track events. Monthly Notices of the Royal Astronomical Society, 451(1), 323-331. https://doi.org/10.1093/mnras/stv899

In this paper we report the results of a γ-ray study of IceCube's extraterrestrial neutrino candidates detected as track-like events. Using 70 months of Fermi-Large Area Telescope (LAT) observations, a likelihood analysis of all 1–300 GeV photons wit... Read More about γ-ray observations of extraterrestrial neutrino track events.

H.E.S.S. reveals a lack of TeV emission from the supernova remnant Puppis A (2015)
Journal Article
Collaboration, H., Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Zechlin, H. (2015). H.E.S.S. reveals a lack of TeV emission from the supernova remnant Puppis A. Astronomy & Astrophysics, 575, https://doi.org/10.1051/0004-6361/201424805

Context. Puppis A is an interesting ~4 kyr-old supernova remnant (SNR) that shows strong evidence of interaction between the forward shock and a molecular cloud. It has been studied in detail from radio frequencies to high-energy (HE, 0.1−100 GeV) γ-... Read More about H.E.S.S. reveals a lack of TeV emission from the supernova remnant Puppis A.

The 2012 Flare of PG 1553+113 Seen with H.E.S.S. and Fermi-LAT (2015)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Backes, M., …Zechlin, H. (2015). The 2012 Flare of PG 1553+113 Seen with H.E.S.S. and Fermi-LAT. Astrophysical Journal, 802(1), https://doi.org/10.1088/0004-637x/802/1/65

Very high energy (VHE, E > 100 GeV) γ-ray flaring activity of the high-frequency peaked BL Lac object PG 1553+113 has been detected by the H.E.S.S. telescopes. The flux of the source increased by a factor of 3 during the nights of 2012 April 26 and 2... Read More about The 2012 Flare of PG 1553+113 Seen with H.E.S.S. and Fermi-LAT.

Constraints on an Annihilation Signal from a Core of Constant Dark Matter Density around the Milky Way Center with H.E.S.S (2015)
Journal Article
Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., Backes, M., …Zechlin, H. (2015). Constraints on an Annihilation Signal from a Core of Constant Dark Matter Density around the Milky Way Center with H.E.S.S. Physical Review Letters, 114(8), https://doi.org/10.1103/physrevlett.114.081301

An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated on-off observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No significant signal is found i... Read More about Constraints on an Annihilation Signal from a Core of Constant Dark Matter Density around the Milky Way Center with H.E.S.S.

Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations (2015)
Journal Article
Collaboration, H., Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Uchiyama, Y. (2015). Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations. Astronomy & Astrophysics, 574, Article A27. https://doi.org/10.1051/0004-6361/201322694

Aims. Previous observations with the High Energy Stereoscopic System (H.E.S.S.) have revealed an extended very-high-energy (VHE; E> 100 GeV) γ-ray source, HESS J1834−087, coincident with the supernova remnant (SNR) W41. The origin of the γ-ray emissi... Read More about Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations.

H.E.S.S. detection of TeV emission from the interaction region between the supernova remnant G349.7+0.2 and a molecular cloud (2015)
Journal Article
Collaboration, H., Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Zechlin, H. (2015). H.E.S.S. detection of TeV emission from the interaction region between the supernova remnant G349.7+0.2 and a molecular cloud. Astronomy & Astrophysics, 574, Article A100. https://doi.org/10.1051/0004-6361/201425070

G349.7+0.2 is a young Galactic supernova remnant (SNR) located at the distance of 11.5 kpc and observed across the entire electromagnetic spectrum from radio to high energy (HE; 0.1 GeV <E< 100 GeV) γ-rays. Radio and infrared observations indicate th... Read More about H.E.S.S. detection of TeV emission from the interaction region between the supernova remnant G349.7+0.2 and a molecular cloud.

The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud (2015)
Journal Article
Collaboration, H., Abramowski, A., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., Angüner, E., …Zechlin, H. (2015). The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud. Science, 347(6220), 406-412. https://doi.org/10.1126/science.1261313

The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. Three sources of different types we... Read More about The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud.

Discovery of the VHE gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2 (2015)
Journal Article
Collaboration, H., Abramowski, A., Acero, F., Aharonian, F., Ait Benkhali, F., Akhperjanian, A., …Zechlin, H. (2015). Discovery of the VHE gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2. Monthly Notices of the Royal Astronomical Society, 446(2), 1163-1169. https://doi.org/10.1093/mnras/stu2148

The region around the supernova remnant (SNR) W41 contains several TeV sources and has prompted the HESS Collaboration to perform deep observations of this field of view. This resulted in the discovery of the new very high energy (VHE) source HESS J1... Read More about Discovery of the VHE gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2.