Outputs (331)

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.

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.

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.

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.

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.