Shedding Light on the Compton-thick Active Galactic Nucleus in the Ultraluminous Infrared Galaxy UGC 5101 with Broadband X-Ray Spectroscopy

We report the broadband X-ray spectra of the ultraluminous infrared galaxy (ULIRG) UGC 5101 in the 0.25-100 keV band observed with the Swift/Burst Alert Telescope (BAT), Nuclear Spectroscopic Telescope Array (NuSTAR), Suzaku, XMM-Newton, and Chandra. A Compton-thick active galactic nucleus (AGN) obs...

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Bibliographic Details
Published in:The Astrophysical journal 2017-02, Vol.835 (2), p.179
Main Authors: Oda, Saeko, Tanimoto, Atsushi, Ueda, Yoshihiro, Imanishi, Masatoshi, Terashima, Yuichi, Ricci, Claudio
Format: Article
Language:English
Subjects:
Active galactic nuclei
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Broadband
COMPARATIVE EVALUATIONS
DENSITY
Deposition
ENERGY SPECTRA
Galaxies
galaxies: active
galaxies: individual (UGC 5101)
GALAXY NUCLEI
HYDROGEN
Infrared astronomy
Infrared spectra
KEV RANGE
LUMINOSITY
OPENINGS
SEYFERT GALAXIES
Spectral energy distribution
Spectroscopic telescopes
Spectroscopy
Spectrum analysis
Stars & galaxies
TELESCOPES
Toruses
X RADIATION
X ray sources
X ray spectra
X-RAY GALAXIES
X-ray spectroscopy
X-rays: galaxies
XMM (spacecraft)
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Description
Summary:We report the broadband X-ray spectra of the ultraluminous infrared galaxy (ULIRG) UGC 5101 in the 0.25-100 keV band observed with the Swift/Burst Alert Telescope (BAT), Nuclear Spectroscopic Telescope Array (NuSTAR), Suzaku, XMM-Newton, and Chandra. A Compton-thick active galactic nucleus (AGN) obscured with a hydrogen column density of cm−2 is detected above 10 keV. A spectral fit with a numerical torus model favors a large half-opening angle of the torus, °, suggesting that the covering fraction of material heavily obscuring the X-ray source is moderate. The intrinsic 2-10 keV luminosity is determined to be erg s−1, which is times larger than the previous estimate using only data below 10 keV with a simple spectral model. We find that UGC 5101 shows the ratio between the [O iv] 26 m line and 2-10 keV luminosities similar to those of normal Seyfert galaxies, along with other ULIRGs observed with NuSTAR, indicating that a significant portion of local ULIRGs are not really "X-ray faint" with respect to the flux of forbidden lines originating from the narrow-line region. We propose a possible scenario that (1) the AGN in UGC 5101 is surrounded not only by Compton-thick matter located close to the equatorial plane but also by Compton-thin ( cm−2) matter in the torus-hole region and (2) it is accreting at a high Eddington rate with a steep UV to X-ray spectral energy distribution. Nevertheless, we argue that AGNs in many ULIRGs do not look extraordinary (i.e., extremely X-ray faint), as suggested by recent works, compared with normal Seyferts.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/835/2/179