Nature of Compton-thick Active Galactic Nuclei in "Non-merging'' Luminous Infrared Galaxies UGC 2608 and NGC 5135 Revealed with Broadband X-ray Spectroscopy

Abstract

We have analyzed the broadband X-ray spectra of active galactic nuclei (AGNs) in two "non-merging" luminous infrared galaxies (LIRGs) UGC 2608 and NGC 5135, utilizing the data of NuSTAR, Suzaku, XMM-Newton, and Chandra. Applying the X-ray clumpy-torus model (XCLUMPY: Tanimoto et al. 2019), we find that both sources have similar spectra characterized by Compton-thick (CT) absorption ($N_{\mathrm{H}}\sim$ 5-7 $\times$ $10^{24}$ cm${}^{-2}$) and small torus angular width ($\sigma$ $<$ 20${}^{\circ }$). The intrinsic 2-10 keV luminosities are $3.9_{-1.7}^{+2.2}$ $\times$ $10^{43}$ erg s${}^{-1}$ (UGC 2608) and $2.0_{-1.0}^{+3.3}$ $\times$ $10^{43}$ erg s${}^{-1}$ (NGC 5135). The [O IV]-to-nuclear-12 $\mu$m luminosity ratios are larger than those of typical Seyferts, which are consistent with the torus covering factors ($C_{\mathrm{T}}\lesssim$ 0.7) estimated from the torus angular widths and column densities by X-ray spectroscopy. The torus covering factors and Eddington ratios (${\lambda }_{\mathrm{Edd}}\sim$ 0.1) follow the relation found by Ricci et al. (2017c) for local AGNs, implying that their tori become geometrically thin due to significant radiation pressure of the AGN that blows out some part of the tori. These results indicate that the CT AGNs in these "non-merger" LIRGs are just a normal AGN population seen edge-on through a large line-of-sight column density. They are in contrast to the buried CT AGNs in late-stage mergers that have large torus covering factors even at large Eddington ratios.

15 pages, 12 figures, and 3 tables, accepted for publication in ApJ

References in corpus (25)

• Cosmic Star Formation History
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• AGN Dusty Tori: I. Handling of Clumpy Media
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• Piecing Together the X-ray Background: Bolometric Corrections for Active Galactic Nuclei
• The close environments of accreting massive black holes are shaped by radiative feedback
• Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured
• Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
• A Spitzer IRS Low-Resolution Spectroscopic Search for Buried AGNs in Nearby Ultraluminous Infrared Galaxies - A Constraint on Geometry between Energy Sources and Dust -
• Seyfert galaxies in the local Universe (z$\le$ 0.1): the average X-ray spectrum as seen by $BeppoSAX$
• AGN dust tori at low and high luminosities
• IACHEC Cross-Calibration of Chandra, NuSTAR, Swift, Suzaku, and XMM-Newton with 3C 273 and PKS 2155-304
• On the difference of torus geometry between hidden and non-hidden broad line active galactic nuclei
• An X-ray spectral model for clumpy tori in active galactic nuclei
• Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies
• The Multi-Layer Variable Absorbers in NGC 1365 Revealed by XMM-Newton and NuSTAR
• The narrow Fe K$\alpha$ line and the molecular torus in active galactic nuclei - an IR/X-ray view
• Does the mid-infrared-hard X-ray luminosity relation for active galactic nuclei depend on Eddington ratio?
• Shedding Light on the Compton-thick Active Galactic Nucleus in the Ultra-luminous Infrared Galaxy UGC 5101 with Broadband X-ray Spectroscopy
• Application of Clumpy Torus Model to Broadband X-ray Spectra of Two Seyfert 1 Galaxies: IC 4329A and NGC 7469
• Luminosity Ratio between [O IV] 25.89 um Line and Nuclear Continuum 12 um as Diagnostic for "Buried" AGN
• Morphological evidence for a past minor merger in the Seyfert galaxy NGC 1068
• On the Anisotropy of Nuclei Mid-Infrared Radiation in Nearby Active Galactic Nuclei
• Unveiling the AGN in IC 883: discovery of a parsec-scale radio jet

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