NuSTAR Observations of a Heavily X-Ray-obscured AGN in the Dwarf Galaxy J144013+024744

Journal
Date Issued
2023
Author(s)
Ansh, Shrey
•
Chen, Chien-Ting J.
•
Brandt, W. N.
•
Hood, Carol E.
•
Kammoun, E. S.
•
Lansbury, G.
•
Paltani, Stéphane
•
Reines, Amy E.
•
Ricci, C.
•
Swartz, Douglas A.
•
Trump, Jonathan R.
•
•
Hickox, Ryan C.
DOI
Abstract
We present a multiwavelength analysis of the dwarf Seyfert 2 galaxy J144013+024744, a candidate obscured active galactic nucleus (AGN) thought to be powered by an intermediate-mass black hole (IMBH, M • ≈ 104-106 M ⊙) of mass M • ~ 105.2 M ⊙. To study its X-ray properties, we targeted J144013+024744 with NuSTAR for ≈100 ks. The X-ray spectrum was fitted with an absorbed power law, Pexmon, and a physical model (RXTorus). A Bayesian X-ray analysis was performed to estimate the posteriors. The phenomenological and the physical models suggest the AGN to be heavily obscured by a column density of N H = (3.4-7.0) × 1023 cm-2. In particular, the RXTorus model with a subsolar metallicity suggests the obscuring column to be almost Compton-thick. We compared the 2-10 keV intrinsic X-ray luminosity with the inferred X-ray luminosities based on empirical scaling relations for unobscured AGNs using L [OIV] 25.89 μm, L [OIII] λ5007, and L 6μm and found that the high-excitation [OIV] line provides a better estimate of the intrinsic 2-10 keV X-ray luminosity ( ${L}_{2\mbox{--}10}^{\mathrm{int}}\sim {10}^{41.41}$ erg s-1). Our results suggest that J144013+024744 is the first type 2 dwarf galaxy that shows X-ray spectroscopic evidence for obscuration. The column density that we estimated is among the highest measured to date for IMBH-powered AGNs, implying that a typical AGN torus geometry might extend to the low-mass end. This work has implications for constraining the BH occupation fraction in dwarf galaxies using X-ray observations.
Volume
942
Issue
2
Start page
82
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2023ApJ...942...82A
Rights
open.access
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