Broadband X-Ray Spectral Analysis of the Dual AGN System Mrk 739

Abstract

We present the result of a broadband (0.5–70 keV) X-ray spectral analysis of the late-merger galaxy Mrk 739, which contains a dual active galactic nucleus (AGN), Mrk 739E and Mrk 739W, with a separation of ≈3.4 kpc. The spectra obtained with NuSTAR, Chandra, XMM-Newton, and Swift/BAT are simultaneously analyzed by separating the contributions from the two AGNs and extended emission with the Chandra data. To evaluate the reflection components from the AGN tori, we consider two models, a phenomenological one (redpexrav and zgauss) and a more physically motivated one (XCLUMPY). On the basis of the results with XCLUMPY, we find that the AGNs in Mrk 739E and Mrk 739W have intrinsic 2–10 keV luminosities of 1.0 × 1043 and 7.5 × 1041 erg s−1 absorbed by hydrogen column densities of N H < 6.5 × 1019 cm−2 and N H = 6.9 − 1.7 + 3.2 × 10 21 cm − 2 , respectively. The torus-covering fraction of the material with N H > 1022cm−2 in Mrk 739E, C T ( 22 ) < 0.50 at a 90% confidence limit, is found to be smaller than those found for late-merger ultra/luminous infrared galaxies, C T ( 22 ) = 0.71 ± 0.16 (mean and standard deviation). Considering the small star formation rate of Mrk 739E, we suggest that the gas-to-mass ratio of the host galaxy is an important parameter to determine the circumnuclear environment of an AGN in a late merger.

NuSTAR Observations of Four Mid-IR–Selected Dual AGN Candidates in Galaxy Mergers

“…While obscuration is now a commonly discussed characteristic of dual AGNs and candidates, a seemingly large fraction of these systems with sufficient counts for spectral analysis also show strong soft X-ray emission that is often well fit via soft X-ray thermal components, as we have found in this work for J0841+0101 and in previous dual AGN candidates (J0122 +0100 and J1221+1137; Pfeifle et al 2019b). A (nonexhaustive) list of examples from the literature includes NGC 6240 (Komossa et al 2003), IRAS 20210+1121 (Piconcelli et al 2010), Mrk 463 (though in this case, the soft X-ray emission was modeled using a series of soft X-ray emission lines; Bianchi et al 2008), Arp 299 (Ballo et al 2004), Mrk 266 (Mazzarella et al 2012), Mrk 739 (Inaba et al 2022), and SDSS J0945+4238 and SDSS J1038+3921 (De Rosa et al 2018. Even in cases where soft thermal components are not seen in the X-rays, there is other multiwavelength evidence for starburst activity (like in Mrk 273; Iwasawa et al 2018) and generally elevated star formation rates.…”

Hard X-Ray to Radio Multiwavelength SED Analysis of Local U/LIRGs in the GOALS Sample with a Self-consistent AGN Model including a Polar-dust Component

“…They also performed an analysis of Swift/X-Ray Telescope (XRT; Burrows et al 2005) data when no other soft X-ray data were obtained, and utilized the Swift/BAT spectra in the 105 month catalog (Oh et al 2018) if detected. Considering that X-ray spectral works support the clumpy nature of AGN tori (see, e.g., Liu & Li 2014;Furui et al 2016;Tanimoto et al 2018Tanimoto et al , 2019Buchner et al 2019), these best-fitting models were provided with a Monte Carlo-based model from a clumpy torus (XCLUMPY; Tanimoto et al 2019), which enables us to constrain the torus covering fractions for individual AGNs (e.g., Ogawa et al 2019Ogawa et al , 2021Tanimoto et al 2020Tanimoto et al , 2022Yamada et al 2020Yamada et al , 2021Uematsu et al 2021;Inaba et al 2022). Broadband X-ray spectral analyses for three other sources, UGC 2608, NGC 5135, and NGC 7469, were also conducted with XCLUMPY (Yamada et al 2020;Ogawa et al 2021).…”

[O iv]- and [Ne v]-weak Active Galactic Nuclei Hidden by Compton-thick Material in Late Mergers

“…), where σ X is the torus angular width and N H Equ is the equatorial hydrogen column density (see Figure 1 in Tanimoto et al 2019; see also, e.g., Uematsu et al 2021;Inaba et al 2022;Nakatani et al 2023). Tanimoto et al (2018Tanimoto et al ( , 2020Tanimoto et al ( , 2022 and Buchner et al (2019) report the difference in the X-ray spectral shape between the clumpy and smooth distribution of the obscurers.…”