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arXiv · 1708.06762

NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543

Michael J. Koss·Ana Glidden·Mislav Balokovic·Daniel Stern·Isabella Lamperti·Roberto Assef·Franz Bauer·David Ballantyne·Steven E. Boggs·William W. Craig·Dancan Farrah·Felix Furst·Poshak Gandhi·Neil Gehrels·Charles J. Hailey·Fiona A. Harrison·Craig Markwardt·Alberto Masini·Claudio Ricci·Ezequiel Treister·Dominic J. Walton·William W. Zhang
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Abstract

We have discovered heavy obscuration in the dual active galactic nucleus (AGN) in the Swift/Burst Alert Telescope (BAT) source SWIFT J2028.5+2543 using Nuclear Spectroscopic Telescope Array (NuSTAR). While an early XMM-Newton study suggested the emission was mainly from NGC 6921, the superior spatial resolution of NuSTAR above 10 keV resolves the Swift/BAT emission into two sources associated with the nearby galaxies MCG +04-48-002 and NGC 6921 (z = 0.014) with a projected separation of 25.3 kpc (91"). NuSTAR's sensitivity above 10 keV finds both are heavily obscured to Compton-thick levels (N H=(1-2)x10^24 cm-2) and contribute equally to the BAT detection ({L}10-50 {keV}{{int}}= 6x10^42 erg s-1). The observed luminosity of both sources is severely diminished in the 2-10 keV band, illustrating the importance of >10 keV surveys like those with NuSTAR and Swift/BAT. Compared to archival X-ray data, MCG +04-48-002 shows significant variability (>3) between observations. Despite being bright X-ray AGNs, they are difficult to detect using optical emission-line diagnostics because MCG +04-48-002 is identified as a starburst/composite because of the high rates of star formation from a luminous infrared galaxy while NGC 6921 is only classified as a LINER using line detection limits. SWIFT J2028.5+2543 is the first dual AGN resolved above 10 keV and is the second most heavily obscured dual AGN discovered to date in the X-rays other than NGC 6240.

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Michael J. Koss, Ana Glidden, Mislav Balokovic, Daniel Stern, Isabella Lamperti, Roberto Assef, Franz Bauer, David Ballantyne, Steven E. Boggs, William W. Craig, Dancan Farrah, Felix Furst, Poshak Gandhi, Neil Gehrels, Charles J. Hailey, Fiona A. Harrison, Craig Markwardt, Alberto Masini, Claudio Ricci, Ezequiel Treister, Dominic J. Walton, William W. Zhang. 2017-08-22. NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543. https://doi.org/10.3847/2041-8205%2F824%2F1%2Fl4

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