A Compton-thick nucleus in the dual active galactic nuclei of Mrk 266

¹ Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Martí i Franquès, 1, 08028 Barcelona, Spain
e-mail: kazushi.iwasawa@icc.ub.edu
² ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
³ Núcleo de Astronomía de la Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
⁴ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁵ Department of Physics and Astronomy, George Mason University, MS 3F3, 4400 University Drive, Fairfax, VA 22030, USA
⁶ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
⁷ Department of Astronomy, University of Florida, PO Box 112055 Gainesville, FL 32611, USA
⁸ Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634, USA
⁹ Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
¹⁰ Department of Physics, University of Crete, 71003 Heraklion, Greece
¹¹ Institute of Astrophysics, Foundation for Research and Technology–Hellas, Heraklion 70013, Greece
¹² Department of Astronomy, University of Virginia, PO Box 400325 Charlottesville, VA 22904, USA
¹³ IPAC, MC 100-22, California Institute of Technology, Pasadena, CA 91125, USA
¹⁴ Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing 100101, PR China

Received: 27 May 2020
Accepted: 6 July 2020

Abstract

We present the results from our analysis of NuSTAR data of the luminous infrared galaxy Mrk 266, which contains two nuclei, south-western (SW) and north-eastern (NE), which were resolved in previous Chandra imaging. Combining this with the Chandra data, we intepret the hard X-ray spectrum obtained from a NuSTAR observation to result from a steeply rising flux from a Compton-thick active galactic nuclei (AGN) in the SW nucleus which is very faint in the Chandra band, confirming the previous claim. This hard X-ray component is dominated by reflection, and its intrinsic 2–10 keV luminosity is likely to be ∼1 × 10⁴³ erg s⁻¹. Although it is bright in soft X-ray, only a moderately absorbed NE nucleus has a 2–10 keV luminosity of 4 × 10⁴¹ erg s⁻¹, placing it in the low-luminosity AGN class. These results have implications for understanding the detectability and duty cycles of emission from dual AGN in heavily obscured mergers.