The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron Kα line
Harrison, F.; Stern, D.; Bauer, F. E.; Bianchi, S.; Gandhi, P.; Matt, G.; Arevalo, P.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Puccetti, S.; Baloković, M.; Walton, D. J.; Marinucci, A.; Zhang, W.; Rivers, E.; Ballantyne, D.; Lu, T. N.
Italy, United States, Chile, Denmark, United Kingdom
Abstract
We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suzaku, BeppoSAX, Chandra and Swift. Simultaneous NuSTAR and Swift broad-band spectra (in the 3-80 keV range) indicate a cutoff energy Ec > 210 keV, with no detectable contribution from Compton reflection. NGC 2110 is one of the very few sources where no evidence for distant Compton-thick scattering is found and, by using temporal information collected over more than a decade, we investigate variations of the iron Kα line on time-scales of years. The Fe Kα line is likely the sum of two components: one constant (originating from distant Compton-thick material) and the other one variable and linearly correlated with the source flux (possibly arising from Compton-thin material much closer to the black hole).