XMM–Newton and NuSTAR joint observations of Mrk 915: a deep look into the X-ray properties★

Abstract

We report on the X-ray monitoring programme (covering slightly more than 11 days) carried out jointly by XMM-Newton and NuSTAR on the intermediate Seyfert galaxy Mrk 915. The light curves extracted in different energy ranges show a variation in intensity but not a significant change in spectral shape. The X-ray spectra reveal the presence of a two-phase warm absorber: a fully covering mildly ionized structure [log ξ/(ergs cm s −1 ) ∼ 2.3, N H ∼ 1.3 × 10 21 cm −2 ] and a partial covering (∼ 90 per cent) lower ionized one [log ξ/(ergs cm s −1 ) ∼ 0.6, N H ∼ 2 × 10 22 cm −2 ]. A reflection component from distant matter is also present. Finally, a high-column density (N H ∼ 1.5 × 10 23 cm −2 ) distribution of neutral matter covering a small fraction of the central region is observed, almost constant, in all observations. Main driver of the variations observed between the datasets is a decrease in the intrinsic emission by a factor of ∼ 1.5. Slight variations in the partial covering ionized absorber are detected, while the data are consistent with no variation of the total covering absorber. The most likely interpretation of the present data locates this complex absorber closer to the central source than the narrow line region, possibly in the broad line region, in the innermost part of the torus, or in between. The neutral obscurer may either be part of this same stratified structure or associated with the walls of the torus, grazed (and partially intercepting) the line of sight.

The nature of X-ray spectral variability in SWIFT J2127.4+5654

“…We note that similar differences between EPIC-pn and FPMA/B slopes have been recently reported in the literature (e.g. Cappi et al 2016;Ballo et al 2017).…”

Testing Physical Scenarios for the Reflection Features of Type-1 AGNs using XMM-Newton and NuSTAR Simultaneous Observations

“…We find that one reflection component is a good representation of the spectra for only three objects in our sample, i.e., Mrk 915, Mrk 1044, and IGRJ 19378-0617. Supporting these results, Ballo et al (2017) find that the reflection component of Mrk 915 can be explained with a cold reflection from distant matter, and Mallick et al (2018) find that the broad-band spectrum of Mrk 1044 can be explained through a relativistic reflection from a high-density accretion disk with a broken power-law emissivity profile.…”

Unveiling sub-parsec supermassive black hole binary candidates in active galactic nuclei

“…We derive a distance between the two hard X-ray-emitting regions of a = (5 ± 1) × 10 −3 pc. Assuming a circular orbit, the relative velocity between the putative black holes is ∆v = 2πaP −1 0 = (3.4 ± 0.7) × 10 −2 c. Previous X-ray spectroscopy analyses of the source (e.g., Severgnini et al 2015;Ballo et al 2017) have not unveiled any double Fe Kα feature. In particular, XMM-Newton, with its energy resolution of ∼ 0.15 keV at the line energy, detects a single Fe Kα line at E = 6.42 ± 0.02 keV with no double peaks (Ballo et al 2017).…”

“…Assuming a circular orbit, the relative velocity between the putative black holes is ∆v = 2πaP −1 0 = (3.4 ± 0.7) × 10 −2 c. Previous X-ray spectroscopy analyses of the source (e.g., Severgnini et al 2015;Ballo et al 2017) have not unveiled any double Fe Kα feature. In particular, XMM-Newton, with its energy resolution of ∼ 0.15 keV at the line energy, detects a single Fe Kα line at E = 6.42 ± 0.02 keV with no double peaks (Ballo et al 2017). We can therefore conclude that, if the binary system is able to produce a double peak, the energy separation between the two peaks would be ∆E 0.15 keV.…”