Search for coronal temperature variation in Seyfert galaxies

Abstract

While the temperature of the X-ray corona ($\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$) in active galactic nuclei (AGN) are known for many sources, its variation, if any, is limited to a handful of objects. This is in part due to the requirement of good signal-to-noise X-ray spectra covering a wide range of energies. We present here results on the X-ray spectral analysis of 18 Seyferts, having more than one epoch of observations to look for variation in $\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$. The data for a total of 52 epochs on these 18 AGN were taken from observations carried out by NuSTAR in the 3$-$79 keV energy band. From phenomenological and physical model fits to the multi-epoch data on these 18 sources from {\it NuSTAR}, we could constrain the cut-off energy ($E_{cut}$) in a large fraction of the sources. Also, from Comptonized model fits, we could obtain $\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$ for our sample. Of the 18 sources, at the 90 per cent confidence level, evidence for variation in $\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$ was found for only one source, namely MCG+08-11-011. For this source, between two epochs, separated by about five years, we found $\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$ to decrease from 57${}_{-16}^{+29}$ keV to 30${}_{-7}^{+11}$ keV. During the same period, the flux decreased from (12.60 to 14.02) $\times$ 10${}^{-11}$ erg cm${}^{-2}$ s${}^{-1}$ and the optical depth increased from 1.68 to 2.73. We thus found a positive correlation between flux and coronal temperature with a reduction of about 40 per cent in optical depth. Our observations tend to favour the vertically outflowing corona scenario for the observed variation in $\mathrm{k}{\mathrm{T}}_{\mathrm{e}}$ in MCG+08-11-011.

arXiv comment17 pages, 7 figuers, accepted for publication in MNRAS-MJ

References in corpus (45)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Calibration of X-ray absorption in our Galaxy
• Broad-band gamma-ray and X-ray spectra of NGC 4151 and their implications for physical processes and geometry
• Improved Reflection Models of Black-Hole Accretion Disks: Treating the Angular Distribution of X-rays
• The May 1989 outburst of the Soft X-ray Transient GS 2023+338 (V404 Cyg)
• A Model for the X-Ray and UV Emission from Seyfert Galaxies and Galactic Black Holes
• The role of the reflection fraction in constraining black hole spin
• X-ray reflected spectra from accretion disk models. I. Constant density atmospheres
• X-ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies
• Reverberation mapping of Active Galactic Nuclei: from X-ray corona to dusty torus
• The Cores of the Fe K$\alpha$ Lines in Active Galactic Nuclei: an Extended Chandra High Energy Grating Sample
• Testing Comptonization models using BeppoSAX observations of Seyfert 1 galaxies
• X-ray reflected spectra from accretion disk models.II. Diagnostic tools for X-ray observations
• A NuSTAR census of coronal parameters in Seyfert galaxies
• Long-term variability of AGN at hard X-rays
• The broad band spectral variability of MCG-6-30-15 observed by NuSTAR and XMM-Newton
• The INTEGRAL high energy cut-off distribution of type 1 AGN
• Testing Comptonizing coronae on a long BeppoSAX observation of the Seyfert 1 galaxy NGC 5548
• X-ray properties of the Northern Galactic Cap AGNs in the 58-month Swift-BAT catalog
• Are X-ray Emitting Coronae around Super Massive Black Holes Outflowing?
• The hard X-ray spectrum of NGC 5506 as seen by NuSTAR
• NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei: II. Median High-energy Cutoff in Seyfert II Hard X-ray Spectra
• NuSTAR Reveals the Comptonizing Corona of the Broad-Line Radio Galaxy 3C 382
• Revealing the accretion disc corona in Mrk 335 with multi-epoch X-ray spectroscopy
• X-ray Coronal Properties of Swift/BAT-Selected Seyfert 1 Active Galactic Nuclei
• NuSTAR/XMM-Newton monitoring of the Seyfert 1 galaxy HE 1143-1810. Testing the two-corona scenario
• Anatomy of the AGN in NGC 5548: III. The high-energy view with NuSTAR and INTEGRAL
• A Long Look At MCG-5-23-16 With NuSTAR: I- Relativistic Reflection And Coronal Properties
• High-energy monitoring of NGC 4593 with XMM-Newton and NuSTAR. X-ray spectral analysis
• Photoionized emission and absorption features in the high-resolution X-ray spectra of NGC 3783
• Broadband X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292
• Relations between phenomenological and physical parameters in the hot coronae of AGNs computed with the MoCA code
• Coronal properties of Swift/BAT-selected Seyfert 1 AGN observed with NuSTAR
• Swift/XRT- NuSTAR spectra of type 1 AGN]{Swift/XRT- NuSTAR spectra of type 1 AGN: confirming INTEGRAL results on the high energy cut-off
• Fundamental X-ray Corona Parameters of Swift/BAT AGN
• The first simultaneous X-ray broad-band view of Mrk 110 with XMM-Newton and NuSTAR
• NuSTAR hard X-ray spectra of radio galaxies
• NuSTAR observation of Ark 564 reveals the variation of coronal temperature with flux
• Correlation between relativistic reflection fraction and photon index in NuSTAR sample of Seyfert 1 AGN
• Distinct High Energy Cutoff Variation Patterns in Two Seyfert Galaxies
• On Measuring the Variation of High Energy Cut-off in Active Galactic Nuclei
• Detection of the high energy cut-off from the Seyfert 1.5 galaxy NGC 5273
• On the Nature of the High-Energy Rollover in 1H 0419-577
• NuSTAR spectral analysis of three Seyfert galaxies: NGC 3227, NGC 5548 and MR 2251$-$178

Cited by in corpus (6)

• Investigating the interplay between the coronal properties and the hard X-ray variability of active galactic nuclei with NuSTAR
• Millimeter emission from supermassive black hole coronae
• On joint analysing XMM-NuSTAR spectra of active galactic nuclei
• Hidden biases in flux-resolved X-ray spectroscopy
• A New Interpretation for the Hot Corona in Active Galactic Nuclei
• A possible two-fold scenario for the disc-corona of the luminous AGN 1H 0419--577: a high-density disc or a warm corona