Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Transient Relativistic Iron Emission Line from an X-ray Flaring Supermassive Black Hole

Xiurui Zhao, Marco Ajello, Francesca Civano, Javier A. Garcıa, Elias Kammoun, Stefano Marchesi, Yue Shen, Daniel Stern, Qian Yang, Peter G. Boorman, Fiona Harrison, Erin Kara, Andrealuna Pizzetti, Ross Silver, Kirill V. Sokolovsky, Zachary Stone, Nuria Torres-Alba, Qiaoya Wu, Peixin Zhu

TL;DR

The study reports the first detection of a transient relativistic Fe Kα line in an AGN, J1047+5907, emerging about 21.5 days after a 2008 coronal X-ray flare. Through time-resolved X-ray spectroscopy and relativistic disk reflection modeling, the authors link the flare to delayed illumination of the accretion disk at radii ~$(~220^{+270}_{-100})\,R_g$ and infer an intermediate disk inclination around a rapidly spinning SMBH. The results demonstrate a causal connection between impulsive coronal activity and disk reflection, and they illustrate the potential of cadence X-ray monitoring to constrain SMBH spin and disk structure in AGN. Future campaigns with existing and upcoming X-ray observatories could extend this approach to map the innermost regions of active galactic nuclei across different radii and timescales.

Abstract

We report the discovery of the first transient relativistic iron Kα line in an Active Galactic Nucleus (AGN) J1047+5907. The line was detected 21.5 days (rest-frame) after an X-ray coronal flare observed in 2008 and it exhibits significant broadening consistent with relativistic reflection from the accretion disk in the vicinity of the central supermassive black hole (SMBH). The line has a width of ~300 eV, corresponding to a Keplerian velocity of 14,000 km s-1, at a distance of 5-41 light-days from the SMBH, strongly implying that the observed coronal flare triggered the emergence of the line. This event provides rare direct evidence of the response of the accretion disk to impulsive coronal illumination and offers a new method to probe the SMBH and disk physics. The relativistic modeling favors a broadened line produced by distant reflection from an accretion disk around a rapidly spinning black hole viewed at an intermediate inclination, consistent with other observations. Systematic monitoring of type 1 AGN following strong X-ray flares may open a new observational window into the innermost regions of AGN, enabling constraints on the physics of SMBH and its accretion disk at different radii that are otherwise challenging to access.

Transient Relativistic Iron Emission Line from an X-ray Flaring Supermassive Black Hole

TL;DR

The study reports the first detection of a transient relativistic Fe Kα line in an AGN, J1047+5907, emerging about 21.5 days after a 2008 coronal X-ray flare. Through time-resolved X-ray spectroscopy and relativistic disk reflection modeling, the authors link the flare to delayed illumination of the accretion disk at radii ~ and infer an intermediate disk inclination around a rapidly spinning SMBH. The results demonstrate a causal connection between impulsive coronal activity and disk reflection, and they illustrate the potential of cadence X-ray monitoring to constrain SMBH spin and disk structure in AGN. Future campaigns with existing and upcoming X-ray observatories could extend this approach to map the innermost regions of active galactic nuclei across different radii and timescales.

Abstract

We report the discovery of the first transient relativistic iron Kα line in an Active Galactic Nucleus (AGN) J1047+5907. The line was detected 21.5 days (rest-frame) after an X-ray coronal flare observed in 2008 and it exhibits significant broadening consistent with relativistic reflection from the accretion disk in the vicinity of the central supermassive black hole (SMBH). The line has a width of ~300 eV, corresponding to a Keplerian velocity of 14,000 km s-1, at a distance of 5-41 light-days from the SMBH, strongly implying that the observed coronal flare triggered the emergence of the line. This event provides rare direct evidence of the response of the accretion disk to impulsive coronal illumination and offers a new method to probe the SMBH and disk physics. The relativistic modeling favors a broadened line produced by distant reflection from an accretion disk around a rapidly spinning black hole viewed at an intermediate inclination, consistent with other observations. Systematic monitoring of type 1 AGN following strong X-ray flares may open a new observational window into the innermost regions of AGN, enabling constraints on the physics of SMBH and its accretion disk at different radii that are otherwise challenging to access.
Paper Structure (13 sections, 3 figures, 3 tables)

This paper contains 13 sections, 3 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Data Reduction and Spectral Analysis
  3. Data Reduction
  4. Spectral Analysis
  5. Results
  6. X-ray Spectral Fitting Results
  7. The Broad Line in the 2008 November 10 Spectrum
  8. Swift-XRT Observations
  9. Discussion
  10. Conclusion
  11. Acknowledgements
  12. A Single Line or Multiple Iron Lines
  13. Analyzing the Broad Line with the Relativistic Model

Figures (3)

  • Figure 1: Upper: the 2--10 keV X-ray light curve of J1047+5907. The inset is the zoom-in of the flare in 2008. Lower: the X-ray spectra of J1047+5907 from 2004 to 2018. The spectra were re-grouped so that each bin has as large as 3$\sigma$ detection with maximum three counts in each bin for plotting purpose. The data has been divided by the response effective area.
  • Figure 2: Schematic illustration of the relativistic iron line produced by a coronal flare. The top panel represents the source in a low-flux state, as observed on 2004 September 23. The middle panel shows the onset of a transient coronal flare, during which both the coronal emission and total X-ray flux increase significantly. The bottom panel depicts the subsequent phase, when the flare has propagated to distances of several hundred gravitational radii and is reflected by the accretion disk, leading to a substantial enhancement in the reflected component and the emergence of a relativistically broadened iron K$\alpha$ line.
  • Figure 3: Upper: Effect of key reflection parameters, ionization, disk inclination, and inner disk radius (top to bottom), on the Fe K$\alpha$ line profile. Left and right panels show the profiles for a non-spinning and a maximally positively spinning black hole, respectively. Lower: Zoom in spectrum from the 2008 November 10 observation with one of the realization of the best-fit from relxill.