A soft X-ray reverberation lag in the AGN ESO 113-G010

TL;DR

This study detects a soft X-ray reverberation lag in the AGN ESO 113-G010, indicating disk-corona interactions and providing insights into the black hole's environment through timing analysis.

Contribution

First detection of a soft X-ray reverberation lag in ESO 113-G010, linking lag properties to black hole mass and accretion disk structure.

Findings

Detected a soft lag of -325 +/- 89 seconds at higher frequencies.

Observed a transition from hard to soft lags with increasing frequency.

Lag properties suggest a black hole mass slightly larger than previous estimates.

Abstract

Reverberation lags have recently been discovered in a handful of nearby, variable AGN. Here, we analyze a ~100 ksec archival XMM-Newton observation of the highly variable AGN, ESO 113-G010 in order to search for lags between hard, 1.5 - 4.5 keV, and soft, 0.3 - 0.9 keV, energy X-ray bands. At the lowest frequencies available in the lightcurve (<1.5E-4 Hz), we find hard lags where the power-law dominated hard band lags the soft band (where the reflection fraction is high). However, at higher frequencies in the range (2-3)E-4 Hz we find a soft lag of -325 +/- 89 s. The general evolution from hard to soft lags as the frequency increases is similar to other AGN where soft lags have been detected. We interpret this soft lag as due to reverberation from the accretion disk, with the reflection component responding to variability from the X-ray corona. For a black hole mass of 7E6 M(solar) this corresponds to a light-crossing time of ~9 R_g/c, however, dilution effects mean that the intrinsic lag is likely longer than this. Based on recent black hole mass-scaling for lag properties, the lag amplitude and frequency are more consistent with a black hole a few times more massive than the best estimates, though flux-dependent effects could easily add scatter this large.