The X-ray Power Spectral Density Function and Black Hole Mass Estimate for the Seyfert AGN IC 4329a

TL;DR

This paper analyzes the X-ray variability of Seyfert galaxy IC 4329a to estimate its black hole mass using the power spectral density function, confirming previous mass estimates and exploring energy band differences.

Contribution

First detailed broadband PSD analysis of IC 4329a, deriving black hole mass and accretion rate from X-ray variability data.

Findings

Detected a significant PSD break at ~2.5e-6 Hz

Estimated black hole mass of ~1.3e8 solar masses

PSD shape consistent across energy bands

Abstract

We present the X-ray broadband power spectral density function (PSD) of the X-ray-luminous Seyfert IC 4329a, constructed from light curves obtained via Rossi X-ray Timing Explorer monitoring and an XMM-Newton observation. Modeling the 3-10 keV PSD using a broken power-law PSD shape, a break in power-law slope is significantly detected at a temporal frequency of 2.5(+2.5,-1.7) * 10^-6 Hz, which corresponds to a PSD break time scale T_b of 4.6(+10.1,-2.3) days. Using the relation between T_b, black hole mass M_BH, and bolometric luminosity as quantified by McHardy and coworkers, we infer a black hole mass estimate of M_BH = 1.3(+1.0,-0.3) * 10^8 solar masses and an accretion rate relative to Eddington of 0.21(+0.06,-0.10) for this source. Our estimate of M_BH is consistent with other estimates, including that derived by the relation between M_BH and stellar velocity dispersion. We also present PSDs for the 10-20 and 20-40 keV bands; they lack sufficient temporal frequency coverage to reveal a significant break, but are consistent with the same PSD shape and break frequency as in the 3-10 keV band.