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

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 −1.7×10 −6 Hz, which corresponds to a PSD break time scale Tb of 4.6 +10.1 −2.3 days. Using the relation between Tb, black hole mass MBH, and bolometric luminosity as quantified by McHardy and coworkers, we infer a black hole mass estimate of MBH = 1.3 +1.0 −0.3 × 10 8 M⊙ and an accretion rate relative to Eddington of 0.21 +0.06 −0.10 for this source. Our estimate of MBH is consistent with other estimates, including that derived by the relation between MBH 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. Subject headings: galaxies: active — galaxies: Seyfert — X-rays: galaxies — galaxies: individual (IC 4329a)