Suzaku Discovery of a Slowly Varying Hard X-ray Continuum from the Type I Seyfert Galaxy NGC 3516

Abstract

The bright type I Seyfert galaxy NGC 3516 was observed by {\it Suzaku} twice, in 2005 October 12--15 and 2009 October 28--November 2, for a gross time coverage of 242 and 544 ksec and a net exposure of 134 and 255 ksec, respectively. The 2--10 keV luminosity was $2.8\times 10^{41}$ erg s${}^{-1}$ in 2005, and $1.6\times 10^{41}$ erg s${}^{-1}$ in 2009. The 1.4--1.7 keV and 2--10 keV count rates both exhibited peak-to-peak variations by a factor of $\sim 2$ in 2005, while $\sim 4$ in 2009. In either observation, the 15--45 keV count rate was less variable. The 2--10 keV spectrum in 2005 was significantly more convex than that in 2009. Through a count-count-plot technique, the 2--45 keV signals in both data were successfully decomposed in a model-independent way into two distinct broadband components. One is a variable emission with a featureless spectral shape, and the other is a non-varying hard component accompanied by a prominent Fe-K emission line at 6.33 keV (6.40 keV in the rest frame). The former was fitted successfully by an absorbed power-law model, while the latter requires a new hard continuum in addition to a reflection component from distant materials. The spectral and variability differences between the two observations are mainly attributed to long-term changes of this new hard continuum, which was stable on time scales of several hundreds ksec.

14 pages, 10 figures

References in corpus (5)

• X-ray Properties of Black-Hole Binaries
• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• An absorption origin for the X-ray spectral variability of MCG-6-30-15
• The variable X-ray spectrum of Markarian 766 - I. Principal components analysis
• Tracing a Disk Wind in NGC 3516

Cited by in corpus (5)

• Revealing the X-ray Variability of AGN with Principal Component Analysis
• Suzaku Studies of the Central Engine in the Typical Type I Seyfert NGC 3227: Detection of Multiple Primary X-ray Continua with Distinct Properties
• Application of Clumpy Torus Model to Broadband X-ray Spectra of Two Seyfert 1 Galaxies: IC 4329A and NGC 7469
• Dust Reverberation Mapping of Type 2 AGN NGC 2110 Realized with X-ray and 3-5 $\mu$m IR monitoring
• Complex optical/UV and X-ray variability in Seyfert 1 galaxy Mrk 509