NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-18 T08:32:59 PDT
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For refcode 2012A&A...544A..80G:
Retrieve 103 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2012A&A...544A..80G X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles Gonzalez-Martin, O.; Vaughan, S. Abstract. Context. Active galactic nuclei (AGN), powered by accretion onto supermassive black holes (SMBHs), are thought to be scaled up versions of Galactic black hole X-ray binaries (BH-XRBs). In the past few years evidence of such correspondence include similarities in the broadband shape of the X-ray variability power spectra, with characteristic bend times-scales scaling with mass. Aims: The aim of this project is to characterize the X-ray temporal properties of a sample of AGN to study the connection among different classes of AGN and their connection with BH-XRBs. Methods: We have performed a uniform analysis of the power spectrum densities (PSDs) of 104 nearby (z < 0.4) AGN using 209 XMM-Newton/pn observations. These PSDs span ~= 3 decades in temporal frequencies, ranging from minutes to days. The PSDs have been estimated in three energy bands: 0.2-10 (total), 0.2-2 (soft), and 2-10 keV (hard). The sample comprises 61 Type-1 AGN, 21 Type-2 AGN, 15 NLSy1, and 7 BLLACS. We have fitted each PSD to two models: (1) a single power-law model and (2) a bending power-law model. Results: Among the entire sample, 72% show significant variability in at least one of the three bands tested. A high percentage of low-luminosity AGN do not show any significant variability (86% of LINERs). The PSD of the majority of the variable AGN was well described by a simple power-law with a mean index of {alpha} = 2.01 +/- 0.01. In 15 sources we found that the bending power law model was preferred with a mean slope of {alpha} = 3.08 +/- 0.04 and a mean bend frequency of < nu_b_ > ~= 2 x 10^-4^ Hz. Only KUG 1031+398 (RE J1034+396) shows evidence for quasi-periodic oscillations. The "fundamental plane" relating variability timescale, black hole mass, and luminosity is demonstrated using the new X-ray timing results presented here together with a compilation of the previously detected timescales from the literature. Conclusions: Both quantitative (i.e. scaling with BH mass) and qualitative (overall PSD shapes) found in this sample of AGN are in agreement with the expectations for the SMBHs and BH-XRBs being the same phenomenon scaled-up with the size of the BH. The steep PSD slopes above the high frequency bend bear a closer resemblance to those of the "soft/thermal dominated" BH-XRB states than other states. Tables 1-4 and Appendices A and B are available in electronic form at http://www.aanda.org Key words: accretion, accretion disks, Galaxy: nucleus, galaxies: active, X-rays: galaxies
Retrieve 103 NED objects in this reference.
Please click here for ADS abstract

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