The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state

Details The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state

2010-10-19

arxiv.org/abs/1010.3771v1

Astronomy and Astrophysics

Astrophysics

High Energy Astrophysical Phenomena

Accepted to ApJ

Scientific paper

The All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) has continuously monitored a number of Active galactic nuclei (AGNs) with similar sampling rates for 14 years from 1996 January to 2009 December. Utilizing the archival ASM data of 27 AGNs, we calculate the normalized excess variances of the 300-day binned X-ray light curves on the longest timescale (between 300 days and 14 years) explored so far. The observed variance appears to be independent of AGN black hole mass and bolometric luminosity, respectively. According to the scaling relation with black hole mass (and bolometric luminosity) from Galactic black hole X-ray binaries (GBHs) to AGNs, the break timescales which correspond to the break frequencies detected in the power spectral density (PSD) of our AGNs are larger than binsize (300 days) of the ASM light curves. As a result, the singly broken power-law (soft-state) PSD predicts the variance to be independent of mass and luminosity, respectively. Nevertheless, the doubly-broken power-law (hard-state) PSD predicts, with the widely accepted ratio of the two break frequencies, that the variance increases with increasing mass and decreases with increasing luminosity, respectively. Therefore, the independence of the observed variance on mass and luminosity suggests that AGNs should have the soft-state PSDs. If taking into account the scaling of breaking timescale with mass and luminosity synchronously, the observed variances are also more consistent with the soft-state than the hard-state PSD predictions. With the averaged variance of AGNs and the soft-state PSD assumption, we obtain a universal PSD amplitude of $0.030\pm0.022$. By analogy with the GBH PSDs in the high/soft state, the longest timescale variability supports the standpoint that AGNs are scaled-up GBHs in the high accretion state, as already implied by the direct PSD analysis.

Affiliated with

Also associated with

No associations

Rating

The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The longest timescale X-ray variability reveals an evidence for active galactic nuclei in the high accretion state will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-267853