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arXiv · 0906.3560

The anti-correlation between the hard X-ray photon index and the Eddington ratio in LLAGNs

Minfeng Gu·Xinwu Cao
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Abstract

We find a significant anti-correlation between the hard X-ray photon index and the Eddington ratio L_Bol/L_Edd for a sample of Low-Ionization Nuclear Emission-line Regions (LINERs) and local Seyfert galaxies, compiled from literatures with Chandra or XMM-Newton observations. This result is in contrast with the positive correlation found in luminous active galactic nuclei (AGNs), while it is similar to that of X-ray binaries (XRBs) in low/hard state. Our result is qualitatively consistent with the spectra produced from advection dominated accretion flows (ADAFs). It implies that the X-ray emission of low-luminosity active galactic nuclei (LLAGNs) may originate from the Comptonization process in ADAF, and the accretion process in LLAGNs may be similar to that of XRBs in the low/hard state, which is different from that in luminous AGNs.

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Minfeng Gu, Xinwu Cao. 2009-06-19. The anti-correlation between the hard X-ray photon index and the Eddington ratio in LLAGNs. https://doi.org/10.1111/j.1365-2966.2009.15277.x

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