Thermal Instability and Photoionized X-ray Reflection in Accretion Disks

Details Thermal Instability and Photoionized X-ray Reflection in Accretion Disks Thermal Instability and Photoionized X-ray Reflection in Accretion Disks

1999-09-21

arxiv.org/abs/astro-ph/9909359v1

Astronomy and Astrophysics

Astrophysics

Submitted to ApJ; 16 pages plus 13 figures

Scientific paper

10.1086/309054

We study the X-ray illumination of an accretion disk. We relax the simplifying assumption of constant gas density used in most previous studies; instead we determine the density from hydrostatic balance. It is found that the thermal ionization instability prevents the illuminated gas from attaining temperatures at which the gas is unstable. In particular, the uppermost layers of the X-ray illuminated gas are found to be almost completely ionized and at the local Compton temperature ($\sim 10^7 - 10^8$ K); at larger depths, the gas temperature drops abruptly to form a thin layer with $T\sim 10^6$ K, while at yet larger depths it decreases sharply to the disk effective temperature. We find that most of the Fe K$\alpha$ line emission and absorption edge are produced in the coolest, deepest layers, while the Fe atoms in the hottest, uppermost layers are generally almost fully ionized, hence making a negligible contribution to reprocessing features in $\sim 6.4-10$ keV energy range. We provide a summary of how X-ray reprocessing features depend on parameters of the problem. The results of our self-consistent calculations are both quantitatively and qualitatively different from those obtained using the constant density assumption. Therefore, we conclude that X-ray reflection calculations should always utilize hydrostatic balance in order to provide a reliable theoretical interpretation of observed X-ray spectra of AGN and GBHCs.

Affiliated with

Also associated with

No associations

Rating

Thermal Instability and Photoionized X-ray Reflection in Accretion Disks 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 Thermal Instability and Photoionized X-ray Reflection in Accretion Disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal Instability and Photoionized X-ray Reflection in Accretion Disks will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-153033