1–4 Aug 2017
Western Michigan University Kalamazoo, MI, USA
US/Eastern timezone

The problem of the high iron abundance in accretion disks around black holes

3 Aug 2017, 16:20
20m
Western Michigan University Kalamazoo, MI, USA

Western Michigan University Kalamazoo, MI, USA

2350 Business Court, Kalamazoo, MI 49008, USA
Contributed talks Atomic Opacities

Speaker

Dr Javier Garcia (California Institute of Technology)

Description

In most accreting black hole systems copious X-rays are emitted from the inner-most regions commonly observed accompanied by a reflection spectrum, which shows signatures of energetic photons being reprocessed by the optical thick material of an accretion disk. Given their abundance and fluorescence yield, K-shell lines from iron are the most prominent in the X-ray reflected spectrum. These line profiles can be grossly broadened and skewed by Doppler effects and gravitational redshift. Consequently, the modeling of the reflection spectrum provides one of the best means to measure the spin of the black hole among other physical quantities. The accuracy of these spin estimates is called into question because fitting the data requires very high iron abundances, typically several times the solar value. Meanwhile, no plausible physical explanation has been proffered for why these black hole systems should be so iron rich. The most likely explanation for the super-solar iron abundances is a deficiency in the models, and the leading candidate cause is that current models are inapplicable at very high densities ($>10^{18}$ cm$^{−3}$), due to the lack of atomic data appropriate for this regime. Here we present the current observational evidence for the super-solar abundance of iron in many black hole systems, and show the effects of high density in the state-of-the-art reflection models. We also briefly discuss our current efforts to produce new atomic for high-density plasmas, which are required to improve the present photoionization models.

Primary author

Dr Javier Garcia (California Institute of Technology)

Co-authors

Claudio Mendoza (Western Michigan University) Mr Jérôme Deprince (University of Mons) Dr Pascal Quinet (UMONS) Dr Patrick Palmeri (University of Mons - UMONS) Dr Timothy Kallman (NASA-GSFC) Dr manuel bautista (Western Michigan University)

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