Strong field effects on emission line profiles:

Kerr black holes and warped accretion disks

9th Group Seminar

Yan Wang 王炎Dept. of Astronomy, Nanjing University

Dec. 2, 2010

Outline

• Introduction• Photon trajectories in the Kerr spacetime• Geometric and kinematic structure of the

warped disk• Emission line profiles and disk images (results)• Semi-analytic, FWZI/FWHI limits• Summary and Conclusions• Appendix A

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Introduction

• Backgrounds Accretion power serves as an important source of energy in

astrophysics, especially in X-ray binaries (XRBs) and active galactic nuclei (AGNs). Accretion onto both stellar mass black holes in XRBs and supermassive black holes ( 10^6− 10^9M_ ) in AGNs is believed to proceed through an ⊙accretion disk, which is truncated at the inner most stable circular orbit (ISCO)…cold disk, corona, external hard X-ray illumination, fluorescence line, warped disk (misalignment) justification.

• Motivationsmeasure black hole spin; study the structure of accretion disk

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Relativistic line models:

a standard thin disk orbiting around a Schwarzschild black hole calculated by Fabian et al. (1989);

a standard thin orbiting an extreme Kerr black hole Laor (1991) and Bromley et al. (1997);

a standard thin orbiting a Kerr black hole(no \phi) (Fanton et al. 1997);

warped disk orbiting a Schwarzschild black hole (Hartnoll & Blackman 2000, Wu et al. 2008);

disk with spiral velocity structure orbiting a Schwarzschild (Hartnoll & Blackman 2002).

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Photon trajectories in the Kerr spacetimeIn the standard Boyer-Lindquist coordinates, the Kerr metric can be written as:

Jason Dexter and Eric Agol (UW-Seattle), “geokerr”. arXiv:0903.0620 6

Geometric and kinematic structure of the warped disk

where

For detailed kinematic structure, see my notes. 7

a=0.998, \theta=70^o, \phi=180^o, (r_ms, 10, 50), q=-2

Emission line profiles and disk images

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a=0.998, \theta=30^o, (r_ms, 10, 50), q=-2

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a=0.998, \theta=70^o, (r_ms, 10, 50), q=-2

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a=0.998, \theta=70^o, \phi=180^o, (r_ms, 10, 50), q=-2

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a=0.998, \theta=70^o, \phi=0^o, (r_ms, 10, 50), q=-2

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Disk image (not finished yet)

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Semi-analytic, FWZI/FWHI limits

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Summary and Conclusions

• We present here, for the first time, the emission line profiles from a warped disk orbiting around a Kerr black hole.

• The calculation is general, details are concerned with trajectories of both photons and particles.

• Multiple peaks, long red tails close to infinite redshifting…• Changing of shape for different azimuthal angles for a fixed

inclination, and for different inclinations• Differences between twist-free and twisted warped disks• Flux incident onto disk from source (source shadowing)• … … …

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Appendix A: Expression of g for the warped disks

For expression of g, see my notes.

Acknowledgment and references.

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Thank You !!

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