Talk detail

Participant	Younsi, Ziri
Institution	Institute for Theoretical Physics, Goethe University of Frankfurt - Max-von-Laue-Strasse 1 - Frankfurt - - Germany

Session	PT2	Accepted		Order	Time
Talk	Oral abstract	Title	Electromagnetic and Observational Signatures of the Kerr-Taub-NUT Spacetime
Coauthors
Abstract	While it is expected that the Galactic centre supermassive black hole Sgr A* is well described by the Kerr solution, general relativity (GR) has yet to be tested rigorously in the strong-field regime. It is eminently possible that alternative spacetimes, and even alternative theories of gravity may describe the black hole candidate in our Galactic centre. To this end, in this talk we investigate the possibility of distinguishing a black hole in the Kerr-Taub-NUT spacetime from the standard Kerr solution. Coupling ray-tracing calculations with a fully covariant GR radiative transport formalism we simulate the observed electromagnetic emissions and images from the vicinity of both the Kerr-Taub-NUT and Kerr spacetimes. Comparing these calculations qualitatively we discuss the prospect of current and future instruments in probing these differences.
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Session	GN1	Accepted		Order	Time
Talk	Oral abstract	Title	Variations in Emission from Episodic Plasmoid Ejecta from Black Holes
Coauthors
Abstract	The X-ray and radio flares observed in X-ray binaries and active galactic nuclei are attributed to energetic electrons in the plasma ejecta from the accretion flows near the black hole in these systems. It is argued that magnetic reconnection occurs in the coronae above the accretion disk around the black hole and that this drives plasmoid outflows resembling the solar coronal mass ejection (CME) phenomenon. The X-ray and radio flares are emission form energetic electrons produced in the process. As the emission region is located near the black hole event horizon, the flare emission would subject to special and general relativistic effects. We present calculations of the flaring emission from plasmoids orbiting around a black hole and plasmoid ejecta launched from the inner accretion disk where general relativistic effects are crucial in determining the observed time-dependent properties of the emission. We consider a fully general relativistic radiative transfer calculation of the emission from evolving ejecta from black hole systems and determine the emission lightcurves of plasmoids when they are in orbit and when they break free from the magnetic confinement. Implications for interpreting time-dependent spectroscopic observations of flaring emission from accreting black holes are also discussed.
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