Relativistic Emission from the Sgr A* Accretion Disk

Research output: Contribution to conferencePaper


The compact radio, infrared and X-ray source Sgr A* is believed to be the manifestation of a supermassive black hole at the center of the Milky Way. Theory and observation attempt to determine the accretion and radiation physics behind the extreme under-luminosity and variability of this radio source. Sgr A* shows the feature of so-called flares, short bursts of increased radiation that last for about 20-100 min, suggesting that the emission is coming from the very close vicinity of the black hole. We investigate light curves from an emitting, variable hot spot co-moving with the accretion disk. Using ray-tracing techniques, we reconstruct time-dependent images and spectra of the accretion emission region, as seen by a distant observer. In the current research, the disk model is supposed to be standard keplerian, geometrically thin and optically thick in a Kerr (spinning) geometry. The trajectories of photons emerging from the emitting blob at the surface of the accretion disk, near the last stable orbit, including all relativistic effects such as light bending, gravitational lensing, redshift or time dilation are calculated. This allows us to explore different accretion and emission models and potentially the parameters of the black hole
Original languageEnglish
Number of pages30
Publication statusPublished - 2008
Externally publishedYes
EventMerging Black Holes in Galaxies: Galaxy Evolution, AGN and Gravitational Waves - Katoomba, NSW
Duration: 15 Jun 200820 Jun 2008


ConferenceMerging Black Holes in Galaxies: Galaxy Evolution, AGN and Gravitational Waves
CityKatoomba, NSW


  • supermassive black holes
  • accretion disk
  • Kerr geometry
  • Galactic Centre

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