Journal
ASTROPHYSICAL JOURNAL LETTERS
Volume 703, Issue 2, Pages L142-L146Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/703/2/L142
Keywords
accretion, accretion disks; black hole physics; Galaxy: center; radiative transfer; relativity
Categories
Funding
- NASA [05-ATP05-96, NNX08AX59H]
- NSF [PHY05-51164]
- NASA [93580, NNX08AX59H] Funding Source: Federal RePORTER
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The recent very long baseline interferometry (VLBI) observation of the Galactic center black hole candidate Sgr A* at 1.3 mm shows source structure on event-horizon scales. This detection enables a direct comparison of the emission region with models of the accretion flow onto the black hole. We present the first results from time-dependent radiative transfer of general relativistic MHD simulation data, and compare simulated synchrotron images at black hole spin a = 0.9 with the VLBI measurements. After tuning the accretion rate to match the millimeter flux, we find excellent agreement between predicted and observed visibilities, even when viewed face-on (i less than or similar to 30 degrees). VLBI measurements on 2000-3000 km baselines should constrain the inclination. The data constrain the accretion rate to be (1.0-2.3)x10(-9) M-circle dot yr(-1) with 99% confidence, consistent with but independent of prior estimates derived from spectroscopic and polarimetric measurements. Finally, we compute light curves, which show that magnetic turbulence can directly produce flaring events with 0.5 hr rise times, 2-3.5 hr durations, and 40%-50% flux modulation, in agreement with observations of Sgr A* at millimeter wavelengths.
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