Measuring the Spin of the Galactic Center Black Hole
Abstract
The Event Horizon Telescope (EHT) is an array of millimeter-wavelength telescopes that participate in very long baseline interferometry (VLBI) observations of supermassive black holes at extremely high angular resolution. For the Galactic Center black hole Sgr A*, the resolution of the EHT is a few Schwarzschild radii, sufficient to probe the inner accretion flow. Since the orbital period of material at the innermost stable circular orbit (ISCO) is a strong function of the spin of the black hole, measuring periodicity in the accretion flow provides a lower limit on the black hole spin. Recent general relativistic magnetohydrodynamic models (GRMHD) of the accretion flow are capable of qualitatively reproducing the variability in flux density seen at millimeter wavelengths. These models exhibit significant variability on scales near the ISCO. We examine prospects for detection of (quasi-)periodicity in the millimeter VLBI signatures of GRMHD models given expected performance parameters of the EHT. These simulations inform the feasibility of measuring the spin of the black hole in Sgr A* assuming a realistic model of the accretion flow around the black hole.
This work is funded by grants from the National Science Foundation.- Publication:
-
American Astronomical Society Meeting Abstracts #218
- Pub Date:
- May 2011
- Bibcode:
- 2011AAS...21822908S