Testing General Relativity with Accretion-Flow Imaging of Sgr A^{*}.
The Event Horizon Telescope is a global, very long baseline interferometer capable of probing potential deviations from the Kerr metric, which is believed to provide the unique description of astrophysical black holes. Here, we report an updated constraint on the quadrupolar deviation of Sagittarius A^{*} within the context of a radiatively inefficient accretion flow model in a quasi-Kerr background. We also simulate near-future constraints obtainable by the forthcoming eight-station array and show that in this model already a one-day observation can measure the spin magnitude to within 0.005, the inclination to within 0.09°, the position angle to within 0.04°, and the quadrupolar deviation to within 0.005 at 3σ confidence. Thus, we are entering an era of high-precision strong gravity measurements.
Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.|Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.|Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8, Canada.
Tim
T
Johannsen
Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Carlos
C
Wang
Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.|Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Avery E
AE
Broderick
MIT Haystack Observatory, Westford, Massachusetts 01886, USA.|Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
Sheperd S
SS
Doeleman
MIT Haystack Observatory, Westford, Massachusetts 01886, USA.
Vincent L
VL
Fish
Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
Abraham
A
Loeb
Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721, USA.
Dimitrios
D
Psaltis