Department of Physics, Engineering Physics & Astronomy

Queen's University
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Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Departmental Colloquium - Into the Heart of the Milky Way: A Multiwavelength View of Sgr A*

Daryl Haggard,
McGill University,

February 10th, 2017
1:30 p.m. Theatre A

Abstract:

 Sagittarius A* is the closest example of a supermassive black hole

(SMBH) buried within a dense, massive stellar cluster. Sgr A* is more than 100 times closer than any other SMBH, and our proximity allows us to detect emission from its accretion flow in the radio, submillimeter (submm), near infrared (NIR), and X-ray regimes. These rich multiwavelength, time-resolved data have the power to probe the physical processes that underlie rapid flares originating near the black hole's event horizon. During ambitious Chandra X-ray and VLA radio monitoring campaigns over the last several years, we have detected the brightest-ever X-ray flares from Sgr A*. However, despite years of observational and theoretical study, we do not have a complete, unique model to explain these high-energy flares, or their relationship to variability at other wavelengths. Viable models range from the tidal disruption of asteroids to gravitational lensing to magnetic reconnection, motivating observers to place tighter constraints on the timing and multiwavelength properties of these outbursts. X-ray flares may also help us relate Sgr A* to weakly accreting black holes across the mass spectrum. I will discuss the possible origins and continuing mysteries surrounding Sgr A*'s high-energy flares and give a brief update on the X-ray and radio view of the Sgr A*/G2 interaction.