Colloquium: Prof. Suvi Gezari, UMCP
Wednesday, November 19, 2014 · 3:30 - 4:30 PM
TITLE: "Black Hole Caught Red-Handed in Stellar Homicide"
ABSTRACT: Theorists in the late 1970's proposed that an inevitable consequence of a massive black hole lurking in the center of a galaxy is that stars will pass close enough to the black hole to be ripped apart by its extreme tidal forces and consumed. It was later appreciated that the luminous flare of radiation from the accretion of the bound tidal debris could be used as a signpost for an otherwise dormant and undetectable black hole. The first observational tidal disruption event candidates emerged in the late 1990's from an archival search of the ROSAT All-Sky Survey, in the form of luminous soft X-ray outbursts from several otherwise inactive galaxies. Since then, about two dozen tidal disruption event candidates have been discovered across the electromagnetic spectrum. I will review these candidates, and highlight our most recent discoveries from coordinated monitoring with the GALEX Time Domain Survey in the UV and the Pan-STARRS1 Survey in the optical. For the first time we are collecting enough information from the crime scene (observations) to determine both the victim (chemical composition and structure of the star) and the identity of the perpetrator (black hole mass). I will conclude with the promising detection rates of the next generation of time domain surveys, and how large samples of these events can be used as transient probes of accretion physics, jet formation, and black hole demographics.
ABSTRACT: Theorists in the late 1970's proposed that an inevitable consequence of a massive black hole lurking in the center of a galaxy is that stars will pass close enough to the black hole to be ripped apart by its extreme tidal forces and consumed. It was later appreciated that the luminous flare of radiation from the accretion of the bound tidal debris could be used as a signpost for an otherwise dormant and undetectable black hole. The first observational tidal disruption event candidates emerged in the late 1990's from an archival search of the ROSAT All-Sky Survey, in the form of luminous soft X-ray outbursts from several otherwise inactive galaxies. Since then, about two dozen tidal disruption event candidates have been discovered across the electromagnetic spectrum. I will review these candidates, and highlight our most recent discoveries from coordinated monitoring with the GALEX Time Domain Survey in the UV and the Pan-STARRS1 Survey in the optical. For the first time we are collecting enough information from the crime scene (observations) to determine both the victim (chemical composition and structure of the star) and the identity of the perpetrator (black hole mass). I will conclude with the promising detection rates of the next generation of time domain surveys, and how large samples of these events can be used as transient probes of accretion physics, jet formation, and black hole demographics.
