Hawking predicted that black holes should radiate thermal radiation, the temperature being a function solely of the geometry near the horizon of the black hole. The same arguments show that one would also expect thermal radiation from other horizons, like the sonic horizon formed in a trans-sonic flow, or the horizon to fluid surface gravity waves formed by a blocking flow. This talk will discuss the phenomenon of black hole thermal emission, problems with its derivation, the ubiquity of such thermal emission by horizons, and the measurements made in the past year of the thermal spectrum of such radiation from a horizon for surface water waves in a flume.
Mot(s) clés libre(s) : Black holes, Hawking, Gravity

The massive black holes found at the centers of most galaxies, including our own, are believed to be the ashes of the fuel that powered quasars early in the life of universe. I will briefly review some of the astronomical evidence for these objects and then describe some of the exotic dynamical phenomena that originate in their vicinity, including hypervelocity stars, resonant dynamical relaxation, phase transitions, and lopsided stellar disks.
Mot(s) clés libre(s) : galaxies, Black holes, Star formation, Stellar dynamics