A Closer Look at Black Holes

Several new techniques are currently being employed to probe the strong gravitational fi�eld in the vicinity of black holes. Long baselineinterferometry at sub-millimeter wavelengths sets constraints on the silhouette of the black holes in the Galactic center (SgrA*) and M87. Stars which get tidally disrupted as they orbit too close to a single black hole are being discovered at cosmological distances. Electromagnetic counterparts of black hole binaries in galaxy mergers are being identifi�ed, and can be used to calibrate the rate of gravitational wave sources. Most interestingly, the recoil induced by the anisotropic emission of gravitational waves in the �nal plunge of binaries leaves unusual imprints on their host galaxies. Finally, the lecture will describe new constraints on the contribution of primordial black holes to the dark matter.