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Explore photon paths, gravitational lenses, and the formation of black holes. Learn about the dynamics near dense objects and wormholes connecting universes.
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Lecture 10: Black Holes and How They Shine Astronomy 5: The Formation and Evolution of the Universe Sandra M. Faber Spring Quarter 2007 UC Santa Cruz
Photon paths around objects of same mass and increasing density.
The surfaces stand for the flat equatorial plane around a condensed object like a dense star or a black hole. Walking uphill (outwards) is analogous to moving radially outward from the dense object. Note that you walk a long way on the surface but the radius does not change very much. The usual formula of the circumference = 2R is wrong … the circumference is smaller than you expect. This is what we mean by “curved space.” We can use curved 2-d surfaces to model curved 3-d space Spacetime near a black hole Spacetime near a dense star
Wormholes are mathematical solutions to GR that may not actually exist Wormhole connecting two universes Wormhole connecting two spots in the same universe.
Relativistic “jet” of ionized plasma 3 billion M central black hole The centers of spheroids host massive black holes When gas falls onto BHs, they become active galactic nuclei (AGN) and quasars (QSOs) The famous active elliptical M87
Feedback generated by stellar mergers (QSO mode) Sources of “feedback” during a merger: • Gas is funneled into the central regions, fueling a starburst and creating a wind (Mihos & Hernquist 1994). • Orbital kinetic energy is converted to heat in cloud-cloud collisions, which drives a wind (Cox et al. 2005). QSO phase • Gas driven to the center fuels a black hole, creating a quasar (QSO) whose feedback quenches further infall and star formation (Hopkins et al. 2005).
Birth and death of a quasar during collision of two disk galaxies (gas only, stars not shown)