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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
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Photon paths around objects of same mass and increasing density.
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Baltimore seen through a strong gravitational lens
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Approaching a black hole. R goes from 112RS down to 10 RS
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Orbiting around a hole at 10 RS
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We can use curved 2-d surfaces to model curved 3-d space
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.” Spacetime near a black hole Spacetime near a dense star
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Wormholes are mathematical solutions to GR that may not actually exist
Wormhole connecting two universes Wormhole connecting two spots in the same universe.
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The centers of spheroids host massive black holes
3 billion M central black hole Relativistic “jet” of ionized plasma When gas falls onto BHs, they become active galactic nuclei (AGN) and quasars (QSOs) The famous active elliptical M87
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Fly-in to the center of the M87 black hole
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Artist’s conception of accretion disk with jet
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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).
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Birth and death of a quasar during collision of two disk galaxies (gas only, stars not shown)
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