ASTR-1010 Lecture Notes - Lecture 17: Active Galactic Nucleus, Galaxy Formation And Evolution, Quasar
6 Oct 2016
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Document Summary
Orbital speed and distance of gas orbiting center of m87 indicate a black hole with mass of 3 billion msun. Orbits of stars at center of milky way stars reveal a black hole with mass of 4 million. Collisions allow the black hole to grow in mass. Gas clouds between a quasar and earth absorb some of a quasar"s light. Analysis so far has shown: more heavy element lines are seen at low redshift (. e. nearby, i. e. later in time, supports element enrichment of galaxies by supernovae. These data support our models of galaxy evolution. The centers of present-day galaxies still contain these massive black holes: the signatures of heavy elements in quasar spectra shows that the universe has been slowly enriched chemically over time, through the star-gas-star cycle. Dark matter: an undetected form of mass that emits little or no light but whose existence we infer from its gravitational influence.
