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Quasars - o what’s driving the activity is a supermassive...

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Quasars Hubble’s Law – v = H 0 d - H 0 -“ H-naught” – Hubble’s constant now o it changes with time o i.e. a galaxy 10 Mpc away receds from us at 710 km/s o derive galaxy distances from Hubble’s law As you look at galaxies with greater redshifts, you are looking billions of years into the past o lookback times are not really distances because the universe expanded while light traveled Lookback times allow for us to see how galaxies formed and evolved most elliptical galaxies formed very early Some galaxies fromed from the agglomeration of numerous small subunits of stars o there used to far more small, blue, irregular galaxies probably merged togethere o most spiral galaxies used to be very peculiar looking By combining apparent brightness with Hubble’s law you can get distance Active Galaxies o Some galaxies have extremely bright nuclei, but it is not because of stars that amount of stars could not fit in the area to make the brightness
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Unformatted text preview: o what’s driving the activity is a supermassive black hole o Radio galaxies – often 2 lobes of radio emission, far from nucleus double-radio lobes usually associated with elliptical galaxies Jets of particles and radiation shot out over hundreds of thousands of light years o Gas from active nuclei shooting around at more than 10000 km/s o Stars are not responsible for the activity in the nuclei supermassive black holes at the center are probably responsible • Quasars o some blue “stars” are very bright at radio wavelengths o optical spectra is bizarre with huge, broad emission lines o It was first thought that these were stars o It was found that one of the quasars had the spectrum of hot hydrogen with a 16% redshift Redshift is huge – leading to first correctly identified quasar...
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