Unlike stars, galaxies arenít born every day.
So we need to look back in time. The Hubble Deep Field.
We assume H and He was fairly uniform in the beginning universe BUT
It had small variations in density
Protogalactic clouds condense until first stars form.
Then galaxies form their halo (population II stars)
Spirals get disk collapse
Why the difference between spirals and ellipticals?
Or hot gas in galaxy clusters can strip the gas from a galaxy.
†What is this? the red shows radio waves.
Quasars and other AGNs
Quasars –strong emission lines, very redshifted, some are radio-loud
The power source - a supermassive black hole with accretion
Why do you need a black hole? It is 100 more efficient than fusion.
Do we have it right? Weighing supermassive black holes
The newest look.
Light from quasars shows us the protogalactic clouds