Question

Astrophysics, please explain all clearly.

1. Describe two components of active galaxies not found in quiescent galaxies. Also,
describe what type of observations reveal these components in active galaxies.

2. Describe the physical origin of the Cosmic Microwave Background radiation.
Approximately how many years after the big bang this occurred?

Answer 1

1) The star forming regions are absent in quiescent galaxies. Also the hydrogen gas is very less in these galaxies. The dying galaxy can be called as a quiescent galaxy. The active galaxy contains star forming regions. These can be observed as below. Key elements of star formation are only available by observing in wavelengths other than the optical. The protostellar stage of stellar existence is almost invariably hidden away deep inside dense clouds of gas and dust left over from the giant molecular clouds.

2) The universe began 13.8 billion years ago, and the Cosmic Microwave background dates back to about 400,000 years after the Big Bang. That's because in the early stages of the universe, when it was just one-hundred-millionth the size it is today, its temperature was extreme: 273 million degrees above absolute zero.

Any atoms present at that time were quickly broken apart into small particles (protons and electrons). The radiation from the CMB in photons (particles representing quantums of light, or other radiation) was scattered off the electrons.