Extragalactic astronomy

The closest objects in extragalactic astronomy include the galaxies of the Local Group, which are close enough to allow very detailed analyses of their contents (e.g. supernova remnants, stellar associations).

[1] Research into distant galaxies (outside of our local group) is valuable for studying aspects of the universe such as galaxy evolution[2] and Active Galactic Nuclei (AGN) which give insight into physical phenomena (e.g. super massive black hole accretion and the presence of dark matter[3]).

A key interest in Extragalactic Astronomy is the study of how galaxies behave and interact through the universe.

Astronomer's methodologies depend — from theoretical to observation based methods.Galaxies form in various ways.

In most Cosmological ''N''-body simulations, the earliest galaxies in the cosmos formed in the first hundreds of millions of years.

Galaxies in the 1995 Hubble Deep Field
NGC 2207 (the bigger galaxy to the left) and IC 2163 (the smaller galaxy to the right) as seen by the Hubble Space Telescope.