Extragalactic astronomy is the branch of astronomy concerned with objects outside the Milky Way galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic 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). As instrumentation has improved, distant objects can now be examined in more detail and so extragalactic astronomy includes objects at nearly the edge of the observable universe. Research into distant galaxies (outside of our local group) is valuable for studying aspects of the universe such as galaxy evolution and Active Galactic Nuclei (AGN) which give insight into physical phenomena (e.g. super massive black hole accretion and the presence of dark matter). It is through extragalactic astronomy that astronomers and physicists are able to study the effects of General Relativity such as gravitational lensing and gravitational waves, that are otherwise impossible (or nearly impossible) to study on a galactic scale.
- Active Galactic Nuclei (AGN), Quasars
- Dark Matter
- Galaxy clusters, Superclusters
- Intergalactic stars
- Intergalactic dust
- the observable universe
- Radio galaxies
- Extragalactic planet
- Andromeda–Milky Way collision
- Galaxy color–magnitude diagram
- Galaxy formation and evolution
- Observational cosmology
- "Extragalactic Astronomy". https://www.as.arizona.edu/extragalactic-astronomy.
- "Astrophysics and General Relativity | Physics and Astronomy". https://physics.missouri.edu/research/astrophysics-and-general-relativity.
- "Extragalactic Astronomy" (in en-US). https://sites.krieger.jhu.edu/astronomy/extragalactic-astronomy/.
- Collett, Thomas E.; Oldham, Lindsay J.; Smith, Russell J.; Auger, Matthew W.; Westfall, Kyle B.; Bacon, David; Nichol, Robert C.; Masters, Karen L. et al. (2018-06-22). "A precise extragalactic test of General Relativity" (in en). Science 360 (6395): 1342–1346. doi:10.1126/science.aao2469. ISSN 0036-8075. PMID 29930135. Bibcode: 2018Sci...360.1342C.
- "Gravitational Lensing" (in en). http://hubblesite.org/contents/articles/gravitational-lensing.
- "Einstein's Relativity". https://www.astronomynotes.com/relativity/s4.htm.
- M. E. Bailey; D. A. Williams (1988), Dust in the universe: the proceedings of a conference at the Department of Astronomy, University of Manchester, 14-18 December 1987, CUP Archive, p. 509, ISBN 978-0-521-35580-3, https://books.google.com/books?id=UPA8AAAAIAAJ&pg=PA509
Original source: https://en.wikipedia.org/wiki/Extragalactic astronomy. Read more