Editing Active galactic nucleus (section)

==Effects on Planets==
It is expected that all [[Supermassive black hole|supermassive black holes]] at the center of [[Galaxy|galaxies]] have gone through high AGN activity to reach the mass we see today. Theses periods of high AGN activity can potentially effect the [[Atmosphere|atmospheres]] of [[Planet|planets]] and their [[Planetary habitability|habitability]]. Planets located in compact galaxies such as “[[Red nugget|Red Nuggets]]” are likely to be more impacted than planets located typical [[Elliptical galaxy|elliptical galaxies]] such as [[Messier 87|M87]] or [[Spiral galaxy|spiral galaxies]] such as the [[Milky Way|Milky Way galaxy]].
For a planet with a high amount of initial [[oxygen]] in their atmosphere, AGN radiation may allow a thicker [[Ozone layer]], potentially from shielding it from other [[Ultraviolet|UV radiation]]. This would potentially increase the habitability of a planet.<ref>{{Cite journal |last1=Sippy |first1=Kendall I. |last2=Eager-Nash |first2=Jake K. |last3=Hickox |first3=Ryan C. |last4=Mayne |first4=Nathan J. |last5=Brumback |first5=McKinley C. |date=2025 |title=Impacts of UV Radiation from an AGN on Planetary Atmospheres and Consequences for Galactic Habitability |journal=The Astrophysical Journal |language=en |volume=980 |issue=2 |pages=221 |doi=10.3847/1538-4357/adac5d |doi-access=free |arxiv=2411.15341 |bibcode=2025ApJ...980..221S |issn=0004-637X}}</ref>

The supermassive black hole at the center of our galaxy ([[Sagittarius A*]]) experienced a phase of AGN activity. This would have caused loss of atmospheres to planets within 1 kpc comparable to present-day [[Earth]]. The [[X-ray]] and extreme [[Ultraviolet|UV radiation]] also would have caused biological damage to surface life on planets which out proper shielding. This would potentially hinder the development of [[Multicellular organism|complex life]] within a few kiloparsecs.<ref>{{Cite journal |last=Balbi |first=Amedeo |last2=Tombesi |first2=Francesco |date=2017-11-30 |title=The habitability of the Milky Way during the active phase of its central supermassive black hole |url=https://www.nature.com/articles/s41598-017-16110-0 |journal=Scientific Reports |language=en |volume=7 |issue=1 |pages=16626 |doi=10.1038/s41598-017-16110-0 |issn=2045-2322|arxiv=1711.11318 }}</ref>

The inherent [[energy]] from AGNs can also heat up the atmosphere of planets leading to ([[atmospheric escape]]). The combined effect of AGN outflows would likely make all planets within 1kpc (~{{convert|1|kpc|ly|0|abbr=off|lk=out|disp=out}}) of the center of a galaxy uninhabitable.<ref>{{Cite journal |last1=Ambrifi |first1=A |last2=Balbi |first2=A |last3=Lingam |first3=M |last4=Tombesi |first4=F |last5=Perlman |first5=E |date=2022-05-01 |title=The impact of AGN outflows on the surface habitability of terrestrial planets in the Milky Way |url=https://academic.oup.com/mnras/article/512/1/505/6539336 |journal=Monthly Notices of the Royal Astronomical Society |volume=512 |issue=1 |pages=505–516 |doi=10.1093/mnras/stac542 |doi-access=free |issn=0035-8711|arxiv=2203.00929 }}</ref>