Little red dot (astronomical object)

Most are extremely compact, averaging around 2% of the radius of the [[Milky Way]]. A typical LRD has a radius no greater than 500 light-years, though many have radii smaller than 150 light-years.{{Cite web |last=Pacucci |first=Fabio |title=JWST's 'Little Red Dots' Offer Astronomers the Universe's Weirdest Puzzle |url=https://www.scientificamerican.com/article/jwsts-little-red-dots-offer-astronomers-the-universes-weirdest-puzzle/ |access-date=2025-02-19 |website=Scientific American |language=en}}

Most are extremely compact, averaging around 2% of the radius of the [[Milky Way]]. A typical LRD has a radius no greater than 500 light-years, though many have radii smaller than 150 light-years.{{Cite web |last=Pacucci |first=Fabio |title=JWST's 'Little Red Dots' Offer Astronomers the Universe's Weirdest Puzzle |url=https://www.scientificamerican.com/article/jwsts-little-red-dots-offer-astronomers-the-universes-weirdest-puzzle/ |access-date=2025-02-19 |website=Scientific American |language=en}}

From a sample of 99 LRDs analyzed for [[Galaxy morphological classification|morphology]], 69 were predominantly compact without extended components, with the other 30 with more complex morphologies. Of these complex galaxies, 50% showed multiple associated components, and the rest showed highly asymmetric structures, with indications of a composite nature. It is hypothesized from this analysis that LRDs may be a product of [[Interacting galaxy|galaxy interactions]] and mergers, with potential evidence to suggest early stages of [[Galaxy formation and evolution|galaxy and black hole growth]].{{Cite journal |last1=Rinaldi |first1=P. |last2=Bonaventura |first2=N. |last3=Rieke |first3=G. H. |last4=Alberts |first4=S. |last5=Caputi |first5=K. I. |last6=Baker |first6=W. M. |last7=Baum |first7=S. |last8=Bhatawdekar |first8=R. |last9=Bunker |first9=A. J. |last10=Carniani |first10=S. |last11=Curtis-Lake |first11=E. |last12=D’Eugenio |first12=F. |last13=Egami |first13=E. |last14=Ji |first14=Z. |last15=Johnson |first15=B. D. |date=2025-10-10 |title=Not Just a Dot: The Complex UV Morphology and Underlying Properties of Little Red Dots |journal=The Astrophysical Journal |volume=992 |issue=1 |pages=71 |doi=10.3847/1538-4357/adfa10 |doi-access=free|arxiv=2411.14383 |bibcode=2025ApJ...992...71R |issn=0004-637X|hdl=11370/df23ecc6-c5d0-470e-b470-104468e02e06 |hdl-access=free }} These suspected young black holes are among the smallest recorded, at 10⁴ - 10⁷ solar masses.{{Cite journal |last1=Rusakov |first1=V. |last2=Watson |first2=D. |last3=Nikopoulos |first3=G. P. |last4=Brammer |first4=G. |last5=Gottumukkala |first5=R. |last6=Harvey |first6=T. |last7=Heintz |first7=K. E. |last8=Damgaard |first8=R. |last9=Sim |first9=S. A. |last10=Sneppen |first10=A. |last11=Vijayan |first11=A. P. |last12=Adams |first12=N. |last13=Austin |first13=D. |last14=Conselice |first14=C. J. |last15=Goolsby |first15=C. M. |date=2026-01-14 |title=Little red dots as young supermassive black holes in dense ionized cocoons |journal=Nature |language=en |volume=649 |issue=8097 |pages=574–579 |doi=10.1038/s41586-025-09900-4 |issn=1476-4687 |pmc=12804088 |pmid=41535486 |arxiv=2503.16595 |bibcode=2026Natur.649..574R }}

From a sample of 99 LRDs analyzed for [[Galaxy morphological classification|morphology]], 69 were predominantly compact without extended components, with the other 30 with more complex morphologies. Of these complex galaxies, 50% showed multiple associated components, and the rest showed highly asymmetric structures, with indications of a composite nature. It is hypothesized from this analysis that LRDs may be a product of [[Interacting galaxy|galaxy interactions]] and mergers, with potential evidence to suggest early stages of [[Galaxy formation and evolution|galaxy and black hole growth]].{{Cite journal |last1=Rinaldi |first1=P. |last2=Bonaventura |first2=N. |last3=Rieke |first3=G. H. |last4=Alberts |first4=S. |last5=Caputi |first5=K. I. |last6=Baker |first6=W. M. |last7=Baum |first7=S. |last8=Bhatawdekar |first8=R. |last9=Bunker |first9=A. J. |last10=Carniani |first10=S. |last11=Curtis-Lake |first11=E. |last12=D’Eugenio |first12=F. |last13=Egami |first13=E. |last14=Ji |first14=Z. |last15=Johnson |first15=B. D. |date=2025-10-10 |title=Not Just a Dot: The Complex UV Morphology and Underlying Properties of Little Red Dots |journal=The Astrophysical Journal |volume=992 |issue=1 |pages=71 |doi=10.3847/1538-4357/adfa10 |doi-access=free|arxiv=2411.14383 |bibcode=2025ApJ...992...71R |issn=0004-637X|hdl=11370/df23ecc6-c5d0-470e-b470-104468e02e06 |hdl-access=free }} These suspected young black holes are among the smallest recorded, at 10⁵ - 10⁷ solar masses.{{Cite journal |last1=Rusakov |first1=V. |last2=Watson |first2=D. |last3=Nikopoulos |first3=G. P. |last4=Brammer |first4=G. |last5=Gottumukkala |first5=R. |last6=Harvey |first6=T. |last7=Heintz |first7=K. E. |last8=Damgaard |first8=R. |last9=Sim |first9=S. A. |last10=Sneppen |first10=A. |last11=Vijayan |first11=A. P. |last12=Adams |first12=N. |last13=Austin |first13=D. |last14=Conselice |first14=C. J. |last15=Goolsby |first15=C. M. |date=2026-01-14 |title=Little red dots as young supermassive black holes in dense ionized cocoons |journal=Nature |language=en |volume=649 |issue=8097 |pages=574–579 |doi=10.1038/s41586-025-09900-4 |issn=1476-4687 |pmc=12804088 |pmid=41535486 |arxiv=2503.16595 |bibcode=2026Natur.649..574R }}

Likely local analogues of LRDs were discovered in a sample of [[Pea galaxy|Green Pea galaxies]] (GP).{{cite journal| author1=Ruqiu Lin| author2=Zhen-Ya Zheng| author3=Chunyan Jiang| author4=Fang-Ting Yuan| author5=Luis C. Ho| author6=Junxian Wang| author7=Linhua Jiang| author8=James E. Rhoads| author9=Sangeeta Malhotra| author10=L. Felipe Barrientos| author11=Isak Wold| author12=Leopoldo Infante| author13=Shuairu Zhu| author14=Xiang Ji| author15=Xiaodan Fu| title=Discovery of Local Analogs to JWST's Little Red Dots| journal=[[The Astrophysical Journal]]| volume=980| issue=2| pages=9| date=17 February 2025| doi=10.3847/2041-8213/adaaf1| doi-access=free| arxiv=2412.08396v1| bibcode=2025ApJ...980L..34L}} These are broad-line AGN-hosting Green Peas (BLGP) with V-shaped rest-frame [[Ultraviolet|UV]]-to-optical SED. Seven such V-shaped BLGPs were identified from a sample size of 2,190. These V-shaped BLGPs host over-massive [[black hole]]s.

Likely local analogues of LRDs were discovered in a sample of [[Pea galaxy|Green Pea galaxies]] (GP).{{cite journal| author1=Ruqiu Lin| author2=Zhen-Ya Zheng| author3=Chunyan Jiang| author4=Fang-Ting Yuan| author5=Luis C. Ho| author6=Junxian Wang| author7=Linhua Jiang| author8=James E. Rhoads| author9=Sangeeta Malhotra| author10=L. Felipe Barrientos| author11=Isak Wold| author12=Leopoldo Infante| author13=Shuairu Zhu| author14=Xiang Ji| author15=Xiaodan Fu| title=Discovery of Local Analogs to JWST's Little Red Dots| journal=[[The Astrophysical Journal]]| volume=980| issue=2| pages=9| date=17 February 2025| doi=10.3847/2041-8213/adaaf1| doi-access=free| arxiv=2412.08396v1| bibcode=2025ApJ...980L..34L}} These are broad-line AGN-hosting Green Peas (BLGP) with V-shaped rest-frame [[Ultraviolet|UV]]-to-optical SED. Seven such V-shaped BLGPs were identified from a sample size of 2,190. These V-shaped BLGPs host over-massive [[black hole]]s.