Little red dots (LRDs) are a class of small, red-tinted astronomical objects with unexpected characteristics observed using the James Webb Space Telescope (JWST). First reported in a preprint in June 2023 and first published in a peer-reviewed scientific journal in March 2024, they appear to have existed between 0.6 and 1.6 billion years after the Big Bang (13.2 to 12.2 billion years ago), with a majority found around 600 million years post-Big Bang. As of 2025, over 300 little red dots have been observed. One theory is that the little red dots are early stages of supermassive black holes, and the original reports identified LRDs as a type of early active galactic nucleus (AGN) containing a supermassive black hole. However, while this explains their age and appearance, they do not have the same characteristics as known AGNs. For example, they do not appear to emit X-rays, have a flattened rather than steeply rising infrared spectrum, and display very little variability between themselves. Models suggest that the red color and spectrum of LRD MoM-BH*-1 is a result of light scattering from dense ionized gas. Another theory holds that little red dots were instead supermassive non-metallic primordial stars—also known as population III stars—of perhaps a million solar masses, seen in the last few thousands of years of their lifetimes. Theoretical modelling of such stars appeared to closely match the spectrum features and luminosity of LRDs, including the presence of a "strong, broad Hβ emission line alongside other Balmer lines in absorption", and in particular the photosphere of such a star would cause the V-shaped Balmer break seen in LRDs. The authors further hypothesized that such stars were progenitors of supermassive black holes, also explaining the early development of the latter objects. Other theories are that they are quasi-stars or similar objects, consisting of a black hole surrounded by a gaseous envelope.
As active galactic nuclei
Little red dots were first reported as abundant, faint active galactic nuclei (AGN) found by seeking broad Balmer line emitters. Subsequent surveys confirmed their abundance and their relative faint UV spectrum. Active galactic nuclei are defined as small regions in the centers of galaxies that emit copious amounts of energy in the form of bright jets and winds. One property of LRDs explained by the AGN theory is the red color of the galaxies themselves. Astrophysicists have determined that the distinct color can be attributed to the massive amounts of gas, dust, and electromagnetic energy that surrounds the AGN and supermassive black hole. This region is also known as the accretion disk. The gas in LRDs spins extremely fast. Scientists argue that the gas is accelerated to these extreme speeds by spinning supermassive black holes. A team using the Webb telescope targeted LRDs in the 'Red Unknowns: Bright Infrared Extragalactic Survey', observing rapid gas orbits of roughly 900 km/s—a strong indicator of black hole accretion. On the other hand, LRDs also exhibit properties that are difficult to explain within the AGN scenario. For example, they have a flat infrared spectrum, and little X-ray emission has been detected. LRDs also show very weak time variability, while high variability is often seen in AGN observation.
Observed properties Several models have been proposed to explain the observed properties of little red dots. The shape of the ultraviolet spectrum can be explained by the scattered AGN light or by the gray dust extinction law. A spectral energy distribution (SED) fit can be modeled for many LRDs from OB stellar clumps within dense dusty regions, with integrated light obscured at the 90–95% level. Research has shown that LRDs do not commonly exist at lower redshifts. One possible reason for this observation is "inside-out growth." When a galaxy evolves and expands outward from its nucleus at lower redshifts, a decreasing amount of gas is deposited near the accreting black hole. Thus, the black hole sheds its outer gas layers, becomes bluer, and is no longer categorized as an LRD. 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. From a sample of 99 little red dots analyzed for 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 galaxy interactions and mergers, with potential evidence to suggest early stages of galaxy and black hole growth. These suspected young black holes are among the smallest recorded, at 105 – 107 solar masses. Likely local analogues of LRDs were discovered in a sample of green pea galaxies (GP). These are broad-line AGN-hosting green peas (BLGP) with V-shaped rest-frame 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 holes.
RUBIES
RUBIES, the "Red Unknowns: Bright Infrared Extragalactic Survey", is a JWST program led by Anna de Graaff and Gabriel Brammer that observed ~300 "very red sources" in the Ultra Deep Survey (UDS) and Extended Groth Strip (EGS) fields. Research conducted in association with RUBIES program has found that sources of a selected group (2 < z < 5) have a majority of massive quiescent galaxies, which is 10 times the original estimated value. The program has also found that observed LRDs have much lower levels of hot and cold gas than models would suggest, pointing away from the possibilities of AGNs or star-forming galaxies, although this is still debated.
Notable LRDs
The Cliff (RUBIES-UDS-154183)
The Cliff is an LRD with a prominent Balmer break, discovered via JWST's RUBIES program. Detailed spectroscopic observations suggest that The Cliff might be a black hole star.
CAPERS-LRD-z9 CAPERS-LRD-z9 is a Little Red Dot confirmed to be a broad-line active galactic nucleus (BLAGN) with the redshift z = 9.288. It is the highest redshift AGN known. CAPERS-LRD-z9 exhibits a prominent Balmer break and "provides strong evidence in support of the 'dense-gas-enshrouded AGN'" explanation. These unusual Balmer jumps are notable properties of LRDs, causing difficulties in observations and spectroscopic analysis. Some LRDs exhibit a symmetrical density distribution of electron scattering, thus a gaseous envelope absorbing nebular spectra is a credible possibility.
A2744–45924 The LRD A2744–45924 is located in the Abell 2744 field, and is the most optically luminous LRD found by JWST.
RUBIES-BLAGN-1 RUBIES-BLAGN-1 is an LRD which is "an unusually bright LRD (zspec = 3.1) observed as part of the RUBIES program. This LRD exhibits broad emission lines ( FWHM ~ 4000 km s−1), a blue UV continuum, a clear Balmer break, and a red continuum sampled out to rest-frame 4 μm with MIRI."
J1007_AGN The LRD J1007_AGN has a redshift z = 7.3, and is "embedded in an overdensity of eight nearby galaxies".
Abell 2744-QSO1 Abell 2744-QSO1 is an little red dot with z = 7.04. It was described as a "naked" black hole, because very few stars are in its vicinity.
MoM-BH*-1
MoM-BH*-1 is a prominent LRD described as "a higher-redshift analogue of The Cliff". MoM-BH*-1 outshines the galaxy it hosts and models suggest its red color derives from light emitted as gas falls into a black hole scattering off surrounding gas on the way to telescopes. A team of astronomers led by Rohan P. Naidu has suggested light from MoM-BH*-1 could be explained in terms of a proposed astrophysical object, a black hole star.
References
Further reading Boyle, Rebecca (March 2026). "Little Red Dots". Scientific American. Vol. 334, no. 3. New York: Springer Nature America. pp. 36–43. Lin, Xiaojing (2025). "The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes". arXiv:2507.10659v1 [astro-ph.GA]. Inayoshi, Kohei; Maiolino, Roberto (February 20, 2025). "Extremely Dense Gas around Little Red Dots and High-redshift Active Galactic Nuclei: A Nonstellar Origin of the Balmer Break and Absorption Features". The Astrophysical Journal Letters. 980 (2): L27. arXiv:2409.07805. Bibcode:2025ApJ...980L..27I. doi:10.3847/2041-8213/adaebd. Kokorev, Vasily; et al. (2023). "UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50". The Astrophysical Journal Letters. 957 (1): L7. arXiv:2308.11610. Bibcode:2023ApJ...957L...7K. doi:10.3847/2041-8213/ad037a. Setton, David J.; et al. (2024). "Little Red Dots at an Inflection Point: Ubiquitous "V-Shaped" Turnover Consistently Occurs at the Balmer Limit". The Astrophysical Journal. 995 (1): 118. arXiv:2411.03424. Bibcode:2025ApJ...995..118S. doi:10.3847/1538-4357/ae1500. Xiao, Mengyuan; et al. (2025). "No [CII] or dust detection in two Little Red Dots at zspec > 7". Astronomy & Astrophysics. 700: A231. arXiv:2503.01945. doi:10.1051/0004-6361/202554361. Whalen, Kelly E.; Weaver, Kimberly A.; Hickox, Ryan C.; Lambrides, Erini (2026). "Limitations on Morphological Fitting for JWST "Little Red Dots"". The Astrophysical Journal. 998 (1): 133. arXiv:2509.21236. Bibcode:2026ApJ...998..133W. doi:10.3847/1538-4357/ae31e5. De Luca, Valerio; Del Grosso, Loris; Franciolini, Gabriele; Kritos, Konstantinos; Berti, Emanuele; d'Orazio, Daniel; Silk, Joseph (2026). "Primordial-Black-Hole-Based Pathways to Little Red Dots". Physical Review Letters. 136 (23) 231402. arXiv:2512.19666. Bibcode:2026PhRvL.136w1402D. doi:10.1103/6y1w-87pd. PMID 42360946.
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