Little red dot (galaxy)
Little red dots (LRDs) are a class of small, red-tinted galaxies discovered by the James Webb Space Telescope.[1][2][3] Their discovery was published in March 2024, and they are currently poorly understood.[4] They appear to have existed between 0.6 and 1.6 billion years after the Big Bang, from 13.2 to 12.2 billion years ago.[1]
LRDs were first selected by photometric methods,[definition needed] but soon 80% of them were found to have very broad Balmer emission lines, suggesting that they are active galactic nuclei (AGN) and host supermassive black holes at their center.[citation needed]
However, LRDs also exhibit properties that are difficult to explain within the AGN scenario. For example, the flat infrared SED[definition needed] and the lack of x-ray detection. LRDs also show very weak variability.[of what?][citation needed]
Several models have been proposed to explain the observed properties of LRDs.[citation needed]
The gas in LRDs spins extremely fast, at around 3,000 km/h where typical gas flow is around 300 km/h.[1] Some scientists argue that the gas is accelerated to these extreme speeds by spinning, supermassive black holes; others suggest that the LRDs are extremely compact in order to spin at their speeds.[1] Most are also small, usually around 2% of the radius of the Milky Way.[3]
References
[edit]- ^ a b c d Boyle, Rebecca (2024-10-09). "The 'Beautiful Confusion' of the First Billion Years Comes Into View". Quanta Magazine. Retrieved 2024-10-18.
- ^ "Little Red Dots: Stars or Black Holes?". NASA Space News. 2024-09-09. Retrieved 2024-10-18.
- ^ a b Pacucci, Fabio; Conversation, The. "Hidden, compact galaxies in the distant universe—searching for the secrets behind the little red dots". phys.org. Retrieved 2024-10-18.
- ^ Matthee, Jorryt; Naidu, Rohan P.; Brammer, Gabriel; Chisholm, John; Eilers, Anna-Christina; Goulding, Andy; Greene, Jenny; Kashino, Daichi; Labbe, Ivo; Lilly, Simon J.; Mackenzie, Ruari; Oesch, Pascal A.; Weibel, Andrea; Wuyts, Stijn; Xiao, Mengyuan (March 2024). "Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys". The Astrophysical Journal. 963 (2): 129. arXiv:2306.05448. Bibcode:2024ApJ...963..129M. doi:10.3847/1538-4357/ad2345. ISSN 0004-637X.
Further reading
[edit]- Matthee, Jorryt; Naidu, Rohan P.; Brammer, Gabriel; Chisholm, John; Eilers, Anna-Christina; Goulding, Andy; Greene, Jenny; Kashino, Daichi; Labbe, Ivo; Lilly, Simon J.; Mackenzie, Ruari; Oesch, Pascal A.; Weibel, Andrea; Wuyts, Stijn; Xiao, Mengyuan (March 2024). "Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys". The Astrophysical Journal. 963 (2): 129. arXiv:2306.05448. Bibcode:2024ApJ...963..129M. doi:10.3847/1538-4357/ad2345. ISSN 0004-637X.
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