Little red dot (galaxy)

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A Little Red Dot galaxy (center) in false color. Little red dot galaxy J1148-18404.jpg
A Little Red Dot galaxy (center) in false color.
False-color stamps of 20 Little Red Dot galaxies. Little red dot galaxy stamps 20 unlabeled.jpg
False-color stamps of 20 Little Red Dot galaxies.

Little red dots (LRDs) are a class of small, red-tinted galaxies discovered by the James Webb Space Telescope (JWST). [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 (13.2 to 12.2 billion years ago), with a majority found around 600 million years post-Big Bang. [1] [5] Only 341 LRD galaxies have been identified thus far with JWST. [6]

LRDs were first selected by photometric methods because they are blue in ultraviolet and red in the optical spectrum. [4] 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. [7] 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. [8] [9] It is important for scientists to model and study the properties of AGNs such that we can better understand supermassive black hole formation and how it contributes to the structure and dynamics of LRDs. [10] One important 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 accredited to the massive amounts of gas, dusk, and electromagnetic energy that surrounds the AGN and supermassive black hole. [11] This region is also known as the accretion disk.

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 [12] and lack x-ray detection. [13] [14] LRDs also show very weak time variability, often seen in AGN observation. [15]

Several models have been proposed to explain the observed properties of LRDs. [16] [17] [18] The shape of the ultraviolet spectrum can be explained by the scattered AGN light [16] [17] or by the gray dust extinction law. [18]

The gas in LRDs spins extremely fast. [1] Some scientists argue that the gas is accelerated to these extreme speeds by spinning, supermassive black holes; it has also been argued that LRDs are extremely compact to spin at their speeds. [1] Most are also small, usually around 2% of the radius of the Milky Way. [3] A team working under the Webb Telescope targeted LRDs in the Red Unknowns: Bright Infrared Extragalactic Survey, observing rapid gas orbits of roughly 2 million miles per hour-- A strong indicator of black hole accretion. [5]

Research has shown that LRDs do not commonly exist at lower redshifts. One possible reason for this observation is what Webb Space Telescope calls "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. [5]

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 spectral energy distribution (SED). Seven such V-shaped BLGPs were identified. These V-shaped BLGPs host over-massive black holes. [19]

Related Research Articles

<span class="mw-page-title-main">Quasar</span> Active galactic nucleus (AGN) containing a supermassive black hole

A quasar is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Quasars are usually categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin.

An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such excess, non-stellar emissions have been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy.

<span class="mw-page-title-main">Supermassive black hole</span> Largest type of black hole

A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.

<span class="mw-page-title-main">Intermediate-mass black hole</span> Class of black holes with a mass range of 100 to 100000 solar masses

An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range of one hundred to one hundred thousand (102–105) solar masses: significantly higher than stellar black holes but lower than the hundred thousand to more than one billion (105–109) solar mass supermassive black holes. Several IMBH candidate objects have been discovered in the Milky Way galaxy and others nearby, based on indirect gas cloud velocity and accretion disk spectra observations of various evidentiary strength.

<span class="mw-page-title-main">NGC 3226</span> Dwarf elliptical galaxy in the constellation Leo

NGC 3226 is a dwarf elliptical galaxy that is interacting with the spiral galaxy NGC 3227. They were both discovered by German-British astronomer William Herschel on 15 February 1784. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.

<span class="mw-page-title-main">Hanny's Voorwerp</span> Astronomical object appearing as a bright blob, discovered by Hanny van Arkel

Hanny's Voorwerp is a type of astronomical object called a quasar ionization echo. It was discovered in 2007 by Dutch schoolteacher Hanny van Arkel while she was participating as a volunteer in the Galaxy Zoo project, part of the Zooniverse group of citizen science websites. Photographically, it appears as a bright blob close to spiral galaxy IC 2497 in the constellation Leo Minor.

<span class="mw-page-title-main">WISE J031624.35+430709.1</span> Star in the constellation Perseus

WISE J031624.35+430709.1 is a brown dwarf of spectral class T8, located in constellation Perseus at approximately 106 light-years from Earth. It was one of the furthest T-class brown dwarfs known. In 2024 a T dwarf about 2 kpc distant, with a low-metallicity was discovered with the JWST. This brown dwarf is called JADES-GS-BD-9. Additional kpc distant T dwarfs were discovered by two teams, with UNCOVER-BD-1 being 4.5 or 4.8 kpc distant.

<span class="mw-page-title-main">CID-42</span> Galaxy quasar in the constellation Sextans

CID-42 is a galaxy quasar about 3.9 billion light years away in the constellation Sextans. It is believed to have a supermassive black hole at its center.

Misty C. Bentz is an American astrophysicist and Professor of Physics and Astronomy at Georgia State University. She is best known for her work on supermassive black hole mass measurements and black hole scaling relationships.

In astronomy, quenching is the process in which star formation shuts down in a galaxy. A galaxy that has been quenched is called a quiescent galaxy. Several possible astrophysical mechanisms have been proposed that could lead to quenching, which either result in a lack of cold molecular gas, or a decrease in how efficiently stars can form from molecular gas.

<span class="mw-page-title-main">NGC 5252</span> Galaxy in the constellation of Virgo

NGC 5252 is a lenticular galaxy located in the constellation Virgo. It is located at a distance of about 220 to 320 million light years from Earth, which, given its apparent dimensions, means that NGC 5252 is about 100,000 light years across. It was discovered by William Herschel on February 2, 1786.

<span class="mw-page-title-main">UHZ1</span> Background galaxy containing a quasar

UHZ1 is a background galaxy containing a quasar. At a redshift of approximately 10.1, UHZ1 is at a distance of 13.2 billion light-years, seen when our universe was about 3 percent of its current age. This redshift made it the most distant, and therefore earliest known quasar in the observable universe as of 2023. To detect this object, astronomers working at the Chandra X-ray Observatory used the Abell 2744's cluster mass as a gravitational lens in order to magnify distant objects directly behind it. At the time of discovery, it exceeded the distance record of QSO J0313−1806.

<span class="mw-page-title-main">IC 1623</span> Galaxy pair in the constellation Cetus

IC 1623 is a galaxy merger in the constellation Cetus. The galaxy lies about 250 million light years away from Earth, which means, given its apparent dimensions, that IC 1623 is approximately 115,000 light years across. It was discovered by Lewis Swift on November 19, 1897.

<span class="mw-page-title-main">SDSS J0849+1114</span> Trio of interacting galaxies in the constellation Cancer

SDSS J0849+1114 is a late-stage galaxy merger forming from a trio of galaxies located in the constellation of Cancer. At the redshift of 0.077, they are located 1.06 billion light-years from Earth. First discovered as a triple active galactic nucleus (AGN) candidate in a Sloan Digital Sky Survey study published in 2011, they received significant attention when astronomers discovered it harbors three supermassive black holes in its center.

<span class="mw-page-title-main">UNCOVER-BD-1</span> UNCOVER-BD-1 is a distant brown dwarf

UNCOVER-BD-1 is a distant brown dwarf. It is the most distant T dwarf discovered to date.

<span class="mw-page-title-main">IC 5063</span> Galaxy in the constellation Indus

IC 5063 is a post-merger system and is a Seyfert 2 galaxy. This active galactic nucleus (AGN) produces on the one hand interactions with the interstellar medium (ISM) and large radio outflows. On the other hand, the accretion disk around the supermassive black hole, produces crepuscular rays. It is the first discovered case of a black hole disk producing such rays, but circumstellar disks around some young stars are already known to produce similar shadows. The crepuscular rays were first noted in an image by Judy Schmidt, who posted her image of IC 5063 on the social media platform Twitter.

In astronomy, a disk wind is a particle outflow observed around accretion disks, mainly near protoplanetary disks and active galactic nulei (AGN). The disk wind is made up of a gaseous and a dusty component. Especially in edge-on protoplanetary disks this disk wind can be directly imaged.

Hagai Netzer is an Israeli astrophysicist and Professor Emeritus at Tel Aviv University, known for his research on quasars, active galactic nuclei (AGNs), Black hole, star-forming galaxies, and the interplay of gas and dust in the universe. He was awarded the Weizmann Prize in 2005 and is a Fellow of the Israel Physical Society as well as an associate of the Royal Astronomical Society. Moreover, he has authored five books on astronomy and science in Hebrew, three books in English, and more than 300 research papers in scientific journals.

References

  1. 1 2 3 4 Boyle, Rebecca (2024-10-09). "The 'Beautiful Confusion' of the First Billion Years Comes Into View". Quanta Magazine. Retrieved 2024-10-18.
  2. ↑ "Little Red Dots: Stars or Black Holes?". NASA Space News. 2024-09-09. Retrieved 2024-10-18.
  3. 1 2 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.
  4. 1 2 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.
  5. 1 2 3 "Newfound Galaxy Class May Indicate Early Black Hole Growth, Webb Finds". Webb. Retrieved 2025-02-03.
  6. ↑ Siegel, Ethan (Jan 22, 2025). "JWST fully solves the mystery of "Little Red Dots"". Medium. Retrieved Jan 29, 2025.{{cite web}}: CS1 maint: url-status (link)
  7. ↑ Greene, Jenny E.; Labbe, Ivo; Goulding, Andy D.; Furtak, Lukas J.; Chemerynska, Iryna; Kokorev, Vasily; Dayal, Pratika; Volonteri, Marta; Williams, Christina C.; Wang 王, Bingjie 冰洁; Setton, David J.; Burgasser, Adam J.; Bezanson, Rachel; Atek, Hakim; Brammer, Gabriel (2024-03-01). "UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5". The Astrophysical Journal. 964 (1): 39. arXiv: 2309.05714 . Bibcode:2024ApJ...964...39G. doi: 10.3847/1538-4357/ad1e5f . ISSN   0004-637X.
  8. ↑ "What Are Active Galactic Nuclei?". Webb. Retrieved 2025-01-30.
  9. ↑ information@eso.org. "Active Galactic Nucleus". esahubble.org. Retrieved 2025-01-30.
  10. ↑ Matthee, Jorryt (March 10, 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) – via Harvard.
  11. ↑ published, Robert Lea (2025-01-27). "Supermassive black holes in 'little red dot' galaxies are 1,000 times larger than they should be, and astronomers don't know why". Space.com. Retrieved 2025-01-30.
  12. ↑ Williams, Christina C.; Alberts, Stacey; Ji, Zhiyuan; Hainline, Kevin N.; Lyu, Jianwei; Rieke, George; Endsley, Ryan; Suess, Katherine A.; Sun, Fengwu; Johnson, Benjamin D.; Florian, Michael; Shivaei, Irene; Rujopakarn, Wiphu; Baker, William M.; Bhatawdekar, Rachana (2024-06-01). "The Galaxies Missed by Hubble and ALMA: The Contribution of Extremely Red Galaxies to the Cosmic Census at 3 < z < 8". The Astrophysical Journal. 968 (1): 34. arXiv: 2311.07483 . Bibcode:2024ApJ...968...34W. doi: 10.3847/1538-4357/ad3f17 . ISSN   0004-637X.
  13. ↑ Ananna তনিমা তাসনিম, Tonima Tasnim অনন্যা; Bogdán, Ákos; Kovács, Orsolya E.; Natarajan, Priyamvada; Hickox, Ryan C. (2024-07-01). "X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes?". The Astrophysical Journal Letters. 969 (1): L18. arXiv: 2404.19010 . Bibcode:2024ApJ...969L..18A. doi: 10.3847/2041-8213/ad5669 . ISSN   2041-8205.
  14. ↑ Yue, Minghao; Eilers, Anna-Christina; Ananna, Tonima Tasnim; Panagiotou, Christos; Kara, Erin; Miyaji, Takamitsu (2024-10-01). "Stacking X-Ray Observations of "Little Red Dots": Implications for Their Active Galactic Nucleus Properties". The Astrophysical Journal Letters. 974 (2): L26. arXiv: 2404.13290 . Bibcode:2024ApJ...974L..26Y. doi: 10.3847/2041-8213/ad7eba . ISSN   2041-8205.
  15. ↑ Kokubo, Mitsuru; Harikane, Yuichi (2024). "Challenging the AGN scenario for JWST/NIRSpec broad Hα emitters/Little Red Dots in light of non-detection of NIRCam photometric variability and X-ray". arXiv: 2407.04777 [astro-ph.GA].
  16. 1 2 Kocevski, Dale D.; Onoue, Masafusa; Inayoshi, Kohei; Trump, Jonathan R.; Arrabal Haro, Pablo; Grazian, Andrea; Dickinson, Mark; Finkelstein, Steven L.; Kartaltepe, Jeyhan S.; Hirschmann, Michaela; Aird, James; Holwerda, Benne W.; Fujimoto, Seiji; Juneau, Stéphanie; Amorín, Ricardo O. (2023-09-01). "Hidden Little Monsters: Spectroscopic Identification of Low-mass, Broad-line AGNs at z > 5 with CEERS". The Astrophysical Journal Letters. 954 (1): L4. arXiv: 2302.00012 . Bibcode:2023ApJ...954L...4K. doi: 10.3847/2041-8213/ace5a0 . ISSN   2041-8205.
  17. 1 2 Labbe, Ivo; Greene, Jenny E.; Bezanson, Rachel; Fujimoto, Seiji; Furtak, Lukas J.; Goulding, Andy D.; Matthee, Jorryt; Naidu, Rohan P.; Oesch, Pascal A.; Atek, Hakim; Brammer, Gabriel; Chemerynska, Iryna; Coe, Dan; Cutler, Sam E.; Dayal, Pratika (2023). "UNCOVER: Candidate Red Active Galactic Nuclei at 3 < z < 7 with JWST and ALMA". arXiv: 2306.07320 [astro-ph.GA].
  18. 1 2 Li, Zhengrong; Inayoshi, Kohei; Chen, Kejian; Ichikawa, Kohei; Ho, Luis C. (2024). "Little Red Dots: Rapidly Growing Black Holes Reddened by Extended Dusty Flows". arXiv: 2407.10760 [astro-ph.GA].
  19. ↑ Lin, Ruqiu; Zheng, Zhen-Ya; Jiang, Chunyan; Yuan, Fang-Ting; Ho, Luis C.; Wang, Junxian; Jiang, Linhua; Rhoads, James E.; Malhotra, Sangeeta (2024-12-11). "Discovery of Local Analogs to JWST's Little Red Dots". arXiv: 2412.08396 [astro-ph].

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