A young starburst galaxy named BOSS-EUVLG1 is by far the most luminous, almost un-obscured star-forming galaxy known at any redshift.
An artist’s impression of BOSS-EUVLG1, a star-forming galaxy located some 12 billion light-years away in the constellation of Virgo. Image credit: Gabriel Pérez Díaz, SMM / IAC.
Also known as SDSS J122040.72+084238.1, BOSS-EUVLG1 is located approximately 12 billion light-years away.
First classified as a quasar, the galaxy is extremely luminous in ultraviolet (UV) and Lyman-α light.
Follow-up observations with the Gran Telescopio Canarias and the Atacama Large Millimeter/submillimeter Array (ALMA), as part of the BOSS Extremely UV-Luminous Galaxies (BOSS-EUVLG) survey, revealed that its extreme luminosity is due to an intense burst of star-formation, and not to an active supermassive black hole or gravitational lensing.
“BOSS-EUVLG1 seems to be dominated by a burst of formation of young, very massive stars, with hardly any dust, and with a very low metallicity,” said Dr. Rui Marques Chaves, an astronomer in the Centro de Astrobiologia (CSIC-INTA).
BOSS-EUVLG1 has a very high rate of star formation — about 1,000 solar masses per year, although the galaxy is 30 times smaller than our Milky Way Galaxy. For comparison, the Milky Way makes about one solar mass worth of stars per year.
“This rate of star formation is comparable only to the most luminous infrared galaxies known, but the absence of dust in BOSS-EUVLG1 allows its ultraviolet and visible emission to reach us with hardly any attenuation,” said co-author Dr. Ismael Pérez Fournon, an astronomer in the Instituto de Astrofisica de Canarias and the Universidad de La Laguna.
BOSS-EUVLG1 is seen at a time when the Universe was just 2 billion years old, about 20% of its current age. Image credit: DESI Legacy Imaging Surveys.
According to the team, BOSS-EUVLG1 is in the earliest stage of massive galaxy formation.
“The galaxy will evolve towards a dustier phase, similar to the infrared galaxies,” said co-author Camilo Jiménez-Ángel, a doctoral student in the Instituto de Astrofisica de Canarias and the Universidad de La Laguna.
“Also, its high luminosity in the UV will last only a few hundred million years, a very short period in the evolution of a galaxy.”
“This would explain why other galaxies similar to BOSS-EUVLG1 have not been discovered,” added co-author Dr. Claudio Dalla Vecchia, also from the Instituto de Astrofisica de Canarias and the Universidad de La Laguna.
The team’s paper will be published in the Monthly Notices of the Royal Astronomical Society Letters.
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R. Marques-Chaves et al. 2020. The discovery of the most UV-Lya luminous star-forming galaxy: a young, dust- and metal-poor starburst with QSO-like luminosities. MNRAS, in press; arXiv: 2009.02177
