October 23, 2020

A galaxy with a luminosity similar to that of a quasar has been found on La Palma

An international scientific team has discovered the galaxy called Boss-Euvlg1, with star formation and hardly any dust, whose luminosity is comparable to that of a quasar, the Instituto de Astrofísica de Canarias (IAC) reported yesterday.

This team, led by researchers from the Astrobiology Center (CAB, CSIC-INTA) and in which the IAC participates, has found this galaxy in observations made with the Gran Telescopio Canarias (GTC), installed at the Roque de los Muchachos Observatory (Garafía, La Palma), and with the Atacama Large Millimeter / submillimeter Array (ALMA), in Chile.

image of the region of the sky where BOSS-EUVLG1 is located and artist’s rendering of the star formation outbreak in BOSS-EUVLG1

The discovery has been published in the Monthly Notices of the Royal Astronomical Society (MNRAS) Letters, and, as noted in an IAC statement, this galaxy has a redshift value of 2.47.

This value represents a measure of the “redness” of the light coming from the galaxy and indicates its distance from Earth and its age.

The IAC explains that the greater this displacement, the further the galaxy is and adds that in the case of Boss-Euvlg1 the value of 2.47 means that the galaxy is observed when the age of the Universe was approximately 2,700 million years, that is, 20% of their current age.

The Boss-Euvlg1 redshift and luminosity values ​​caused it to be classified by the Baryon Oscillation Spectroscopic Survey (Boss) project as a quasar.

From observations made with the GTC’s Osiris and Emir instruments and the Alma radio telescope, researchers have shown that it is not a quasar, but that it is actually a galaxy with extreme and exceptional properties.

The study indicates that the high luminosity that Boss-Euvlg1 presents in the ultraviolet range and in the Lyman Alpha emission line is due to the large number of young and massive stars it has.

This high luminosity, much greater than that of other galaxies, led to the initial thought that it was a quasar, but in quasars the high luminosity is due to the activity of supermassive black holes in the nuclei and not to the formation of stars.

Massive and young

Boss-Euvlg1 seems to be dominated by a very massive and young outbreak of star formation, with hardly any dust and with a very low metal content, indicates Rui Marques Chaves, a researcher at CAB, formerly a doctoral student at the Instituto de Astrofísica de Canarias and the University of La Laguna (ULL), and lead author of the study.

The star formation rate of this galaxy is very high, about a thousand solar masses a year, and it is about a thousand times greater than that of the Milky Way, although it is a galaxy 30 times smaller than ours.

“This rate of star formation is only comparable to that of the most luminous infrared galaxies known, but the absence of dust in Boss-Euvlg1 allows its emission in the ultraviolet and the visible to reach us with hardly any attenuation”, explains Ismael Pérez Fournon, Researcher at the IAC and the University of La Laguna and co-author of the study.

Thus, the results of the study suggest this galaxy constitutes an example of the initial phases of the formation of massive galaxies.


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