Astronomers are compared to a quasar with extreme ultraviolet luminescence.


Left and center: Image of the boss’ area containing the BOSS-EUVLG1, which stands out due to its blue color. Credit: Desi Legacy Imaging Survey. Right: Artist’s drawing of the star formation burst in BOSS-EUVLG1, which includes a large number of young giant stars, and hardly any dust. Credit: Gabriel Peraj Diz, SMM (IAC).

This was found at the Rook de los Mucos Observatory (Garafia, La Palma, Canary Islands) with the Grain Telescopio Canaria (GTC) and using observations made with the ATATMA Large Millimeter / Submillimeter Array.Alma), in Chile. This discovery was recently published in the journal Monthly notifications of Royal Astronomical Society letters.

The galaxy called BOSS-EUVLG1 has a red-shift of 2.47. It is a measure of the light coming from the galaxy to be red, and can be used to find its distance, the farther away from the galaxy, the higher the value. For BOSS-EUVLG1, a value of 2.47 means that we are observing the galaxy when the universe was some 2 thousand million years old, about 20% of its present age.

Due to the large redshift and luminosity values ​​of the BOSS-EUVLG1, it was classified previolly in the BOSS (Baryon Oscillation Spectroscopic Survey) project as a quasar. However, from observations made on the GTC with OSIRIS and EMIR devices and the millimeter wave telescope ALMA, researchers have shown that it is not a quasar, but indeed a galaxy with extreme, extraordinary properties.

The study showed that the high brightness of BOSS-EUVLG1 in ultraviolet and in Lyman-alpha emission is due to the large number of young, massive stars in the galaxy. Over the range of other galaxies, this high luminosity led to its initial recognition as a quasar. However, the high luminosity in quasars is due to the activity around the supermassive black hole in their nucleus, and not to star formation.

“BOSS-EUVLG1 appears to dominate the bursting of young, very massive stars, with hardly any dust, and very little metal,” says Rui Merks Chews, a CAB researcher, formerly a doctorate at Instituto The student explains. De Astrofísica de Canarias and the University of La Laguna (ULL), and the first author of the article.

The rate of star formation in this galaxy is very high, about one thousand times higher than one thousand solar mass per year Galaxy, Although the galaxy is 30 times smaller. “The rate of star formation is comparable to that known only to the brightest infrared galaxies, but the absence of dust in BOSS-EUVLG1 allows its ultraviolet and visible emission to reach us with hardly any attenuation,” IAM researchers And Parleys Foron explains. Co-author of the article.

So, the study results suggest that BOSS-EUVLG1 is an example of the early stages of formation of massive galaxies. Despite its high luminosity and star-making rate, its low metallicity suggests that the galaxy does not have time to enrich its interstellar medium with dust and newly formed metals. Nevertheless, “the galaxy will evolve towards a dustier phase similar to infrared galaxies,” -Calcillo e. Jimenez is a doctoral student at ngel, IAC, and co-author of the article. Furthermore, its high brightness in UV will only last a few hundred million years, which is a very short period in the evolution of the galaxy. ”

“This will explain why other galaxies similar to BOSS-EUVLG1 have not been discovered,” concludes Claudio Dalla Vecchia, researcher and co-author of the article at the IAC.

BOSS-EUVLG1 was discovered in the Sloan Digital Sky Survey (SDSS) BOSS project through analysis of half a million spectra of galaxies and quasars and observations with large telescopes such as GTC and ALMA.

Reference: “The most UV-ly-alpha luminous star-forming galaxy by R. Marques-Cheves, J. Allarez-Merquez, L.: A young, dust- and QSO-like metal with corroded stars”. Colina, I. Perez-Fournon, d. Shehrer, c. Dalla Vekia, t. Hashimoto, c. Jimenez-Ongel and Y. Shu, 28 September 2020, Monthly notifications of Royal Astronomical Society letters.
arXiv: 2009.02177v1