“Soon the skies showed an unusual appearance, as all the stars just behind me were already deep red, while those directly in front were purple,” said science fiction philosopher and author Olaf Stapledon, describing the phenomena known as “redshifts.” “In his science fiction novel, Creator of stars, a history of life in the universe. In 1929, Edwin Hubble discovered that the universe was expanding, with most other galaxies moving away from us. The light from these galaxies shifts to longer (farther and redder) wavelengths – in other words, it shifts to red as a result of the expansion of the universe.
Quasar – Bright as 600 trillion suns
A quasar can overshadow 10,000 galaxies for millions of years. In January 2019, astronomers using data from the NASA / ESA Hubble Space Telescope announced that the discovery of the brightest quasar ever seen in the early universe with a brightness of about 600 trillion suns – the brightest nucleus ever found in an active galaxy and its powerful radiance, created by the energy released by gas falling into the supermassive black hole at its center several hundred million times more massive than our sun. Ancient quasars can give an idea of the birth of galaxies when the universe was about a billion years old.
Fast forward this week, astronomers at the Canary Institute of Astrophysics (IAC) announced the discovery of a galaxy with an ultraviolet luminosity comparable to that of a quasar, using observations made with the Gran Telescopio Canarias (GTC) at the Roque de Los Muchachos Observatory islands and with a large millimeter / submillimeter massif ATACAMA (ALMA) in Chile.
Forces beyond understanding – the Horizon telescope magnifies the massive quasar jet
The galaxy, called BOSS-EUVLG1, has a redshift of 2.47. This is a measure of the redness of light coming from the galaxy, and can be used to find its distance, the farther away the galaxy, the greater the value. For BOSS-EUVLG1, the value of 2.47 means that we are observing the galaxy when the universe was about 2,000 million years old, about 20% of its current age.
Pictured above, left and center: shows the sky area containing BOSS-EUVLG1, which stands out due to its blue color. Credit: DESI Legacy Imaging Surveys. Right: A painting by the artist of the burst of star formation in BOSS-EUVLG1, which contains a large number of young massive stars and almost no dust. (Gabriel Perez Diaz, SMM, IAC).
The large redshift and luminosity values of BOSS-EUVLG1 led to its earlier classification in the BOSS (Baryon Oscillation Spectroscopic Survey) project as a quasar. However, from observations made with the OSIRIS and EMIR instruments on the GTC and the millimeter-wave telescope ALMA, the researchers showed that this is not a quasar, but in fact a galaxy with extreme, exceptional properties.
Young, massive stars – 1000 times the Milky Way
The study reveals that the high brightness of BOSS-EUVLG1 in ultraviolet and Lyman-alpha emissions is due to the large number of young, massive stars in the galaxy. This high luminosity, well above the range of other galaxies, led to its initial identification as a quasar. However, in quasars, the high luminosity is due to the activity around the supermassive black holes in their nuclei, not to the formation of stars.
“BOSS-EUVLG1 appears to be dominated by a burst of young, very massive star formation, with almost no dust and very low metallicity,” said Rui Marquis Chavez, a CAB researcher and former doctoral student at the Institut de Astrofísica de Canarias and the University of La Laguna. ULL) and the first author of the article.
“Puzzling” – Radio galaxies from the early universe still look huge
The rate of star formation in this galaxy is very high, about a thousand solar masses per year, about a thousand times higher than in the Milky Way, although the galaxy is 30 times smaller. “This rate of star formation is comparable only to the brightest infrared galaxies known, but the absence of dust in BOSS-EUVLG1 allows its ultraviolet and visible radiation to reach us with almost no attenuation,” explains Ismail Perez Furnon. IAC researcher and co-author.
Short lifespan with high brightness in UV
Thus, the results of the study suggest that BOSS-EUVLG1 is an example of the initial stages of the formation of massive galaxies. Despite its high luminosity and rate of star formation, its low metallicity indicates that the galaxy has hardly had time to enrich its interstellar medium with dust and newly formed metals. Nevertheless, “the galaxy will evolve into a more dusty phase, similar to infrared galaxies,” said Camilo E. Jimenez Angel, a doctoral student at IAC and co-author of the article. Also, its high brightness in UV will last only a few hundred million years, a very short period of galaxy evolution.
“This would explain why other galaxies like BOSS-EUVLG1 have not been discovered,” said Claudio Dala Vecchia, an IAC researcher and co-author.
Source: “The discovery of the most radiant star-forming galaxy with UV-Ly-alpha: a young, dust- and metal-poor stellar wave with luminosity-like brightness.”
The Daily Galaxy, Sam Cabot, through the IAC and the Hubble Space Telescope
The image at the top of the page shows four “ultra-red” galaxies that formed when our universe was about a billion years old, discovered by a team of astronomers led by Jasheng Huang (Harvard-Smithsonian Center for Astrophysics) using the Spitzer Space Telescope.