Astronomers reported the discovery of a new large, dormant galaxy with a high redshift. The galaxy, named COSMOS-1047519, was discovered using the Keck I telescope. The discovery was detailed in a paper published Aug. 29 on the preprocessing server. arXiv.

Massive galaxies that have stopped forming stars (known as dormant galaxies) are likely ancestors of giant elliptical galaxies. Given that these objects form stars sooner and accumulate stellar masses faster, they could be key in improving our understanding of the evolutionary process of the galaxy.

Only a very small number of spectroscopically confirmed high redshift (above 4.0) dormant galaxies have been detected to date. The search for such new galaxies is of great importance to astronomers because they can improve our understanding of the early stages of the universe.

Now, a team of astronomers led by Takumi Kakimoto of Japan’s Advanced Research University has confirmed the discovery of another high-mass stable galaxy with a redshift of 4.53. The discovery was made using the Keck/MOSFIRE spectrograph.

“Based on Keck/MOSFIRE observations, we present spectroscopic verification of a massive dormant galaxy at z = 4.53. Very high star mass and very low star formation rates have been confirmed through extensive SED fitting. [спектрального розподілу енергії]”Using both photometry and spectrum,” the researchers write in the paper.

Observations have shown that COSMOS-1047519 has a mass of about 60 billion solar masses and a star formation rate (SFR) of only 10 solar masses per year. The stellar age of the galaxy is estimated to be 180 million years.

The astronomers noted that the estimated SFR is 1 dex lower than the main star-forming sequence with a redshift of 4.5. The star formation history of COSMOS-1047519, extracted from the SED alignment, shows that the galaxy experienced a burst of starburst at redshift 5.0 followed by a rapid extinction on a timescale of about 100 million years.

The results therefore make COSMOS-1047519 one of the youngest resident galaxies with a redshift of over 3.0. The data also shows that COSMOS-1047519 is likely a galaxy in the process of extinction.

Trying to find the physical processes responsible for suppressing star formation in COSMOS-1047519, the authors of the paper propose the most plausible hypothesis.

“These findings suggest that gas depletion from stellar explosions and/or AGN feedback caused by intergalactic interactions or mergers may be responsible for the extinction,” the researchers concluded. Source