Astronomers detect nearly 100 new extremely-metal poor galaxies

By analyzing the early information from the Darkish Vitality Spectroscopic Instrument (DESI), a world workforce of astronomers has recognized 95 new extraordinarily metal-poor galaxies at a low redshift. The discovering is detailed in a paper published December 1 on the pre-print server arXiv.

Extraordinarily metal-poor galaxies (XMPGs) are those with metallicity beneath 0.1 of the photo voltaic metallicity. Provided that these galaxies are chemically unevolved, they’ll function wonderful laboratories for investigating the chemical evolution theories of galaxies and finding out the physical processes within the early phases of their evolution.

Though XMPGs are assumed to be fairly frequent at excessive redshift, they’re troublesome to watch as a consequence of their low plenty. Subsequently, astronomers have an interest within the observations of native XMPGs at low redshift, as they’re perceived as potential analogs of primeval high-redshift younger galaxies of this sort when it comes to mass and metallicity.

Now, a bunch of astronomers led by Hu Zou of the College of Chinese language Academy of Sciences in Beijing, China, has obtained a big pattern of XMPGs primarily based on the early information from DESI.

“This work focuses on the evaluation of DESI early information, together with the Early Information Launch (EDR; DESI Collaboration et al. 2023b), the detection of XMPGs and exploration of their mass-metallicity relation,” the researchers wrote within the paper.

All in all, the workforce first chosen 1,623 star-forming galaxies with important oxygen emission traces detection. From this pattern, they recognized 223 extraordinarily metal-poor galaxies at redshifts beneath 1.0. Lastly, they confirmed 95 of them as bona fide XMPGs, whereas the 128 galaxies stay XMPG candidates.

Many of the XMPGs reported within the examine have been discovered at a low redshift of beneath 0.3 and turned out to be dwarf galaxies—with stellar plenty not exceeding 1 billion solar masses. Essentially the most metal-poor galaxy within the pattern, designated DESIJ150535.89+314639.4, has an oxygen abundance at a stage of only one/34 of that of the solar, has a stellar mass of about 15 million photo voltaic plenty, and its star-forming price was calculated to be 0.22 photo voltaic plenty per 12 months.

The astronomers famous that preliminary imaging examination of the 2 most metal-poor galaxies found from their pattern revealed two totally different morphologies. This implies totally different evolution and bodily origins; nonetheless, additional research are required as a way to affirm this speculation.

Summing up the outcomes, the authors of the paper underlined that the extraordinarily metal-poor galaxies detected by them are presumably low-redshift analogs of galaxies at excessive redshifts reaching 6.0 and even past. Subsequently, they could possibly be wonderful objects for exploring the universe at its early phases of evolution.

Extra info:
Hu Zou et al, A Giant Pattern of Extraordinarily Metallic-poor Galaxies at z<1 Recognized from the DESI Early Information, arXiv (2023). DOI: 10.48550/arxiv.2312.00300

Journal info:
arXiv

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