A Tezpur University research scholar has discovered new stars forming beyond the visible boundaries, 1.5 to 3.9 billion light years away from Earth. Anshuman Borgohain, the research scholar and main author of the study, was part of a team of astronomers from India, the United States, and France who carried out the research.
Tezpur University Research Team Discovers Dwarf Galaxy Formation and Evolution
According to Bruce Elmegreen, a principal research staff member in the IBM research division in the United States, who was also involved in the study, it has been a mystery how some small galaxies can have active star formation.
According to Borgohain, it is still unclear how dwarf galaxies from the past evolved into the ones we see today. As a result, capturing their assembly process over cosmic ages is regarded as one of the critical links in completing the picture of galaxy formation and evolution.
The study published in Nature was conceived using the ultraviolet imaging telescope (UVIT) onboard AstroSat. The imaging capabilities of India's first dedicated multi-wavelength space observatory, AstroSat/UVIT, have opened up promising avenues in the field of extragalactic astronomy. The ability of AstroSat to resolve ultra-violet light and UV deep field imaging techniques have allowed for the detection of these very young, faint, and massive star-forming clumps.
According to Gogoi, the current work inspires young researchers in the country because it uses data from India's indigenous satellite AstroSat.The discovery of such previously unknown phenomena in the distant dwarf galaxies is just one more piece of the puzzle and a preview of what new, state-of-the-art observatories will soon be able to reveal.
Detailed Research on Dwarf Galaxy Formation and Evolution
The formation and growth of blue compact dwarf (BCD) galaxies are difficult to observe directly because these galaxies are too small to resolve at high redshift and too faint to reveal their outer regions in the local universe. Observations in the far ultraviolet at intermediate redshifts are required to demonstrate star formation in their external disks while they are still growing. The researchers used a sample of BCDs for this purpose through Ultraviolet Imaging Telescope deep observations (UVIT).
Most emit extended amounts of far-ultraviolet light beyond their optical disks, which the Hubble Space Telescope Telescope well resolves in Space (HST). It is the first time such large far-ultraviolet (FUV) disks have been observed in distant dwarfs. In the XUV regions of GS3 and GS6, there are also large FUV clumps of magnitude 25.3 (C3A), 25.46 (C3B), and 26.8 (C6A).
The majority of clumps were detected using automated software with a minimum area of five pixels. Some had to be visually separated from the main galaxy. All of the magnitudes discussed in the paper have been corrected.
The report presents evidence for excess far-ultraviolet (FUV) emission in the outer regions of BCDs in the GOODS South field at redshifts ranging from 0.1 to 0.24, corresponding to look-back times ranging from 1.3 to 2.8 billion years in standard cosmology. The Ultra-Violet Imaging Telescope on AstroSat7 made these observations.
The radial profiles of intrinsic FUV emission for ten BCDs, corrected for the instrument point spread function, have longer scale lengths than their optical counterparts observed with the Hubble Space Telescope. Such shallow FUV profiles imply that extended star formation occurs in cosmically accreting disks. The FUV's clumpy structure suggests that the outer FUV disks are gravitationally unstable. Dynamical friction on the clumps forces them inwards at a rate that exceeds 106 solar masses per billion years.
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