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| Rare runaway dwarf galaxy hiding a violent past/photo/paudel et al |
Astronomers have found a small, ghostly galaxy in a distant part of the universe, likely a cosmic outcast that was thrown from its original galactic group billions of years ago and left to drift in almost complete solitude.This discovery offers rare observational proof that some galaxies currently seen in isolation might actually be remnants of violent expulsions from dense galactic groups. Formed through intense interactions in crowded, chaotic environments billions of years ago, these galaxies indicate that a galaxy's current position may not fully reflect its past.
The newly discovered galaxy, named SDSS J011754.86+095819.0, or dE01+09, seems to be one of these "runaway" systems. Galaxies like dE01+09, which are small, faint, and no longer producing stars, are usually found in dense galaxy clusters where strong gravitational forces and harsh conditions strip them of gas and halt star formation.
However, dE01+09 is located over 3.9 million light-years away from its nearest likely host, the NGC 524 group in the Pisces constellation — far beyond the gravitational influence of the group
According to ,Paudel's team utilized a machine learning model that was trained on 5,000 previously cataloged early-type dwarf galaxies to analyze imaging data from the Sloan Digital Sky Survey and the DESI Legacy Imaging Survey. Among 751 candidates, dE01+09 was notable for its isolation and absence of recent star formation.The researchers also verified that no large galaxies are located within approximately 2.3 million light-years of dE01+09.
The speed at which dE01+09 travels in relation to Earth, referred to by astronomers as radial velocity, closely aligns with that of the five galaxies in the NGC 524 group, supporting the notion that it once belonged to that group.
Further observations might uncover visible evidence of that connection, such as faint tidal tails or other characteristics, Paudel explained.