Universe Today | 2023 Feb 15
Astronomers have discovered a galaxy with very little or no stellar mass. Galaxies like these are called ‘dark galaxies’. It contains clouds of gas but very few stars, possibly none. This is the only isolated dark dwarf galaxy in the local universe.
All galaxies are made of mostly dark matter. The visible matter, like stars, gas and dust, makes up only a small percentage of a galaxy’s mass. But galaxies like this one, named FAST J0139+4328, are even more extreme, and its low luminosity suggests there are no stars, only clouds of gas. The astronomers who discovered it say the galaxy is “without any optical counterpart.”
Astronomers found the new dark galaxy with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). It’s a newly discovered galaxy and appears in most ways to be a typical disk galaxy. But it has an extremely low magnitude and low stellar mass. “These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083. This is the first time that an isolated dark galaxy has been detected in the nearby universe,” the researchers write in their article. ...
A redshift of z = 0.0083 means the galaxy is between about 1 million and 1.25 million light-years away. It’s an isolated HI cloud, meaning it’s a cloud of neutral hydrogen rather than ionized hydrogen or molecular hydrogen. The researchers say it’s in the form of a disk galaxy due to its shape and its rotational structure. ...
Discovery of an isolated dark dwarf galaxy in the nearby universe ~ Jin-Long Xu et al
- arXiv > astro-ph > arXiv:2302.02646 > 06 Feb 2023