While satellite galaxies around massive systems like the Milky Way have been widely explored, this study turns its focus to the faint companions of dwarf galaxies - systems less than one-tenth the size of the Milky Way. These smaller galaxies are particularly rich in dark matter and are ideal for studying the underlying physics of galaxy formation.
"Studying these systems can help us piece together conditions in the early universe," said lead researcher Burcin Mutlu-Pakdil, assistant professor of physics and astronomy at Dartmouth.
"This project fills a critical gap, offering fresh insights into the process of how galaxies form and its connection to dark matter," she added. "Our goal is to build a statistical sample of the smallest galaxies in the universe, as they are the most dominated by dark matter and serve as clean laboratories for understanding its nature."
The team analyzed data from the publicly available Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, applying algorithms to remove background noise and isolate potential satellite galaxies. From there, each candidate was manually reviewed to rule out image defects and other false positives.
"With this survey, we'll be able to test whether those predictions hold true with much smaller host galaxies," said Laura Hunter, a postdoctoral fellow at Dartmouth and corresponding author on the paper.
"Astronomy is a field where you can't run experiments," Hunter noted. "All you can do is observe and make as many measurements as you can, and then put that data into a simulation and see whether it reproduces your observations. If it doesn't, that tells us that there's something wrong with our assumptions or our model of the universe."
The hosts studied varied in size and environment - factors that could influence the number and characteristics of satellites. The ongoing follow-up phase aims to confirm the satellite status of the candidates and assess their star formation rates, gas content, structure, and spatial distribution.
"Getting the answers will require a lot of resources and telescope time, but the impact will be incredible for understanding the nature of dark matter and galaxy formation at the smallest scale," said Mutlu-Pakdil. "Each one of them holds a little clue about the physics of how galaxies form."
Research Report:Identifying Dwarfs of MC Analog GalaxiEs (ID-MAGE): The Search for Satellites Around Low-mass Hosts
Related Links
Dartmouth College
Stellar Chemistry, The Universe And All Within It
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