All articles tagged with #dwarf galaxies
Astronomers analyzing metal-poor stars in the Milky Way’s plane have found chemical fingerprints suggesting a long-vanished dwarf galaxy, dubbed Loki, was absorbed by the Milky Way billions of years ago; Loki’s stars orbit both prograde and retrograde, indicating a chaotic early accretion and a relic of our galaxy’s growth.
A new JCAP study suggests dark matter may consist of two different particle types whose likelihood of annihilation depends on their relative abundances in a given galaxy. This two-component model could reconcile the Milky Way’s gamma-ray excess with the lack of a similar signal in dwarf galaxies, offering a flexible alternative to traditional single-particle dark matter theories. Future observations, especially with the Fermi Gamma-ray Telescope, could help test this idea.
New JWST and Hubble observations reveal ultra-faint dwarf galaxies were the primary engines of cosmic reionization, outnumbering large galaxies 100 to 1 and collectively emitting enough ionizing radiation to turn neutral hydrogen into ionized gas, effectively lighting up the early Universe by about a billion years after the Big Bang.
Astronomers using NASA's Chandra X-ray Observatory and Hubble traced a short gamma-ray burst (GRB 230906A) to a neutron-star merger inside a tiny dwarf galaxy, revealed by its placement in a long tidal tail; the finding shows such powerful explosions can occur in faint hosts and helps explain how heavy elements are dispersed into galactic outskirts.
A comprehensive census of over 8,000 nearby galaxies finds that active galactic nuclei are more common in dwarf galaxies than previously thought—roughly 2–5%—though far less than in mid-sized or large galaxies, suggesting a mass-dependent increase in AGN activity and underscoring the need for improved detection of faint black holes.
A JWST-backed study using gravitational lensing of galaxy cluster Abell 2744 analyzes faint, distant galaxies from the Epoch of Reionization. It finds a drop-off in ultrafaint galaxies—faint-end suppression—contradicting the expectation that there should be many more tiny galaxies. The result implies early radiation heated surrounding gas, preventing star formation in low‑mass halos and challenging the idea that the smallest galaxies powered reionization; however, conclusions depend on the cluster's lens model, and more JWST data across additional clusters are needed to confirm whether this is a universal trend.
A recent study analyzing 12 dwarf galaxies provides strong evidence supporting the existence of dark matter, challenging alternative theories like Modified Newtonian Dynamics (MOND). The findings show that the gravitational fields of these galaxies cannot be explained by visible matter alone, reinforcing the dark matter hypothesis and narrowing the search for its nature.
A study analyzing the smallest and faintest galaxies supports the presence of dark matter over modified gravity theories like MOND, showing that their gravitational behavior cannot be explained by visible matter alone and challenging previous assumptions about galaxy dynamics.
Astronomers discovered a massive, nearly invisible gas bridge and a record-breaking tail connecting two dwarf galaxies, NGC 4532 and DDO 137, located 53 million light-years away, providing insights into galaxy interactions and evolution.
Recent observations from the Hubble and James Webb Space Telescopes suggest that small dwarf galaxies played a crucial role in illuminating the early Universe during cosmic reionization, challenging previous assumptions that larger galaxies and black holes were the primary sources of ionizing radiation. This discovery highlights the importance of low-mass galaxies in shaping the Universe's evolution and opens new avenues for understanding our cosmic origins.
The article reviews the formation, properties, and significance of globular clusters and globular-cluster-like dwarfs in galaxy formation, highlighting their roles in understanding dark matter, galaxy evolution, and the early universe.
A new survey has discovered 355 mini galaxies, nearly tripling the known satellite galaxies around dwarf galaxies, which could provide valuable insights into dark matter and galaxy formation theories. The findings, made possible by the ID-MAGE survey, highlight the importance of small galaxies in understanding the universe's structure and evolution.
New research combining simulations and mathematical modeling suggests the Milky Way may have up to 100 undetected 'orphan' dwarf galaxies orbiting it, which could support the standard Lambda Cold Dark Matter (LCDM) cosmological model and help explain the discrepancy between observed and predicted satellite galaxies.
Astronomers using the JWST have discovered numerous tiny, energetic galaxies from about 800 million years after the Big Bang that likely played a key role in reionizing the universe, challenging previous ideas that larger galaxies or quasars were the main contributors.
The article explores the role of supermassive black holes in anchoring tiny galaxies, highlighting that smaller galaxies tend to be more dark matter dominated and may host supermassive black holes, with some evidence suggesting a connection between black holes and the structure of these faint galaxies, especially in the context of dark matter and galaxy formation.