Andromeda XXXVI Discovery Sheds Light on Dark Matter Rich Dwarf Galaxies

Andromeda XXXVI is a newly found ultra-faint dwarf satellite tv for pc galaxy of Andromeda. It was noticed in archival Pan-Andromeda Survey photographs by an newbie and confirmed with deep imaging on the ten.4-m GTC (Gran Telescopio Canarias). It lies ~2.5 million light-years away, is extraordinarily faint (absolute magnitude ~–6), and solely about 200 ly throughout. With only a few stars and an enormous dark-matter element, it’s thought of a fossil of the early universe.

Discovery and Characteristics of Andromeda XXXVI

According to the analysis paper, Andromeda XXXVI was first noticed in PAndAS photographs by Giuseppe Donatiello and confirmed with deep OSIRIS/GTC imaging. Its coloration–magnitude diagram matches an outdated (~12.5 Gyr), metal-poor ([Fe/H] ≈ –2.5) stellar inhabitants. This locations the galaxy ~2.53 million ly from Earth (388 kly from M31). Its absolute magnitude (M_V ≈ –6.0) and half-light radius (~200 ly) make it amongst Andromeda’s faintest, most compact satellites. Spectroscopic follow-up shall be wanted to measure its darkish matter mass and make sure its classification.

Implications for Dark Matter and Galaxy Formation

Similar to different ultra-faint galaxies, Andromeda XXXVI is sort of faint however considerably darkish matter-dominated, making it an vital laboratory for testing galaxy formation principle and darkish matter theories. Should it kind most of its stars earlier than cosmic reionization, Andromeda XXXVI may be termed as “fossil”, with its stars being extraordinarily outdated (~12.5 Gyr), and low on metals. It also needs to be famous that such a discovery aids the understanding of the entire satellite tv for pc inhabitants round Andromeda. For occasion, in response to principle, Andromeda is anticipated to harbour as much as ~100 dwarf satellite tv for pc methods, whereas solely about ~50 have been found thus far.