Three ultra-faint dwarf galaxies have been discovered around a distant spiral galaxy with a mass similar to that of the Milky Way. Dwarf galaxies are believed to be about 12 billion years old, meaning their stars formed within 2 billion years of the Big Bang early in the history of the universe.
At a distance of about 11.4 million years from Earth, the super-faint galaxies are the first to orbit a galaxy like the Milky Way outside our Milky Way’s cosmic backyard, known by astronomers as its “Local Group” which includes Andromeda and Huh. other neighboring galaxies.
Despite their vast distances and origins in the early universe, the three ultra-faint dwarf galaxies that orbit the spiral galaxy known as NGC253, or the Sculptor Galaxy, have characteristics that differ from the ultra-faint dwarf galaxies in the Local Group. are similar.
This means the new discovery may reveal more about ultra-faint dwarf galaxies in addition to helping unlock the secrets of the early universe and early galaxies.
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“Our work is an essential first step toward understanding faint galaxies beyond the Local Group and further constraining the demographics of super-faint dwarf galaxies,” said Mutlu-Pakdil, principal investigator and assistant professor of physics and astronomy at Dartmouth College. ” said one Statement. (opens in new tab) “We still don’t know if Local Group super-faint dwarf galaxies are typical or unusual. To answer this fundamental question, we need to discover more super-faint dwarf galaxies beyond our local environment and study them in detail.” need to.”
The three galaxies were first identified by MEGACAM on the Magellan Clay Telescope at Las Campanas Observatory in Chile. The discovery was later confirmed with the Hubble Space Telescope.
Ultra-faint dwarf galaxies are thought to be the least luminous and least chemically rich galaxies known to astronomers. However, dark matter is dominated by low-mass satellite galaxies. Dark matter is a mysterious form of matter that comprises about 85% of the mass of the universe, but is invisible because it does not interact with light or other forms of electromagnetic radiation. Instead its presence is known to exist based on observations of gravitational effects caused by this invisible matter.
The fact that dark matter does not interact with light means that its constituent particles cannot be protons or neutrons, the particles that make up the everyday matter that includes stars, planets and us. Until now, the particles that make up dark matter have remained mysterious. Physicists are keen to answer questions about their nature and what role they may have played in the evolution of the universe.
Most galaxies are surrounded by dark matter halos that can only be inferred from their interactions with the fundamental force of gravity, but in ultra-faint dwarf galaxies, the effect of dark matter is more significant.
This means that astronomers consider ultra-faint dwarfs to be well-preserved galactic chemical-ancient fossils that provide insight into conditions in the early universe and a path toward probing how dark matter evolved the universe. Is. This makes these three distant 12-billion-year-old dwarf galaxies ideal for studying the conditions in the universe when the first galaxies began to form.
“Dwarf galaxies are the building blocks of larger galaxies,” Mutlu-Pakdil said. “Ultra-faint dwarf galaxies are the best places to study galaxy formation on the smallest scales and learn how the tiniest dark matter clumps populate with stars and turn into galaxies.”
The team’s findings were announced Wednesday, Jan. 12, at the 241st meeting of the American Astronomical Society.
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