The discovery of three faint, distant galaxies may expand knowledge of the early universe

The discovery of three faint, distant galaxies may expand knowledge of the early universe

Researchers have discovered the first ultra-faint dwarf galaxies found around a Milky Way-mass spiral galaxy outside the group of galaxies that includes the Milky Way and Andromeda. Pictured here is one of the three galaxies, Scl-MM-dw5, with its stars clustered in the center. Galaxies are estimated to be 12 billion years old, and almost all of their stars formed in the early Universe. The galaxies were identified from observations of the Magellan Megacam, and then confirmed by deeper observations from the Hubble Space Telescope. (Image by NASA, HST-GO-15938, PI: Mutlu-Pakdil). Credit: NASA, HST-GO-15938, PI: Mutlu-Pakdil

The discovery of the faintest known galaxies outside the Milky Way could help scientists develop global models of how the oldest galaxies in the universe formed, according to findings announced Jan. 11 at the 241st meeting of the American Astronomical Society.

A team of researchers led by Burçin Mutlu-Pakdil, now an assistant professor of physics and astronomy at Dartmouth College, has identified three very faint dwarf galaxies (UFDs) that are among the faintest detected outside the Local Group, a galaxy cluster that includes the Milky Way and Andromeda. .

Falls approximately 11.4 million light years From Earth, galaxies are estimated to be 12 billion years old, with nearly all of their stars forming in the early universe, researchers report in Astrophysical Journal.

The galaxies are the first UFDs found around a spiral galaxy With a mass of the Milky Way, it orbits a galaxy known as NGC253, or the Sculptor Galaxy. However, their properties are consistent with UFDs within the local group, which can help scientists develop more accurate models of UFDs in general. Most of the known examples of UFDs are within the local group, but different environments could influence their formation and evolution, Mutlu-Pakdil said.

“Our work is a necessary first step toward further understanding of weak galaxies outside the Local Group, and toward constraining the demographics of ultralight dwarf galaxies,” Mutlu Pakdel said. “We still don’t know if local group UFDs are typical or unusual. To answer this fundamental question, we need to discover more UFDs outside of our range.” local environment and study it in detail.

UFDs are the least known and least chemically evolved galaxies. However, they are more dominant than before dark matter, which is the mysterious form of matter that is believed to make up most of the universe. For these reasons, astronomers consider UFDs to be primitive fossils of early universe It could provide the best opportunities to study the formation of the universe and the formation of the first galaxies.

“Dwarf galaxies are the building blocks of larger galaxies,” Mutlu Pakdel said. “UFDs are the best place to study galaxy formation on the smallest scales and see how the smallest clumps of dark matter are filled with stars and turn into galaxies.”

The paper, “Hubble Space Telescope Observations of NGC 253 Dwarf Satellite: Three Very Faint Dwarf Galaxies” is published by Astrophysical Journal. This study was conducted as part of the Panoramic Centaur and Sculptor Imaging Survey (PISCeS) project, a Magellan + Megacam survey that aims to find new faint satellite galaxies, including UFDs.

more information:
Burçin Mutlu-Pakdil et al, Hubble Space Telescope observations of the NGC 253 dwarf satellite: three very faint dwarf galaxies*, Astrophysical Journal (2022). DOI: 10.3847/1538-4357/ac4418

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Dartmouth College

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