It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, January 18, 2023
Scientists in Canada detected an 8 billion-year-old radio signal in a distant galaxy
Scientists have detected a record-breaking radio signal from atomic hydrogen in a very distant galaxy.
The galaxy that the signal originated from is believed to have come from a galaxy at redshift z=1.29.
Because of the galaxy’s immense distance, the emission line had shifted to a 48 cm line from the 21 cm line they had expected.
This discovery is phenomenal because the galaxy that it originated from is believed to have existed when the universe was only 4.9 billion years old – making the source of the record-breaking radio signal 8.8 billion years old.
The detection was possible because the scientists used gravitational lensing to detect and follow the signal back to its source galaxy. The magnification of the lensing was a factor of 30, the scientists explained, which allowed the group to see through the high redshift of the universe. Further, the team observed that the atomic hydrogen mass of the galaxy was twice as high as its stellar mass.
These findings were published in the Monthly Notices of the Royal Astronomy Society, and they show that the overall feasibility of observing the atomic gas in galaxies at long distances. It could also open new doors for probing the cosmic evolution of neutral gas with exiting and upcoming low-frequency radio telescopes in the future.
The astronomers involved in the study work with the McGill University in Canada, as well as the Institute of Science (IISc) in Bengaluru. The team used data from the Giant Meterwave Radio Telescope (GMRT) in Pune. This instrument allowed the team to detect the record-breaking radio signal originating from the distant galaxy, allowing the researchers to dig deeper into the discovery.
By detecting these kinds of record-breaking radio signals, we may be able to use similar instances to explore the mysteries of the early universe more thoroughly.
Discovery of three faint, distant galaxies may expand knowledge of early universe
First ultra-faint dwarf galaxies found around Milky Way-mass galaxy similar to those within Milky Way’s neighborhood
IMAGE: RESEARCHERS DISCOVERED THE FIRST ULTRA-FAINT DWARF GALAXIES TO BE FOUND AROUND A SPIRAL GALAXY WITH THE MASS OF THE MILKY WAY THAT’S OUTSIDE OF THE CLUSTERING OF GALAXIES THAT INCLUDES THE MILKY WAY AND ANDROMEDA. PICTURED IS ONE OF THE THREE GALAXIES, SCL-MM-DW5, WITH ITS STARS CLUSTERED AT CENTER. THE GALAXIES ARE ESTIMATED TO BE 12 BILLION YEARS OLD, WITH NEARLY ALL THEIR STARS HAVING FORMED IN THE EARLY UNIVERSE. THE GALAXIES WERE IDENTIFIED FROM MAGELLAN MEGACAM OBSERVATIONS, THEN CONFIRMED WITH DEEPER HUBBLE SPACE TELESCOPE OBSERVATIONS. (IMAGE BY NASA, HST-GO-15938, PI: MUTLU-PAKDIL)view more
CREDIT: NASA, HST-GO-15938, PI: MUTLU-PAKDIL
The discovery of the faintest known galaxies beyond the neighborhood of the Milky Way could help scientists develop universal models for how the universe’s oldest galaxies 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, identified three ultra-faint dwarf galaxies (UFDs) that are among the faintest galaxies discovered outside of the Local Group, the clustering of galaxies that includes the Milky Way and Andromeda. Located roughly 11.4 million light years from Earth, the galaxies are estimated to be 12 billion years old, with nearly all their stars having formed in the early universe, the researchers reported in The Astrophysical Journal.
The galaxies are the first UFDs to be found around a spiral galaxy with a mass of the Milky Way, orbiting a galaxy known as NGC253, or the Sculptor Galaxy. Yet, their characteristics are consistent with UFDs within the Local Group, which could help scientists develop more accurate models of UFDs overall. Most known examples of UFDs are within the Local Group, but different environments can affect their formation and evolution, Mutlu-Pakdil said.
“Our work is the necessary first step toward further understanding the faintest galaxies beyond the Local Group, and toward more robustly constraining the demographics of ultra-faint dwarf galaxies,” Mutlu-Pakdil said. “We still do not know whether the Local Group UFDs are typical or unusual. To answer this fundamental question, we need to discover more UFDs beyond our local environment and study them in detail.”
UFDs are the least luminous and least chemically evolved galaxies known. Yet, they are the most dominated by dark matter, which is the mysterious form of matter thought to constitute most of the universe. For these reasons, astronomers consider UFDs to be pristine fossils of the early universe that could provide the best opportunities for studying the composition of the universe and the formation of its first galaxies.
“Dwarf galaxies are the building blocks of larger galaxies,” Mutlu-Pakdil said. “UFDs are the best place to study galaxy formation on the smallest scales and learn how the smallest dark matter clumps get populated with stars and turn into galaxies.”
The paper, “Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Three Ultra-faint Dwarf Galaxies,” was published by The Astrophysical Journal Feb. 10, 2022. This study was conducted as part of the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) project, which is a Magellan+Megacam survey aimed at finding new faint satellite galaxies, including UFDs.
The work was supported by the National Science Foundation (grants AST-1821967, 1813708, AST-1814208, AST-1412792, AST-1812856), an NSF Astronomy and Astrophysics Postdoctoral Fellowship (AST-2001663), the Packard Foundation, and the Natural Sciences and Engineering Research Council of Canada.
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