Forty X-ray binaries—a class on binary star in which a black hole or neutron star consumes matter from its companion—have been discovered by the NASA Nuclear Spectroscopic Telescope Array (NuSTAR) in new, high-energy observations of our neighboring galaxy Andromeda.
The discovery, which was made following new, high-energy X-ray views of Andromeda believed to be the best captured to date, could help determine whether or not these binaries play a key role in the formation and evolution of galaxies, NASA said in a statement.
X-ray binaries, NASA explained, may be involved in heating the gases from which the very first galaxies formed—and Andromeda is the only large spiral galaxy where individual X-ray binaries can be observed in detail, noted Daniel Wik of the Goddard Space Flight Center in Maryland.
Wik, who presented his team’s findings at the 227th meeting of American Astronomical Society (AAS) in Florida earlier this week, added that the data gathered through these observations could be used “to deduce what’s going on in more distant galaxies, which are harder to see.”
Findings could shed new light on how galaxies originally formed
Like the Milky Way, Andromeda is a spiral galaxy, but it is slightly larger than the galaxy that we call home and is located 2.5 million light-years away from our solar system. Although other NASA missions, including the Chandra X-ray Observatory, have obtained clearer images of the galaxy, they were at lower X-ray energies than those provided by NuSTAR.
The NuSTAR images will be used along with those obtained by Chandra and other spacecraft to provide the best possible look at the spiral galaxy’s X-ray binaries. Wik and his colleagues hope to use the new observations to identify what percentage of the binaries are home to neutron stars and which house black holes.
“We have come to realize in the past few years that it is likely the lower-mass remnants of normal stellar evolution, the black holes and neutron stars, may play a crucial role in heating of the intergalactic gas at very early times in the universe, around the cosmic dawn,” explained Ann Hornschemeier, principal investigator of the NuSTAR Andromeda studies.
“Observations of local populations of stellar-mass-sized black holes and neutron stars with NuSTAR allow us to figure out just how much power is coming out from these systems,” she added. The findings could also provide new insight as to how Andromeda is different from the Milky Way, according to NuSTAR mission chief Fiona Harrison.
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Feature Image: NASA/NuSTAR/Goddard
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