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An object called GRB 150101B, first detected in January 2015 by NASA's Fermi Gamma gamma space telescope, could indicate a fusion of two neutron stars. This image shows data from NASA's Chandra X-ray observatory (in purple in the inserted boxes) in the context of a Hubble Space Telescope GRB 150101B optical image.
Credit: X-rays: NASA / CXC / GSFC / UMC / E. Troja et al. Optics and Infrared: NASA / STScI
A new study suggests that cataclysmic fusions of superdell stellar bodies called neutron stars may be commonplace in the cosmos.
Last October, an international team of researchers made an astonishing announcement: they had detected light and gravitational waves generated by the crash of two neutron stars, an event called GW170817 (because it had been observed on August 17, 2017).
This discovery opened the era of "multimessenger astronomy" – the use of electromagnetic radiation combined with gravitational waves (the ripples in space-time predicted by Albert Einstein a century ago) to probe cosmic objects and phenomena. [Gravitational Waves from Neutron Stars: The Discovery Explained]
GW170817 was the first documented star-neutron fusion. But now he seems to have company.
In January 2015, NASA's Fermi gamma-ray space telescope detected a powerful high-energy gamma-ray discharge in a galaxy 1.7 billion light years from Earth. Shortly after, several other instruments observed this source, known as GRB 150101B. ("GRB" is an abbreviation for "gamma-ray burst".) Among these tracking telescopes are the NASA Hubble Space Telescope, the Chandra X-ray Observatory and the Neil Gehrels Observatory. Swift, as well as the Discovery Channel telescope at the Lowell Observatory in Flagstaff, Arizona.
The combined observations revealed key similarities between GW170817 and GRB 150101B. For example, both events produced unusually ephemeral, short-lived gamma ray bursts, bright blue visible light that lasted for several days, and longer X-ray emissions, the study said. And both sources reside in elliptical galaxies with stars a few billion years old, with no regions that form clearly.
The team therefore believes that the GRB 150101B was probably generated by a neutron star fusion. (Neutron stars result from the death of giant stars in supernova explosions, the remains of the largest stars collapse into black holes, and slightly smaller stars initially become neutron stars, which form more from the mass of the sun in a sphere, or 20 kilometers, across.)
"We have a case of cosmic look-alikes," said in a statement Geoffrey Ryan, co-author of the University of Maryland at College Park (UCMP). "They look alike, act the same way and come from similar neighborhoods, so the easiest explanation is that they belong to the same family of objects."
Moving from one detected object to another is a big problem, said lead author Eleonora Troja of NASA's Goddard Space Flight Center in Greenbelt, Maryland and UCMP.
"Our discovery tells us that events such as GW170817 and GRB 150101B could represent a whole new category of erupted and x-ray-disabled objects that may be relatively common," Troja said in the same statement.
The team did not observe any gravitational waves from GRB 150101B. The gravitational wave observatory at Advanced Laser Interferometer (LIGO) was not operational in January 2015 and, even though it had been, it probably would not have been in operation. could not capture the waves from such a remote source, said members of the study team. (GW170817, observed by both Advanced LIGO and its European counterpart Virgo, is produced only 130 million light-years from Earth.)
Without gravitational wave measurements, researchers can not say for sure how much the two GRB 150101B objects were massive. Thus, it is possible that the merger involves a neutron star and a black hole, said members of the study team.
"We need more cases, such as the GW170817, combining gravitational and electromagnetic wave data to find an example between a neutron star and a black hole." Such a detection would be the first of its kind. " – wrote Hendrik Van Eerten, of the University of Bath. in the United Kingdom, said in the same statement. "Our results are encouraging to find more mergers and make such a detection."
The new study was published online today (Oct. 16) in the journal Nature Communications. You can read a pre-print for free on arXiv.org.
Mike Wall's book on the quest for extraterrestrial life, "Out There," will be published on November 13 by Grand Central Publishing. Follow him on Twitter @michaeldwall. follow us @Spacedotcom or Facebook. Originally posted on Space.com.
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