Another fusion of neutron stars may have been spotted

Geoffrey Ryan, co-author of the University of Maryland (UMD) and Joint Space-Science Institute, described the events as "cosmic look-alikes," saying, "They look alike, act the same way and come from similar neighborhoods. the simplest explanation is that they belong to the same family of objects.

However, despite all their similarities, GW170817 and GRB 150101B have some essential differences. GW170817 was also detected by gravitational waves, while GRB 150101B was not. Without this key information, astronomers can not be sure that GRB 150101B is the result of the fusion of two neutron stars; it may be the fusion of a black hole and a neutron star. In addition, the host galaxy of GRB 150101B is much farther away than that of GW170817 – the former is 1.7 billion light-years away, while the latter is only 130 million years old. But since GRB 150101B has gone so far, the team stated that even though LIGO had been operational by the time it was seen, the observatory would probably not have detected gravitational waves.

Build a database

The first step towards a better understanding of these events is to find more. And, the team said, it is possible that astronomers saw others, but simply could not identify them because they lacked data at other wavelengths. Although astronomers have detected many gamma-ray bursts, it can be difficult to locate these events accurately on the sky without data from X-ray or optical observations. While faster observation with multiple telescopes becomes the rule rather than the exception, astronomers could soon double their database on neutron star mergers again.

But it is important to keep in mind the initial differences between the only two known events. GW170817 and GRB 150101B may not be as similar as it seems, and this could be important. "If the next observation of this type reveals a fusion between a neutron star and a black hole, it would be truly revolutionary," said co-author Alexander Kutyrev, also associated with UMD and the Goddard Space Flight Center. . "Our last observations give us hope that we will see such an event for too long."

One thing is certain: as detectors and detection techniques improve, astronomers will not fail to see more and more astronomical events at different wavelengths, providing a clearer picture of how our universe works. Astronomers best able to identify the types of emission (such as light or gravitational waves) associated with an event, plus they will spot them using many different techniques. "We were able to identify this kilonova without gravitational wave data," Troja said. "Maybe in the future we can even do it without directly observing a burst of gamma rays."