The spectacular fusion of two neutron stars that spawned gravitational waves, recorded last fall, probably concealed something: the birth of a black hole. This newborn black hole will be the most low-mass black hole of all that has ever been found. A new analysis of the Chandra X-ray Observatory took days, weeks and even months after the discovery of gravitational waves by the LIGO observatory in August 2017.
While almost every telescope at the disposal of professional astronomers observed the source of GW170817, the X-rays of the Chandra the most important role in understanding what happened after the collision of two neutron stars.
From the LIGO data, astronomers concluded that the mass of the object resulting from the fusion of neutron stars is about 2.7 times the mass of C the Sun. This puts his identity into question, implying that this is either the most massive neutron star, or the lightest black hole of all that has ever been found. Previous record holders of the last have a mass of not less than four or five times more than solar.
“Although neutron stars and black holes are mysterious phenomena, we studied many of them throughout the universe using telescopes like” Chandra “, says Dave Pooley from University of Trinity in San Antonio, Texas, author of the work. “This means we have both data and theories on how such objects should behave in the x-ray spectrum.”
Observations of the “Chandra” speak not only about what they showed, but also about what they did not show. If neutron stars had merged to form a heavier neutron star, astronomers would expect it to rotate rapidly and create a very strong magnetic field. This, in turn, will create an expanding bubble of high-energy particles, which will lead to bright X-rays. But instead, the Chandra data show X-ray levels that are several hundred times lower than what is expected for a fast-rotating neutron star and the associated bubble of high-energy particles, implying that a black hole instead forms.
If this is confirmed , one thing will become known: the recipe for creating a black hole can sometimes be not so simple. In the case of GW170817, it would take two supernova explosions, which left behind two neutron stars in close orbits and gravitational-wave radiation that brought the neutron stars together.