LIGO team detects second merger of two neutron starsDate: 11 January 2020 Tags: Space
Gravitational waves from the merger of two neutron stars were observed by the LIGO Livingston detector, according to an international team of astrophysicists in the LIGO and Virgo collaborations.
This is the second time that a signal from such an event has been seen and the merger is puzzling astrophysicists because it appears to have created an object with “unusually high mass”.
The signal (dubbed GW 190425) was not recorded by the LIGO Hanford detector, which was not operating at the time, nor was it detected by the Virgo detector.
A recent researchfrom an independent team of astronomers in Russia suggests that two gamma-ray pulses were also emitted during the merger. No other electromagnetic radiation associated with the event has been reported.
LIGO comprises two 4 km long interferometers in the US – one in Livingston, Louisiana and the other in Hanford, Washington.
The Virgo interferometer stretches over 3 km in the Italian countryside near Pisa. In August 2017 the two LIGO detectors spotted gravitational waves from the merger of two neutron stars, the first time ever that such an observation was made.
A signal was not seen in Virgo, but this non-detection allowed LIGO–Virgo scientists to better locate the merger in the sky.
The merger created a huge “kilonova” explosion and astronomers observed signals across a wide range of the electromagnetic spectrum from radio waves to gamma-rays.
This high mass had led to early speculation that GW 190425 could have been the result of a merger of a neutron star and a black hole , making it the first such event to be observed.