lpetrich
Contributor
Testing General Relativity with Pulsars - AAS Nova
noting
The Orbital-decay Test of General Relativity to the 2% Level with 6 yr VLBA Astrometry of the Double Neutron Star PSR J1537+1155 - IOPscience
Earlier measurements of the inspiral rate had a 9% difference with GR. But it was difficult to model what kind of galactic orbit this pulsar has. Lao Ding and his colleagues decided to resolve this issue by finding the parallax of this pulsar using the Very Large Baseline Array (VLBA), a set of radio telescopes with outputs combined to make them act like a single Earth-sized radio telescope. With the VLBA, they found a very precise position for this pulsar, and the watched it change over a year to measure its parallax. They found its distance to be 0.94 kiloparsecs (3,066 light years). This enabled them to model its galactic orbit much better, and to get that 2% of agreement.
List of pulsars in binary systems
The two neutron stars in PSR J1537+1155 have masses 1.333 and 1.345 Msun.
Gravitational-wave detection
I'd mentioned the detection of G-wave events earlier, events caused by inspiraling black holes and/or neutron stars.
GW170817 - two neutron stars merging. They made a gamma-ray burst that arrived 1.3 seconds after the G-wave event, thus constraining differences in their speeds to around 10-15.
A different sort of detection was recently made by correlating pulsar timings: Physics - Researchers Capture Gravitational-Wave Background with Pulsar “Antennae” - pulsars in different directions have correlations that vary like what one expects of a random collection of G-waves with GR-like polarizations.
Remarkable how well GR has held up.
noting
The Orbital-decay Test of General Relativity to the 2% Level with 6 yr VLBA Astrometry of the Double Neutron Star PSR J1537+1155 - IOPscience
Earlier measurements of the inspiral rate had a 9% difference with GR. But it was difficult to model what kind of galactic orbit this pulsar has. Lao Ding and his colleagues decided to resolve this issue by finding the parallax of this pulsar using the Very Large Baseline Array (VLBA), a set of radio telescopes with outputs combined to make them act like a single Earth-sized radio telescope. With the VLBA, they found a very precise position for this pulsar, and the watched it change over a year to measure its parallax. They found its distance to be 0.94 kiloparsecs (3,066 light years). This enabled them to model its galactic orbit much better, and to get that 2% of agreement.
List of pulsars in binary systems
The two neutron stars in PSR J1537+1155 have masses 1.333 and 1.345 Msun.
Gravitational-wave detection
I'd mentioned the detection of G-wave events earlier, events caused by inspiraling black holes and/or neutron stars.
GW170817 - two neutron stars merging. They made a gamma-ray burst that arrived 1.3 seconds after the G-wave event, thus constraining differences in their speeds to around 10-15.A different sort of detection was recently made by correlating pulsar timings: Physics - Researchers Capture Gravitational-Wave Background with Pulsar “Antennae” - pulsars in different directions have correlations that vary like what one expects of a random collection of G-waves with GR-like polarizations.
Remarkable how well GR has held up.