LIGO news

[John Clark]

On Wednesday Ligo/Virgo released a more detailed analysis of the first half of its third observational run which went from  April 1 2019  to October 1 2019 which added 39 additional gravitational wave events bringing the total number seen up to 50. The list includes the most powerful Black Hole merger ever seen, the most distant, the largest Black Hole ever detected by gravitational waves, 2 neutron star collisions, and something it was either the most massive Neutron Star ever detected or the least massive Black Hole ever detected. With all the improvements and the help of Virgo in Italy they were finding on average one and a half events per week. The second part of the run which went from October 2019 to March 2020 hasn't yet had a similar statistical analysis.

LIGO Had to be shut down prematurely in March because of the pandemic, it's not clear when they will be able to resume operations. It's a pity they could've have gone on a little longer because about a month after they shut down the new KAGRA Gravitational wave detector in Japan came online, there could have been 4 widely spaced detectors running at the same time. Although slightly smaller than LIGO (3 km arms rather than 4) KAGRA has several features that LIGO doesn't have, It is deep underground which reduces seismic noise by a factor of 100, and it's mirrors are cryogenically cooled to 20 degrees Kelvin further reducing errors.

Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run

John K Clark

[Lawrence Crowell]

The KAGRA is set on one of the most seismic active areas of the world. My paper, publisher website https://www.mdpi.com/1099-4300/22/3/301 and arxiv https://arxiv.org/abs/2007.01106  , requires a LIGO or LISA capable of detecting changes in metric with BMS symmetries. I read a report on how LIGO detectors are being deformed slightly in permanent ways. This could be a manifestation of BMS charge, but also instrument responses. With space based LISA this will be detectable.

LC