New binary black-hole mergers

Almost exactly a year ago, I wrote a post about how quickly the discovery of black-hole mergers through gravitational waves was becoming run o’ the mill.

All of the gravitational wave detection announcements before this were accompanied by an embargo, lots of hype building up, press releases from various groups associated with the data analysis, and of course reporters scrambling under the radar to get their stories ready. There was none of that this time. This time, the LIGO scientific collaboration published their press release with links to the raw data and the preprint paper (submitted to the Astrophysical Journal Letters) on November 15. I found out about it when I stumbled upon a tweet from Sean Carroll.

This week, the LIGO team may just have one-upped itself. On December 1, Shane Larson, a physicist at Northwestern University, Chicago, and member of the LIGO Scientific Collaboration, wrote on his blog that the LIGO and Virgo teams were releasing a joint catalogue of their gravitational-wave detections till date. And in that catalog, Larson drew readers’ attention to the presence of not one, not two, but four new black-hole merger events.

Can you spot the new events? Credit: LIGO-Virgo collaboration

He continued:

What stands out the most in the new LIGO catalog? We are still letting the implications settle in, but the most important thing the new events do is it makes our estimate of the population of black holes in the Universe more accurate, and we’ve started to examine those implications in a new study that is being released in tandem with this announcement.

This study is available here.

To (shamelessly) quote myself once more:

In the near future, the detectors – LIGO, Virgo, etc. – are going to be gathering data in the background of our lives, like just another telescope doing its job. The detections are going to stop being a big deal: we know LIGO works the way it should. Fortunately for it, some of its more spectacular detections … were also made early in its life. What we can all look forward to now is reports of first-order derivatives from LIGO data.