Archive for LIGO

Gravitational Wave Flash!

Posted in The Universe and Stuff with tags , , , , on April 9, 2019 by telescoper

The third observing run for Advanced LIGO – O3 – started on April 1 2019, after 19 months upgrading the detectors. Last night, April 8, saw the first new detection of a candidate gravitational wave source, apparently another black hole binary, dubbed S190408an.

It is anticipated that sources like this will be discovered at a rate of roughly one per week for the (planned) year-long run. Given the likely rate of events the policy of LIGO is now to make data publicly available directly without writing papers first. You can find the data entry for this event here, including this map of its position.

Whether the LIGO Scientific Collaboration will release sufficient data for others to perform a full analysis of the signal remains to be seen, but if the predicted detection rate matches reality, the field is going to move very rapidly from studies of individual events to statistical analysis of large populations. Such is the way of science!

A LIGO Orrery

Posted in The Universe and Stuff with tags , , , , on December 5, 2018 by telescoper

Following yesterday’s post here is a nice video visualization of all the black hole binary mergers so far claimed to have been detected by Advanced LIGO. They’re computer simulations, of course, not actual black holes (which you wouldn’t be able to see). I always thought an Orrery was a clockwork device, rather than a digital computer, but there you go. Poetic license!

I can’t say I’m very keen on the music.

GW170608—The underdog

Posted in The Universe and Stuff with tags , , on November 20, 2017 by telescoper

Interesting post from a gravitational wave researcher, telling the inside story of the latest gravitational wave detection (a binary black hole merger) announced last week.

 

 

Christopher Berry

Detected in June, GW170608 has had a difficult time. It was challenging to analyse, and neglected in favour of its louder and shinier siblings. However, we can now introduce you to our smallest chirp-mass binary black hole system!

Family of adorable black holes The growing family of black holes. From Dawn Finney.

Our family of binary black holes is now growing large. During our first observing run (O1) we found three: GW150914, LVT151012 and GW151226. The advanced detector observing run (O2) ran from 30 November 2016 to 25 August 2017 (with a couple of short breaks). From our O1 detections, we were expecting roughly one binary black hole per month. The first same in January, GW170104, and we have announced the first detection which involved Virgo from August, GW170814, so you might be wondering what happened in-between? Pretty much everything was dropped following the detection of our first…

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And then there were five….

Posted in The Universe and Stuff with tags , , , , , , on November 17, 2017 by telescoper

…black hole mergers detected via gravitational waves, that is. Here are the key measurements for Number 5, codename GW170608. More information can be found here.

Here is the abstract of the discovery paper:

On June 8, 2017 at 02:01:16.49 UTC, a gravitational-wave signal from the merger of two stellar-mass black holes was observed by the two Advanced LIGO detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses 12+7-2 M⊙ and 7+2-2 M⊙ (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through gravitational waves with electromagnetic observations. The source’s luminosity distance is 340 +140-140Mpc, corresponding to redshift 0.07+0.03-0.03. We verify that the signal waveform is consistent with the predictions of general relativity.

This merger seems to have been accompanied by a lower flux of press releases than previous examples…

Gravitational Waves Flash!

Posted in The Universe and Stuff with tags , , , , on October 13, 2017 by telescoper

I got up early this morning to hitch a ride in a car to Mumbai so that I can give a talk this afternoon. We left Pune about 6am and got here about 8.30 so the trip was a quite a bit quicker than coming here! I’ll post about that and include some pictures when I get a moment, but first I’ll post a quick announcement.

There will be an announcement on Monday 16th October at 10am EDT (3pm BST; 7.30pm in Pune) by `the National Science Foundation (NSF) as it brings together scientists from the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations, as well as representatives for some 70 observatories’. Further details can be found here. The European Southern Observatory has also announced that it will be holding a press conference on Monday about an `unprecedented discovery’.

The fact that it involves LIGO, Virgo and representatives of other observatories strongly suggests that this announcement will address the subject of the rumours that were flying around in August. In other words, it’s likely that on Monday we will hear about the first detecting of a coalescing binary neutron star system with an optical counterpart. Exciting times!

I’ll be back in Pune by Monday and will probably be able to watch the announcement and will update if and when I can.

Gravitational Wave Flash

Posted in The Universe and Stuff with tags , , , on September 27, 2017 by telescoper

Inconveniently timed just before I was due to go to the pub, a new announcement has come out from the LIGO and Virgo gravitational wave detectors. This time it reports a coalescing binary black hole system detected by all three instruments. The new source is called GW170814, which indicates that the signal from it was received by the detectors on the day I returned from Copenhagen this summer!

Here’s the key figure:

The paper is here and there’s a Nature comment piece here.

I have to say that, on its own, the Virgo `detection’ looks rather marginal to me, but assuming that it is a detection this graphic shows how much it helps to localize the source compared to previous signals:

More on this in due course, perhaps, but now I’m off for a pint or two…

LIGO/VIRGO Update

Posted in The Universe and Stuff with tags , , on August 30, 2017 by telescoper

Judging by by the WordPress blog statistics page, there’s been a lot of traffic here in the past week owing to my post about the rumours of a new gravitational wave source detected by LIGO (and possibly VIRGO). In the interest of completeness I’ll just post a quick update to mention that the latest Observation run at LIGO  finished as planned on 25th August, and this has been marked by an official announcement which I have taken the liberty of presenting here in full:

The Virgo and LIGO Scientific Collaborations have been observing since November 30, 2016 in the second Advanced Detector Observing Run ‘O2’ , searching for gravitational-wave signals, first with the two LIGO detectors, then with both LIGO and Virgo instruments operating together since August 1, 2017. Some promising gravitational-wave candidates have been identified in data from both LIGO and Virgo during our preliminary analysis, and we have shared what we currently know with astronomical observing partners. We are working hard to assure that the candidates are valid gravitational-wave events, and it will require time to establish the level of confidence needed to bring any results to the scientific community and the greater public. We will let you know as soon we have information ready to share.

The last two sentences can be translated roughly as “Back off, and give us time to analyse the data!”, which is not an unreasonable request. Judging by the timescale between detection and publication of the previous LIGO events, it will probably be a matter of months before a formal announcement is made.

I hope this clarifies the situation.