VIRGO

tullio
tullio
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Hint. If a GW signal was

Hint. If a GW signal was detected also by Virgo besides LIGO, this may have given a clue about its coordinates in the sky. Therefore many telescopes were pointed to that position. Am I wrong?

Tullio

astro-marwil
astro-marwil
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Hallo Tullio!Am I

Hallo Tullio!

|  Am I wrong?

No, not at all. Even the two LIGO-detectors give some information about the dircetion towards the source. But with the third detector VIRGO  they can point with higher accuracy. The following graphs are taken from the actual homepage of LIGO. They show the pointing areas for four GW-events from LIGO and in a simulation the expected accuracy with the signal from VIRGO.

The different influence of VIRGO on the pointing accuracy results from the non equal sensitivity in all directions.

So more GW-detectors are wellcome, like LIGO-India and KAGRA.

 

Kind regards and happy crunching

Martin

tullio
tullio
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VIRGO has detected a signal

VIRGO has detected a signal on August 14, contemporary with LIGO signals.It stopped collecting data on August 25 and is now due for an upgrade.The wires supporting the mirrors which are now metallic will be substituted by silica wires, like the LIGOs.

Tullio

tullio
tullio
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GW170817 signal was

GW170817 signal was registered on August 17, not 14, and was caused by the fusion of two neutron stars, not black holes, and comes from a distance of 130 million light years, not billions like the ones caused by the merging of black holes. The event was seen also in the EM range as a gamma-ray burst. This was announced by a LIGO-Virgo conference in Washington. It is the first of such events.

Tullio

Shawn Kwang
Shawn Kwang
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tullio wrote:GW170817 signal

tullio wrote:

GW170817 signal was registered on August 17, not 14, and was caused by the fusion of two neutron stars, not black holes, and comes from a distance of 130 million light years, not billions like the ones caused by the merging of black holes. The event was seen also in the EM range as a gamma-ray burst. This was announced by a LIGO-Virgo conference in Washington. It is the first of such events.

Tullio

Just to be clear, there were two events that occurred within days. GW170814 was detected by LIGO and VIRGO. It was a binary black hole merger.

GW170817 was detected by LIGO. It was a binary neutron star merger. In fact, the absence of a strong signal in VIRGO allowed scientists to locate the area of the sky, which then allowed other telescopes: x-ray, optical, UV, IR, and radio to observe the area where the merger took place.

Einstein@Home Project

tullio
tullio
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NASA Within hours of the

NASA

Within hours of the initial Fermi detection, LIGO and the Virgo detector at the European Gravitational Observatory near Pisa, Italy, greatly refined the event's position in the sky with additional analysis of gravitational wave data. Ground-based observatories then quickly located a new optical and infrared source -- the kilonova -- in NGC 4993. 

astro-marwil
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Hallo ! It´s realy a GREAT

Hallo !

It´s realy a GREAT success!

Wasn´t it detected by GEO600? The distance is 1/10 and the masses are also about 1/10 - so this cancels about for intensity - but the frequency is about a factor 5 higher in the end than in the former events. So, for GEO600 it should be better suitable because of its shorter armlength. But may be, he wasn´t active at this time, in service shutdown, as 3 other detectors where active?

Kind regards and happy crunching

Martin

tullio
tullio
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I cannot reach the GEO600

I cannot reach the GEO600 site. It says it is forbidden. I don't think GEO600 is active now. I could read two articles in "Nature" magazine with many details. The source is in NGC 4993, as I had written earlier. Firstly I did not understand that the August 14 and August 17 signals were due to two separate events. Virgo had started observing on August 1 and it received two signals in less that 20 days.

Tullio

Gary Roberts
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tullio wrote:Firstly I did

tullio wrote:
Firstly I did not understand that the August 14 and August 17 signals were due to two separate events.

Yes, I didn't understand that either until reading about it today.

tullio wrote:
Virgo had started observing on August 1 and it received two signals in less that 20 days.

I read today that Virgo didn't see a signal from the NS-NS merger.  Apparently it came from a direction that was a 'blind spot' for that detector and this, when superimposed on the probable regions defined by the other two detectors, allowed the search area for an optical/other EM signal to be further refined.  The fact that the source has been clearly defined as a result of this is really good news.

I'm wondering if the result of the merger is still an NS or is it big enough to now be a BH?

 

Cheers,
Gary.

astro-marwil
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Hallo Tullio! You´r right.

Hallo Tullio! 

You´r right. The address of AEI has changed, but it became not corrected in BOINC-Manager/Projects.  I put a note in the "Problems and Bugs" forum.

Here ist the link to the appropriate page at AEI.

The best in this event was, it was also observed by the SWIFT-satelite in gamms-rays 1.7 sec after the GW-signal, and it was observed in the optical by the telescopes in Chile. It´s the first time of an counterpart in the elctromagnetic spectrum.

It´s realy astonishing, how fast it´s going forward with this new scientific window.

 

Kind regards and happy crunching

Martin

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