Tag: Virgo

Italy delays restart of its gravitational wave detector Virgo

9:36 am

After three years of upgrades, the engineers running Italy’s Virgo gravitational wave detector have decided to delay its restart later this month due to unexplained noise issues found inside some older components.

Getting to these parts to find the cause of the noise however will not be simple, as they are housed inside a vacuum chamber.

[According to Virgo spokesperson Gianluca Gemme. “Until we break the vacuum and open the towers to check the interferometer components directly, we cannot be one hundred percent sure what the problem is. … We therefore decided to take action now to resolve the technical issue that is slowing down the interferometer’s sensitivity growth. These are operations that, apart from the work we will have to do, involve time to remove and then restore the ultra-high vacuum conditions.

Once this work is completed it will then require further testing to make sure all is well. It is therefore unclear when Virgo will resume observations.

Meanwhile, the two detectors in the United States plan to resume operations as scheduled later this month. Without Virgo working in tandem, however, the resolution for any detections will be reduced.

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New catalog of 90 gravitational wave detections published

9:24 am

The scientists operating the world’s three gravitational wave detectors today released a new catalog of all their detections, totaling 90 with 35 never before published.

All signals come from merging black holes and neutron stars. The new catalog contains some surprises, such as an unusual neutron-star–black-hole merger, a massive black hole merger, and binary black holes revealing information about their spins.

…The researchers have also published two papers accompanying their new catalog today. One looks at what the events can tell us about the population of compact objects in our Universe, how often they merge, and how their masses are distributed. In the other paper the researchers employed the gravitational waves to better understand the expansion history of the cosmos by measuring the Hubble constant.

Because of the tiny sample so far detected, these generalized results cannot be taken too seriously, though they do give hints at the larger context.

All three observatories are now undergoing upgrades, and will resume operations in a few weeks.

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More gravitational waves detected

9:47 am

Using the LIGO and Virgo gravitational wave telescopes astronomers have detected two more gravitational waves.

On April 25, 2019, one of the twin LIGO instruments and the Virgo detector observed a candidate signal which – if confirmed – would be the first binary neutron star merger during the third observation run, which began on April 1. A second candidate signal was seen on April 26, which – if confirmed – could be a never-observed-before collision of a neutron star with a black hole. The latter candidate was observed by both LIGO instruments and the Virgo detector. Dozens of telescopes on the Earth and in space are searching for electromagnetic or astro-particle counterparts. No identification with an electromagnetic transient signal nor a host galaxy has been made to date for either candidate.

The resolution of LIGO and VIRGO are somewhat limited, so other telescopes have to scan a very large part of the sky to spot a counterpart. It is therefore likely that it will be years before the first counterpart event is identified. When it is however it will tell us how far away the event was and confirm what kind of event it was. Right now, they are only making educated guesses.

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