Wednesday , January 20 2021

LIGO and Virgo are opening a New Hunting Season

two technicians with equipment

Engineers Hugh Radkins and Betsy Weaver are working inside the detector's vacuum system in LIGO Hanford Observatory, Washington, USA, during a recent harness upgrade. With the upgrade to be completed, both UL LIGO facilities, in partnership with Virgo facility in Italy, are ready to start the third observation session. [Image: LIGO/Caltech/MIT/Jeff Kissel] [Enlarge image]

1 April 2019—There is a little more than three years after the first, remarkable discovery of gravitational waves, LIGO's and Virgo's interferometer laser gravity observatories today begin their third observation session.

Known in the GW community simply as “O3,” the year-long observation run is likely to produce a crop of new astronomical observations – the result of a 40 per cent improvement in the sensitivity of the two existing LIGO facilities in the United States. States and almost doubled sensitivity Virgo facility in Italy. The O3 period was also able to see the long-awaited observatory of the GW KAGRA observatory in Japan. And, in a new time, the LIGO / Virgo Scientific Cooperation (LSC) will make data about possible GW disclosures available to the public in a near time.

Promote laser power

The O3 run will add to the distinctive milestone line achieved in the first two GW runs. These include the detection of gravitational waves of ten binary black hole joints, as well as from a collision between a pair of intense neutron stars. He acknowledged the last – with observations of more traditional optical telescopes, x-rays and gamma-rays in an innovative example of “multi-dimensional astronomy” – produced in a stunning harvest of new scientific knowledge.

technician in front of baffle

LIGO team member Alena Ananyeva at Livingston LIGO Observatory, installing “baffles” to control stray light. [Image: LIGO/Caltech/MIT/Matt Heintze] [Enlarge image]

LSC scientists are confident that LIGO and Virgo observatories will record observations on a clip even earlier in O3, as a result of technical improvements implemented since the end of the last observation, O2, in August 2017 (see “Gravitational Wave: Y Next Step, ”OPN, May 2018). These include doubling power lasers facilities, which are combined in a Michelson-interferometer L-shaped set to lift the subtle disturbance in space space that can show a wave of gravity that t Passing. Also installed in the upgrade round were diffuse light inhibitors, or “baffles,” designed to control stray light within the massive interference.

Cut down noise

In addition to laser power, other recent updates have focused on efforts to promote sensitivity through abstraction and removal of noise sources in a range of sub-systems. In LIGO, this has included the huge engineering challenge of exchanging a number of 40-kg mirrors, or the test masses, which have definitely stopped on either side of the t laser interferometer arms. As a gravitational wave passing by penetrating through space time, small movements in these mirrors result in infinite changes of the arms being read in the interferometric signal. The new versions, which are performed better, the mirrors contain better layers to reduce thermal noise.

Virgo mirror fitted

One of Virgo's mirrors, or test bases, looks behind, as a researcher removes the safety stops from the mirror after the recent upgrade. (The mirror is reflective in the infrared range used by Virgo intervention, but transparent to visible light.) [Image: EGO/Virgo Collaboration/Perciballi] [Enlarge image]

In Virgo, meanwhile, the steel wires stopping the main mirrors have been replaced by fused silica versions that calm the vibrating noise and extend the facility's ability. to collect low and medium frequency GWS. And LIGO and Virgo will now use a trick of quantum mechanics, an injection of “pressing” light in the photodetector, to reduce the uncertainty in photon turnaround times attributable to quantum vacuum fluctuations.

These and other technical improvements have been partially developed and matured in another facility, GEO 600, a smaller GW observatory in Europe which has been a vital test for technologies to sharpen the observation power of the larger sites. GEO 600 will also take part in the O3 race.

Sampling more of the cosmos

installation of equipment

Researchers set the light source squeezed in a cleaning room in the Virgo wave gravity sensor. [Image: © H. Lück/B. Knispel/Max Planck Institute for Gravitational Physics] [Enlarge image]

The recent sensitivity upgrade will enable the global GW network to taste a large part of the cosmos for evidence of high-energy astronomical events. In the O3 run, for example, LIGO sensitivity from the recent updates should allow it to smell binary neutron star joints to a distance of 550 million light years – more than 190 million light years later than in O2.

This, together with an eight-fold expansion of space now visible to Virgo, could increase the detection of binary black hole collisions to a few incidents each month to just a week, and binary neutron star combinations to between one a year and one per month. There is also the possibility of raising more exotic, inaccessible events of the front, such as a black hole merger and a neutron star.

Quick access to data

The public will have close access to this harvest of finds, through new software developed by Legal Services Commission scientists. The software “will be able to send open public notices within five minutes” after discovering GW, according to Sarah Antier, a post-doctoral research link at Université Paris Diderot, France.

That will allow rapid access to the public for parameters such as the type of signal, position of the air and the estimated distance for a particular GW event. Those parameters, in turn, will allow professional and amateur astronomers looking at different slices of the electromagnetic spectrum to train their instruments quickly on the right piece of the air to follow up on the GW observation. .

KAGRA on the way?


Part of a KAGRA intervention arm, under construction in 2015. [Wikimedia Commons/Christopher Berry]

The ability to locate GW sources quickly and immediately could receive another boost again late in the O3 year period, with the first time KAGRA stayed long. An underground 3-km laser GW-observatory whose design includes suspended chicken-sapphire test masks to 20 K, KAGRA has been under construction in Japan since 2010. But its development has is contaminated by continued difficulty in banning vibration noise attributable to the chip of cooling equipment and even to water infiltration in the underground facility.

In January this year, however, from the end, the KAGRA team reported a successful 10-day trial of the intervention at cryogenic temperature. With that important milestone behind it, the team is hopeful that the facility will be able to make its first scientific observations at the end of 2019.

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