Science Insider | 2017 Aug 01
Virgo, Europe’s premier gravitational wave detector, today joined forces with the two detectors of its U.S. counterpart, the Laser Interferometer Gravitational-Wave Observatory (LIGO), in the hunt for ripples in space-time following a €24 million upgrade. In March, the two observatories were meant to begin joint observations—which allow researchers to pinpoint the locations of sources of cosmic waves, such as merging black holes, more accurately. But problems with fragile glass-fiber suspensions for Virgo’s mirrors delayed its startup. Engineers were forced to temporarily install wire suspensions, reducing Virgo’s sensitivity; it will now take a supporting role during the last few weeks of LIGO’s current observing run. ...
The upgraded Virgo was due to join LIGO during its second observing run, which began in November 2016 but problems with the suspensions holding up the mirrors (these bounce the laser beam back and forth along the arms) led to delays. The run was due to finish in May, but the LIGO team, hoping for at least a brief period of joint observation, has stretched out the timeline as the Virgo upgrade neared completion. Because of Virgo’s loss of sensitivity with the wire suspensions, it will not be able to detect gravitational waves independently, but it will be able to help confirm a potential detection made by LIGO and locate sources in the sky with greater accuracy. LIGO’s run will finally finish on 25 August.
Both observatories will then carry out further upgrades, including restoration of Virgo’s glass-fiber suspensions, before the next run starts in the second half of 2018.