In search of the dark matter of the universe: Virgo, the gravitational wave detector, grows and becomes more powerful

Pisa is listening to the deep cosmos thanks to a technological “ear” which is growing and, once the work to increase its power has been completed, will make it possible to explore a sphere of the universe with a radius that is ten times larger than at present. Virgo, the gravitational wave detector in Cascina, will be transformed into “Advanced Virgo”, to improve its sensitivity exponentially and give greater chances of being able to isolate the signals.

The new “space scanner” will come into service after 2015 along with its ‘‘twin’’, the American Advanced Ligo, which was switched off a few months ago in order to make some important modifications. In four years, all of the scanners, having become more sensitive, will be able to listen to gravitational collapses hat have occurred at distances ten times greater.

“Having the chance to explore a sphere of the universe with a radius 10 times larger and a volume one thousand times greater increases the probability of capturing an event by one thousand times,” explains Carlo Bradaschia, one of Virgo’s builders and researcher at INFN in Pisa. “In this way we’ll see the birth of gravitational astronomy.” The instrument will be used to trace totally new maps of the sky, which will show sources of gravitational waves as stars and which could reveal new details about the universe’s “dark matter”.

For the whole summer Virgo worked together with its European “colleague” GEO600 (located in Hannover) to capture signals from the sky. The two scanners were active at the moment of the supernova of 24 August which however, being too distant, was not able to be captured by the instruments in operation. Conceived by the Italian physicist Adalberto Giazzotto and completed in 2003, Virgo’s home is in the municipality of Cascina, in the province of Pisa, on the site of the European Gravitational Observatory (EGO). It is a super-antenna, three kilometres long, for capturing and studying gravitational waves.