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Gravitational waves: 4 signs capted by Virgo and Ligo

Gravitational waves

The detectors Virgo and Ligo were switched on again just a month ago and they already noted 4 signs, which can be generated by gravitational waves. In the scientific world there is a huge buzz but it’s still too soon for the conclusions.

Virgo and Ligo

Virgo and Ligo are two laser interferometers, respectively situated in America and in Italy, that firstly directly releaved the gravitational waves. The first direct detection, infact, happened in the 2015, a century after they were theorized.

The american laser interferometer Ligo (Laser Interferometer Gravitational Wave Observatory) thanks to its two sophisticated antennas found the first gravitational wave, GW150914.

After that the second antenna has been activated, the european Virgo, situated in Italy, next to Pisa, which opened a new way to make astrophysics: the multimessaging astrophysics.


The first gravitational wave found with the new combined system of two advanced antennas was GW170817, generated by the fusion of two neutron stars.


At the end of August 2017 they finished their second phase of cooperative research. Since there they made extensive upgrade works on both antennas.

As result they became much more sensitive and their range is doubled. Furhtermore, even the precision is substantially increased, with the possibility to place the origin of the gravitational waves much more carefully.

The researches started again

Virgo and Ligo have been switched on again the 31st March 2019, for the third time, the longest one until now. This time they will look the sky for a whole year, seven days a week, twentyfour hours per day.

The phase one and the phase two were able to see ten fusions between black holes and a fusion between neutron stars. Now, in less then one month, they saw already four events.

Onde gravitazionali
Rappresentation of a collision between two neutron stars

“In this new campaign of data taking we wonder to record some fusions of neutron stars and many fusions, up to one per week, of black holes. Besides to those events, we hope to observe something new, like the fusion of a neutron star and a black hole. It would be amazing to record for the first time the emission of gravitational waves produced by an explosion of supernova or the ones emitted by the pulsars, the neutron stars with double rotation”, tells Viviana Fafone, national responsible INFN for the cooperation Virgo.

And infact she wasn’t wrong, until now the events recorded are right an average of one per week and it’s still missed 11 months, who knows how many things the two interferometer will be able to notice.

The gravitational waves

But what are the gravitational waves? We said that to directly  notice them we had to wait until the 2015, one century after their theorization.

Let’s, so, come back to the 1919, when the astronomous Sir Arthur Stanley Eddington, tried to demonstrate the theories presented just few years before by Einsten. But we had to wait until the 1969 for the realization of the first gravitational waves’ detector.

Gravitational waves
Rappresentation Gravitational waves

That year Joseph Weber claimed to have noticed for the first time a gravitational wave. By the way his work was criticised and he gave up. Even though the initial failures Weber is considered the father of the gravitational waves’ direct research.

Research that had its maximum with the antennas Virgo and Ligo.

Virgo and Ligo in their third phase of research

And we are one more time here. Just a month after they have been switched on again they boast four discoveries.

The first three events probably came from fusions between two black holes. But the one that created more interest is the last one. The gravitational wave releaved the 25th April seems to have something special.

It is, probably, made by a collision between two neutron stars. The event could bring a quantity of informations never seen before. But the research isn’t easy.

Because the sign arrives from a point really remote in the universe and to find out the galaxy where the collision happened they will need to look through thousands of galaxies.

Gravitational waves
Rappresentation of a fusion between two black holes

They will need months to have much more detailed informations about this event, meanwhile Virgo and Ligo will go on looking through the sky, looking for gravitational waves, mysterious signs from remote places, hidden somewhere in the universe.

This post is also available in: Italiano