A new detection of gravitational waves has been confirmed. Although, the “new” we have to take it with tweezers.
In reality it is a detection of less relevance and that was also overshadowed (pun intended) by two other much more important and mediatic ones: on the one hand, the one related to the merger of neutron stars (GW170817) and on the other, the related with the collision, much more shocking than the current one, of another pair of black holes (GW170814).
Curiously, the latter happened just a few weeks after the one that concerns us now.
The detection took place on June 8th and has received the name GW170608. Let us briefly remember that these findings are baptized with the letters “GW”, followed by the date in American format (year-month-day). This time it was about the merger of two black holes of 7 and 12 solar masses located one billion light years from our beloved planet Earth.
As in the other two mergers mentioned above, this has been another fruit of the successful LIGO-VIRGO collaboration, although in this case, and as we will now explain, only one interferometer was truly and fully operational. Another “minor” reason for the delay in the dissemination of this discovery has been, as on other occasions, the duty of scientists to first publish in journals of the field and managed and reviewed by the scientific community.
The article in question is freely available and you just have to take a look at the list of authors to get an idea of how huge this type of scientific challenge is.
But as we were saying, there is a more profound reason that has further influenced the delay in the announcement of this detection. The cause has had to do with something, at least, witty. It turns out that the Hanford interferometer (in Washington) was being checked at the time of detection. This revision consisted of manually “shaking” the mirrors of the same at known frequencies.
As the device was in ‘review’ mode, the alarms did not go off when the GW170608 wave passed, but they did so in the twin interferometer located in Livingston (Louisiana). Specifically, the aforementioned wave modified the path of light at this location 7 milliseconds later , just what it takes for the speed of light to cross the US from coast to coast.
Unfortunately, only with an interferometer (Livingston’s) it is not possible to rigorously affirm that the phenomenon that occurred is due to a gravitational wave. Confirmation of the second detector (Hanford’s, currently under maintenance) needs to be given.
However, all was not lost: a more rigorous analysis of the data recorded by this last device has made it possible to separate the signals of the gravitational wave from the “artificial” ones generated during the maintenance phase. After this analysis it has already been possible to affirm beyond any doubt that in truth, on June 8 last, the Earth was once again shaken by the hungry guts of the cosmos.
At this time, both LIGO and VIRGO are turned off to undergo much more substantial improvements that improve their sensitivity. Meanwhile, scientists will continue to scrutinize the data collected over the past months in order to find new events that would have gone unnoticed by the real-time warning system.
Alberto Corbi is a professor at the Higher School of Engineering and Technology (ESIT) of the International University of La Rioja (UNIR).
