VIRGO and LIGO together, in quest of gravitational waves
Cascina, 4 August 2017 – On Tuesday August 1st at 10 UCT the LIGO and VIRGO interferometers officially started taking data jointly.
Two perspectives justify the interest of international physics community on this date, the first concerns the conclusion of the construction and the start of operations of the European detector VIRGO, the second is the beginning of the systematic exploration of the Universe with the global network of new generation interferometers.
Once the funding Agencies (INFN, CNRS, Nikhef) approved the Advanced Virgo Technical Design Report at the beginning of 2012, it took five years of intense and innovative work to realize the ambitious objectives of the first phase of VIRGO upgrade. I wish to recognize the dedication of the members of the VIRGO Collaboration, of the EGO staff and of the twenty participating labs in the six Countries involved into the project.
Since the inauguration of VIRGO on February 20, commissioning went very well: the progress in sensitivity was rapid, the stability of the interferometer results even better of expectation and the adequate conditions to contribute significantly to the observation run O2, started by LIGO interferometers on 30 November 2016, have been achieved.
The current VIRGO sensitivity significantly exceeds the previous first-generation VIRGO record sensitivity, allowing exploring a volume of Universe 15 times larger. Even if the VIRGO horizon for the detection of collapsing neutron start binary systems results actually lower by a factor 3 with respect to the most performing LIGO interferometer, the presence of VIRGO is crucial for localizing the source of a gravitational wave signal on the sky. This is a fundamental move to open exciting perspectives for the multi-messenger investigation of our universe: the network of three high sensitivity detectors is the key to achieve it.
After the completion of O2, under the guidance of the Spokesman Jo van den Brand, the VIRGO operation will proceed to further improve the sensitivity of the detector by reducing the main sources of noise and introducing several key improvements, among which the installation of monolithic suspensions, thin and strong fused-silica fibers, which will replace the current metal wires for suspending the extraordinary mirrors. In Spring 2018, a new commissioning phase will start, with the goal of having a more sensitive detector by the time the LIGO-VIRGO “Observation Run 3” (O3) starts in Fall 2018.
VIRGO is one of the three pillars of the physics of gravitational waves, after having contributed with ideas and technologies adopted in the first version of the interferometer to mark the progress of the field. The intuition of Adalberto Giazotto on the improvement of the sensitivity in the low frequency region, below 100 Hz, has opened the road to the first three detections of signals generated by binary black holes systems.
The scientific and technological expectancies I nurtured since I took the direction of the European Gravitational Observatory EGO on January 2011 have been realised in almost seven years by the Virgo Collaboration and EGO staff. A large merit must be ascribed to Giovanni Losurdo, project leader who coordinated with equilibrium and enthusiasm the complex process of the upgrade.
Now, selfishly, I hope that before the end of my mandate on December 2017, the Nature would be so generous to give us a gift: a signal revealed by the three extraordinary detectors.
Federico Ferrini
Director of the European Gravitational Observatory
