Gravitational wave astronomy
The Advanced Ligo and Advanced Virgo observatories announced the first detection of a gravitational waves that has been recorded by all three interferometers simultaneously. The paper describing the event has been published by PRL. The merger event itself, a binary black hole composed of a black hole with ~30 solar masses and another one with ~25 solar masses at a redshift of about 0.1, are matching nicely the previous detections:
The crucial part of this detection is that is has been seen by all three instruments. It is thus confirming the performance of the Virgo instrument that had been switched on only two weeks before this observation. It also illustrates the power of combining the data from the different instruments to significantly improve the localisation uncertainty of the origin of the gravitational wave. Using only data from the two Ligo detectors, the 90% uncertainty maps spans 1160deg^2 across the sky, impossible to scan with typical telescope searching for a counterpart/afterglow/etc. Adding the data from Virgo this region shrinks to less then 100deg^2!! This improvement is clearly visible in the skymaps below.
Regions of this size become accessible for pointing telescopes. As example: we managed to cover almost the complete region with H.E.S.S. observations searching for high-energy gamma rays emitted by the black hole merger. As everybody else we didn't see any... See GCN #21673 for a summary of our observations.
The importance of this event is thus primarily its illustration of the achieved precision of the GW localisation allowing for follow-up observations across the electromagnetic spectrum. Astronomy with gravitational waves is thus becoming a reality... Stay tuned for more...
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