IceCube and Antares have looked for evidence of neutrino emission coincident with the gravitational wave signal seen by LIGO. They see no evidence of neutrinos being emitted by the gravitational wave source. That doesn’t mean there are no neutrinos, just that even if there are, not enough reached us to be able to see them. But, as the article points out, this means that gravitational wave and neutrino observatories can now work together to try to study rare astrophysical events.
LIGO has confirmed the rumors about what they had seen and announced that they have found the signature of a merger of two black holes over a billion light years away. This event was actually very fortunate, as it happened before the main science run started but while the detectors were operating as if a regular science run was going on. The signal is good enough to tell how long ago the event happened and even how much mass the system has and how much energy was lost due to radiation.
Both LIGO sites – Louisiana and Washington – saw the signal but unfortunately, there were no other interferometry experiments operating at the time to get a third signal. Hopefully some new sites will come online in the near future so that a worldwide gravitational wave measurement network can be set up. Large neutrino detectors do something similar for supernovas so that if several detectors see a bunch of events at once, we know that a supernova will be seen in a particular part of the sky. With three sites, there would be some ability to point back at the direction of the source of the gravitational wave using timing information.
Regardless, this is a very strong signal that was seen at two sites that are several thousand miles apart. It looks quite convincing, and hopefully if we’ve already seen one event in a short run time, we’ll see a lot more as LIGO continues to run and as other experiments are built.
Now that rumors have been flying around for a few weeks, LIGO has announced that there will be an update on their latest gravitational wave results on Thursday at 10:30 am. This kind of thing isn’t very common, so it does sound quite likely that they will announce that they have found something. A discovery of gravitational waves would be one of the most important physics results of the last few decades.
The LISA Pathfinder spacecraft launched a few days. While the LISA Pathfinder won’t be making serious physics measurements, it will be testing new technologies that are expected to be used in the final LISA experiment. LISA is planned to be an orbital gravitational wave experiment, similar to LIGO but in space and with a much longer arm distance. It will be sensitive to different types of gravitational waves than LIGO.