Rumors of Gravitational Wave Inspiral at Advanced LIGO | Sept 2015 Launch

[Jonathan Scott]

The really interesting point is that according to the usual standard interpretation of General Relativity, no significant electromagnetic radiation is expected from a black hole merger event, but there was an apparent gamma-ray burst detected by the Fermi Gamma-ray Burst Monitor within about half a second of the first gravitational wave event. This means one of three things: the gamma-ray burst detection was spurious (unrelated or background noise), the event was not a simple black hole merger but rather a more complex physical event (for example some people have suggested some sort of merger occurring inside a star) or that General Relativity isn't quite right in that extreme situation. If an apparent gamma-ray burst accompanies another detection that would greatly reduce the probability of it being spurious, which would suggest exciting new physics.

 

[PAllen]

The really interesting point is that according to the usual standard interpretation of General Relativity, no significant electromagnetic radiation is expected from a black hole merger event, but there was an apparent gamma-ray burst detected by the Fermi Gamma-ray Burst Monitor within about half a second of the first gravitational wave event. This means one of three things: the gamma-ray burst detection was spurious (unrelated or background noise), the event was not a simple black hole merger but rather a more complex physical event (for example some people have suggested some sort of merger occurring inside a star) or that General Relativity isn't quite right in that extreme situation. If an apparent gamma-ray burst accompanies another detection that would greatly reduce the probability of it being spurious, which would suggest exciting new physics.

Weakening this finding is failure to detect this signal in other detectors that should have seen it (and that looked carefully for it, e.g. the INTEGRAL detector), and the the random chance probability (given the wide search area) could be as high as 2.8%, depending on assumptions uses (per the paper reporting this find). Using standard priors, the paper quoted .2% chance of coincidence, but noted that other assumptions could lead to the much higher coincidence figure.

To me, this is most likely a non-observation given the whole context. That would obviously change if some future similar detection were made.

 

[mfb]

We'll probably know in a year, with the second LIGO run. and now without necessity to keep the events somewhat secret.

 

[websterling]

there was an apparent gamma-ray burst detected by the Fermi Gamma-ray Burst Monitor

Actually the "burst" was most likely due to improper statistical modeling of a background fluctuation according to this paper on the arXiv and accepted to the Astrophysical Journal Letters- "On the GBM event seen 0.4 sec after GW 150914"

From the abstract- "We find that after proper accounting for low count statistics, the GBM transient event at 0.4 s after GW 150914 is likely not due to an astrophysical source, but consistent with a background fluctuation." The new statistical modeling is said to be a major advancement in detecting low count events with the GBM.

Ethan Siegel (Starts With A Bang) also has an article "NASA's Big Mistake: LIGO's Merging Black Holes Were Invisible After All"