GW Detection Confirmation: Time, Rate, & GRB?

[Gravitoastronomy]

I understand that the LIGO experiment was very lucky to find a very strong signal of a very energetic event (binary black hole merger). Having into account the non-negligible possibility that the signal may be spurious or some problem in the data adquisition, how much time must pass before we can confirm (with a second event) that the result was likely genuine, or that could be spurious (for example, if months pass without other detection). In other words, what is the average rate of expected discoveries similar to the event on 11th December?

I have also heard that there has been independent confirmation of Gamma-ray burst coincident in time with the event (0.4 seconds shift). How trusty are those news?

 

[Orodruin]

The rate is unknown. The best bounds on the rate (which are rather weak) comes from the LIGO event.

 

[Gravitoastronomy]

The rate is unknown. The best bounds on the rate (which are rather weak) comes from the LIGO event.

So we must wait. After the first announcement and all the excitement, I read the paper and I changed mood, it was too good to be true, like a kind of WOW! signal. I hope that new events will confirm the data, they had detected a few candidates but with much lower sigma.

 

[vanhees71]

The rate is unknown. The best bounds on the rate (which are rather weak) comes from the LIGO event.

That was one of my questions, left open in a discussion in our institute. How were the bounds on the rate estimated from just a single event?

 

[Orodruin]

That was one of my questions, left open in a discussion in our institute. How were the bounds on the rate estimated from just a single event?

I would assume that this was inferred in the standard way. If the signal+background rate was too low, it would be very unlikely to already have an event, which would put a lower bound on signal+background rate (translating to a lower bound on the signal rate given that the background rate is minuscule). If the signal+background rate was too high, it would be very unlikely to not have observed more events, which would put an upper bound on the rate.

Of course, one event is not much statistics and therefore the resulting allowed range is going to be large (2-400 Gpc^-3 yr^-1 as quoted in the LIGO paper).

 

[vanhees71]

I see, thanks for the quick response!