3 ms·

At the moment, the researches don't believe that the light was slower, but that it took that much time for the electromagnetic "flash" to be produced, compared

by acqq 9y ago

At the moment, the researches don't believe that the light was slower, but that it took that much time for the electromagnetic "flash" to be produced, compared to some specific point in the signal observed by the gravitational waves detectors. The later signal is not a point-like but a long signal which gets stronger as the stars get closer and closer to one another and then it disappears once there are no two stars anymore. https://www.forbes.com/sites/startswithabang/2017/10/17/why-neutron-stars-not-black-holes-show-the-future-of-gravitational-wave-astronomy/ https://www.forbes.com/sites/startswithabang/2017/10/17/why-... "It's anticipated that these two speeds are exactly equal, and the delay of the light signal comes from the fact that the light-producing reactions in the neutron star take a second or two to reach the surface." A lot about this event was modeled even before this observation, and there will now be more attempts to make more precise models that better match what was measured. And the best is, these models will be evaluated by the next, planned observations.

lutorm 9y ago
The same process, but in a different scenario, was observed in supernova 1987a: "Approximately two to three hours before the visible light from SN 1987A reached Earth, a burst of neutrinos was observed at three separate neutrino observatories. This is likely due to neutrino emission, which occurs simultaneously with core collapse, but preceding the emission of visible light. Transmission of visible light is a slower process that occurs only after the shock wave reaches the stellar surface." This result set a pretty strong upper bound on the neutrino mass because it must be small enough that, across the 168,000 light year distance from the LMC to us, the neutrinos kept their lead on the photons emitted a few hours later. A neutron star is much smaller, the process is much faster, and the event happened much further away, so the constraints on the difference in speed between the gravitational waves and photons should be even more tightly constrained in this event.

by acqq 9y ago

lutorm 9y ago

The same process, but in a different scenario, was observed in supernova 1987a: "Approximately two to three hours before the visible light from SN 1987A reached Earth, a burst of neutrinos was observed at three separate neutrino observatories. This is likely due to neutrino emission, which occurs simultaneously with core collapse, but preceding the emission of visible light. Transmission of visible light is a slower process that occurs only after the shock wave reaches the stellar surface." This result set a pretty strong upper bound on the neutrino mass because it must be small enough that, across the 168,000 light year distance from the LMC to us, the neutrinos kept their lead on the photons emitted a few hours later. A neutron star is much smaller, the process is much faster, and the event happened much further away, so the constraints on the difference in speed between the gravitational waves and photons should be even more tightly constrained in this event.