Detecting the Gravitational Wave Memory Effect From Core-Collapse Supernovae
taylorvich writes:
https://phys.org/news/2024-12-gravitational-memory-effect-core-collapse.html
Einstein's theory of gravity, general relativity, has passed all tests with predictions that are spot-on. One prediction that remains is "gravitational wave memory"-the prediction that a passing gravitational wave will permanently change the distance between cosmic objects.
Supernovae-collapsing stars that explode outward-are thought to be generators of gravitational waves, though none have yet been definitively detected by the gravitational wave interferometers on Earth. Nor has the gravitational wave memory effect been seen, from mergers or supernovae, due to the limited sensitivity of interferometers below wave frequencies of 10 hertz.
But now a new study presents an approach to detecting the effect using currently existing gravitational wave observatories. The paper is published in Physical Review Letters.
To-date, all the gravitational waves that have been detected originated from black hole-black hole mergers, neutron star-neutron star mergers, or mergers of one of each. But collapsing supernovae of mass greater than about 10 solar masses are expected to emit gravitational waves as well, though of lower wave amplitude and with a different signature in a gravitational wave interferometer.
In such supernovae, called "core-collapsing supernovae" (CCSN), the core of a massive star undergoes sudden collapse when the energy generated from its fusion energy can no longer counteract the star's own gravity.
This results in an outgoing shock wave from the implosion. Some of the outward energy will be in the form of gravitational waves due to the star's changing quadrupole moment-with total energy of about 1040 joules-unless the star's matter is spewed isotropically. (Unlike electromagnetic waves, gravitational waves have no dipole moment due to conservation of momentum.)
Emitted as well are visible light and neutrinos, opening up the possibility of a multi-messenger detection when they arrive at Earth.
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