Heikenwaelder Hugo, heikenwaelder.at [CC BY-SA 2.5] Astro-Particle Physics 12 Gravitational waves Heikenwaelder Hugo, heikenwaelder.at [CC BY-SA 2.5] Manfred Jeitler WS 2018/19

Mass is always positive Differently from electric charge, magnetic fields and color charge, there is no “negative” mass Even antimatter has “positive” mass Therefore there cannot be gravitational monopole or dipole fields Have to look for quadrupole fields

Hulse-Taylor binary indirect demonstration of gravitational waves Orbital decay of PSR B1913+16.The data points indicate the observed change in the epoch of periastron with date while the parabola illustrates the theoretically expected change in epoch according to general relativity. Nobel prize 1993 to Hulse and Taylor PSR B1913+16 (also known as PSR J1915+1606 and PSR 1913+16) is a pulsar in a binary star system, in orbit with another neutron star around a common center of mass. In 1974 it was discovered by Russell Alan Hulse and Joseph Hooton Taylor, Jr., of Princeton University, a discovery for which they were awarded the 1993 Nobel Prize in Physics. It is also called the Hulse-Taylor binary pulsar after its discoverers. pulse period is 59 milliseconds orbit period is 7.75 hours

Michelson interferometer

LIGO (Laser Interferometer Gravitational Wave Observatory, USA) measurement of gravitational waves The gravitational interaction is so weak that the “graviton” which is supposed to mediate it has not been found yet. It is hoped to find gravitons and gravitational waves arriving from outer space (for instance from supernova explosions). The expected effects are very small and demand very accurate detectors and an extremely good compensation of interfering environmental effects. LIGO (Laser Interferometer Gravitational Wave Observatory, USA)

GW170817

localization of source

present and future gravitational-wave observatories

Ground-based detectors like the Laser Interferometer Gravitational-Wave Observatory (LIGO) will view the high-frequency waves from transient phenomena, like supernovae and the final minutes of inspiraling neutron-star binaries. LISA will observe the lower frequency waves from quasi-periodic sources, like compact star binaries long before coalescence, and supermassive black-hole binaries in the final months of coalescence.