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Astronomy & Astrophysics 101: Gravitational Waves

This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Credit: LIGO/T. Pyle

Gravitational waves are distortions in spacetime that result from the movements of objects with mass.

Gravitational waves are not simple conceptually, as they require one to think of the fabric of the Universe in terms of spacetime. Spacetime is a four-dimensional quantity, described by Einstein’s general theory of relativity, which fuses three-dimensional space with time. Mass warps spacetime, and gravity is actually the result of spacetime’s being curved by an object’s mass. Ripples through spacetime are created by the movement of any object with mass, and these are known as gravitational wavesGravitational waves are distortions or ripples in the fabric of space and time. They were first detected in 2015 by the Advanced LIGO detectors and are produced by catastrophic events such as colliding black holes, supernovae, or merging neutron stars.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>gravitational waves. Gravitational waves are constantly passing unnoticed through the Earth. Only the waves created by extremely intense events — events that result in very rapid changes in the velocity of very massive objects — can be detected by present-day instruments. The gravitational waves that are currently detectable on Earth are generated by incredibly dramatic collision events, such as when two black holes or neutron stars merge.

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Gravitational waves are distortions in spacetime which result from the movements of objects with mass. Credit: ESOCreated in 1962, the European Southern Observatory (ESO), is a 16-nation intergovernmental research organization for ground-based astronomy. Its formal name is the European Organisation for Astronomical Research in the Southern Hemisphere.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>ESO/L. Calçada

In 2017 Hubble observed for the first time the source of a gravitational wave, created by the merger of two neutron stars. This discovery was the first glimpse of multi messenger astronomy (in which coordinated observations and interpretations are undertaken of different astronomical signals), bringing together both gravitational waves and electromagnetic radiation.

Word Bank Gravitational Wave

Credit: NASA & ESA

Also in 2017, an international team of astronomers using Hubble uncovered a supermassive black hole that had been propelled out of the center of the distant galaxy 3C186. They concluded that it was likely ejected by the powerful gravitational waves unleashed by the merger of two massive black holes at the center of its host galaxy. This was the first time that astronomers found a supermassive black holeA black hole is a place in space where the pull of gravity is so strong not even light can escape it. Astronomers classify black holes into three categories by size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass smaller than our Sun and supermassive black holes could have a mass equivalent to billions of our Sun.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>black hole at such a large distance from the center of its host galaxy.

Source: SciTechDaily