Introduction to gravitational wave astronomy

blue and red galaxy artwork
Photo by Suzy Hazelwood on

Gravitational-wave astronomy is an evolving branch of astronomy that aims to use gravitational waves to accumulate observational data about objects such as black holes and neutron stars, events such as supernovae, and means including those of the ancient universe after the Big Bang.

Ordinary Gravitational waves

Ordinary gravitational waves’ frequencies are incredibly low and comparatively harder to detect, while higher frequencies occur in more tense events and thus have become the first to be recognized.

In addition to a consolidation of black holes, a double neutron star merger has been detected: a gamma-ray burst (GRB) was seen by the orbiting Fermi gamma-ray burst monitor on 2017 August 2017 CE, triggering an electronic notice worldwide. Six minutes later, a single detector at Hanford LIGO, a gravitational-wave observatory, recorded a gravitational-wave nominee befalling around 2 seconds before the gamma-ray burst.

High frequency

In 2015 CE, the LIGO project was the first to observe gravitational waves using laser interferometers directly. The LIGO detectors saw gravitational waves from the consolidation of two stellar-mass black holes, matching forecasts of general relativity. These checks confirmed the existence of binary stellar-mass black hole systems. They were the first direct discovery of gravitational waves and the first observation of a binary black hole merger. This conclusion has been characterized as revolutionary to science because of the attestation of our ability to use gravitational-wave astronomy to proceed in our search and exploration of the big bang and dark matter.

There are many current scientific collaborations for observing gravitational waves. There is a global network of ground-based detectors; these are kilometer-scale laser interferometers, including 

  1. The Laser Interferometer Gravitational-Wave Observatory (LIGO), a joint project between MIT, Caltech, and the scientists of the LIGO Scientific Collaboration with detectors in Livingston, Louisiana, and Hanford, Washington; 
  2. Virgo, at the European Gravitational Observatory, Cascina, Italy; 
  3. GEO600 in Sarstedt, Germany, and
  4. The Kamioka Gravitational Wave Detector (KAGRA), operated by the University of Tokyo in the Kamioka Observatory, Japan. LIGO and Virgo are currently being upgraded to their advanced configurations.
Binary systems made up of two massive objects orbiting each other are an important source for gravitational-wave astronomy. The system emits gravitational radiation as it orbits, these carry away energy and momentum, causing the orbit to shrink. Shown here is a binary white dwarf system, an important source for space-borne detectors like LISA. The eventual merger of the white dwarfs may result in a supernova, represented by the explosion in the third panel.

Low frequency

Astronomy has relied on electromagnetic radiation in the past. As technology advanced, starting with the visible band, it became possible to see other parts of the electromagnetic spectrum, from gamma to radio rays. Each new frequency band gave a new outlook on the universe and publicized discoveries. During the later 20th century, secondary and later direct measures of high-energy, massive particles produced an additional window into the universe. Late in the 20th century, the discovery of solar neutrinos established the field of neutrino astronomy, providing an insight into earlier inaccessible phenomena, such as the inner workings of our Sun. The observation of gravitational waves presents a further means of securing astrophysical observations.


As a new area of research, gravitational-wave astronomy is still evolving; however, there is consensus within the astrophysics community that this field will grow to become an approved component of 21st-century multi-messenger astronomy.

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