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In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with renormalization in general relativity. In string theory, believed by some to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. These observatories use mirrors spaced four kilometers apart which are capable of detecting a change of less than one ten-thousandth the charge diameter of a proton.
The Laser Interferometer Space Antenna (LISA) is a proposed space probe to detect and accurately measure gravitational waves—tiny ripples in the fabric of spacetime—from astronomical sources. LISA would be the first dedicated space-based gravitational-wave observatory. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept has a constellation of three spacecraft arranged in an equilateral triangle with sides 2.5 million kilometres long, flying along an Earth-like heliocentric orbit. The distance between the satellites is precisely monitored to detect a passing gravitational wave.
The gravitational wave background is a random background of gravitational waves permeating the Universe, which is detectable by gravitational-wave experiments, like pulsar timing arrays. The signal may be intrinsically random, like from stochastic processes in the early Universe, or may be produced by an incoherent superposition of a large number of weak independent unresolved gravitational-wave sources, like supermassive black-hole binaries. Detecting the gravitational wave background can provide information that is inaccessible by any other means, about astrophysical source population, like hypothetical ancient supermassive black-hole binaries, and early Universe processes, like hypothetical primordial inflation and cosmic strings.
The Virgo interferometer is a large Michelson interferometer designed to detect gravitational waves predicted by general relativity. It is located in Santo Stefano a Macerata, near the city of Pisa, Italy. The instrument's two arms are three kilometres long, housing its mirrors and instrumentation inside an ultra-high vacuum.
Gravitational waves are waves of the intensity of gravity that are generated by the accelerated masses of binary stars and other motions of gravitating masses, and propagate as waves outward from their source at the speed of light. They were first proposed by Oliver Heaviside in 1893 and then later by Henri Poincaré in 1905 as the gravitational equivalent of electromagnetic waves.
Gravitational-wave astronomy is an emerging field of science, concerning the observations of gravitational waves to collect relatively unique data and make inferences about objects such as neutron stars and black holes, events such as supernovae, and processes including those of the early universe shortly after the Big Bang.
The LIGO Scientific Collaboration (LSC) is a scientific collaboration of international physics institutes and research groups dedicated to the search for gravitational waves.
Alessandra Buonanno is an Italian naturalized-American theoretical physicist and director at the Max Planck Institute for Gravitational Physics in Potsdam. She is the head of the "Astrophysical and Cosmological Relativity" department. She holds a research professorship at the University of Maryland, College Park, and honorary professorships at the Humboldt University in Berlin, and the University of Potsdam. She is a leading member of the LIGO Scientific Collaboration, which observed gravitational waves from a binary black-hole merger in 2015.
In cosmology, primordial black holes (PBHs) are hypothetical black holes that formed soon after the Big Bang. In the inflationary era and early radiation-dominated universe, extremely dense pockets of subatomic matter may have been tightly packed to the point of gravitational collapse, creating primordial black holes without the supernova compression needed to make black holes today. Because the creation of primordial black holes would pre-date the first stars, they are not limited to the narrow mass range of stellar black holes.
INDIGO or IndIGO is a consortium of Indian gravitational-wave physicists. It is an initiative to set up advanced experimental facilities for a multi-institutional observatory project in gravitational-wave astronomy to be located near Aundha Nagnath, Hingoli District, Maharashtra, India. Predicted date of commission is in 2030.
Multi-messenger astronomy is astronomy based on the coordinated observation and interpretation of signals carried by disparate "messengers": electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays. They are created by different astrophysical processes, and thus reveal different information about their sources.
The first direct observation of gravitational waves was made on 14 September 2015 and was announced by the LIGO and Virgo collaborations on 11 February 2016. Previously, gravitational waves had been inferred only indirectly, via their effect on the timing of pulsars in binary star systems. The waveform, detected by both LIGO observatories, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent "ringdown" of the single resulting black hole. The signal was named GW150914. It was also the first observation of a binary black hole merger, demonstrating both the existence of binary stellar-mass black hole systems and the fact that such mergers could occur within the current age of the universe.
Carlos O. Lousto is a Distinguished Professor in the School of Mathematical Sciences in Rochester Institute of Technology, known for his work on black hole collisions.
GW 170817 was a gravitational wave (GW) signal observed by the LIGO and Virgo detectors on 17 August 2017, originating from the shell elliptical galaxy NGC 4993. The signal was produced by the last minutes of a binary pair of neutron stars' inspiral process, ending with a merger. It is the first GW observation that has been confirmed by non-gravitational means. Unlike the five previous GW detections, which were of merging black holes not expected to produce a detectable electromagnetic signal, the aftermath of this merger was also seen by 70 observatories on 7 continents and in space, across the electromagnetic spectrum, marking a significant breakthrough for multi-messenger astronomy. The discovery and subsequent observations of GW 170817 were given the Breakthrough of the Year award for 2017 by the journal Science.
PyCBC is an open source software package primarily written in the Python programming language which is designed for use in gravitational-wave astronomy and gravitational-wave data analysis. PyCBC contains modules for signal processing, FFT, matched filtering, gravitational waveform generation, among other tasks common in gravitational-wave data analysis.
Samaya Michiko Nissanke is an astrophysicist, associate professor in gravitational wave and multi-messenger astrophysics and the spokesperson for the GRAPPA Centre for Excellence in Gravitation and Astroparticle Physics at the University of Amsterdam. She works on gravitational-wave astrophysics and has played a founding role in the emerging field of multi-messenger astronomy. She played a leading role in the discovery paper of the first binary neutron star merger, GW170817, seen in gravitational waves and electromagnetic radiation.
Michel Davier is a French physicist.
Lisa Barsotti is a research scientist at the Massachusetts Institute of Technology Kavli Institute.
References
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- ↑ "International Astronomical Union | IAU". www.iau.org. Retrieved 2017-12-28.
- ↑ "L'Aquila, la prof Marica Branchesi tra i grandi della scienza". Il Centro (in Italian). Retrieved 2017-12-28.
- ↑ "Marica e Jan, astronoma e fisico 'a caccia di onde'. La coppia che ha scelto Urbino per la ricerca". il Ducato (in Italian). 2016-02-10. Retrieved 2017-12-28.
- ↑ "L'Italia deve investire di più sulla scienza, è la nostra scommessa per il futuro". Repubblica.it (in Italian). 2017-12-19. Retrieved 2017-12-28.
- ↑ "Gentiloni proud of astrophysicist in Nature's Top Ten (3) - English Service". ANSA.it. 2017-12-19. Retrieved 2017-12-28.
- ↑ "NSF ANNOUNCES NEW GRAVITATIONAL WAVE FINDINGS, Oct 16, 2017, DC, 10:00-12:30 ET (webcast)". spacepolicyonline.com. Retrieved 2017-12-28.
- 1 2 "Nature's 10" . Retrieved 2017-12-28.
- ↑ "BRANCHESI Marica" . Retrieved 2018-07-26.
- ↑ "Breakthrough Prize – Special Breakthrough Prize In Fundamental Physics Awarded For Detection Of Gravitational Waves 100 Years After Albert Einstein Predicted Their Existence". breakthroughprize.org. Retrieved 2017-12-28.
- ↑ Malaspina, Marco. "Un'onda da tre milioni di dollari". MEDIA INAF (in Italian). Retrieved 2017-12-28.
- ↑ "Marica Branchesi: The World's 100 Most Influential People". Time. Retrieved 2018-07-26.
