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Pulsar Timing Array
A pulsar timing array (PTA) is a set of pulsars which is analysed to search for correlated signatures in the pulse arrival times. There are many applications for pulsar timing arrays. The best known is the use of an array of millisecond pulsars to detect and analyse gravitational waves. Such a detection would result from a detailed investigation of the correlation between arrival times of pulses emitted by the millisecond pulsars as a function of the pulsars' angular separations. Overview Millisecond pulsars are used because they are not prone to the starquakes and accretion events which can affect the period of classical pulsars. One influence on these propagation properties are low-frequency gravitational waves, with a frequency of 10−9 to 10−6 hertz; the expected astrophysical sources of such gravitational waves are massive black hole binaries in the centres of merging galaxies, where tens of millions of solar masses are in orbit with a period between months and a few years. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulsar
A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth (similar to the way a lighthouse can be seen only when the light is pointed in the direction of an observer), and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays. (See also centrifugal mechanism of acceleration.) The periods of pulsars make them very useful tools for astronomers. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation. The first extrasolar planets were discovered aroun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lovell Telescope
The Lovell Telescope is a radio telescope at Jodrell Bank Observatory, near Goostrey, Cheshire in the north-west of England. When construction was finished in 1957, the telescope was the largest steerable dish radio telescope in the world at 76.2 m (250 ft) in diameter; it is now the third-largest, after the Green Bank Telescope, Green Bank telescope in West Virginia, United States, and the Effelsberg 100-m Radio Telescope, Effelsberg telescope in Germany. It was originally known as the "250 ft telescope" or the Radio Telescope at Jodrell Bank, before becoming the Mark I telescope around 1961 when future telescopes (the Mark II (radio telescope), Mark II, Mark III (radio telescope), III, and IV) were being discussed.Lovell, ''The Jodrell Bank Telescopes'' It was renamed to the Lovell Telescope in 1987 after Sir Bernard Lovell, and became a Grade I listed building in 1988. The telescope forms part of the MERLIN and European VLBI Network arrays of radio telescopes. Both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Metrewave Radio Telescope
The Giant Metrewave Radio Telescope (GMRT), located near Pune, Junnar, near Narayangaon at khodad in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research, Mumbai. It was conceived and built under the direction of Late Prof. Govind Swarup during 1984 to 1996. It is an interferometric array with baselines of up to . It was recently upgraded with new receivers, after which it is also known as the Upgraded Giant Metrewave Radio Telescope (uGMRT). Location The GMRT Observatory is located about 80 km north of Pune at Khodad. A nearby town is Narayangaon which is around 9 km from the telescope site. The office of NCRA is located in the Savitribai Phule Pune University campus. Science and observations One of the aims for the telescope during its development was to search for the highl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Bank Radio Telescope
The Robert C. Byrd Green Bank Telescope (GBT) in Green Bank, West Virginia, US is the world's largest fully steerable radio telescope, surpassing the Effelsberg 100-m Radio Telescope in Germany. The Green Bank site was part of the National Radio Astronomy Observatory (NRAO) until September 30, 2016. Since October 1, 2016, the telescope has been operated by the independent Green Bank Observatory. The telescope's name honors the late Senator Robert C. Byrd who represented West Virginia and who pushed the funding of the telescope through Congress. The Green Bank Telescope operates at meter to millimeter wavelengths. Its 100-meter diameter collecting area, unblocked aperture, and good surface accuracy provide superb sensitivity across the telescope's full 0.1–116 GHz operating range. The GBT is fully steerable, and 85 percent of the local celestial hemisphere is accessible. It is used for astronomy about 6500 hours every year, with 2000–3000 hours per year going to high-f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. Following two breaks in cables supporting the receiver platform in mid-2020, the NSF decommissioned the telescope. A partial collapse of the telescope occurred on December 1, 2020, before controlled demolition could be conducted. In 2022, the NSF announced the telescope will not be rebuilt, with an educational fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Nanohertz Observatory For Gravitational Waves
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is a consortium of astronomers who share a common goal of detecting gravitational waves via regular observations of an ensemble of millisecond pulsars using the Green Bank and Arecibo radio telescopes. This project is being carried out in collaboration with international partners in the Parkes Pulsar Timing Array in Australia and the European Pulsar Timing Array as part of the International Pulsar Timing Array. Gravitational wave detection using pulsar timing Gravitational waves are an important prediction from Einstein's general theory of relativity and result from the bulk motion of matter, fluctuations during the early universe and the dynamics of space-time itself. Pulsars are rapidly rotating, highly magnetized neutron stars formed during the supernova explosions of massive stars. They act as highly accurate clocks with a wealth of physical applications ranging from celestial mechanics, neutron star s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sardinia Radio Telescope
The Sardinia Radio Telescope (SRT) is 64-metre fully steerable radio telescope near San Basilio, Sardinia, San Basilio, Province of Cagliari, Sardinia, Italy. Completed in 2011, it is a collaboration between the Istituto di Radioastronomia di Bologna, the Cagliari Observatory (Cagliari) and the Arcetri Observatory, Arcetri Astrophysical Observatory (Florence). Design The telescope is in Sardinia, north of Cagliari, and is the largest of a set of three telescopes operated by INAF, along with telescopes at the Medicina Radio Observatory and the Noto Radio Observatory. It operates as a stand-alone instrument and as part of global networks of telescopes. The telescope and its structure weighs around . The primary mirror is in diameter. It has an active surface consisting of 1008 aluminum panels in 14 rows. Each panel has an area between 2.4 and 5.3 square metres. There are 1116 actuators mounted on the backing structure, which move the surface panels correct for the distortion of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effelsberg Telescope
The Effelsberg 100-m Radio Telescope is a radio telescope in the Ahr Hills (part of the Eifel) in Bad Münstereifel, Germany. For 29 years the Effelsberg Radio Telescope was the largest fully steerable radio telescope on Earth, surpassing the Lovell Telescope in the UK. In 2000, it was surpassed by the Green Bank Observatory's Robert C. Byrd Green Bank Telescope in Green Bank, US, which has a slightly larger elliptical 100 by 110-metre aperture. Geography The telescope is located about 1.3 km northeast of Effelsberg, a southeastern part of the town of Bad Münstereifel in North Rhine-Westphalia. It is less than 300 m west of the 398 m high Hünerberg, which is in neighbouring Rhineland-Palatinate. The boundary is a stream, the Effelsberger Bach, which runs only a few metres east of the telescope. The Effelsberger Bach is 6.5 km long, flowing from the Effelsberger Wald into the Sahrbach, which in turn flows south and into the Ahr river. A hiking path leads ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Westerbork Synthesis Radio Telescope
The Westerbork Synthesis Radio Telescope (WSRT) is an aperture synthesis interferometer built on the site of the former World War II Nazi detention and transit camp Westerbork, north of the village of Westerbork, Midden-Drenthe, in the northeastern Netherlands. Overview The WRST comprises fourteen 25-metre radio telescopes deployed in a linear array arranged on a East-West line, of which 10 are in a fixed equidistant position, 2 are nearby on a 300 m rail track, and 2 are located a kilometer eastwards on another 200 m rail track. It has a similar arrangement to other radio telescopes such as the One-Mile Telescope, Australia Telescope Compact Array and the Ryle Telescope. Its Equatorial mount is what sets it apart from most other radio telescopes, most of which have an Altazimuth mount. This makes it specifically useful for specific types of science, like polarized emission research as the detectors maintain a constant orientation on the sky during an observation. Ten of the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Pulsar Timing Array
The European Pulsar Timing Array (EPTA) is a European collaboration to combine five 100-m class radio-telescopes to observe an array of pulsars with the specific goal of detecting gravitational waves. It is one of three pulsar timing array projects in operation, the others being the Parkes Pulsar Timing Array and the North American Nanohertz Observatory for Gravitational Waves. Pulsars and high-precision timing Pulsars are rapidly rotating, highly magnetised neutron stars that emit radio waves from their magnetic poles that are, due to the star's rotation, observed on Earth as a string of pulses. Due to the extremely high density of neutron stars, their rotation periods are very stable, hence the observed arrival time of the pulses are highly regular. These arrival times are called TOAs (time of arrival) and can be used to perform high-precision timing experiments. The stability of the TOAs from most pulsars is limited due to the presence of red noise, also called "timing noise" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millisecond Pulsar
A millisecond pulsar (MSP) is a pulsar with a rotational period less than about 10 milliseconds. Millisecond pulsars have been detected in radio, X-ray, and gamma ray portions of the electromagnetic spectrum. The leading theory for the origin of millisecond pulsars is that they are old, rapidly rotating neutron stars that have been spun up or "recycled" through accretion of matter from a companion star in a close binary system. For this reason, millisecond pulsars are sometimes called recycled pulsars. Millisecond pulsars are thought to be related to low-mass X-ray binary systems. It is thought that the X-rays in these systems are emitted by the accretion disk of a neutron star produced by the outer layers of a companion star that has overflowed its Roche lobe. The transfer of angular momentum from this accretion event can theoretically increase the rotation rate of the pulsar to hundreds of times per second, as is observed in millisecond pulsars. There has been recent evidence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
