From U Manchester via phys.org: “Astronomers find black hole in Sagittarius constellation”

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University of Manchester

phys.org

April 28, 2017

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Sagittarius region of milky way. Credit: Wikipedia

An international team of astronomers led The University of Manchester have found evidence of a new ‘missing-link’ black hole in the Milky Way galaxy, hidden in the Sagittarius constellation.

The black hole is located approximately 26,000 light years, or 7.9 Kiloparsecs (kpc), from Earth in a globular cluster called, NGC 6624. A globular cluster is a gravitationally bound swarm of millions of old stars occupying regions that are just a few light years across.

The team, led by Dr Benetge Perera, have found evidence that the millisecond pulsar (PSR B1820-30A) – a pulsar is highly magnetized, rapidly rotating neutron star that emits a beam of electromagnetic radiation – in NGC 6624 is most likely orbiting around an intermediate-mass black hole (IMBH) located at the cluster’s centre. The mass of black hole is so big, it is the equivalent to weight of 7,500 of our suns.

PSR B1820 30A is the closest-known pulsar to the centre of any globular cluster and it is the first pulsar to be found orbiting a black hole. The detection of IMBHs is extremely important as they can help astronomers understand the ‘missing link’ between stellar mass black holes (SMBH), the smallest kind, and supermassive black holes (SMBH), which are the largest.

Dr Perera, from the Jodrell Bank Centre for Astrophysics in the University’s School of Physics and Astronomy, explains: “High stellar densities towards the centre of globular clusters provide a likely environment for the formation of massive black holes. The detection of IMBHs is important for understanding the missing link between the different kinds of black holes.

“It is generally thought that they could be formed by the direct collapse of very massive primordial stars or successive mergers of stellar-mass black holes and runaway collisions in dense young star clusters.”

The pulsar was discovered using the Lovell Telescope, based at Jodrell Bank, in 1990. Since then the team has analysed more than 25 years of observations from PSR B1820- 30A made with the telescope. In addition to Jodrell Bank, the analysis included data obtained using the Nançay Radio Telescope in France.

U Manchester Jodrell Bank Lovell Telescope

Nançay decametric radio telescope Nançay France

Professor Andrew Lyne, also from the School of Physics and Astronomy, explains the importance of discovering such pulsars: “Pulsars like PSR B1820 30A act as fantastically accurate clocks and allow us to determine precisely their distance from the Earth in the same way that global positioning satellites work. The pulsar is therefore very sensitive to any motion arising from the gravity of other nearby massive objects, such as black holes, making it easier for us to detect them.”

Dr Perera added: “We have determined the orbital parameters and the companion mass of PSR B1820-30A from the motion measured through pulsar timing. Simply put, this means our results are consistent with the pulsar being in orbit around a central intermediate-mass black hole.

“This discovery provides important input to our understanding of how intermediate-mass black holes and the clusters themselves form and evolve.”

See the full article here .

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The University of Manchester (UoM) is a public research university in the city of Manchester, England, formed in 2004 by the merger of the University of Manchester Institute of Science and Technology (renamed in 1966, est. 1956 as Manchester College of Science and Technology) which had its ultimate origins in the Mechanics’ Institute established in the city in 1824 and the Victoria University of Manchester founded by charter in 1904 after the dissolution of the federal Victoria University (which also had members in Leeds and Liverpool), but originating in Owens College, founded in Manchester in 1851. The University of Manchester is regarded as a red brick university, and was a product of the civic university movement of the late 19th century. It formed a constituent part of the federal Victoria University between 1880, when it received its royal charter, and 1903–1904, when it was dissolved.

The University of Manchester is ranked 33rd in the world by QS World University Rankings 2015-16. In the 2015 Academic Ranking of World Universities, Manchester is ranked 41st in the world and 5th in the UK. In an employability ranking published by Emerging in 2015, where CEOs and chairmen were asked to select the top universities which they recruited from, Manchester placed 24th in the world and 5th nationally. The Global Employability University Ranking conducted by THE places Manchester at 27th world-wide and 10th in Europe, ahead of academic powerhouses such as Cornell, UPenn and LSE. It is ranked joint 56th in the world and 18th in Europe in the 2015-16 Times Higher Education World University Rankings. In the 2014 Research Excellence Framework, Manchester came fifth in terms of research power and seventeenth for grade point average quality when including specialist institutions. More students try to gain entry to the University of Manchester than to any other university in the country, with more than 55,000 applications for undergraduate courses in 2014 resulting in 6.5 applicants for every place available. According to the 2015 High Fliers Report, Manchester is the most targeted university by the largest number of leading graduate employers in the UK.

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