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X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the donor, to the other component, called the accretor, which is either a neutron star or black hole. The infalling matter releases gravitational potential energy, up to 30 percent of its rest mass, as X-rays. The lifetime and the mass-transfer rate in an X-ray binary depends on the evolutionary status of the donor star, the mass ratio between the stellar components, and their orbital separation.
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A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.
A stellar black hole is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. The process is observed as a hypernova explosion or as a gamma ray burst. These black holes are also referred to as collapsars.
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In astronomy, the intracluster medium (ICM) is the superheated plasma that permeates a galaxy cluster. The gas consists mainly of ionized hydrogen and helium and accounts for most of the baryonic material in galaxy clusters. The ICM is heated to temperatures on the order of 10 to 100 megakelvins, emitting strong X-ray radiation.
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GRS 1915+105 or V1487 Aquilae is an X-ray binary star system which features a regular star and a black hole. It was discovered on August 15, 1992 by the WATCH all-sky monitor aboard Granat. "GRS" stands for "GRANAT source", "1915" is the right ascension and "105" reflects the approximate declination. The near-infrared counterpart was confirmed by spectroscopic observations. The binary system lies 11,000 parsecs away in Aquila. GRS 1915+105 is the heaviest of the stellar black holes so far known in the Milky Way Galaxy, with 10 to 18 times the mass of the Sun. It is also a microquasar, and it appears that the black hole rotates at least 950 times per second, close to the maximum of 1,150 times per second, with a spin parameter value between 0.82 and 1.00.
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An accretion disk is a structure formed by diffuse material in orbital motion around a massive central body. The central body is most frequently a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other forces induce instabilities causing orbiting material in the disk to spiral inward toward the central body. Gravitational and frictional forces compress and raise the temperature of the material, causing the emission of electromagnetic radiation. The frequency range of that radiation depends on the central object's mass. Accretion disks of young stars and protostars radiate in the infrared; those around neutron stars and black holes in the X-ray part of the spectrum. The study of oscillation modes in accretion disks is referred to as diskoseismology.
Laura A. Lopez is an associate professor of astronomy at Ohio State University studying the life cycle of stars. She was awarded the Annie Jump Cannon Award in Astronomy in 2016, which is awarded by the American Astronomical Society (AAS) for outstanding research and promise for future research by a postdoctoral woman researcher.
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References
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- 1 2 3 4 Luque-Escamilla, Pedro L.; Martí, Josep; Martínez-Aroza, José (2015-12-01). "The precessing jets of 1E 1740.7−2942". Astronomy & Astrophysics. 584: A122. arXiv: 1511.01425 . doi: 10.1051/0004-6361/201527238 . ISSN 0004-6361.
- ↑ Sunyaev, R. A.; Borozdin, K. N.; Aleksandrovich, N. L.; Arefev, V. A.; Kaniovskii, A. S.; Efremov, V. V.; Maisack, M.; Reppin, C.; Skinner, J. K. (November 1994). "Observations of X-ray novae in Vela (1993), Ophiuchus (1993), and Perseus (1992) using the instruments of the Mir-Kvant module". Astronomy Letters. 20 (6): 777. Bibcode:1994AstL...20..777S.
- ↑ Odenwald, Sten (1997). "What do we know about the 'Great Annihilator' in the center of the Milky Way?". Astronomy Cafe. Archived from the original on 16 January 2013. Retrieved 4 August 2014.
- ↑ Mirabel, I. F. "The Great Annihilator in the Central Region of the Galaxy" (PDF). eso.org. pp. 51–54.
- ↑ Stecchini, Paulo Eduardo; Castro, Manuel; Jablonski, Francisco; D’Amico, Flavio; Braga, João (2017-06-30). "Tandem Swift and INTEGRAL Data to Revisit the Orbital and Superorbital Periods of 1E 1740.7–2942". The Astrophysical Journal. 843 (1): L10. arXiv: 1707.00730 . Bibcode:2017ApJ...843L..10S. doi: 10.3847/2041-8213/aa7942 . ISSN 2041-8213. S2CID 119354178.
- ↑ Hertz, P.; Grindlay, J. E. (1984-03-01). "The Einstein galactic plane survey : statistical analysis of the complete X-ray sample". The Astrophysical Journal. 278: 137–149. Bibcode:1984ApJ...278..137H. doi:10.1086/161775. ISSN 0004-637X.
- 1 2 Sunyaev, R.; Churazov, E.; Gilfanov, M.; Pavlinsky, M.; Grebenev, S.; Babalyan, G.; Dekhanov, I.; Khavenson, N.; Bouchet, L.; Mandrou, P.; Roques, J. P. (December 1991). "Three spectral states of 1E 1740.7-2942 – From standard Cygnus X-1 type spectrum to the evidence of electron-positron annihilation feature". The Astrophysical Journal. 383: L49. Bibcode:1991ApJ...383L..49S. doi: 10.1086/186238 . ISSN 0004-637X.
- ↑ Bouchet, L.; Mandrou, P.; Roques, J. P.; Vedrenne, G.; Cordier, B.; Goldwurm, A.; Lebrun, F.; Paul, J.; Sunyaev, R.; Churazov, E.; Gilfanov, M. (December 1991). "Sigma discovery of variable e(+)–e(−) annihilation radiation from the near Galactic center variable compact source 1E 1740.7-2942". The Astrophysical Journal. 383: L45. doi:10.1086/186237. ISSN 0004-637X.
- ↑ "Milky Way Monster". Time. 1992-07-27. ISSN 0040-781X . Retrieved 2019-10-24.
- ↑ Mirabel, I. F.; Rodríguez, L. F.; Cordier, B.; Paul, J.; Lebrun, F. (July 1992). "A double-sided radio jet from the compact Galactic Centre annihilator 1E1740.7–2942". Nature. 358 (6383): 215–217. Bibcode:1992Natur.358..215M. doi:10.1038/358215a0. ISSN 0028-0836. S2CID 4264588.