Image of Black Hole Released for First Time
by Owen Borville
The first direct images of a black hole were released this month (April 10, 2019), after observations were made by the Event Horizon Telescope in 2017 of a massive black hole. The massive black hole is at the center of the elliptical galaxy Messier 87 (M87). Scientists calculate the mass at six to seven billion times the mass of our Earth's sun. Scientists describe a black hole as an incredibly massive region of space-time where nothing can escape its gravitational pull, including particles and electromagnetic radiation such as light. No light is reflected from a black hole. The boundary of the region from which no escape is possible is called the event horizon. The theory of general relativity proposed by Albert Einstein predicts that a sufficiently compact mass can deform spacetime to form a black hole.
Black holes are believed to form when massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form and there is a widespread belief among scientists that supermassive black holes exist in the centers of most galaxies.
Scientists detect the presence of a black hole from its interaction with other matter and electromagnetic radiation. The mass and location of a black hole can be detected and determined by the orbits of other stars rotating around the black hole and this information can be used to differentiate the presence of a black hole in contrast to a neutron star, which is a collapsed or exploded star that is not as massive as a black hole.
On February 11, 2016, the LIGO collaboration (Laser Interferometer Gravitational-Wave Observatory) announced the first direct detection of gravitational waves, which also represented the first observation of a black hole merger.
Black holes and their event horizons are believed to be surrounded by glowing gas and this gas is visible from the recently released images from the black hole observation. The dark central region of the black hole is not the event horizon, but is the black hole's shadow, which is the central region of emitting gas darkened by the central black hole's gravity.
The size and shape of the shadow is determined by bright gas near the event horizon, by strong gravitational lensing deflections, and by the black hole's spin. By resolving the black hole's shadow, the Event Horizon Telescope (EHT) strengthened evidence that Einstein's gravity works even in extreme regions, and gave clear evidence that the M87 galaxy has a central spinning black hole of about 6 billion solar masses.
Wald, R. M. (1997). "Gravitational Collapse and Cosmic Censorship". In Iyer, B. R.; Bhawal, B. Black Holes, Gravitational Radiation and the Universe. Springer. pp. 69–86. arXiv:gr-qc/9710068. doi:10.1007/978-94-017-0934-7. ISBN 978-9401709347.
Overbye, Dennis (8 June 2015). "Black Hole Hunters". NASA. Archived from the original on 9 June 2015. Retrieved 8 June 2015.
Abbott, B.P.; et al. (2016). "Observation of Gravitational Waves from a Binary Black Hole Merger". Phys. Rev. Lett. 116 (6): 061102. arXiv:1602.03837. Bibcode:2016PhRvL.116f1102A. doi:10.1103/PhysRevLett.116.061102. PMID 26918975.
Astronomy Picture of the Day, (https://apod.nasa.gov/apod/ap190411.html).
by Owen Borville
The first direct images of a black hole were released this month (April 10, 2019), after observations were made by the Event Horizon Telescope in 2017 of a massive black hole. The massive black hole is at the center of the elliptical galaxy Messier 87 (M87). Scientists calculate the mass at six to seven billion times the mass of our Earth's sun. Scientists describe a black hole as an incredibly massive region of space-time where nothing can escape its gravitational pull, including particles and electromagnetic radiation such as light. No light is reflected from a black hole. The boundary of the region from which no escape is possible is called the event horizon. The theory of general relativity proposed by Albert Einstein predicts that a sufficiently compact mass can deform spacetime to form a black hole.
Black holes are believed to form when massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form and there is a widespread belief among scientists that supermassive black holes exist in the centers of most galaxies.
Scientists detect the presence of a black hole from its interaction with other matter and electromagnetic radiation. The mass and location of a black hole can be detected and determined by the orbits of other stars rotating around the black hole and this information can be used to differentiate the presence of a black hole in contrast to a neutron star, which is a collapsed or exploded star that is not as massive as a black hole.
On February 11, 2016, the LIGO collaboration (Laser Interferometer Gravitational-Wave Observatory) announced the first direct detection of gravitational waves, which also represented the first observation of a black hole merger.
Black holes and their event horizons are believed to be surrounded by glowing gas and this gas is visible from the recently released images from the black hole observation. The dark central region of the black hole is not the event horizon, but is the black hole's shadow, which is the central region of emitting gas darkened by the central black hole's gravity.
The size and shape of the shadow is determined by bright gas near the event horizon, by strong gravitational lensing deflections, and by the black hole's spin. By resolving the black hole's shadow, the Event Horizon Telescope (EHT) strengthened evidence that Einstein's gravity works even in extreme regions, and gave clear evidence that the M87 galaxy has a central spinning black hole of about 6 billion solar masses.
Wald, R. M. (1997). "Gravitational Collapse and Cosmic Censorship". In Iyer, B. R.; Bhawal, B. Black Holes, Gravitational Radiation and the Universe. Springer. pp. 69–86. arXiv:gr-qc/9710068. doi:10.1007/978-94-017-0934-7. ISBN 978-9401709347.
Overbye, Dennis (8 June 2015). "Black Hole Hunters". NASA. Archived from the original on 9 June 2015. Retrieved 8 June 2015.
Abbott, B.P.; et al. (2016). "Observation of Gravitational Waves from a Binary Black Hole Merger". Phys. Rev. Lett. 116 (6): 061102. arXiv:1602.03837. Bibcode:2016PhRvL.116f1102A. doi:10.1103/PhysRevLett.116.061102. PMID 26918975.
Astronomy Picture of the Day, (https://apod.nasa.gov/apod/ap190411.html).
