Gravitationally redshifted emission implying an accretion disk and massive black hole in the active galaxy MCG-6-30-15
Article Abstract:
The relativistic effects of active galactic nuclei and quasars influenced by the gravitational field of a black hole, such as the velocity of the gas near the event horizon, should provide observable evidence for the existence of black holes. The velocity of gas at the speed of light has been detected in an X-ray emission line (the K-alpha line) from ionized iron in the active galaxy MCG-6-30-15, suggesting the presence of a black hole. The asymmetrical lines are broad, having a velocity of nearly 100,000 Km per second, with most of the line flux being redshift. This indicates that the line arises from the innermost region on the accretion disk.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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A large nuclear accretion disk in the active galaxy NGC4261
Article Abstract:
A large, cool disk of dust in NGC4261 appears to be the outer accretion disk surrounding and feeding a black hole. Observations with the Hubble Space Telescope's Planetary Camera, Palomar Mountain's 48'' Schmidt telescope, and the National Radio Astronomy Observatory's Very Large Array reveal an outer disk surrounding a point source with two lobed jets. The inner source seems to be an inner accretion disk, through which the outer disk feeds the structure's engine.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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A Cepheid distance to the Fornax cluster and the local expansion rate of the Universe
Article Abstract:
Galaxy distances and velocities are needed to determine the expansion rate of the Universe, as described by the Hubble constant H(sub 0). Accurate distances of nearby galaxies and clusters are needed to measure indirect distance indicators, using Cepheid variable stars. A Cepheid distance of 18.6 plus or minus 1.9 (statistical error) plus or minus 1.9 Mpc (systematic error) for the galaxy NGC1365 in Fornax is reported.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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