MadSci Network: Astronomy
Query:

Re: What is the age and average temperature for the black hole NGC 4261?

Date: Fri Oct 13 16:49:05 2000
Posted By: Joseph Lazio, Radio Astronomer
Area of science: Astronomy
ID: 968528052.As
Message:

Observations by Jones et al. suggest that the jets emanating from NGC 4261 have been unchanged for at least 100 million years. The jets are thought to originate from the region right around the black hole, so that would suggest that the black hole itself is at least this old.

More generally, there is growing evidence to suggest that the mass of a black hole and the mass of the central region of galaxies (technically the bulge) are related. If this is correct, then that would mean that black holes at the centers of galaxies are about as old as the galaxies themselves. (It is not known at all whether this means that black holes came before galaxies, vice versa, or the two formed together.) The typical age of a galaxy is about 10 billion years.

The temperature of a black hole is more problematic. An isolated black hole does have a temperature, due to an effect known as Hawking evaporation. However, the black hole in NGC 4261 is surrounding by an accretion disk of material (that how the jets are thought to be produced). The temperature of the accretion disk could be quite high, perhaps millions of degrees.


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