Type

Intermediate mass

Location

in the constellation Pisces

Distance

32 million light-years

Mass

10000 times the mass of the Sun

Size

Diameter about 37,000 miles (60,000 km), a bit larger than the planet Uranus

Discovery Methods

• Detection of an accretion disk

M74

The orbiting Chandra X-Ray Observatory has discovered the X-ray glow of thousands of possible black holes in many galaxies beyond our own. The X-ray spectra of these objects are similar to those of the disks of superhot gas that orbit known black holes.

One of the best examples is found in one of the spiral arms of M74, a galaxy that is slightly smaller than the Milky Way.

Chandra found an X-ray source that “flickers” about every two hours. The characteristics of the X-rays indicate that they are coming from an accretion disk around a black hole. (Such measurements are not considered as conclusive as other methods of detecting a black hole.)

Using mathematical models that relate the period of such a variation to the mass of the black hole, a team of astronomers led by Jifeng Liu of the University of Michigan in Ann Arbor deduced that this one is 10,000 times the mass of the Sun. That would make it one of only a handful of suspected intermediate-mass black holes discovered to date.

Alternatively, the system might not contain such a massive black hole. Instead, we might be looking directly at a “beam” of X-ray energy from a binary system that contains either a stellar-mass black hole or a neutron star. In that case, much of the X-ray energy is concentrated in a powerful beam, and we just happen to be looking into it — like looking directly into the beam of a lighthouse instead of viewing it from an angle.

References

X-rays Signal Presence of Elusive Intermediate-Mass Black Hole (Chandra)

X-rays Signal Presence of Elusive Intermediate-Mass Black Hole (U. of Mich.)

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This document was last modified: November 19, 2009.