Nearby Galaxy Holds First Ultraluminous X-Ray Source that is a Pulsar

A research team led by Caltech astronomers of Pasadena California have discovered an ultraluminous X-ray (ULX) source that is pulsating. Their analysis concluded that the source in a nearby galaxy – M82 – is from a rotating neutron star, a pulsar. This is the first ULX source attributed to a pulsar.

Matteo Bachetti of the Université de Toulouse in France first identified the pulsating source and is the lead author of the paper, “An ultraluminous X-ray source powered by an accreting neutron star” in the journal Nature. Caltech astronomer Dr. Fiona Harrison, the team leader, stated “This compact little stellar remnant is a real powerhouse. We’ve never seen anything quite like it. We all thought an object with that much energy had to be a black hole.”

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Took a little bit of reading to figure out what an “Ultraluminous X-ray source” is. We know them better as intermediate mass black holes, black holes that have a mass intermediate between those of stellar black holes and galactic black holes.

It is startling to find that the most famous of these, the one in nearby galaxy M82, is pulsing. The luminosity is according to theory too large to be generated by any object of stellar size, and that includes all neutron star pulsars. On the other hand black holes shouldn’t pulse. So this observation shows that something is very wrong with astrophysical theory, one way or another. To put it another way, the brightness of this as a neutron star pulsar is 100 times as large as the theoretical upper limit on its brightness.