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Updated: Jul 6, 2026

The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry
Published on: August 12, 2013
The orbital period of the ultraluminous x-ray source in M82
Philip Kaaret1, Melanie G Simet, Cornelia C Lang
1Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA. philip-kaaret@uiowa.edu
Abstract:
The ultraluminous x-ray source (ULX) in the galaxy M82 has been identified as a possible intermediate-mass black hole formed in stellar collisions in the super star cluster MGG 11. The x-ray flux from M82 is modulated, with a peak-to-peak amplitude corresponding to an isotropic luminosity of 2.4 _ 1040 erg s-1 in M82 and a period of 62.0 +/- 2.5 days, which we interpret as the orbital period of the ULX binary. This orbital period implies that the mass-donor star must be a giant or supergiant. Large mass-transfer rates, sufficient to fuel the ULX, are expected for a giant-phase mass donor in an x-ray binary. The giant phase has a short lifetime, indicating that we see the ULX in M82 in a brief and unusual period of its evolution.
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