Astrophysics Seminar with Mengjiao Xiao on Axion-like Particles

Axion or Axion-like particles (ALPs) are among the leading candidates of dark matter. ALPs can be produced in stellar plasmas due to their coupling with photons or electrons. Light ALPs produced in this way can escape the star and be converted back into photons in the presence of an external Galactic magnetic field. Betelgeuse (α-Orionis, spectral type M2Iab), a nearby red supergiant star, provides an excellent laboratory for ALP searches, as it (i) has a hot core, and thus is potentially a copious producer of ALPs that, after re-conversion, produces a photon signal peaked in the hard X-ray (E>10 keV) range, (ii) is in region of Hertzsprung-Russel diagram where no stable corona is expected, and thus has essentially zero standard astrophysical X-ray background, and (iii) is nearby, at a distance d~200 pc, and thus in a region of the local magnetic field that is relatively easier to constrain with future observations.

In this talk, I will report a novel search for ALPs using the first observation of Betelgeuse by the NuSTAR satellite telescope in hard X-rays, while focusing on the data analysis, results and impact, and emphasizing the astrophysical uncertainties.

Sponsored by the McDonnell Center for the Space Sciences.