Non-thermal X-rays from colliding wind shock acceleration in the massive binary Eta Carinae

作者：Hamaguchi Kenji^*; Corcoran Michael F; Pittard Julian M; Sharma Neetika; Takahashi Hiromitsu; Russel Christopher M P; Grefenstette Brian W; Wik Daniel R; Gull Theodore R; Richardson Noel D; Madura Thomas I; Moffat Anthony F J

来源：Nature Astronomy, 2018, 2(9): 731-736.

DOI：10.1038/s41550-018-0505-1

Cosmic-ray acceleration has been a long-standing mystery(1,2) and, despite more than a century of study, we still do not have a complete census of acceleration mechanisms. The collision of strong stellar winds in massive binary systems creates powerful shocks that have been expected to produce high-energy cosmic rays through Fermi acceleration at the shock interface. The accelerated particles should collide with stellar photons or ambient material, producing non-thermal emission observable in X-rays and gamma-rays(3,4). The supermassive binary star Eta Carinae (eta Car) drives the strongest colliding wind shock in the solar neighbourhood(5,6). Observations with non-focusing high-energy observatories indicate a high-energy source near eta Car, but have been unable to conclusively identify eta Car as the source because of their relatively poor angular resolution(7-9). Here we present direct focussing observations of the non-thermal source in the extremely hard X-ray band, which is found to be spatially coincident with the star within several arc-seconds. These observations show that the source of non-thermal X-rays varies with the orbital phase of the binary, and that the photon index of the emission is similar to that derived through analysis of the gamma-ray spectrum. This is conclusive evidence that the high-energy emission indeed originates from non-thermal particles accelerated at colliding wind shocks.

• 出版日期2018-9