Hamaguchi, K, Corcoran, MF, Pittard, JM orcid.org/0000-0003-2244-5070 et al. (9 more authors) (2018) Non-thermal X-rays from colliding wind shock acceleration in the massive binary Eta Carinae. Nature Astronomy, 2 (9). pp. 731-736. ISSN 2397-3366
Abstract
Cosmic-ray acceleration has been a long-standing mystery1,2 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 γ-rays3,4. The supermassive binary star Eta Carinae (η Car) drives the strongest colliding wind shock in the solar neighbourhood5,6. Observations with non-focusing high-energy observatories indicate a high-energy source near η Car, but have been unable to conclusively identify η Car as the source because of their relatively poor angular resolution7,8,9. 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 γ-ray spectrum. This is conclusive evidence that the high-energy emission indeed originates from non-thermal particles accelerated at colliding wind shocks.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018, Springer Nature. This is a post-peer-review, pre-copyedit version of an article published in Nature Astronomy. The final authenticated version is available online at: https:// doi.org/10.1038/s41550-018-0505-1. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Colliding Winds; Massive stars; η Carinae; Non-thermal X-rays; Shock Acceleration |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 18 Jul 2018 11:58 |
Last Modified: | 02 Jan 2019 01:38 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/s41550-018-0505-1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:133419 |