Hamaguchi, K, Corcoran, MF, Takahashi, H et al. (6 more authors) (2014) Suzaku monitoring of hard X-ray emission from η carinae over a single binary orbital cycle. Astrophysical Journal, 795 (2). 119. 1 - 12 (12). ISSN 0004-637X
Abstract
The Suzaku X-ray observatory monitored the supermassive binary system η Carinae 10 times during the whole 5.5 yr orbital cycle between 2005 and 2011. This series of observations presents the first long-term monitoring of this enigmatic system in the extremely hard X-ray band between 15 and 40 keV. During most of the orbit, the 15-25 keV emission varied similarly to the 2-10 keV emission, indicating an origin in the hard energy tail of the kT ∼ 4 keV wind-wind collision (WWC) plasma. However, the 15-25 keV emission declined only by a factor of three around periastron when the 2-10 keV emission dropped by two orders of magnitude due probably to an eclipse of the WWC plasma. The observed minimum in the 15-25 keV emission occurred after the 2-10 keV flux had already recovered by a factor of ∼3. This may mean that the WWC activity was strong, but hidden behind the thick primary stellar wind during the eclipse. The 25-40 keV flux was rather constant through the orbital cycle, at the level measured with INTEGRAL in 2004. This result may suggest a connection of this flux component to the γ-ray source detected in this field. The helium-like Fe Kα line complex at ∼6.7 keV became strongly distorted toward periastron as seen in the previous cycle. The 5-9 keV spectra can be reproduced well with a two-component spectral model, which includes plasma in collision equilibrium and a plasma in non-equilibrium ionization (NEI) with τ ∼ 1011 cm-3 s-1. The NEI plasma increases in importance toward periastron.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | (c) 2014. The American Astronomical Society. All rights reserved. This is an author produced version of a paper published in Astrophysical Journal. Uploaded in accordance with the publisher's self-archiving policy |
Keywords: | Binaries: general; Stars: early-type; Stars: individual (Eta Carinae); Stars: winds, outflows; X-rays: stars |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 20 Apr 2015 11:06 |
Last Modified: | 16 Jan 2018 00:50 |
Published Version: | http://dx.doi.org/10.1088/0004-637X/795/2/119 |
Status: | Published |
Publisher: | American Astronomical Society / IOP Publishing |
Identification Number: | 10.1088/0004-637X/795/2/119 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:84007 |