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Herschel Observations of Circinus X-1 during Outburst and Quiescence

Harrison, Thomas E. and Gelino, Dawn M. and Buxton, Michelle and Fost, Tyler (2014) Herschel Observations of Circinus X-1 during Outburst and Quiescence. Astronomical Journal, 148 (1). Art. No. 22. ISSN 0004-6256. doi:10.1088/0004-6256/148/1/22.

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We have used the Photodetector Array Camera and Spectrometer and Spectral and Photometric Imaging REceiver instruments on the Herschel Space Observatory to observe Cir X-1 both in and out of outburst. We detected Cir X-1 during outburst at 70 μm. Unfortunately, a cold background source dominates Cir X-1 at longer wavelengths. We have assembled optical and infrared (IR) data for Cir X-1 to model its spectral energy distribution (SED) in both quiescence and outburst and find that in both states it is consistent with a heavily reddened, 10,000 K blackbody. We believe this behavior is completely consistent with previous suggestions that these outbursts are due to accretion disk events, not unlike those of dwarf novae. To explore the behavior of other low-mass X-ray binaries with reported synchrotron jets, we have extracted and/or compiled optical and near- and mid-IR data sets for five such systems to construct their SEDs. The Z-source GX 349+2 and the black hole system GRS 1915+105 have strong and variable mid-IR excesses that suggest synchrotron emission. The other Z-sources have rather weak (or no) IR excesses that can be explained as reddened blackbody spectra with the addition of either synchrotron or bremsstrahlung components.

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Gelino, Dawn M.0000-0003-1274-2784
Additional Information:© 2014 American Astronomical Society. Received 2013 December 4; accepted 2014 May 7; published 2014 June 13. This work is based in part on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This publication makes use of data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work is also based in part on observations made with the Spitzer Space Telescope, obtained from the NASA/IPAC Infrared Science Archive, both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. Swift/BAT transient monitor results were provided by the Swift/BAT team. This research has made use of the MAXI data provided by RIKEN, JAXA, and the MAXI team. M.M.B. is supported by NSF/AST grants 0407063 and 070707.
Group:Infrared Processing and Analysis Center (IPAC)
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Subject Keywords:stars: neutron
Issue or Number:1
Record Number:CaltechAUTHORS:20140808-093653350
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Official Citation:Herschel Observations of Circinus X-1 during Outburst and Quiescence Thomas E. Harrison et al. 2014 The Astronomical Journal 148 22
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48229
Deposited By: Ruth Sustaita
Deposited On:08 Aug 2014 16:53
Last Modified:10 Nov 2021 18:30

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