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Title: Herschel observations of Circinus X-1 during outburst and quiescence

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.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Department of Astronomy, New Mexico State University, Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States)
  2. NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States)
  3. Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06520-81801 (United States)
  4. John Jay High School, 60 North Salem Road, Cross River, NY 10518-1104 (United States)
Publication Date:
OSTI Identifier:
22342292
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 148; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; BREMSSTRAHLUNG; EMISSION; ENERGY SPECTRA; GESELLSCHAFT FUER ANLAGEN- UND REAKTORSICHERHEIT; INFRARED RADIATION; INTERMEDIATE INFRARED RADIATION; NEUTRONS; NOVAE; SPACE; SPECTROMETERS; VISIBLE RADIATION; WAVELENGTHS; X RADIATION