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Variability Of Optical Counterparts In The Chandra Galactic Bulge Survey, C. T. Britt, R. I. Hynes, C. B. Johnson, A. Baldwin, P. G. Jonker, G. Nelemans, M. A.P. Torres, T. Maccarone, D. Steeghs, S. Greiss, C. Heinke, C. G. Bassa, A. Collazzi, A. Villar, M. Gabb, L. Gossen
Variability Of Optical Counterparts In The Chandra Galactic Bulge Survey, C. T. Britt, R. I. Hynes, C. B. Johnson, A. Baldwin, P. G. Jonker, G. Nelemans, M. A.P. Torres, T. Maccarone, D. Steeghs, S. Greiss, C. Heinke, C. G. Bassa, A. Collazzi, A. Villar, M. Gabb, L. Gossen
Faculty Publications
We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4 m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ∼2 hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray …
The Galactic Bulge Survey: Completion Of The X-Ray Survey Observations, Peter G. Jonker, Manuel A.P. Torres, Robert I. Hynes, Thomas J. Maccarone, Danny Steeghs, Sandra Greiss, Christopher T. Britt, Jianfeng Wu, Christopher B. Johnson, Gijs Nelemans, Craig Heinke
The Galactic Bulge Survey: Completion Of The X-Ray Survey Observations, Peter G. Jonker, Manuel A.P. Torres, Robert I. Hynes, Thomas J. Maccarone, Danny Steeghs, Sandra Greiss, Christopher T. Britt, Jianfeng Wu, Christopher B. Johnson, Gijs Nelemans, Craig Heinke
Faculty Publications
We provide the Chandra source list for the last quarter of the area covered by the Galactic Bulge Survey (GBS). The GBS targets two strips of 6° × 1° (12 square degrees in total), one above (1° < b < 2°) and one below (-2° < b < -1°) the Galactic plane in the direction of the Galactic center at X-ray, optical, and near-infrared wavelengths. For the X-ray part of the survey we use 2 ks per Chandra pointing. We find 424 X-ray sources in the 63 Chandra observations on which we report here. These sources are in addition to the 1216 X-ray sources discovered in the first part of the GBS survey described previously. We discuss the characteristics and the X-ray variability of the brightest of the sources as well as the radio properties from existing radio surveys. We point out an interesting asymmetry in the number of X-ray sources as a function of their Galactic l and b coordinates which is probably caused by differences in average extinction toward the different parts of the GBS survey area. © 2014. The American Astronomical Society. All rights reserved..
Multiwavelength Observations Of Swift J1753.5-0127, Cynthia S. Froning, Thomas J. Maccarone, Kevin France, Lisa Winter, Edward L. Robinson, Robert I. Hynes, Fraser Lewis
Multiwavelength Observations Of Swift J1753.5-0127, Cynthia S. Froning, Thomas J. Maccarone, Kevin France, Lisa Winter, Edward L. Robinson, Robert I. Hynes, Fraser Lewis
Faculty Publications
We present contemporaneous X-ray, ultraviolet (UV), optical, and near-infrared observations of the black hole binary system Swift J1753.5-0127 acquired in 2012 October. The UV observations, obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, are the first UV spectra of this system. The dereddened UV spectrum is characterized by a smooth, blue continuum and broad emission lines of C IV and He II. The system was stable in the UV to <10% during our observations. We estimated the interstellar reddening by fitting the 2175 Å absorption feature and fit the interstellar absorption profile of Lyα to directly measure the neutral hydrogen column density along the line of sight. By comparing the UV continuum flux to steady-state thin accretion disk models, we determined upper limits on the distance to the system as a function of black hole mass. The continuum is well fit with disk models dominated by viscous heating rather than irradiation. The broadband spectral energy distribution shows the system has declined at all wavelengths since previous broadband observations in 2005 and 2007. If we assume that the UV emission is dominated by the accretion disk, the inner radius of the disk must be truncated at radii above the innermost stable circular orbit to be consistent with the X-ray flux, requiring significant mass loss from outflows and/or energy loss via advection into the black hole to maintain energy balance. © 2014. The American Astronomical Society. All rights reserved.