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Discovery Of A High State Am Cvn Binary In The Galactic Bulge Survey, T. Wevers, M. A.P. Torres, P. G. Jonker, J. D. Wetuski, G. Nelemans, D. Steeghs, T. J. Maccarone, C. Heinke, R. I. Hynes, A. Udalski, Z. Kostrzewa-Rutkowska, P. J. Groot, R. Gazer, M. K. Szymański, C. T. Britt, L. Wyrzykowski, R. Poleski
Discovery Of A High State Am Cvn Binary In The Galactic Bulge Survey, T. Wevers, M. A.P. Torres, P. G. Jonker, J. D. Wetuski, G. Nelemans, D. Steeghs, T. J. Maccarone, C. Heinke, R. I. Hynes, A. Udalski, Z. Kostrzewa-Rutkowska, P. J. Groot, R. Gazer, M. K. Szymański, C. T. Britt, L. Wyrzykowski, R. Poleski
Faculty Publications
We report on the discovery of a hydrogen-deficient compact binary (CXOGBS J175107.6- 294037) belonging to the AM CVn class in the Galactic Bulge Survey. Deep archival X-ray observations constrain the X-ray positional uncertainty of the source to 0.57 arcsec, and allow us to uniquely identify the optical and UV counterpart. Optical spectroscopic observations reveal the presence of broad, shallow He I absorption lines while no sign of hydrogen is present, consistent with a high state system. We present the optical light curve from Optical Gravitational Lensing Experiment monitoring, spanning 15 yr. It shows no evidence for outbursts; variability is present …
On The Optical-X-Ray Correlation From Outburst To Quiescence In Low-Mass X-Ray Binaries: The Representative Cases Of V404 Cyg And Cen X-4, F. Bernardini, D. M. Russell, K. I.I. Kolojonen, L. Stella, R. I. Hynes, S. Corbel
On The Optical-X-Ray Correlation From Outburst To Quiescence In Low-Mass X-Ray Binaries: The Representative Cases Of V404 Cyg And Cen X-4, F. Bernardini, D. M. Russell, K. I.I. Kolojonen, L. Stella, R. I. Hynes, S. Corbel
Faculty Publications
Low-mass X-ray binaries (LMXBs) show evidence of a global correlation of debated origin between X-ray and optical luminosity. We study for the first time this correlation in two transient LMXBs, the black hole (BH) V404 Cyg and the neutron star Cen X-4, over six orders of magnitude in X-ray luminosity, from outburst to quiescence. After subtracting the contribution from the companion star, the Cen X-4 data can be described by a single powerlaw correlation of the form Lopt ∝ LX0.44, consistent with disk reprocessing. We find a similar correlation slope for V404 Cyg in quiescence (0.46) and a steeper one …
Fermi Gbm Observations Of V404 Cyg During Its 2015 Outburst, P. A. Jenke, C. A. Wilson-Hodge, Jeroen Homan, P. Veres, M. S. Briggs, E. Burns, V. Connaughton, M. H. Finger, M. Hui
Fermi Gbm Observations Of V404 Cyg During Its 2015 Outburst, P. A. Jenke, C. A. Wilson-Hodge, Jeroen Homan, P. Veres, M. S. Briggs, E. Burns, V. Connaughton, M. H. Finger, M. Hui
Faculty Publications
V404 Cygni was discovered in 1989 by the Ginga X-ray satellite during its only previously observed X-ray outburst and soon after confirmed as a black hole binary. On 2015 June 15, the Gamma-ray Burst Monitor (GBM) triggered on a new outburst of V404 Cygni. We present 13 days of GBM observations of this outburst, including Earth occultation flux measurements and spectral and temporal analysis. The Earth occultation fluxes reached 30 Crab with detected emission to 100 keV and determined, via hardness ratios, that the source was in a hard state. At high luminosity, spectral analysis between 8 and 300 keV …
Kepler K2 Observations Of Sco X-1: Orbital Modulations And Correlations With Fermi Gbm And Maxi, Robert I. Hynes, Bradley E. Schaefer, Zachary A. Baum, Ching Cheng Hsu, Michael L. Cherry, Simone Scaringi
Kepler K2 Observations Of Sco X-1: Orbital Modulations And Correlations With Fermi Gbm And Maxi, Robert I. Hynes, Bradley E. Schaefer, Zachary A. Baum, Ching Cheng Hsu, Michael L. Cherry, Simone Scaringi
Faculty Publications
We present a multi-wavelength study of the low-mass X-ray binary Sco X-1 using Kepler K2 optical data and Fermi GBM and MAXI X-ray data. We recover a clear sinusoidal orbital modulation from the Kepler data. Optical fluxes are distributed bimodally around the mean orbital light curve, with both high and low states showing the same modulation. The high state is broadly consistent with the flaring branch of the Z-diagram and the low state with the normal branch. We see both rapid optical flares and slower dips in the high state, and slow brightenings in the low state. High-state flares exhibit …
Furiously Fast And Red: Sub-Second Optical Flaring In V404 Cyg During The 2015 Outburst Peak, P. Gandhi, S. P. Littlefair, L. K. Hardy, V. S. Dhillon, T. R. Marsh, A. W. Shaw, D. Altamirano, M. D. Caballero-Garcia, J. Casares, P. Casella, A. J. Castro-Tirado, P. A. Charles, Y. Dallilar, S. Eikenberry, R. P. Fender, R. I. Hynes, C. Knigge, E. Kuulkers, K. Mooley, T. Muñoz-Darias, M. Pahari, F. Rahoui, D. M. Russell, J. V. Hernández Santisteban, T. Shahbaz, D. M. Terndrup, J. Tomsick, D. J. Walton
Furiously Fast And Red: Sub-Second Optical Flaring In V404 Cyg During The 2015 Outburst Peak, P. Gandhi, S. P. Littlefair, L. K. Hardy, V. S. Dhillon, T. R. Marsh, A. W. Shaw, D. Altamirano, M. D. Caballero-Garcia, J. Casares, P. Casella, A. J. Castro-Tirado, P. A. Charles, Y. Dallilar, S. Eikenberry, R. P. Fender, R. I. Hynes, C. Knigge, E. Kuulkers, K. Mooley, T. Muñoz-Darias, M. Pahari, F. Rahoui, D. M. Russell, J. V. Hernández Santisteban, T. Shahbaz, D. M. Terndrup, J. Tomsick, D. J. Walton
Faculty Publications
We present observations of rapid (sub-second) optical flux variability in V404 Cyg during its 2015 June outburst. Simultaneous three-band observations with the ULTRACAM fast imager on four nights show steep power spectra dominated by slow variations on ~100-1000 s time-scales. Near the peak of the outburst on June 26, a dramatic change occurs and additional, persistent sub-second optical flaring appears close in time to giant radio and X-ray flaring. The flares reach peak optical luminosities of ~ few × 1036 erg s-1. Some are unresolved down to a time resolution of 24 ms. Whereas the fast flares are stronger in …