The X-ray, optical, and radio behavior of Scorpius X-1 - The 1971 coordinated observations

Bradt, H.; Moore, G. K. G.; Braes, L. L. E.; Miley, G. K.; Forman, W.; Kellogg, E.; Hesser, J. E.; Kunkel, W. E.; Hiltner, W. A.; Hjellming, R. M.

doi:10.1086/153529

Cited by 22 publications

(18 citation statements)

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“…Peak B magnitudes in the 1967, 1968, 1969, 1970, 1972, and 1977 histograms were identified in the same manner as for the 1994-1995 data. Peaks in the 1971 histogram are based on visual estimates because B magnitudes in Bradt et al (1975) were presented in a logarithmic plot that made reconstruction of a histogram like those shown in Figure 1 impossible. Five statements can be made based on all of this information: (1) during an observing season Sco X-1 can occupy discrete brightness states, but the peak B magnitudes of these states are generally not the same from year to year; (2) the amount of time Sco X-1 spends in its bright, intermediate, and faint states varies from season to season; (3) the peak B brightness of Sco X-1 appears to have increased by approximately 0.2 mag since the early 1970s; (4) Sco X-1 varies between B = 12.1 and B = 13.4 (a factor of 3.3 in brightness), and its BÀV color increases from 0.04 to 0.17 as its brightness decreases; and (5) the most stable Sco X-1 B-magnitude peak appears to be located at B $ 12.60.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…In an optical and X-ray study conducted in 1970 using Vela spacecraft data, Mook et al (1975) found that Sco X-1 possessed a trimodal histogram of B magnitudes, whereas only a single strong peak was present in its X-ray histogram. One year later, Bradt et al (1975) collected data from Uhuru and a network of optical observatories and found that Sco X-1 then possessed a bimodal histogram of B magnitudes and an X-ray histogram that possessed only a 1 Visiting Astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.…”

Section: Introductionmentioning

confidence: 99%

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The Behavior of the Optical and X-Ray Emission from Scorpius X-1

McNamara¹,

Harrison²,

Zavala³

et al. 2003

The Astronomical Journal

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In 1970, Hiltner & Mook reported the results of the first multiyear study of the optical emission from Sco X-1. They found that the Sco X-1 B-magnitude histograms changed from year to year. Subsequent multiwavelength campaigns confirmed the variable nature of these optical histograms and also found that the X-ray and optical emissions were only correlated when Sco X-1 was brighter than about B = 12.6. Models had suggested that the optical emission from this source arose from X-rays reprocessed in an accretion disk surrounding the central neutron star. It was therefore difficult to explain why the optical and X-ray fluxes were not more closely correlated. In 1994 and 1995, two new simultaneous optical and X-ray campaigns on Sco X-1 were conducted with the Burst and Transient Source Experiment on the Compton Gamma Ray Observatory and the 1 m Yale telescope at Cerro Tololo Inter-American Observatory. Using these data and models by Psaltis, Lamb, & Miller, it is now possible to provide a qualitative picture of how the X-ray and optical emissions from Sco X-1 are related. Differences in the B-magnitude histograms are caused by variations in the mass accretion rate and the relatively short time period typically covered by optical investigations. The tilted-C pattern seen in plots of the simultaneous X-ray and optical emission from Sco X-1 arises from (1) the nearly linear relation between the optical B magnitude and the mass accretion rate in the range 13.3 ! B ! 12.3 and an asymptotic behavior in the B magnitude outside this range, and (2) a double-valued relation between the X-ray emission and mass accretion rate along the normal branch and lower flaring branch of this source.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Behavior of the Optical and X-Ray Emission from Scorpius X-1

McNamara¹,

Harrison²,

Zavala³

et al. 2003

The Astronomical Journal

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“…: [873]; no X-ray pulsations: [531,1449]; hard X-rays: [628,1103,1305]; X-ray/opt./radio obs. : [104,139]; X-ray/opt. obs.…”

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confidence: 99%

A catalogue of low-mass X-ray binaries

Liu

Paradijs

Heuvel

2001

A&A

210

206

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Abstract. We present a catalogue of low-mass X-ray binaries. The catalogue is an updated version of the catalogue of van Paradijs (1995). This new catalogue contains 150 sources, 31 new low-mass X-ray binaries in addition to the 119 sources listed in van Paradijs' catalogue. The aim of this catalogue is to help the reader gain easy access to the recent literature (up to about August 2000) on individual sources, and to provide of some basic information on the X-ray sources and their counterparts in other wavelength ranges (UV, optical, IR, and radio). In cases where there is some doubt about the low-mass nature of the X-ray binary, this is mentioned. In an appendix we list the Anomalous X-ray Pulsars (AXPs), which nowadays are no longer thought to be low-mass X-ray binaries.

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“…Early coordinated studies identified a pattern of correlations between X-ray and optical flux (Mook et al 1975;Bradt et al 1975;Canizares et al 1975). At low optical brightnesses the X-ray emission appeared approximately constant, but above a threshold optical brightness X-rays became extremely variable and on average brighter.…”

Section: Correlations With Maxi and Fermi Gbmmentioning

confidence: 99%

“…The optical counterpart to Sco X-1, V818 Sco, was discovered by Sandage et al (1966), opening the door for subsequent multi-wavelength studies aiming to study optical variability and relate X-ray and optical behavior (Hiltner & Mook 1967, 1970Mook et al 1975;Bradt et al 1975;Canizares et al 1975). This early work established large amplitude optical variability, with several preferred optical flux levels resulting in bimodal or trimodal flux histograms.…”

Section: Introductionmentioning

confidence: 99%

KeplerK2 observations of Sco X-1: orbital modulations and correlations withFermiGBM and MAXI

Hynes

Schaefer

Baum

et al. 2016

Mon. Not. R. Astron. Soc.

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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 a narrow range of amplitudes with a striking cut-off at a maximum amplitude. Optical fluxes correlate with X-ray fluxes in the high state, but in the low state they are anti-correlated. These patterns can be seen clearly in both fluxflux diagrams and cross-correlation functions and are consistent between MAXI and GBM. The high state correlation arises promptly with at most a few minutes lag. We attribute this to thermal reprocessing of X-ray flares. The low state anti-correlation is broader, consistent with optical lags of between zero and 30 min, and strongest with respect to high energy X-rays. We suggest that the decreases in optical flux in the low state may reflect decreasing efficiency of disc irradiation, caused by changes in the illumination geometry. These changes could reflect the vertical extent or covering factor of obscuration or the optical depth of scattering material.

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The X-ray, optical, and radio behavior of Scorpius X-1 - The 1971 coordinated observations

Cited by 22 publications

References 0 publications

The Behavior of the Optical and X-Ray Emission from Scorpius X-1

The Behavior of the Optical and X-Ray Emission from Scorpius X-1

A catalogue of low-mass X-ray binaries

KeplerK2 observations of Sco X-1: orbital modulations and correlations withFermiGBM and MAXI

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