Simultaneous Observations of the Optical and X-Ray Spectra of SCO XR-1

Chodil, G.; Mark, Hans; Rodrigues, R.; Seward, F. D.; Swift, C. D.; Turiel, I.; Hiltner, W. A.; Wallerstein, George; Mannery, Edward J.

doi:10.1086/149786

Cited by 47 publications

(16 citation statements)

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“…Their X-ray emission was discovered at the dawn of X-ray astronomy. Already first observations of the brightest NS binaries have shown that their emission is likely thermal (Chodil et al 1968;Toor et al 1970). Numer-arXiv:1306.6237v1 [astro-ph.HE] 26 Jun 2013 ous observations of a set of NS binaries in our Galaxy have shown that the whole variety of their energy spectra can be broadly separated into two main classes, with the spectral cutoff at energies below 6-10 keV and around 50-100 keV, which are called soft and hard spectral states, respectively (here we consider only active sources, which have luminosities Lx > 10 35 erg s −1 ).…”

Section: Introductionmentioning

confidence: 99%

On the spreading layer emission in luminous accreting neutron stars

Revnivtsev¹,

Suleimanov²,

Poutanen³

2013

Monthly Notices of the Royal Astronomical Society

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Emission of the neutron star surface potentially contains information about its size and thus of vital importance for high energy astrophysics. In spite of the wealth of data on the emission of luminous accreting neutron stars, the emission of their surfaces is hard to disentangle from their time averaged spectra. A recent X-ray transient source XTE J1701−462 has provided a unique dataset covering the largest ever observed luminosity range for a single source and showing type I (thermonuclear) X-ray bursts. In this paper, we extract the spectrum of the neutron star surface (more specifically, the spectrum of the boundary layer between the inner part of the accretion disc and the neutron star surface) with the help of maximally spectral model-independent method. We show compelling evidences that the energy spectrum of the boundary layer stays virtually the same over factor of 20 variations of the source luminosity. It is rather wide and cannot be described by a single temperature blackbody spectrum, probably because of the inhomogeneity of the boundary layer and a spread in the colour temperature. The observed maximum colour temperature of the boundary/spreading layer emission of kT ≈2.4-2.6 keV is very close to the maximum observed colour temperature in the photospheric radius expansion X-ray bursts, which is set by the limiting Eddington flux at the neutron star surface. The observed stability of the boundary layer spectrum and its maximum colour temperature strongly supports theoretical models of the boundary/spreading layers on surfaces of luminous accreting neutron stars, which assume the presence of a region emitting at the local Eddington limit. Variations in the luminosity in that case lead to changes in the size of this region, but affect less the spectral shape. Elaboration of this model will provide solid theoretical grounds for measurements of the neutron star sizes using the emission of the boundary/spreading layers of luminous accreting neutron stars.

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Section: Introductionmentioning

confidence: 99%

On the spreading layer emission in luminous accreting neutron stars

Revnivtsev¹,

Suleimanov²,

Poutanen³

2013

Monthly Notices of the Royal Astronomical Society

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“…The calculated standard deviation of temperature as a parameter is +3 keV; a chi-squared test, however, permits the temperature to have remained constant. The higher best-fit temperatures are associated with increased optical emission as observed by LRL (Chodil et al, 1968b). The variation of total flux at a given energy is a complex function of the change of temperature and emission measure.…”

Section: Scorpius Xr-1mentioning

confidence: 92%

“…If indeed the X-ray emission from Scorpius is due to a hot gas, as the spectral measurements and other evidence indicate, it would seem that the X-ray emission and the optical emission must be coupled, and the variations should be correlated. Attempts to perform simultaneous observations have been made by the Lawrence Radiation Laboratory from short duration rocket flights, in conjunction with photometric observations by Hiltner (Chodil et al, 1968b). UCSD has also attempted simultaneous observations from balloons in order to observe the higher energy component over an interval of several hours.…”

Section: Scorpius Xr-1mentioning

confidence: 99%

Properties of individual X-ray sources: (Invited discourse)

Peterson

1970

Symp. - Int. Astron. Union

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Abstract. Observations to determine the spectra and time variations of hard X-rays from cosmic sources have been made from balloons and from the OSO-III satellite. These data have been obtained using actively collimated scintillation counters with apertures between 6 and 24° FWHM, areas between 10 and 50 cm 2 and which operate over the 10-300 keV range. The Crab Nebula has been observed on three occasions over a 22-month period between September 1965 and July 1967. The power law spectrum has a number index of 2.0 ± 0.1. No long-term changes were observed over the 30-100keV range with a limit at 3%/yr. A balloon search with a 10 cm 2 Ge(Li) detector for X-ray lines at 62.5 keV, 110 keV and 180 keV due to heavy element radioactive decays which would be produced in the initial Crab explosion based on the Cf 254 hypothesis has resulted in upper limits at about 10" 3 y-rays cm 2 -sec. This is about a factor of 20 above the predicted levels. Simultaneous X-ray and optical observations of SCO XR-1 from OSO-III confirm that X-ray and optical flaring are indeed coincident phenomena, and that although the X-ray intensity increases about a factor of two during the flare, the equivalent temperature of the excess radiation is nearly the same as that of the quiescent object. Upper limits, 95% confidence, on the flux of M-87 at 40 keV have been obtained. These are inconsistent with the flux of 1.2 x 10~4 photons/cm 2 -sec-keV reported in the literature. CYG X-l has been observed to have a power law of number index 2.0 ± 0.2. The OSO-III has observed a number of sources in the southern skies including NOR XR-2 and the variable source Centaurus XR-2.

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“…LRL group carried out the first simultaneous optical and X-ray observation of Sco X-1 and obtained the first evidence for a positive correlation between X-ray and optical flux from Sco X-1 (Chodil et al, 1968;Mark et al, 1969;Burginyon et al, 1970). Kitamura et al (1971) also performed the simultaneous observation at optical and X-ray wave lengths and compiled relationships between the hardness of the X-ray spectrum and the X-ray intensity, and between the X-ray and the optical luminosity.…”

Section: Relationmentioning

confidence: 99%

“…One is a hot (T-5 x 107K) plasma model, self-absorbing in the optical and lower frequency regions by the plasma itself which emits both the observed X-rays and the continuum optical flux (Chodil, 1968;Neugebauer et al, 1969;Kitamura et al, 1971;Hayakawa et al, 1974). The other is a model attributing to other emitters from which the large fraction of the optical radiations comes besides the X-ray emitting plasma (Katz, 1975;Milgrom, 1976), which includes the heating model of the primary star by X-rays.…”

Section: Observationsmentioning

confidence: 99%

Sco X-1

Miyamoto

Matsuoka

1977

Space Sci Rev

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Abstract. The physical properties of X-ray, optical and radio emissions from Sco X-1 are reviewed. Sco X-I is a typical X-ray source which has an optically thick hot plasma. The observational spectra of X-ray and optical emissions are consistent with theoretical ones from the hot plasma, but the radio emission shows a non-thermal feature. The restrictive conditions for the model of Sco X-1 are discussed from the observational facts. In spite ot numerous observational facts on Sco X-1 further detailed and elaborate studies are necessary to understand this object and general compact X-ray sources comprehensively.Contents:

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Simultaneous Observations of the Optical and X-Ray Spectra of SCO XR-1

Cited by 47 publications

References 0 publications

On the spreading layer emission in luminous accreting neutron stars

On the spreading layer emission in luminous accreting neutron stars

Properties of individual X-ray sources: (Invited discourse)

Sco X-1

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