Spectral and Location Measurements of Several Cosmic X-Ray Sources Including a Variable Source in Centaurus

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

doi:10.1103/physrevlett.19.681

Cited by 66 publications

(32 citation statements)

References 7 publications

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“…Cen X−3 was discovered by Chodil et al (1967) and became the first detected binary X-ray pulsar (Giacconi et al 1971;Schreier et al 1972b). The V = 13.3 mag optical counterpart V779 Cen was identified by Krzeminski (1974), an O6-7 II-III star (Ash et al 1999) in a 2.09 d circular orbit with the 4.84 s X-ray pulsar.…”

Section: Cen X−3mentioning

confidence: 99%

Determination of the mass of the neutron star in SMC X-1, LMC X-4, and Cen X-3 with VLT/UVES

Meer¹,

Kaper²,

Kerkwijk

et al. 2007

A&A

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We present the results of a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X−1, LMC X−4 and Cen X−3. High-resolution optical spectra obtained with UVES on the ESO Very Large Telescope are used to determine the radial-velocity orbit of the OB (super)giants with high precision. The excellent quality of the spectra provides the opportunity to measure the radial-velocity curve based on individual lines, and to study the effect of possible distortions of the line profiles due to e.g. X-ray heating on the derived radial-velocity amplitude. Several spectral lines show intrinsic variations with orbital phase. The magnitude of these variations depends on line strength, and thus provides a criterion to select lines that do not suffer from distortions. The undistorted lines show a larger radial-velocity amplitude than the distorted lines, consistent with model predictions. Application of our line-selection criteria results in a mean radial-velocity amplitude K opt of 20.2± 1.1, 35.1± 1.5, and 27.5± 2.3 km s −1 (1σ errors), for the OB companion to SMC X−1, LMC X−4 and Cen X−3, respectively. Adding information on the projected rotational velocity of the OB companion (derived from our spectra), the duration of X-ray eclipse and orbital parameters of the X-ray pulsar (obtained from literature), we arrive at a neutron star mass of 1.06−0.10 , 1.25−0.10 and 1.34 +0.16−0.14 M for SMC X−1, LMC X−4 and Cen X−3, respectively. The mass of SMC X−1 is near the minimum mass (∼1 M ) expected for a neutron star produced in a supernova. We discuss the implications of the measured mass distribution on the neutron-star formation mechanism, in relation to the evolutionary history of the massive binaries.

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Section: Cen X−3mentioning

confidence: 99%

Determination of the mass of the neutron star in SMC X-1, LMC X-4, and Cen X-3 with VLT/UVES

Meer¹,

Kaper²,

Kerkwijk

et al. 2007

A&A

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show abstract

“…well within reach of VLT/UVES. Cen X−3 is located in our own galaxy and was identified as the first Xray pulsar Chodil et al (1967); Giacconi et al (1971). The system consists of an O6-7 II-III star (Ash et al 1999) with a neutron star in a 2.09 day orbit (Nagase et al 1992).…”

Section: Observationsmentioning

confidence: 99%

On the mass distribution of neutron stars in HMXBs

Meer

Kaper

Kerkwijk

et al. 2005

AIP Conference Proceedings

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Abstract.We present the results of a monitoring campaign of three eclipsing high-mass X-ray binaries (HMXBs: SMC X−1, LMC X−4 and Cen X−3). Highresolution VLT/UVES spectra are used to measure the radial velocities of these systems with high accuracy. We show that the subsequent mass determination of the neutron stars in these systems is significantly improved and discuss the implications of this result.

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“…At the position of GS 1354-64, the source is detected with more than 10σ significance (shown in blue circle) whereas within the red circle of Cen X-2 (Chodil et al 1967), no source is detected above the background limit. However, due to poor spatial resolution, the position uncertainties of the mean position of Cen X-2 are ± 2.5 degrees (Chodil et al 1967). Using Swift/XRT photon counting (PC) mode data, we are also able to extract the source image in the 0.3-10.0 keV energy range.…”

Section: Check For Contaminationmentioning

confidence: 99%

“…With an increase in X-ray luminosity, the X-ray QPO frequency increases to ∼0.19 Hz while the optical PDS shows no QPO and no In the hard X-ray band, the source is significantly detected. The position of the historical (Chodil et al 1967) soft X-ray transient Cen X−2 is shown by the red circle, and given the uncertainties involved is consistent with being the same source in spite of their different spectral properties (see Kitamoto et al (1990)). The circle size denotes the position uncertainty of Cen X−2 as quoted by Chodil et al (1967).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous optical/X-ray study of GS 1354-64 (=BW Cir) during hard outburst: evidence for optical cyclo-synchrotron emission from the hot accretion flow

Pahari

Gandhi

Charles

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present results from simultaneous optical (SALT) and X-ray (Swift and IN-TEGRAL) observations of GS 1354-64/BW Cir during the 2015 hard state outburst. During the rising phase, optical/X-ray time series show a strong anti-correlation with X-ray photons lagging optical. Optical and X-ray power spectra show quasi-periodic oscillations at a frequency of ∼ 18 mHz with a confidence level of at least 99%. Simultaneous fitting of Swift/XRT and INTEGRAL spectra in the range 0.5−1000.0 keV shows non-thermal, power-law dominated (> 90%) spectra with a hard powerlaw index of 1.48 ± 0.03, inner disc temperature of 0.12 ± 0.01 keV and inner disc radius of ∼3000 km. All evidence is consistent with cyclo-synchrotron radiation in a non-thermal, hot electron cloud extending to ∼ 100 Schwarzschild radii being a major physical process for the origin of optical photons. At outburst peak about one month later, when the X-ray flux rises and the optical drops, the apparent features in the optical/X-ray correlation vanish and the optical auto correlation widens. Although ∼0.19 Hz QPO is observed from the X-ray power spectra, the optical variability is dominated by the broadband noise, and the inner disc temperature increases. These results support a change in the dominant optical emission source between outburst rise and peak, consistent with a weakening of hot flow as the disc moves in.

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Spectral and Location Measurements of Several Cosmic X-Ray Sources Including a Variable Source in Centaurus

Cited by 66 publications

References 7 publications

Determination of the mass of the neutron star in SMC X-1, LMC X-4, and Cen X-3 with VLT/UVES

Determination of the mass of the neutron star in SMC X-1, LMC X-4, and Cen X-3 with VLT/UVES

On the mass distribution of neutron stars in HMXBs

Simultaneous optical/X-ray study of GS 1354-64 (=BW Cir) during hard outburst: evidence for optical cyclo-synchrotron emission from the hot accretion flow

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