The mass of the neutron star in Centaurus X-3

Ash, T. D. C.; Reynolds, A. P.; Roche, P.; Norton, A. J.; Still, M.; Morales-Rueda, L.

doi:10.1046/j.1365-8711.1999.02605.x

Cited by 48 publications

(26 citation statements)

References 10 publications

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“…It is an eclipsing HMXB pulsar with a pulse period of ∼4.8 s and an orbital period of ∼2.1 days (Schreier et al 1972). The binary system consists of a neutron star with a mass of 1.21 ± 0.21 M accompanied by an O 6-8 III supergiant star (V779 Cen) with a mass and radius of 20.5 ± 0.7 M and 12 R , respectively (Hutchings et al 1979;Rappaport & Joss 1983;Ash et al 1999). The distance to the binary system was earlier estimated to be ∼8 kpc (Krzeminski 1974).…”

Section: Introductionmentioning

confidence: 99%

X-Ray Spectroscopy of the High-Mass X-Ray Binary Pulsar Centaurus X-3 Over Its Binary Orbit

Naik

Paul

Ali

2011

ApJ

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We present a comprehensive spectral analysis of the high-mass X-ray binary (HMXB) pulsar Centaurus X-3 with the Suzaku observatory covering nearly one orbital period. The light curve shows the presence of extended dips which are rarely seen in HMXBs. These dips are seen up to as high as ∼40 keV. The pulsar spectra during the eclipse, out-of-eclipse, and dips are found to be well described by a partial covering power-law model with high-energy cutoff and three Gaussian functions for 6.4 keV, 6.7 keV, and 6.97 keV iron emission lines. The dips in the light curve can be explained by the presence of an additional absorption component with high column density and covering fraction, the values of which are not significant during the rest of the orbital phases. The iron line parameters during the dips and eclipse are significantly different compared to those during the rest of the observation. During the dips, the iron line intensities are found to be lesser by a factor of 2-3 with a significant increase in the line equivalent widths. However, the continuum flux at the corresponding orbital phase is estimated to be lesser by more than an order of magnitude. Similarities in the changes in the iron line flux and equivalent widths during the dips and eclipse segments suggest that the dipping activity in Cen X-3 is caused by an obscuration of the neutron star by dense matter, probably structures in the outer region of the accretion disk, as in the case of dipping low-mass X-ray binaries.

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Section: Introductionmentioning

confidence: 99%

X-Ray Spectroscopy of the High-Mass X-Ray Binary Pulsar Centaurus X-3 Over Its Binary Orbit

Naik

Paul

Ali

2011

ApJ

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“…Unfortunately only 10 such systems are currently known, and only 6 of these have previously had mass measurements made (e.g. Ash et al 1999;Quaintrell et al 2003;Val Baker et al 2005). In this paper we present the preliminary results from our on-going work on the mass of the High Mass X-ray Binary (HMXB) accretion driven pulsar EXO 1772-363.…”

Section: Introductionmentioning

confidence: 99%

Preliminary determinations of the masses of the neutron star and mass donor in the high mass X-ray binary system EXO 1722–363

Mason¹,

Norton²,

Clark³

et al. 2010

A&A

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Aims. We intended to measure the radial velocity curve of the supergiant companion to the eclipsing high mass X-ray binary pulsar EXO 1722-363 and hence determine the stellar masses of the components. Methods. We used a set of archival K s -band infrared spectra of the counterpart to EXO 1722-363 obtained using ISAAC on the VLT, and cross-correlated them in order to measure the radial velocity of the star. Results. The resulting radial velocity curve has a semi-amplitude of 24.5 ± 5.0 km s −1 . When combined with other measured parameters of the system, this yields masses in the range 1.5 ± 0.4−1.6 ± 0.4 M for the neutron star and 13.6 ± 1.6−15.2 ± 1.9 M for the B0-1 Ia supergiant companion. These lower and upper limits were obtained under the assumption that the system is viewed edge-on (i = 90 • ) for the lower limit and the supergiant fills its Roche lobe (β = 1) for the upper limit respectively. The system inclination is constrained to i > 75 • and the Roche lobe-filling factor of the supergiant is β > 0.9. Additionally we were able to further constrain our distance determination to be 7.1 ≤ d ≤ 7.9 kpc for EXO 1722-363. The X-ray luminosity for this distance range is 4.7 × 10 35 ≤ L X ≤ 9.2 × 10 36 erg s −1 . Conclusions. EXO 1722-363 therefore becomes the seventh of the ten known eclipsing X-ray binary pulsars for which a dynamical neutron star mass solution has been determined. Additionally EXO 1722-363 is the first such system to have a neutron star mass measurement made utilising near-infrared spectroscopy.

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“…The binary system consists of a neutron star with a mass of 1:21 AE 0:21 M accompanied by an O 6Y8 III supergiant star with a mass of 20:5 AE 0:7 M ( Hutchings et al 1979;Ash et al 1999). The distance of the binary system has been estimated to be roughly 8 kpc, with a lower limit of 6.2 kpc ( Krzeminski 1974) and an eccentricity of 0.0016 ( Bildsten et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Pulse Phase‐Resolved Analysis of the High‐Mass X‐Ray Binary Centaurus X‐3 over Two Binary Orbits

Suchy

Pottschmidt

Wilms

et al. 2008

ApJ

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We present a detailed analysis of observations of the high-mass X-ray binary Cen X-3, spanning two consecutive binary orbits performed with the RXTE satellite in early March 1997. During this time Cen X-3 had a luminosity of L 2Y10 keV $ (4Y5) ; 10 37 ergs s À1 and a pulse period of 4.814 s. The PCA and HEXTE light curves both show a clear reduction in count rate after midorbit for both binary revolutions. We therefore analyze two broadband spectra for each orbit, before and after midorbit. Consistent with earlier observations, these four joint PCA and HEXTE spectra can be well described using a phenomenological pulsar continuum model, including an iron emission line and a cyclotron resonance-scattering feature. While no strong spectral variations were detected, the second half of orbit 2 shows a tendency toward being softer and more strongly absorbed. In order to follow the orbital phase-dependent evolution of the spectrum in greater detail, we model spectra for shorter exposures, confirming that most spectral parameters show either a gradual or sudden change for the second half of the second orbit. A comparison with a simple wind model indicates the existence of an accretion wake in this system. We also present and discuss highresolution pulse profiles for several different energy bands, as well as their hardness ratios. PCA and HEXTE spectra were created for 24 phase bins and fitted using the same model as in the phase-averaged case. Systematic pulse phasedependent variations of several continuum and cyclotron line parameters were detected, most notably a significant increase of the cyclotron line energy during the early rise of the main peak, followed by a gradual decrease. We show that applying a simple dipole model for the magnetic field is not sufficient to describe our data.

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The mass of the neutron star in Centaurus X-3

Cited by 48 publications

References 10 publications

X-Ray Spectroscopy of the High-Mass X-Ray Binary Pulsar Centaurus X-3 Over Its Binary Orbit

X-Ray Spectroscopy of the High-Mass X-Ray Binary Pulsar Centaurus X-3 Over Its Binary Orbit

Preliminary determinations of the masses of the neutron star and mass donor in the high mass X-ray binary system EXO 1722–363

Pulse Phase‐Resolved Analysis of the High‐Mass X‐Ray Binary Centaurus X‐3 over Two Binary Orbits

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