Discovery of 69 ms periodic X-ray pulsations in A0538 — 66

Skinner, G. K.; Bedford, D. K.; Elsner, Ronald F.; Leahy, D. A.; Weisskopf, Martin C.; Grindlay, J.

doi:10.1038/297568a0

Cited by 110 publications

(81 citation statements)

References 12 publications

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“…It has long been known that high B-field NSs can switch off their pulsations yet continue to emit X-rays. The best known example is A0538-66 which has been detected on numerous occasions, but only once have pulsations been seen (Skinner et al 1982). Magnetospheric accretion that is gated by rotational inhibition may also be able to create unpulsed emission.…”

Section: Discussionmentioning

confidence: 99%

Revisiting the dynamical case for a massive black hole in IC10 X-1

Laycock

Maccarone

Christodoulou

2015

Monthly Notices of the Royal Astronomical Society: Letters

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The relative phasing of the X-ray eclipse ephemeris and optical radial velocity (RV) curve for the X-ray binary IC10 X-1 suggests the He[λ4686] emission-line originates in a shadowed sector of the stellar wind that avoids ionization by X-rays from the compact object. The line attains maximum blueshift when the wind is directly toward us at mid X-ray eclipse, as is also seen in Cygnus X-3. If the RV curve is unrelated to stellar motion, evidence for a massive black hole evaporates because the mass function of the binary is unknown. The reported X-ray luminosity, spectrum, slow QPO, and broad eclipses caused by absorption/scattering in the WR wind are all consistent with either a low-stellar-mass BH or a NS. For a NS, the centre of mass lies inside the WR envelope whose motion is then far below the observed 370 km/s RV amplitude, while the velocity of the compact object is as high as 600 km/s. The resulting 0.4% doppler variation of X-ray spectral lines could be confirmed by missions in development. These arguments also apply to other putative BH binaries whose RV and eclipse curves are not yet phase-connected. Theories of BH formation and predicted rates of gravitational wave sources may need revision.

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Section: Discussionmentioning

confidence: 99%

Revisiting the dynamical case for a massive black hole in IC10 X-1

Laycock

Maccarone

Christodoulou

2015

Monthly Notices of the Royal Astronomical Society: Letters

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“…In contrast to SAX J2103.5+4545 a spin period of only 66 ms has been reported for A0538−66 (Skinner et al 1982), which would be indicative of large amounts of angular momentum transfer. In the early 80's A0538−66 experienced a series of very luminous (super-Eddington) outbursts regularly separated by 16.7 d, which was interpreted as the orbital period.…”

Section: The Spin Period-orbital Period Correlationmentioning

confidence: 99%

Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545

Reig

Negueruela²,

Fabregat³

et al. 2004

A&A

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Abstract. We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar SAX J2103.5+4545 with a moderately reddened V = 14.2 B0Ve star. This identification makes SAX J2103.5+4545 the Be/X-ray binary with the shortest orbital period known, P orb = 12.7 days. The amount of absorption to the system has been estimated to be A V = 4.2 ± 0.3, which for such an early-type star implies a distance of about 6.5 kpc. The optical spectra reveal major and rapid changes in the strength and shape of the Hα line. The Hα line was initially observed as a double peak profile with the ratio of the intensities of the blue over the red peak greater than one (V/R > 1). Two weeks later this ratio reversed (V/R < 1). Subsequently, in less than a month, the emission ceased and Hα appeared in absorption. This fast spectral variability is interpreted within the viscous decretion disc model and demonstrates the significant role of the neutron star on the evolution of the circumstellar disc around the Be star. The implications of the small orbit and moderate eccentricity on the spin period of the neutron star are discussed.

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“…Optical observations also unveiled a super-orbital modulation of ∼421 days (Alcock et al 2001). A 0538−66 contains a 69 ms X-ray pulsar (Skinner et al 1982) and it showed iron line-emission in at least one lowamplitude flare (Corbet et al 1997).…”

Section: Ls I +61mentioning

confidence: 99%

Swift/XRT monitoring of five orbital cycles of LS I +61° 303

Esposito

Caraveo

Luca

et al. 2007

A&A

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Context. LS I +61• 303 is one of the most interesting high-mass X-ray binaries owing to its spatially resolved radio emission and its TeV emission, generally attributed to non-thermal particles in an accretion-powered relativistic jet or in the termination shock of the relativistic wind of a young pulsar. Also, the nature of the compact object is still debated. Only LS 5039 and PSR B1259−63 (which hosts a non-accreting millisecond pulsar) have similar characteristics. Aims. We study the X-ray emission from LS I +61 • 303 covering both short-term and orbital variability. We also investigate the source spectral properties in the soft X-ray (0.3-10 keV) energy range. Methods. Twenty-five snapshot observations of LS I +61 • 303 were collected in 2006 with the XRT instrument on-board the Swift satellite over a period of four months, corresponding to about five orbital cycles. Since individual data sets have too few counts for a meaningful spectral analysis, we extracted a cumulative spectrum. Results. The count rate folded at the orbital phase shows a clear modulation pattern at the 26.5 days period and suggests that the X-ray peak occurs around phase 0.65. Moreover, the X-ray emission appears to be variable on a timescale of ∼1 ks. The cumulative spectrum is well described by an absorbed power-law model, with hydrogen column density N H = (5.7 ± 0.3) × 10 21 cm −2 and photon index Γ = 1.78 ± 0.05. No accretion disk signatures, such as an iron line, are found in the spectrum.

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Discovery of 69 ms periodic X-ray pulsations in A0538 — 66

Cited by 110 publications

References 12 publications

Revisiting the dynamical case for a massive black hole in IC10 X-1

Revisiting the dynamical case for a massive black hole in IC10 X-1

Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545

Swift/XRT monitoring of five orbital cycles of LS I +61° 303

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