A Parameterization Study of the Properties of the X‐Ray Dips in the Low‐Mass X‐Ray Binary X1916−053

Hu, Chin-Ping; Chou, Yi; Chung, Yi Ying

doi:10.1086/527549

Cited by 23 publications

(51 citation statements)

References 17 publications

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“…Galloway et al (2001), analysing a Type-I X-ray burst, discovered a highly coherent oscillation drifting from 269.4 Hz up to 272 Hz. Interpreting the asymptotic frequency of the oscillation in terms of a decoupled surface burning layer, the neutron star could have a spin period around 3.7 ms. Hu et al (2008) inferred thatṖ orb /P orb = (1.62 ± 0.34) × 10 −7 yr −1 by analysing archival X-ray data from 1978 to 2002 and adopting a quadratic ephemeris to fit the dip arrival times. In this work, we update the previously determined ephemeris using data from 1978 to 2014.…”

Section: Introductionmentioning

confidence: 99%

Signature of the presence of a third body orbiting around XB 1916-053

Iaria

Salvo

Gambino

et al. 2015

A&A

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Context. The ultra-compact dipping source XB 1916-053 has an orbital period of close to 50 min and a companion star with a very low mass (less than 0.1 M ). The orbital period derivative of the source was estimated to be 1.5(3) × 10 −11 s/s through analysing the delays associated with the dip arrival times obtained from observations spanning 25 years, from 1978 to 2002. Aims. The known orbital period derivative is extremely large and can be explained by invoking an extreme, non-conservative mass transfer rate that is not easily justifiable. We extended the analysed data from 1978 to 2014, by spanning 37 years, to verify whether a larger sample of data can be fitted with a quadratic term or a different scenario has to be considered. Methods. We obtained 27 delays associated with the dip arrival times from data covering 37 years and used different models to fit the time delays with respect to a constant period model. Results. We find that the quadratic form alone does not fit the data. The data are well fitted using a sinusoidal term plus a quadratic function or, alternatively, with a series of sinusoidal terms that can be associated with a modulation of the dip arrival times due to the presence of a third body that has an elliptical orbit. We infer that for a conservative mass transfer scenario the modulation of the delays can be explained by invoking the presence of a third body with mass between 0.10-0.14 M , orbital period around the X-ray binary system of close to 51 yr and an eccentricity of 0.28 ± 0.15. In a non-conservative mass transfer scenario we estimate that the fraction of matter yielded by the degenerate companion star and accreted onto the neutron star is β = 0.08, the neutron star mass is ≥2.2 M , and the companion star mass is 0.028 M . In this case, we explain the sinusoidal modulation of the delays by invoking the presence of a third body with orbital period of 26 yr and mass of 0.055 M . Conclusions. From the analysis of the delays associated with the dip arrival times, we find that both in a conservative and nonconservative mass transfer scenario we have to invoke the presence of a third body to explain the observed sinusoidal modulation. We propose that XB 1916-053 forms a hierarchical triple system.

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Section: Introductionmentioning

confidence: 99%

Signature of the presence of a third body orbiting around XB 1916-053

Iaria

Salvo

Gambino

et al. 2015

A&A

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“…1 it is evident that the choice of the dip state boundaries (i=1 and i=N) can be arbitrary. This is widely demonstrated by Hu et al (2008) with different tests, and could be naively explained with the fact that the points lying in the persistent state beside the dip give little contribution to the sum (i.e. I 0 − I i ≃ 0), and hence to the determination of the time t dip at which the dip occurs.…”

Section: Discussionmentioning

confidence: 92%

“…For this reason, we cannot fit the dip with a specific function since this implies the assumption that the dip has always the same shape (see Gambino et al, 2016;Iaria et al, 2017, in preparation). To address this issue, we take advantage from the method developed by Hu et al (2008) to parameterize the dipping behaviour of XB 1916-053, and to systematically study its variation. The method can be applied both to dippers and eclipsing sources, and represents a powerful tool to obtain the dip arrival time for sources showing dips strongly variable in width and depth during different orbital cycles.…”

Section: Discussionmentioning

confidence: 99%

“…The method can be applied both to dippers and eclipsing sources, and represents a powerful tool to obtain the dip arrival time for sources showing dips strongly variable in width and depth during different orbital cycles. The only constraint of this method is that the observation of at least a complete dip is required (Hu et al, 2008). Therefore we selected all the available pointed observations in which single dips appear to be complete, collecting a total of 14 dips to analyse.…”

Section: Discussionmentioning

confidence: 99%

“…In each light curve we excluded all the type I X-ray bursts present, removing temporal intervals starting 5 s before the rise time and ending 100 s after the peak time of each burst. We implemented the method of Hu et al (2008) on the available complete dips to find the dip arrival times. For each of these light curves we distinguished between the dip and the persistent (non-dip) states, by roughly guessing the boundaries of the dip (see Table 2).…”

Section: Discussionmentioning

confidence: 99%

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Updating the orbital ephemeris of the dipping source XB 1254–690 and the distance to the source

Gambino

Iaria

Salvo

et al. 2017

Res. Astron. Astrophys.

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XB 1254-690 is a dipping low mass X-ray binary system hosting a neutron star and showing type I X-ray bursts. We aim at obtaining a more accurate orbital ephemeris and at constraining the orbital period derivative of the system for the first time. In addition, we want to better constrain the distance to the source in order to locate the system in a well defined evolutive scenario. We apply, for the first time, an orbital timing technique to XB 1254-690, using the arrival times of the dips present in the light curves that have been collected during 26 yr of X-ray pointed observations acquired from different space missions. We estimate the dip arrival times using a statistical method that weights the count-rate inside the dip with respect to the level of persistent emission outside the dip. We fit the obtained delays as a function of the orbital cycles both with a linear and a quadratic function. We infer the orbital ephemeris of XB 1254-690, improving the accuracy of the orbital period with respect to previous estimates. We infer a mass of M 2 = 0.42 ± 0.04 M ⊙ for the donor star, in agreement with estimations already present in literature, assuming that the star is in thermal equilibrium while it transfers part of its mass via the inner Lagrangian point, and assuming a neutron star mass of 1.4 M ⊙ . Using these assumptions, we also constrain the distance to the source, finding a value of 7.6±0.8 kpc. Finally, we discuss the evolution of the system, suggesting that it is compatible with a conservative mass transfer driven by magnetic braking.

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