On the geometry of the X-ray emission from pulsars: the changing aspect of the Be/X-ray pulsar SXP348

Cappallo, R.; Laycock, S.; Christodoulou, Dimitris M.; Coe, M. J.; Zezas, A.

doi:10.1093/mnras/stz1087

Cited by 5 publications

(8 citation statements)

References 35 publications

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“…from a universal energy range of 3 to 10 keV and then folded on the periods found from a Lomb-Scargle periodogram analysis (Lomb 1976;Scargle 1982) with detections at s ≥ 99% significance, following the same data-reduction prescription and timing analysis as described in Cappallo et al (2019). All observations used in this study are given in Table 1 and occurred at different points in the ephemeris, as presented in Fig.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…We followed the same prescription laid out in § 4.2 of Cappallo et al (2019) for the fitting performed in this paper. Briefly stated, each profile was fit with an antipodal, 6-parameter version of Polestar where the inclination angle (0 • ≤ i ≤ 90 • ), the angle of the primary hot spot (0 • ≤ θ ≤ 90 • ), the longitude (0 • ≤ φ ≤ 360 • ), the power of the cosine emission function (1 ≤ P cos ≤ 9), the power of the sine emission function (1 ≤ P sin ≤ 9), and the contribution from the two functions to the overall emission (0 ≤ P rat ≤ 1, Observations of SXP 1062 fitted with Polestar.…”

Section: Fitting Strategymentioning

confidence: 99%

“…In order to reduce fitting time Polestar incorporates a modified coordinate descent algorithm (see § 3.1 in Cappallo et al (2019) for a discussion on this technique). Similarly, the model itself was simplified for the fitting performed in this study.…”

Section: R Nsmentioning

confidence: 99%

“…We have extracted light curves from archival Chandra, XMM-Newton, and NuSTAR observations and have used our geometric model Polestar (Cappallo et al 2017(Cappallo et al , 2019 in order to produce individual fits to 19 unique pulse profiles (see Table 1 for the ObsIDs and observation dates corresponding to these profiles). We have performed a statistical analysis of the results in an attempt to find the best-fit geometric parameters of the pulsar and the orientation of its magnetic dipole axis relative to its spin axis.…”

Section: Introductionmentioning

confidence: 99%

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On the Geometry of the X-ray emission from pulsars a consistent inclination and beaming solution for the Be/X-ray pulsar SXP 1062

Cappallo

Laycock

Christodoulou

et al. 2020

Monthly Notices of the Royal Astronomical Society

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SXP 1062 is a long-period X-ray pulsar (XRP) with a Be optical companion located in the Small Magellanic Cloud. First discovered in 2010 from XMM–Newton data, it has been the target of multiple observational campaigns due to the seeming incongruity between its long spin period and recent birth. In our continuing modelling efforts to determine the inclination angle (i) and magnetic axis angle (θ) of XRPs, we have fitted 19 pulse profiles from SXP 1062 with our pulsar model, Polestar, including three consecutive Chandra observations taken during the trailing end of a Type I outburst. These fittings have resulted in most likely values of i = 76○ ± 2○ and θ = 40○ ± 9○. SXP 1062 mostly displays a stable double-peaked pulse profile with the peaks separated by roughly a third of a phase, but recently the pulsar has spun up and widened to a spacing of roughly half of a phase, yet the Polestar fits for i and θ remain constant. Additionally, we note a possible correlation between the X-ray luminosity and the separation of the peaks in the pulse profiles corresponding to the highest luminosity states.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Fitting Strategymentioning

confidence: 99%

Section: R Nsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the Geometry of the X-ray emission from pulsars a consistent inclination and beaming solution for the Be/X-ray pulsar SXP 1062

Cappallo

Laycock

Christodoulou

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…There are also cases of significant variations in observed profiles of transient sources during an outburst, where the pulse profiles can dramatically change their looks and behaviour (see e.g. Brumback et al 2021;Camero Arranz et al 2007;Cappallo et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Common patterns in pulse profiles of high-mass X-ray binaries

Alonso-Hernández

Fürst

Kretschmar

et al. 2022

A&A

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Context. X-ray pulsars are binary systems which consist of a neutron star in orbit with a mass donor (companion). In these systems the neutron accretes matter from the companion star, which creates accretion columns or hot spots on the neutron star surface and gives rise to pulsations in the X-ray light curve. The pulse profiles carry information about the accretion and magnetic field geometry.Here we present a study and classification of energy-resolved pulse profiles of a sample of X-ray pulsars, focusing on high-mass X-ray binaries. Aims. Our goal is to perform a classification of X-ray pulsars based on their observed pulse profiles and look for correlations between this classification and their principle physical observables. The analysis pipeline is available online. Methods. We analysed the pulse profiles of a sample of X-ray pulsars using data obtained with the X-ray Multi-Mirror Mission (XMM-Newton) and the Nuclear Spectroscopic Telescope Array (NuSTAR ). We fitted the energy-resolved pulse profiles with a Fourier series of up to five harmonics. We then used the energy evolution of the different Fourier components to classify the pulse profiles into groups. We investigated relationships between the pulse profile properties and other observables of the systems (e.g. orbital period, magnetic field strength, and luminosity) to study the extreme physics of these systems.Results. The sources were divided into three groups using a classification based on the shape, the dominance of the fitted Fourier harmonics, and their respective evolution with energy. We do not find a conclusive correlation between the pulse profile shapes or groups and other parameters of the systems. However, a weak trend was found when comparing our classification to the sources' locations in the spin period-orbital period diagram. Further studies are required to confirm this trend. Conclusions. Despite the large variety of pulse profiles of the X-ray pulsars, we found that with our approach clear categories emerge which we use to classify their behaviour as a function of energy. As we do not find a clear relationship between our classification scheme and other parameters, like the luminosity, the magnetic field strength, or the orbital and spin periods, we conclude that X-ray pulse profiles are influenced by other hidden variables.

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The giant outburst of EXO 2030+375

Thalhammer,

Ballhausen,

Sokolova-Lapa

et al. 2024

A&A

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The Be X-ray binary EXO 2030+375 went through its third recorded giant outburst from June 2021 to early 2022. We present the results of both spectral and timing analysis based on NICER monitoring, covering the 2−10 keV flux range from 20 to 310 mCrab. Dense monitoring with observations carried out about every second day and a total exposure time of ∼160 ks allowed us to closely track the source evolution over the outburst. Changes in the spectral shape and pulse profiles showed a stable luminosity dependence during the rise and decline. The same type of dependence has been seen in past outbursts. The pulse profile is characterized by several distinct peaks and dips. The profiles show a clear dependence on luminosity with a stark transition at a luminosity of ∼2 × 1036 erg s−1, indicating a change in the emission pattern. Using relativistic raytracing, we demonstrate how anisotropic beaming of emission from an accretion channel with a constant geometrical configuration can give rise to the observed pulse profiles over a range of luminosities.

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On the geometry of the X-ray emission from pulsars: the changing aspect of the Be/X-ray pulsar SXP348

Cited by 5 publications

References 35 publications

On the Geometry of the X-ray emission from pulsars a consistent inclination and beaming solution for the Be/X-ray pulsar SXP 1062

On the Geometry of the X-ray emission from pulsars a consistent inclination and beaming solution for the Be/X-ray pulsar SXP 1062

Common patterns in pulse profiles of high-mass X-ray binaries

The giant outburst of EXO 2030+375

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