Phase Variation in the Pulse Profile of SMC X-1

Neilsen, Joey; Hickox, Ryan C.; Vrtilek, S. D.

doi:10.1086/426890

Cited by 22 publications

(40 citation statements)

References 15 publications

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“…9 of Hickox et al 2004). This is consistent with the pulse profile analysis of these data by Neilsen et al (2004): they find that both the soft pulses and the blackbody component originate in the inner edge of the accretion disk. For model 3 there is no particular correlation between the Fe line and either of the continuum fluxes.…”

Section: The Fe Linesupporting

confidence: 89%

“…SMC X-1 thus continues to be the only X-ray pulsar for which no spin-down episodes have been observed. Pulse profile analysis of the high-state data show a hard pulse profile that is consistently double-peaked with a soft pulse profile that varies in shape between single and double peak (Neilsen et al 2004). Although the data cover a small fraction of the superorbital cycle, these profiles are consistent with a model in which the soft pulses occur by reflection of the hard pulses at the inner edge of the accretion disk, with different segments of the inner edge in the observer's line of view, as a function of superorbital phase.…”

Section: Discussionmentioning

confidence: 95%

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Photoionized Lines in X‐Ray Spectra of SMC X‐1

Vrtilek

Raymond

Boroson

et al. 2005

ApJ

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We present a detailed spectral analysis of Chandra ACIS-S continuous clocking (CC) mode observations of the massive X-ray binary system SMC X-1. The system was observed during both the high and low X-ray states of the roughly 60 day superorbital period. The continuum spectra during both states are well represented by a power law with photon index ¼ 0:9 and a blackbody of kT ¼ 0:15 keV. The high-state spectra are dominated by the continuum and independent of orbital phase, whereas the low-state spectra show a strong orbital dependence as well as line emission from O, Ne, Mg, Fe, and Si. This is consistent with the states attributed to disk precession: during the high state, X-ray emission is dominated by the compact source, which is abruptly eclipsed; during the low state, the compact object is hidden by the disk, and a larger, less luminous scattering region is responsible for the X-ray emission. A prominent Ne ix feature places a stringent limit ( log ¼ 2:0 2:5) on the ionization parameter, which constrains the wind dynamics of the system. The Fe line fluxes are related linearly to the blackbody fluxes, indicating that both originate in the same region or are excited by the same mechanism. There is evidence for structure in the Fe line that cannot be fully resolved by the current observations. The pulse period measured during our observations, 0:7057147 AE 0:00000027 s, shows that the uninterrupted spin-up trend of SMC X-1 continues. We discuss the implications of our results for models of SMC X-1.

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Section: The Fe Linesupporting

confidence: 89%

Section: Discussionmentioning

confidence: 95%

Photoionized Lines in X‐Ray Spectra of SMC X‐1

Vrtilek

Raymond

Boroson

et al. 2005

ApJ

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“…Interestingly, all these three sources also have a superorbital intensity modulation at timescales of several times the orbital period, presumably caused by a precessing warped accretion disk. In accordance with this scenario, the phase differene of the soft X-rays with respect to the power-law continuum has also been found to vary with the superorbital phase (Neilsen, Hickox and Vrtilek 2004).…”

Section: Reprocessing In Accretion Disksupporting

confidence: 59%

Neutron Stars in X-ray Binaries and their Environments

Paul

2017

J Astrophys Astron

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Abstract.Neutron stars in X-ray binary systems are fascinating objects that display a wide range of timing and spectral phenomena in the X-rays. Not only parameters of the neutron stars, like magnetic field strength and spin period evolve in their active binary phase, the neutron stars also affect the binary systems and their immediate surroundings in many ways. Here we discuss some aspects of the interactions of the neutron stars with their environments that are revelaed from their X-ray emission. We discuss some recent developments involving the process of accretion onto high magnetic field neutron stars: accretion stream structure and formation, shape of pulse profile and its changes with accretion torque. Various recent studies of reprocessing of X-rays in the accretion disk surface, vertical structures of the accretion disk and wind of companion star are also discussed here. The X-ray pulsars among the binary neutron stars provide excellent handle to make accurate measurement of the orbital parameters and thus also evolution of the binray orbits that take place over time scale of a fraction of a million years to tens of millions of years. The orbital period evolution of X-ray binaries have shown them to be rather complex systems. Orbital evolution of X-ray binaries can also be carried out from timing of the X-ray eclipses and there have been some surprising results in that direction, including orbital period glitches in two X-ray binaries and possible detection of the most massive circum-binary planet around a Low Mass X-ray Binary.

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“…Assuming that this object is located within M31, the corresponding luminosity is 4.0×10 38 erg s −1 in the 0.5-50 keV band. The brightest known accreting X-ray pulsars typically achieve similar luminosities (e.g., LMC X-4, Hung et al 2010; SMC X-1, Neilsen et al 2004; RX J0059.2-7138, Hughes 1994; M82 X-2, NGC7793 P13, and NGC 5907 ULX1 for exceptionally bright examples; Bachetti et al 2014;Fürst et al 2016;Israel et al 2016Israel et al , 2017.…”

Section: Nustar and Swift Spectral Analysismentioning

confidence: 99%

Identification of the Hard X-Ray Source Dominating the E > 25 keV Emission of the Nearby Galaxy M31

Yukita

Ptak

Hornschemeier

et al. 2017

ApJ

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We report the identification of a bright hard X-ray source dominating the M31 bulge above 25 keV from a simultaneous NuSTAR-Swift observation. We find that this source is the counterpart to Swift J0042.6+4112, which was previously detected in the Swift BAT All-sky Hard X-ray Survey. This Swift BAT source had been suggested to be the combined emission from a number of point sources; our new observations have identified a single X-ray source from 0.5 to 50 keV as the counterpart for the first time. In the 0.5-10 keV band, the source had been classified as an X-ray Binary candidate in various Chandra and XMM-Newton studies; however, since it was not clearly associated with Swift J0042.6+4112, the previous E<10 keV observations did not generate much attention. This source has a spectrum with a soft X-ray excess (kT ∼ 0.2 keV) plus a hard spectrum with a power law of 1 G~and a cutoff around 15-20 keV, typical of the spectral characteristics of accreting pulsars. Unfortunately, any potential pulsation was undetected in the NuSTAR data, possibly due to insufficient photon statistics. The existing deep HST images exclude high-mass (>3 M  ) donors at the location of this source. The best interpretation for the nature of this source is an X-ray pulsar with an intermediate-mass (<3 M  ) companion or a symbiotic X-ray binary. We discuss other possibilities in more detail.

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Phase Variation in the Pulse Profile of SMC X-1

Cited by 22 publications

References 15 publications

Photoionized Lines in X‐Ray Spectra of SMC X‐1

Photoionized Lines in X‐Ray Spectra of SMC X‐1

Neutron Stars in X-ray Binaries and their Environments

Identification of the Hard X-Ray Source Dominating the E > 25 keV Emission of the Nearby Galaxy M31

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