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Register a new userRXTE confirmation of the Intermediate Polar status of Swift J0732.5-1331
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Aims. We intend to establish the X-ray properties of Swift J0732.5-1331 and therefore confirm its status as an intermediate polar. Method. We analysed 36,240 s of X-ray data from RXTE. Frequency analysis was used to constrain temporal variations and spectral analysis used to characterise the emission and absorption properties. Results. The X-ray spin period is confirmed to be 512.4(3) s with a strong first harmonic. No modulation is detected at the candidate orbital period of 5.6 h, but a coherent modulation is present at the candidate 11.3 h period. The spectrum is consistent with a 37 keV bremsstrahlung continuum with an iron line at 6.4 keV absorbed by an equivalent hydrogen column density of around 10^22 atoms cm^-2. Conclusions. Swift J0732-1331 is confirmed to be an intermediate polar.
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Aims. To determine the credentials of nine candidate intermediate polars in order to confirm whether or not they are magnetic cataclysmic variables. Methods. Frequency analysis of RXTE and XMM data was used to search for temporal variations which could be associated with the spin period of the magnetic white dwarf. X-ray spectral analysis was carried out to characterise the emission and absorption properties of each target. Results. The hard X-ray light curve of V2069 Cyg shows a pulse period of 743.2 s, and its spectrum is fit by an absorbed bremsstrahlung model with an iron line, confirming this to be a genuine intermediate polar. The hard X-ray light curve of the previously confirmed intermediate polar IGR J00234+6141 is shown to be consistent with the previous low energy X-ray detection of a 563.5 s pulse period. The likely polar IGR J14536-5522 shows no coherent modulation at the previously identified period of 3.1 hr, but does exhibit a clear signal at periods likely to be harmonically related to it. Whilst our RXTE observations of RX J0153.3+7447, Swift J061223.0+701243.9, V436 Car and DD Cir are largely too faint to give any definitive results, the observation of IGR J16167-4957 and V2487 Oph show some characteristics of intermediate polars and these objects remain good candidates. Conclusions. We confirmed one new hard X-ray selected intermediate polar from our sample, V2069 Cyg.
Intermediate polars are members of the cataclysmic variable binary stars. They are characterized by a moderately magnetized white dwarf accreting matter from a cool main-sequence companion star. In many cases, this accretion gives rise to a detectable $X$-ray emission. VZ Sex is an interesting $X$-ray source whose nature needs a robust confirmation. Here, we used archive $XMM$-Newton observation to assign the source to the intermediate polar class. We applied the Lomb-Scargle periodogram method to detect any relevant periodic feature in the $0.1$--$10$ keV light curve and performed a spectral fitting of the $X$-ray spectrum in order to get information on the on-going accretion mechanism. By inspecting the periodogram, we detected a clear periodic feature at $simeq 20.3$ minutes that we interpret as the spin period of the white dwarf. We additionally found the typical side bands expected as the consequence of the beat between the spin and the orbital period of $simeq 3.581$ hours. The source is characterized by a unabsorbed flux of $simeq 2.98times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ corresponding to an intrinsic luminosity {of $simeq 7 times 10^{31}$ erg s$^{-1}$ } {for a distance of $simeq 433$ pc}. The existence of such features allow us to classify VZ Sex as a clear member of the intermediate polar class. Furthermore, with the estimated WD spin, the ratio $P_{spin}/P_{orb}$ is $simeq 0.09$, i.e. consistent with that expected for a typical IP system above the period gap. In addition, the estimated intrinsic luminosity opens the possibility that a bridge linking the normally bright IPs to the faint population of sources does exist.
We present timing and spectral analysis of emph{Swift}$-$XRT and emph{RXTE}$-$PCA observations of the transient Be/X-ray pulsar SWIFT J0513.4--6547 during its outburst in 2009 and its rebrightening in 2014. From 2009 observations, short term spin-up rate of the source after the peak of the outburst is found to have about half of the value measured at the peak of the outburst by Coe et al. When the source is quiescent between 2009 and 2014, average spin-down rate of the source is measured to be $sim 1.52 times 10^{-12}$ Hz s$^{-1}$ indicating a surface dipole magnetic field of $sim 1.5 times 10^{13}$ Gauss assuming a propeller state. From 2014 observations, short term spin-down rate of the source is measured to be about two orders smaller than this long-term spin-down rate. The orbit of the source is found to be circular which is atypical for transient Be/X-ray binary systems. Hardness ratios of the source correlate with the X-ray luminosity up to $8.4times 10^{36}$ erg s$^{-1}$ in 3-10 keV band, whereas for higher luminosities hardness ratios remain constant. Pulsed fractions are found to be correlated with the source flux. Overall emph{Swift}$-$XRT and emph{RXTE}$-$PCA energy spectrum of the source fit equally well to a model consisting of blackbody and power law, and a model consisting of a power law with high energy cut-off. From the pulse phase resolved spectra and pulse phase resolved hardness ratios obtained using emph{RXTE}$-$PCA, it is shown that spectrum is softer for the phases between the two peaks of the pulse.
We analyze emph{RXTE} and emph{Swift} observations of SWIFT J1729.9$-$3437 after its outburst from 2010 July 20 to 2010 August 12. We calculate a spin frequency and spin frequency derivative of $1.8734(8) times 10^{-3}$ Hz and $6.42(6) times 10^{-12}$ Hz/s respectively from the quadratic fit of pulse arrival times. The quadratic fit residuals fit well to a circular orbital model with a period of $15.3(2)$ days and a mass function of about $1.3M_{odot}$, but they can also be explained by a torque noise strength of $6.8 times 10^{-18}$ Hz sec$^{-2}$. Pulse profiles switches from double-peaked to single-peaked as the source flux continues to decrease. We find that the pulse shape generally shows no strong energy dependence. The hardness ratios reveal that the source becomes softer with decreasing flux. We construct a single spectrum from all the available RXTE and Swift observations. We find that adding an emph{Fe} line complex feature around 6.51 keV slightly improves the spectral fit and that this feature is more likely to originate from the source rather than the Galactic ridge. From the pulse phase spectral analysis, it is shown that that photon index and folding energy of the high energy cut-off vary with varying pulse phase.
We report on the Swift/XRT Deep Galactic Plane Survey discovery and multi-wavelength follow-up observations of a new intermediate polar Cataclysmic Variable, Swift J183920.1-045350. A 449.7 s spin period is found in Xmm-Newton and NuSTAR data, accompanied by a 459.9 s optical period that is most likely the synodic, or beat period, produced from a 5.6 h orbital period. The orbital period is seen with moderate significance in independent long-baseline optical photometry observations with ZTF and SAAO. We find that the source X-ray pulsed fraction decreases with increasing energy. The X-ray spectra are consistent with the presence of an Fe emission line complex with both local and interstellar absorption. In the optical spectra, strong H$alpha{}$, H I, He I and He II emission lines are observed, all common features in magnetic CVs. The source properties are thus typical of known intermediate polars, with the exception of its estimated distance of 2.26$^{+1.93}_{-0.83}$ kpc, which is larger than typical, extending the reach of the CV population in our Galaxy.
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