ترغب بنشر مسار تعليمي؟ اضغط هنا

RXTE & Swift Observations of SWIFT J0513.4--6547

109   0   0.0 ( 0 )
 نشر من قبل S. Cagdas Inam
 تاريخ النشر 2015
  مجال البحث فيزياء
والبحث باللغة English
 تأليف S. Sahiner




اسأل ChatGPT حول البحث

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.



قيم البحث

اقرأ أيضاً

89 - S. Sahiner 2013
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.
112 - R. Landi , L. Bassani , A. Malizia 2009
The 4th IBIS/ISGRI survey lists 723 hard X-ray sources many still unidentified. We cross-correlated the list of the sources included in the 4th IBIS catalogue with the Swift/XRT data archive, finding a sample of 20 objects for which XRT data could he lp in the search for the X-ray and hence optical counterpart and/or in the study of the source spectral and variability properties below 10 keV. Four objects (IGR J00465-4005, LEDA 96373, IGR J1248.2-5828 and IGR J13107-5626) are confirmed or likely absorbed active galaxies, while two (IGR J14080-3023 and 1RXS J213944.3+595016) are unabsorbed AGN. We find three peculiar extragalactic objects, NGC 4728 being a Narrow Line Seyfert galaxy, MCG+04-26-006 a type 2 LINER and PKS 1143-693 probably a QSO; furthermore, our results indicate that IGR J08262+4051 and IGR J22234-4116 are candidate AGN, which require further optical spectroscopic follow-up observations to be fully classified. In the case of 1RXS J080114.6-462324 we are confident that the source is a Galactic object. For IGR J10447-6027, IGR J12123-5802 and IGR J20569+4940 we pinpoint one X-ray counterpart, although its nature could not be assessed despite spectral and sometimes variability information being obtained. Clearly, we need to perform optical follow-up observations in order to firmly assess their nature. There are five objects for which we find no obvious X-ray counterpart (IGR J07506-1547 and IGR J17008-6425) or even no detection (IGR J17331-2406, IGR J18134-1636 and IGR J18175-1530); apart from IGR J18134-1636, all these sources are found to be variable in the IBIS energy band, therefore it is difficult to catch them even in X-rays.
We present results from a long-term monitoring campaign on the TeV binary LSI +61 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between September 2006 and F ebruary 2008. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8 sigma (2006/2007) and 7.3 sigma (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5 to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6 sigma significance level) for TeV emission outside of the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0*10^-11 ergs cm^-2 s^-1 over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.
We present contemporaneous X-ray, ultraviolet, optical and near-infrared observations of the black hole binary system, Swift J1753.5-0127, acquired in 2012 October. The UV observations, obtained with the Cosmic Origins Spectrograph on the Hubble Spac e Telescope, are the first UV spectra of this system. The dereddened UV spectrum is characterized by a smooth, blue continuum and broad emission lines of CIV and HeII. The system was stable in the UV to <10% during our observations. We estimated the interstellar reddening by fitting the 2175 A absorption feature and fit the interstellar absorption profile of Ly$alpha$ to directly measure the neutral hydrogen column density along the line of sight. By comparing the UV continuum flux to steady-state thin accretion disk models, we determined upper limits on the distance to the system as a function of black hole mass. The continuum is well fit with disk models dominated by viscous heating rather than irradiation. The broadband spectral energy distribution shows the system has declined at all wavelengths since previous broadband observations in 2005 and 2007. If we assume that the UV emission is dominated by the accretion disk the inner radius of the disk must be truncated at radii above the ISCO to be consistent with the X-ray flux, requiring significant mass loss from outflows and/or energy loss via advection into the black hole to maintain energy balance.
Supernova (SN) 2018cow (or AT2018cow) is an optical transient detected in the galaxy CGCG 137-068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results o f the analysis of ~62ks of X-ray observations taken with the Neil Gehrels Swift Observatory over 27 days. We found a variable behavior in the 0.3-10 keV X-ray light curve of SN 2018cow, with variability timescales of days. The observed X-ray variability could be due to the interaction between the SN ejecta and a non-uniform circumstellar medium, perhaps related to previous mass ejections from a luminous-blue-variable-like progenitor.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا