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تسجيل مستخدم جديدSwift/XRT observations of newly discovered INTEGRAL sources
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R. Landi
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With respect to the recent INTEGRAL/IBIS 9-year Galactic Hard X-ray Survey (Krivonos et al. 2012), we use archival Swift/XRT observations in conjunction with multi-wavelength information to discuss the counterparts of a sample of newly discovered objects. The X-ray telescope (XRT, 0.3-10 keV) on board Swift, thanks to its few arcseconds source location accuracy, has been proven to be a powerful tool with which the X-ray counterparts to these IBIS sources can be searched for and studied. In this work, we present the outcome of this analysis by discussing four objects (SWIFT J0958.0-4208, SWIFT J1508.6-4953, IGR J17157-5449, and IGR J22534+6243) having either X-ray data of sufficient quality to perform a reliable spectral analysis or having interesting multiwaveband properties. We find that SWIFT J1508.6-4953 is most likely a Blazar, while IGR J22534+6243 is probably a HMXB. The remaining two objects may be contaminated by nearby X-ray sources and their class can be inferred only by means of optical follow-up observations of all likely counterparts.
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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
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RT data archive is of key importance to search for the X-ray counterparts; in fact, the positional accuracy of few arcseconds obtained with XRT allows us to perform more efficient and reliable follow-up observations at other wavelengths (optical, UV, radio). In this work, we present the results of the XRT observations for four new gamma-ray sources: IGR J12123-5802, IGR J1248.2-5828, IGR J13107-5626 and IGR J14080-3023. For IGR J12123-5802 we find a likely counterpart, but further information are needed to classified this object, IGR J1248.2-5828 is found to be a Seyfert 1.9, for IGR J13107-5626 we suggest a possible AGN nature, while IGR J14080-3023 is classified as a Seyfert 1.5 galaxy.
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Swift J1818.0-1607 is a new radio-loud magnetar discovered by the Swift Burst Alert Telescope on 2020 March 12. It has a magnetic field B~2.5e14 G, spin-down luminosity of 7.2e35 ergs/s, and characteristic age of ~470yr. Here we report on the Chandra
observations of Swift J1818.0-1607, which allowed for a high-resolution imaging and spectroscopic study of the magnetar and its environment. The 1-10 keV spectrum of the magnetar is best described by a single blackbody model with a temperature of 1.2pm0.1 keV and an unabsorbed flux of 1.9e-11 ergs/cm^2/s. This implies an X-ray luminosity of ~9.6e34 ergs/s and an efficiency of ~0.13 at a distance of 6.5 kpc. The Chandra image also shows faint diffuse emission out to >10 from the magnetar, with its spectrum adequately described by a powerlaw with a photon index of 2.0pm0.5 and a luminosity of ~8.1e33 ergs/s. The extended emission is likely dominated by a dust scattering halo and future observations of the source in quiescence will reveal any underlying compact wind nebula. We conclude that Swift J1818.0-1607 is a transient source showing properties between high-B pulsars and magnetars, and could be powered at least partly by its high spin-down similar to the rotation-powered pulsars.
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