Swift/XRT monitoring of five orbital cycles of LSI +61 303

Abstract

LSI +61 303 is one of the most interesting high-mass X-ray binaries owing to its spatially resolved radio emission and its TeV emission, generally attributed to non-thermal particles in an accretion-powered relativistic jet or in the termination shock of the relativistic wind of a young pulsar. Also, the nature of the compact object is still debated. Only LS 5039 and PSR B1259-63 (which hosts a non-accreting millisecond pulsar) have similar characteristics. We study the X-ray emission from LSI +61 303 covering both short-term and orbital variability. We also investigate the source spectral properties in the soft X-ray (0.3-10 keV) energy range. 25 snapshot observations of LSI +61 303 have been collected in 2006 with the XRT instrument on-board the Swift satellite over a period of four months, corresponding to about five orbital cycles. Since individual data sets have too few counts for a meaningful spectral analysis, we extracted a cumulative spectrum. The count rate folded at the orbital phase shows a clear modulation pattern at the 26.5 days period and suggests that the X-ray peak occurs around phase 0.65. Moreover, the X-ray emission appears to be variable on a timescale of ~1 ks. The cumulative spectrum is well described by an absorbed power-law model, with hydrogen column density Nh=(5.7+/-0.3)E+21 cm^-2 and photon index 1.78+/-0.05. No accretion disk signatures, such as an iron line, are found in the spectrum.

arXiv commentRevised to match the A&A version

References in corpus (15)

• The Swift X-ray Telescope
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• INTEGRAL and XMM-Newton observations of LSI +61 303
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• Simultaneous X-ray and Radio Monitoring of the Unusual Binary LSI+61 303: Measurements of the Lightcurve and High-Energy Spectrum
• XMM-Newton observation of a spectral state transition in the peculiar radio/X-ray/gamma-ray source LS I +61 303
• Very Energetic Gamma-Rays from Microquasars and Binary Pulsars
• Chandra Observations of the Gamma-ray Binary LSI+61303: Extended X-ray Structure?
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Cited by in corpus (25)

• Gamma-ray binaries and related systems
• Fermi LAT Observations of LS I +61 303: First detection of an orbital modulation in GeV Gamma Rays
• The gas-to-extinction ratio and the gas distribution in the Galaxy
• HESS J0632+057 : A new gamma-ray binary?
• Periodic very high energy gamma-ray emission from LS I +61 303 observed with the MAGIC telescope
• A magnetar-like event from LS I +61 303 and its nature as a gamma-ray binary
• Modelling the spectral response of the Swift-XRT CCD camera: Experience learnt from in-flight calibration
• Correlated X-ray and Very High Energy emission in the gamma-ray binary LS I +61 303
• Multiwavelength Observations of LS I +61 303 with VERITAS, Swift and RXTE
• The radio counterpart of the likely TeV binary HESS J0632+057
• Deep Chandra observations of TeV binaries I: LSI +61 303
• Deep Chandra observations of TeV binaries II: LS 5039
• Long-term X-ray monitoring of LS I +61 303: analysis of spectral variability and flares
• Variability in the orbital profiles of the X-ray emission of the gamma-ray binary LS I +61 303
• Exceptionally bright TeV flares from the binary LS I +61${}^{\circ }$ 303
• Long-term monitoring of LS I+61303 with INTEGRAL
• The TeV binary HESS J0632+057 in the low and high X-ray state
• The missing GeV γ-ray binary: Searching for HESS J0632+057 with Fermi-LAT
• Multiwavelength Observations of The TeV Binary LS I +61 303 with VERITAS, Fermi-LAT and Swift-XRT During a TeV Outburst
• Does the gamma-ray binary LS I +61°303 harbor a magnetar?
• Achromatic rapid flares in hard X-rays in the $\gamma$-ray binary LS I +61-303
• Rapid X-ray variability of the gamma-ray binary LS I+61 303
• Gamma ray attenuation in X-ray binaries: An application to LSI +61 303
• Optical microflares in LS I +61 303 and the search for their multiwavelength counterpart
• On the X-ray/TeV connection in Galactic jet sources