Probing the Nature of the unidentified TeV Gamma-ray source HESS J0632+057 with Swift

Abstract

New generation TeV gamma-ray telescopes have discovered many new sources, including several enigmatic unidentified TeV objects. HESS J0632+057 is a particularly interesting unidentified TeV source since: it is a point source, it has a possible hard-spectrum X-ray counterpart and a positionally consistent Be star, it has evidence of long-term VHE flux variability, and it is postulated to be a newly detected TeV/X-ray binary. We have obtained Swift X-ray telescope observations of this source from MJD 54857 to 54965, in an attempt to ascertain its nature and to investigate the hypothesis that it's a previously unknown X-ray/TeV binary. Variability and spectral properties similar to those of the other 3 known X-ray/TeV binaries have been observed, with measured flux increases by factors of approximately 3. X-ray variability is present on multiple timescales including days to months; however, no clear signature of periodicity is present on the timescales probed by these data. If binary modulation is present and dominating the measured variability, then the period of the orbit is likely to be more than 54 days (half of this campaign), or it has a shorter period with a variable degree of flux modulation on successive high states. If the two high states measured to date are due to binary modulation, then the favored period is approximately 35-40 days. More observations are required to determine if this object is truly a binary system and to determine the extent that the measured variability is due to inter-orbit flaring effects or periodic binary modulation.

accepted for publication in Astrophysical Journal Letters, 13 pages with 4 figures

References in corpus (10)

• Fermi Large Area Telescope Bright Gamma-ray Source List
• VERITAS Observations of the gamma-Ray Binary LS I +61 303
• Discovery of a point-like very-high-energy gamma-ray source in Monoceros
• HESS J0632+057 : A new gamma-ray binary?
• A description of sources detected by INTEGRAL during the first 4 years of observations
• A Rigid-Field Hydrodynamics approach to modeling the magnetospheres of massive stars
• Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057
• Multiwavelength Observations of LS I +61 303 with VERITAS, Swift and RXTE
• The radio counterpart of the likely TeV binary HESS J0632+057
• The Galactic population of HMXBs as seen with INTEGRAL during its four first years of activity

Cited by in corpus (19)

• The gas-to-extinction ratio and the gas distribution in the Galaxy
• A magnetar-like event from LS I +61 303 and its nature as a gamma-ray binary
• A New TeV Binary: The Discovery of an Orbital Period in HESS J0632+057
• On the binary nature of the gamma-ray sources AGL J2241+4454 (=MWC 656) and HESS J0632+057 (=MWC 148)
• Long-term TeV and X-ray Observations of the Gamma-ray Binary HESS J0632+057
• Large-scale flow dynamics and radiation in pulsar gamma-ray binaries
• HD 259440: The Proposed Optical Counterpart of the gamma-ray Binary HESS J0632+057
• On the origin of correlated X-ray/VHE emission from LS I +61 303
• Overview of non-transient gamma-ray binaries and prospects for the Cherenkov Telescope Array
• Detection of VHE γ-rays from HESS J0632+057 during the 2011 February X-ray outburst with the MAGIC Telescopes
• GeV detection of HESS J0632+057
• The TeV binary HESS J0632+057 in the low and high X-ray state
• Monte-Carlo Simulations of Radio Emitting Secondaries in Gamma-Ray Binaries
• Very high energy Fermi/LAT detection of HESS J0632+057
• Decade-long X-ray observations of HESS J0632+057
• Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations
• Modeling the GeV emission of HESS J0632+057
• First multicolour polarimetry of TeV gamma-ray binary HESS J0632+057 close to periastron passage
• The strange case of HESS J0632+057 and the γ-ray High Mass X-ray Binaries