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تسجيل مستخدم جديدMAGIC detection of the putative gamma-ray binary HESS J0632+057
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The variable gamma-ray source HESS J0632+057 is an excellent candidate for a gamma-ray binary. The putative binary system was discovered as a point-like VHE gamma-ray source by HESS. Later measurements by VERITAS yielding no detection, provided evidence for variable emission in the gamma-ray domain. A variable X-ray source as well as a Be star (MWC 148) are found at the location of the gamma-ray source. Recently a periodic X-ray outburst occurring about every 320 days was reported by Swift (ATel 3152). The putative binary system was observed by the MAGIC stereo system in 2010 and 2011. Our measurements demonstrate significant activity in the gamma-ray (E > 200 GeV) band in February 2011. Our detection of the system occurred during an X-ray outburst reported by Swift. Here we present the obtained light curve and spectrum during this outburst and put them into context with the X-ray measurements.
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We study changes in the $gamma$--ray intensity at very high energies observed from the $gamma$--ray binary HESS J0632+057. Publicly available data collected by Cherenkov telescopes were examined by means of a simple method utilizing solely the number
of source and background events. Our results point to time variability in signal from the selected object consistent with periodic modulation of the source intensity.
The gamma-ray binary HESS J0632+057 has been observed at very-high energies (E $>$ 100 GeV) for more than ten years by the major systems of imaging atmospheric Cherenkov telescopes. We present a summary of results obtained with the H.E.S.S., MAGIC, a
nd VERITAS experiments based on roughly 440 h of observations in total. This includes a discussion of an unusually bright TeV outburst of HESS J0632+057 in January 2018. The updated gamma-ray light curve now covers all phases of the orbital period with significant detections in almost all orbital phases. Results are discussed in context with simultaneous observations with the X-ray Telescope onboard the Neil Gehrels Swift Observatory.
The High Energy Stereoscopic System (HESS) survey of the Galactic plane has established the existence of a substantial number (~40) of Galactic TeV gamma-ray sources, a large fraction of which remain unidentified. HESS J0632+057 is one of a small fra
ction of these objects which is point-like in nature(<2 rms), and is one of only two point-like sources that remain unidentified. Follow-up observations of this object with XMM-Newton have revealed an X-ray source coincident with the TeV source and with the massive star MWC 148, of the spectral type B0pe. This source exhibits a hard spectrum, consistent with an absorbed power law with Gamma = 1.26 +/- 0.04, and shows significant variability on hour timescales. We discuss this spatial coincidence and the implied spectral energy distribution of this object and argue that it is likely a new gamma-ray binary system with a close resemblance to the three known members of this class, and in particular to LS I +61 303. Further X-ray, radio and optical observations of this system are needed to firmly establish HESS J0632+057 as a new member of this rare class of Galactic objects.
HESS J0632+057 is a gamma-ray binary composed of a compact object and a Be star, with an orbital period of about 315 days. The actual nature of its non-thermal emission, spanning from radio to very-high-energy (VHE, >100 GeV) gamma-rays, is currently
unknown. In this contribution we will present the results of a set of simultaneous observations performed by the NuSTAR X-ray telescope and the VERITAS observatory. The combination of hard X-rays (3-30 keV) and VHE gamma-rays (0.1-5 TeV) provide valuable information for the understanding of the radiative processes occurring in the system. The spectral energy distributions (SED) derived from the observations are used to probe the pulsar scenario, in which the system is powered by a rapidly rotating neutron star. The non-thermal emission is produced by the particles accelerated at the shock formed by the collision of the pulsar and stellar winds. As a results of the model fitting, we constrain the relation between the pulsar spin-down luminosity and the magnetization of the pulsar wind.
Context. After the detection of a 321-days periodicity in X-rays, HESS J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries. These sources are known to show extended radio structure at scales of milliarcsecond
s (mas). Aims. We present the expected extended radio emission on mas scales from HESS J0632+057. Methods. We observed HESS J0632+057 with the European VLBI Network (EVN) at 1.6 GHz in two epochs: during the January/February 2011 X-ray outburst and 30 days later. Results. The VLBI image obtained during the outburst shows a compact ~0.4 mJy radio source, whereas 30 days later the source has faded and appears extended, with a projected size of ~75 AU. The peak of the emission is displaced between runs 21+/-5 AU, which is bigger than the orbit size. The position of the radio source is compatible with the Be star MWC 148, which sets the proper motion of the binary system below 3 mas yr^-1 in each coordinate. The brightness temperature of the source is above 2 times 10^6 K. We compare the multiwavelength properties of HESS J0632+057 with those of the previously known gamma-ray binaries. Conclusions. HESS J0632+057 displays extended and variable non-thermal radio emission. Its morphology, size, and displacement at AU scales are similar to those found in the other gamma-ray binaries, PSR B1259-63, LS 5039 and LS I +61 303, supporting a similar nature for HESS J0632+057.
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