Search for VHE gamma rays from SS433/W50 with the CANGAROO-II telescope

Abstract

SS433, located at the center of the supernova remnant W50, is a close proximity binary system consisting of a compact star and a normal star. Jets of material are directed outwards from the vicinity of the compact star symmetrically to the east and west. Non-thermal hard X-ray emission is detected from lobes lying on both sides. Shock accelerated electrons are expected to generate sub-TeV gamma rays through the inverse-Compton process in the lobes. Observations of the western X-ray lobe region of SS433/W50 system have been performed to detect sub-TeV gamma-rays using the 10m CANGAROO-II telescope in August and September, 2001, and July and September, 2002. The total observation times are 85.2 hours for ON source, and 80.8 hours for OFF source data. No significant excess of sub-TeV gamma rays has been found at 3 regions of the western X-ray lobe of SS433/W50 system. We have derived 99% confidence level upper limits to the fluxes of gamma rays and have set constraints on the strengths of the magnetic fields assuming the synchrotron/inverse-Compton model for the wide energy range of photon spectrum from radio to TeV. The derived lower limits are 4.3 microgauss for the center of the brightest X-ray emission region and 6.3 microgauss for the far end from SS433 in the western X-ray lobe. In addition, we suggest that the spot-like X-ray emission may provide a major contribution to the hardest X-ray spectrum in the lobe.Comment: 7 pages, 8 figures, to be published in Astroparticle Physic

Dynamical and radiative simulations of γ-ray jets in microquasars

“…restrial Cherenkov arrays (e.g. Orellana et al 2007a, Hayashi et al 2009, Saito et al 2009), and from orbital platforms (e.g. Geldzahler et al 1984, Abdo et al 2009).…”

“…Abdo et al 2009). For further information, the reader is referred to Orellana et al (2007a), Hayashi et al (2009), Saito et al (2009). Concerning neutrino emission, although detection of such particles ⋆ E-mail:hkosmas@uoi.gr from microquasars has not been clearly achieved to date, estimates for their intensity have been derived (Aiello et al 2007).…”

High energy γ-ray emission from compact galactic sources in the context of observations with the next generation Cherenkov Telescope Arrays

“…The γ-ray emission from microquasars in the low mass binary systems have not been discovered up to now in spite of extensive observations, see e.g. GRS 1915+105 [29,259] or SS433 [36,178,259].…”

γ-rays from anisotropic inverse Compton e± pair cascades in microquasars: application to Cyg X-3

“…Other microquasars, such as GRS 1915+105 and SS433, have also been observed at TeV energies by the Cherenkov telescopes but without positive results (see e.g. Aharonian et al 2005;Hayashi et al 2009;Acero et al 2009; Saito E-mail: jusi@kfd2.phys.uni.lodz.pl (JS); bednar@astro.phys.uni.lodz.pl (WB) Aleksić et al 2011). GeV-TeV emission has also been detected from a few other massive binary systems, namely LS 5039 and LSI 61 303.…”