Search for VHE signals from microquarsars with MAGIC

Roberta Zanin; Takayuki Sayto; Victor Zabalza; Pol Bordas; Tobias Jogler; Juan Cortina; Josep Maria Paredes; Marc Ribó; Javier Rico

arXiv · 1110.1581

Search for VHE signals from microquarsars with MAGIC

Roberta Zanin·Takayuki Sayto·Victor Zabalza·Pol Bordas·Tobias Jogler·Juan Cortina·Josep Maria Paredes·Marc Ribó·Javier Rico

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Abstract

Microquasars are accreting binary systems displaying relativistic radio jets where very high energy gamma rays might be produced via Inverse Compton scattering. The detection of the microquasar Cygnus X-3 above 100 MeV by both Fermi/LAT and AGILE satellites, together with the short flares from Cygnus X-1 reported by AGILE, confirmed that this class of astrophysical objects are interesting candidates for very high energy gamma-ray observations. The stand-alone imaging atmospheric Cherenkov MAGIC telescope, and later on the recently inaugurated stereoscopic system, made a significant effort to search for signals from microquasars. This paper reviews all MAGIC results of Cygnus X-3, Cygnus X-1, Scorpius X-1, and SS 433 observations. The stand-alone MAGIC telescope observed Cygnus X-3 for almost 60 hrs from March 2006 until August 2009 in many different X-ray spectral states where a very high energy emission is predicted and also simultaneously with a flux enhancement at high energies detected by Fermi/LAT. No significant signal was found in any of the observed conditions. The MAGIC stereoscopic system pointed at the Z-type low-mass X-ray binary Scorpius X-1 in May 2010 for ~8 hrs. Simultaneous soft X-ray measurements allowed to define the X-ray spectral state of the source which could emit very-high-energy photons in the horizontal branch. MAGIC did not detect the source and put some constraints on the maximum TeV luminosity to jet power ratio. Further observations of Cygnus X-1 were also carried out with the new and twice as sensitive stereoscopic system in Autumn 2009 for a total amount of 30 hrs. Finally, we also report on SS 433 observations obtained during two periods of minimum absorption processes from the accretion disk.

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Roberta Zanin, Takayuki Sayto, Victor Zabalza, Pol Bordas, Tobias Jogler, Juan Cortina, Josep Maria Paredes, Marc Ribó, Javier Rico. 2011-10-07. Search for VHE signals from microquarsars with MAGIC. https://arxiv.org/abs/1110.1581

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