A search for very high energy gamma-ray emission from Scorpius X-1 with the MAGIC telescopes



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Antoranz Canales, Pedro and Barrio Uña, Juan Abel and Contreras González, José Luis and Fonseca González, Mª Victoria and Miranda Pantoja, José Miguel and Nieto, Daniel (2011) A search for very high energy gamma-ray emission from Scorpius X-1 with the MAGIC telescopes. Astrophysical journal letters, 735 (1). ISSN 2041-8205

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Official URL: http://dx.doi.org/10.1088/2041-8205/735/1/L5


The acceleration of particles up to GeV or higher energies in microquasars has been the subject of considerable theoretical and observational efforts in the past few years. Sco X-1 is a microquasar from which evidence of highly energetic particles in the jet has been found when it is in the so-called Horizontal Branch (HB), a state when the radio and hard X-ray fluxes are higher and a powerful relativistic jet is present. Here we present the first very high energy gamma-ray observations of Sco X-1, obtained with the MAGIC telescopes. An analysis of the whole data set does not yield a significant signal, with 95% CL flux upper limits above 300 GeV at the level of 2.4 x 10(-12) cm(-2) s(-1). Simultaneous RXTE observations were conducted to provide the X-ray state of the source. A selection of the gamma-ray data obtained during the HB based on the X-ray colors did not yield a signal either, with an upper limit of 3.4 x 10(-12) cm(-2) s(-1). These upper limits place a constraint on the maximum TeV luminosity to non-thermal X-ray luminosity of L-VHE/L-ntX less than or similar to 0.02 that can be related to a maximum TeV luminosity to jet power ratio of L-VHE/L-j less than or similar to 10(-3). Our upper limits indicate that the underlying high-energy emission physics in Sco X-1 must be inherently different from that of the hitherto detected gamma-ray binaries.

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© The American Astronomical Society. This research project has made use of data collected by NASA's RXTE. We thank the RXTE scheduling team for their help in coordinating the simultaneous observations. We also thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Marie Curie program, by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the YIP of the Helmholtz Gemeinschaft, by the DFG Cluster of Excellence "Origin and Structure of the Universe," and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0.

Uncontrolled Keywords:X-Ray, Binary, Radio, Discovery, Radiation, Pulsar, Microquasar, Evolution, Field, Hess.
Subjects:Sciences > Physics > Electronics
Sciences > Physics > Electricity
Sciences > Physics > Nuclear physics
ID Code:22056
Deposited On:25 Jun 2013 13:41
Last Modified:10 Dec 2018 14:58

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