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J. Marti'

Publications and source records attributed to J. Marti'.

2 recordsLinked to original sources

The gamma-ray emitting microquasar LSI+61303

LS I +61 303 is one of the most studied X-ray binary systems because of its two peculiarities: On the one hand being the probable counterpart of the variable gamma ray source 2CG 135+01 (Gregory and Taylor 1978; Tavani et al. 1998) and on the other hand being a periodic radio source (Taylor and Gregory 1982). The recent discovery of a radio emitting jet extending ca. 200 AU at both sides of a central core (Massi et al. 2004) in all evidence has shown the occurrence of accretion/ejection processes in this system. However, the radio outbursts do not occur at periastron passage, where the accretion is at its maximum, but several days later. In addition, when the gamma-ray emission of 2CG 135+01 is examined along the orbital phase of LS I +61 303 one sees that this emission seems to peak at periastron passage (Massi 2004). Here in detail we analyse the trend of the gamma-ray data versus orbital phase and discuss the delay between peaks at gamma-rays and in the radio band within the framework of a two-peak accretion/ejection model proposed by Taylor et al. (1992) and further developed by Marti' and Paredes (1995).

astro-ph

Search for the optical and infrared counterpart of GRS 1758-258

We report the results of a deep search for the optical and near infrared counterpart of the microquasar source GRS1758-258. At least two possible candidate counterparts of the binary star companion have been recognized on the basis of astrometric coincidence to within 1". Our photometric study shows that the brightest of them would be consistent with a K-type giant star, while the weakest one would be a main sequence F companion. Follow up spectroscopic observations in the near infrared H and K-bands have failed so far to provide evidence for emission lines that may support an unambiguous identification. However, the proximity of these two sources to the sub-arcsec VLA radio position of GRS 1758-258 makes them deserving further attention in the future.

astro-ph