Sabyasachi Pal1, Sandip K. Chakrabarti2,1, Alex
Kraus3 and Samir Mandal1
1 Centre for Space Physics, Chalantika 43, Garia Station Rd., Garia,
Kolkata 700084, India
2 S.N. Bose National Centre for Basic Sciences, JD Block, Salt Lake,
Sector III, Kolkata 700098,
India
3 Max Plank Institute for Radio Astronomy, 53902 Bad
Munstereifel-Effelsberg Germany
Abstract. We obtained a broadband radio spectrum of the galactic compact object SS433 through the multi-wavelength campaign using the Giant Meter Radio Telescope (GMRT) and the Effelsberg 100-m Radio Telescope. The observations took place from 2005 January 03 to 2005 February 08 using eight different frequencies. We observed a flare which appeared to have started prior to January 18 and lasted till February 08. The light curves show a progressively larger time-delay as the radio frequency goes down. The peak of the 6 cm lightcurve is delayed by ~3 days with respect to the peak of the 9 mm lightcurve. There is an indication of the flattening of the spectrum and possibly a turnover at ~1.5 GHz. If we interpret this to be due to synchrotron self-absorption, the required magnetic field would become too large, however, free-free absorption by hot thermal surrounding medium formed due to stellar winds is still a possibility. All sky monitor (ASM) aboard Rossi X-ray Timing Experiment (RXTE) showed very high X-ray count on 2005 January 25 when the flare was well underway. This may be due to slamming of the radio `bullets' with previously ejected, relatively slowly moving material.
Keywords: Stars (individual): SS433 Radio Radio sources Radio- frequency spectra