Low-frequency radio spectrum and spectral turnover of LS 5039

Abstract

LS 5039, a possible black hole X-ray binary, was recently observed with Giant Metrewave Radio Telescope. The observed spectrum presented here shows that the spectrum is inverted at low frequency. When combined with the archival data with orbital phase similar to the present observations, it shows a clear indication of a spectral turnover. The combined data are fitted with a broken power-law and the break frequency signifies a possible spectral turnover of the spectrum around 964 MHz. Truly simultaneous observations in radio wavelength covering a wide range of frequencies are required to fix the spectrum and the spectral turnover which will play a crucial role in developing a deeper understanding of the radio-emitting jet in LS 5039. © 2008 The Authors. Journal compilation © 2008 RAS.