Long-term X-ray variability of the microquasar system LS 5039/RX J1826.2-1450

¹ G.A.C.E., Institut de Ciències dels Materials, Universitat de Valencia, 46071 Paterna-Valencia, Spain e-mail: pablo.reig@uv.es
² Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Spain e-mail: mribo@am.ub.es; josep@am.ub.es
³ Departamento de Física, Escuela Politécnica Superior, Universidad de Jaén, Virgen de la Cabeza 2, 23071 Jaén, Spain e-mail: jmarti@ujaen.es

Corresponding author: P. Reig, pablo.reig@uv.es

Received: 14 February 2003
Accepted: 16 April 2003

Abstract

We report on the results of the spectral and timing analysis of a BeppoSAX observation of the microquasar system LS 5039/RX J1826.2-1450. The source was found in a low-flux state with F_X(1–10 keV) = erg cm^-2 s^-1, which represents almost one order of magnitude lower than a previous RXTE observation 2.5 years before. The 0.1–10 keV spectrum is described by an absorbed power-law continuum with photon-number spectral index and hydrogen column density of cm^-2. According to the orbital parameters of the system, the BeppoSAX observation covers the time of an X-ray eclipse should one occur. However, the 1.6–10 keV light curve does not show evidence of such an event, which allows us to give an upper limit to the inclination of the system. The low X-ray flux detected during this observation is interpreted as a decrease in the mass accretion rate onto the compact object due to a decrease in the mass-loss rate from the primary.