Microquasars: Open Questions and Future Perspectives

Abstract

Abstract. The discovery and subsequent study of microquasars lead to major progress in our understanding of: 1) the nature of relativistic jets seen elsewhere in the universe, and 2) the connection between the accretion onto compact objects and the formation of collimated jets. A detailed account of the major progress accomplished until present was published in Annual Review of Astronomy & Astrophysics . Here I review the questions that remain unanswered, as well as the future perspectives that this new field of research is opening.

Timing and Spectral Studies of the Peculiar X-ray Binary Circinus X-1

“…The onset of radio flares has been used to derive an ephemeris for the source (Nicolson 1980;Stewart et al 1991), though since the mid-1980's these flares have been too weak to derive an updated ephemeris (Fender et al 1998). Besides showing periodic radio flares, Cir X-1 is embedded in a synchrotron nebula of arcminute scales and also displays an asymmetric jet on arcsecond scales (see Figure 1.3) with outflow velocity of at least 0.1c (Fender et al 1998), making it part of a growing family of microquasars in our Galaxy (Mirabel 2001). Fender et al (1998) stress that this is the first source to provide evidence that a black hole may not be necessary for the production of relativistic jets in X-ray binaries.…”