Global Jet Watch

Abstract:

We present the X-ray images of all the available Chandra observations of the galactic jet source SS 433. We have studied the morphology of the X-ray images and inspected the evolution of the arcsec X-ray jets, recently found to be manifestations of in situ reheating of the relativistic gas downstream in the jets. The Chandra images reveal that the arcsec X-ray jets are not steady long term structures; the structure varies, indicating that the reheating processes have no preference for a particular precession phase or distance from the binary core. Three observations made within about five days in May 2001, and a 60 ks observation made in July 2003 show that the variability of the jets can be very rapid, from timescales of days to (possibly) hours. The three May 2001 images show two resolved knots in the east jet getting brighter one after the other, suggesting that a common phenomenon might be at the origin of the sequential reheatings of the knots. We discuss possible scenarios and propose a model to interpret these brightenings in terms of a propagating shock wave, revealing a second, faster outflow in the jet.

Abstract:

We present results from the first near-IR imaging of the weak X-ray sources discovered in the Chandra/ACIS-I survey (Wang et al. 2002) towards the. Galactic Centre (GC). These 800 discrete sources, which contribute significantly to the GC X-ray emission, represent an important and previously unknown population within the Galaxy. From our VLT observations we will identify likely IR counterparts to a sample of the hardest sources, which am most likely X-ray binaries, With these data we can place constraints on the nature of the discrete weak X-ray source population of the GC.

Abstract:

I discuss the importance of studies of jets and outflows in the Galaxy from binary star systems, popularly known as microquasars. Because of the rapid timescales on which they evolve, pertinent observations of microquasar jets can help tighten up the theoretical framework in which jet properties of quasars can be interpreted. I draw attention to a new method for constraining jet speed which renders original approaches, which do not incorporate jet evolution, obsolete. I describe new results on two particular microquasars, SS 433 and Cygnus X-3. I compare and contrast the jet characteristics of these two microquasars, noting the persistent jet activity of SS 433 with the intermittent jet activity of Cygnus X-3.