Understanding Disk-Jet coupling in Black hole transients

Black holes are enigmatic sources observed in the galactic system and are end

products of stellar evolution of some of the massive stars. If they exist in a binary

system along-with a normal star as companion, the matter from the companion gets

accreted towards the Black hole and this matter will form an accretion disk in or-
der to conserve angular momentum. Nearer to the Black hole, matter in the disk

will radiate in X-rays. These emissions play a significant role in understanding the

accretion process and the characteristics of the Black hole. The process of accre-
tion exhibits several spectral and temporal characteristics during an outburst of a

Galactic black hole binary, which have been observed to follow canonical spectral

states. Strong radio Jet emissions are also observed to emerge from Black holes

which makes the whole process complex. Based on observational results for several

sources, it has been found that during the hard state, a steady jet is produced. Dur-
ing the transition to the soft intermediate state, the properties of the jet changes

giving rise to a relativistic motion.

In this talk I will summarize my studies on the disk-jet coupling observed in

several Black hole transients. It has been found that during the Radio flare, the

QPOs are not observed in the power spectra and the spectral evolution suggests that

the emission of soft flux increases at the same time. The observational results imply

that due to lack of continuous and simultaneous Radio and X-ray observations, it

could not be observed exactly when the Jet ejection occurred, and in some situations

the observations seem to have missed some radio flare.