black hole candidates. We discuss the implications of such periodic variations.'
author:
- |
    Santabrata Das$^{1}$[^1], Indranil Chattopadhyay$^{2}$, Anuj Nandi$^{3}$, D. Molteni$^{4}$\
    $^{1}$Indian Institute of Technology Guwahati, Guwahati, 781039, India.\
    $^{2}$ARIES, Manora Peak, Naintal, 263002, India.\
    $^{3}$Space Astronomy Group, SSIF/ISITE Campus, ISRO Satellite Centre, Outer Ring Road, Marathahalli, Bangalore, 560037, India.\
    $^{4}$Dipartimento di Fisica e Chimica, University of Palermo, Italy.
date: 'Accepted . Received ; in original form '
title: Periodic massloss from viscous accretion flows around black holes
---

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accretion, accretion disc - black hole physics - shock waves - ISM: jets and outflows.

Introduction
============

Luminosities and spectra emanating from the microquasars and AGNs are best explained by the gravitational energy released due to accretion onto compact objects such as black holes. However, it has been established in recent years, that black hole candidates, be it stellar mass or super massive, emits powerful collimated outflows or jets [@l99]. Since black holes do not have intrinsic atmosphere or hard surface, these jets have to be generated from the accretion disc itself. In a very interesting paper, @jetal99 had shown that jets originate from around a region less than $100r_g$ ($r_g{\equiv}$ Schwarzschild radius) across the central object of the 