Episodic jets are usually observed in the intermediate state of black hole transients during their X-ray outbursts .
Here we report the discovery of a strong positive correlation between the peak radio power of the episodic jet P _ { jet } and the corresponding peak X-ray luminosity L _ { x } of the soft state ( in Eddington units ) in a complete sample of the outbursts of black hole transients observed during the RXTE era of which data are available , which follows the relation \log P _ { jet } = ( 2.2 \pm { 0.3 } ) + ( 1.6 \pm 0.2 ) \times \log { L _ { x } } .
The transient ultra-luminous X-ray source in M31 and HLX-1 in EXO 243-49 fall on the relation if they contain stellar mass black hole and either stellar mass black hole or intermediate mass black hole , respectively .
Besides , a significant correlation between the peak power of the episodic jet and the rate-of-increase of the X-ray luminosity dL _ { x } / dt during the rising phase of those outbursts is also found , following \log P _ { jet } = ( 2.0 \pm { 0.4 } ) + ( 0.7 \pm 0.2 ) \times \log { d } L _ { x } / { d } t .
In GX 339 - 4 and H 1743 - 322 in which data for two outbursts are available , measurements of the peak radio power of the episodic jet and the X-ray peak luminosity ( and its rate-of-change ) shows similar positive correlations between outbursts , which demonstrate the dominant role of accretion over black hole spin in generating episodic jet power .
On the other hand , no significant difference is seen among the systems with different measured black hole spin in current sample .
This implies that the power of the episodic jet is strongly affected by non-stationary accretion instead of black hole spin characterized primarily by the rate-of-change of the mass accretion rate .