Disk-jet connection in GRS 1915+105: X-ray soft dips as cause of radio flares

We have examined the radio emission characteristics of the micro-quasar GRS 1915+105 during its X-ray emission states as classified by Belloni et al. (2000). We find that the radio emission is high during the chi (1) and chi (3) states (the radio "plateau" state) and also during the beta and theta s tates when X-ray soft dips are present in the X-ray light curve. For all th e other X-ray states we find that the radio emission is low (< 20 mJy at 2. 25 GHz). This result supports the suggestion made by Naik et al. (2000) tha t the radio fares are caused by a series of X-ray dip events. To further co nfirm this result, we have made a systematic study of all the PCA RXTE obse rvations for those days when a radio flare was present. We find 11 such obs ervations and find that all of them are of class <beta>, theta or chi. Furt her, we have classified all the RXTE PCA observations obtained from 1996 No vember to 2000 February (when the radio data is available) and confirm that the radio flux, on an average, is much higher during the states beta, thet a and chi. Based on these results, we argue that the radio flares are cause d by the X-ray dips in the source.