Multiple relativistic outbursts of GRS 1915+105: radio emission and internal shocks |
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| Authors: | J C A Miller-Jones D G McCormick R P Fender R E Spencer T W B Muxlow G G Pooley |
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| Institution: | Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands;The University of Manchester, Jodrell Bank Observatory, Cheshire SK11 9DL;School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ;Mullard Radio Astronomy Observatory, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE |
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| Abstract: | We present 5-GHz Multi-Element Radio-Linked Interferometer Network (MERLIN) radio images of the microquasar GRS 1915+105 during two separate outbursts in 2001 March and July, following the evolution of the jet components as they move outwards from the core of the system. Proper motions constrain the intrinsic jet speed to be >0.57 c , but the uncertainty in the source distance prevents an accurate determination of the jet speed. No deceleration is observed in the jet components out to an angular separation of ～300 mas. Linear polarization is observed in the approaching jet component, with a gradual rotation in position angle and a decreasing fractional polarization with time. Our data lend support to the internal shock model whereby the jet velocity increases leading to internal shocks in the pre-existing outflow before the jet switches off. The compact nuclear jet is seen to reestablish itself within 2 d, and is visible as core emission at all epochs. The energetics of the source are calculated for the possible range of distances; a minimum power of 1–10 per cent of the Eddington luminosity ( L Edd) is required to launch the jet. |
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| Keywords: | accretion accretion discs stars: individual: GRS 1915+105 stars: variables ISM: jets and outflows radio continuum: stars X-rays: stars |
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