Revisiting the relativistic ejection event in XTE J1550−564 during the 1998 outburst |
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| Authors: | D C Hannikainen R W Hunstead K Wu V McIntyre J E J Lovell D Campbell-Wilson M L McCollough J Reynolds A K Tzioumis |
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| Institution: | Metsähovi Radio Observatory, TKK, Metsähovintie 114, FI-02540 Kylmälä, Finland;Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia;Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK;ATNF, CSIRO, PO Box 76, Epping, NSW 1710, Australia;School of Mathematics &Physics, Private Bag 21, University of Tasmania, Hobart TAS 7001, Australia;Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA |
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| Abstract: | We revisit the discovery outburst of the X-ray transient XTE J1550?564 during which relativistic jets were observed in 1998 September, and review the radio images obtained with the Australian Long Baseline Array, and light curves obtained with the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array. Based on H i spectra, we constrain the source distance to between 3.3 and 4.9 kpc. The radio images, taken some 2 d apart, show the evolution of an ejection event. The apparent separation velocity of the two outermost ejecta is at least 1.3 c and may be as large as 1.9 c ; when relativistic effects are taken into account, the inferred true velocity is ≥ 0.8 c . The flux densities appear to peak simultaneously during the outburst, with a rather flat (although still optically thin) spectral index of ?0.2. |
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| Keywords: | stars: individual: XTE J1550?564 radio continuum: stars radio lines: stars X-rays: binaries |
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