Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47.
Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and, hence, the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. Energetic considerations and circular-polarization measurements have provided conflicting circumstantial evidence for the presence or absence of baryons in jets, and the only system in which they have been unequivocally detected is the peculiar X-ray binary SS 433 (refs 4, 5). Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black-hole candidate X-ray binary, 4U 1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise from baryonic matter in a jet travelling at approximately two-thirds the speed of light, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the accretion disk than by the spin of the black hole, and if the baryons can be accelerated to relativistic speeds, the jets should be strong sources of γ-rays and neutrino emission.
European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany.
María Díaz
MD
Trigo
International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
James C A
JC
Miller-Jones
Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Martí I Franquès 1, 08028 Barcelona, Spain.
Simone
S
Migliari
School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK.
Jess W
JW
Broderick
Australia Telescope National Facility, CSIRO, PO Box 76, Epping, New South Wales 1710, Australia.
Tasso
T
Tzioumis