Artist impression of the black hole candidate 4U 1630-47 at two different epochs. During the first observation the X-ray emission can be fully described by emission from a standard accretion disc. Image: Riccardo Lanfranchi
During the second observation the appearance of a jet is detected in radio emission and the X-ray spectrum requires an additional component attributed to coronal emission above the disc and three narrow emission lines indicating the presence of Baryons. Image: Riccardo Lanfranchi
“In this work, we have found the composition of relativistic jets launched from around black holes; however, more studies are needed to understand if results can be extrapolated to other relativistic jet sources”, explains Simone Migliari, from the Institute of Sciences of the Cosmos of the UB (ICCUB). According to the researcher, the research proves that relativistic jets might be ‘heavy jets’ containing atomic nuclei, rather than ‘light jets’ consisting of electrons and positrons only”. “The finding —he adds— implies that ‘heavy jets’ carry away significantly more energy from the black hole than ‘lighter’ ones”.
Such baryonic jets, composed by heavy matter, are more likely to be powered by the accretion disc rather than the spin of the black hole. “If baryons can be accelerated to relativistic speeds, these systems should be strong sources of gamma rays and neutrino emission”, concludes Migliari, visiting researcher at the Astrobiology Centre (CAB) of the National Institute for Aerospace Technology (CSIC-INTA).
Black holes in binary systems catch companions’ matter in order to create a disc that rotates around the black hole at high speed. Consequently, matter is compressed and it gets enough hot to emit X-rays. The research also provides an accurate estimate of the speed of the jets, which was found to be 2/3 of the speed of light, by detecting the presence of Fe atomic nuclei in Doppler-shift.
In 2012, observations were done nearly simultaneously by means of two types of facilities: on one hand, the telescopes XMM-Newton of the European Space Agency, which enable to perform X-ray observations in order to observe the disc that surrounds the black hole; and on the other hand, the Australia Telescope Compact Array (ATCA), used to carry out radio observations to see the relativist jet.
Concerning the relevance of the work published on Nature, it is important to highlight that 4U 1630-47 is a common binary system in accreting black holes; therefore, these results can be extrapolated to other similar systems.
Image credits: Riccardo Lanfranchi