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    Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47 (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-11-15
    Description: 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 gamma-rays and neutrino emission.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Trigo, Maria Diaz -- Miller-Jones, James C A -- Migliari, Simone -- Broderick, Jess W -- Tzioumis, Tasso -- England -- Nature. 2013 Dec 12;504(7479):260-2. doi: 10.1038/nature12672. Epub 2013 Nov 13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munchen, Germany. ; International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia. ; Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Marti I Franques 1, 08028 Barcelona, Spain. ; School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK. ; Australia Telescope National Facility, CSIRO, PO Box 76, Epping, New South Wales 1710, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24226774" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    X-ray diagnostics of chemical composition of the accretion disc and donor star in UCXBs - II. XMM-Newton observations (2014)
    Oxford University Press
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    Publication Date: 2014-06-29
    Description: We search for the Fe Kα line in spectra of ultra-compact X-ray binaries (UCXBs). For this purpose we have analysed XMM–Newton observations of five confirmed UCXBs. We find that the object 2S 0918–549 – whose optical spectrum bears tentative signatures of a C/O accretion disc – is devoid of any emission features in the 6–7 keV range, with an upper limit of less than 10 eV for the equivalent width (EW) of the Fe line. 4U 1916–05 – whose optical spectrum is consistent with reflection from a He-rich accretion disc – exhibits a bright broad iron emission line. This behaviour is in agreement with the theoretical predictions presented in Koliopanos et al. Namely, we expect strong suppression of the Fe Kα emission line in spectra originating in moderately bright (log L X less than 37.5) UCXBs with C/O- or O/Ne/Mg-rich donors. On the other hand the EW of the Fe line in spectra from UCXBs with He-rich donors is expected to retain its nominal value of 100 eV. Our analysis also reveals a strong Fe Kα line in the spectrum of 4U 0614+091. This detection points towards a He-rich donor and seems to be at odds with the source's classification as C/O rich. Nevertheless, a He-rich donor would explain the bursting activity reported for this system. Lastly, based on our theoretical predictions, we attribute the lack of a strong iron emission line – in the two remaining UCXB sources in our sample (XTE J1807–294 and 4U 0513–40) – as an indication of a C/O or O/Ne/Mg white dwarf donor. From the upper limits of the Fe Kα line EW in 4U 0513–40, 2S 0918–549 and XTE J1807–294 we obtain a lower limit on the oxygen-to-iron ratio, O/Fe ≥ 10[O/Fe] .
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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