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  • 1
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    Synchronous x-ray and radio mode switches: a rapid global transformation of the pulsar magnetosphere (2013)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2013-01-26
    Description: Pulsars emit from low-frequency radio waves up to high-energy gamma-rays, generated anywhere from the stellar surface out to the edge of the magnetosphere. Detecting correlated mode changes across the electromagnetic spectrum is therefore key to understanding the physical relationship among the emission sites. Through simultaneous observations, we detected synchronous switching in the radio and x-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio-"bright" mode, the x-rays show only an unpulsed, nonthermal component. Conversely, when the pulsar is in a radio-"quiet" mode, the x-ray luminosity more than doubles and a 100% pulsed thermal component is observed along with the nonthermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hermsen, W -- Hessels, J W T -- Kuiper, L -- van Leeuwen, J -- Mitra, D -- de Plaa, J -- Rankin, J M -- Stappers, B W -- Wright, G A E -- Basu, R -- Alexov, A -- Coenen, T -- Griessmeier, J-M -- Hassall, T E -- Karastergiou, A -- Keane, E -- Kondratiev, V I -- Kramer, M -- Kuniyoshi, M -- Noutsos, A -- Serylak, M -- Pilia, M -- Sobey, C -- Weltevrede, P -- Zagkouris, K -- Asgekar, A -- Avruch, I M -- Batejat, F -- Bell, M E -- Bell, M R -- Bentum, M J -- Bernardi, G -- Best, P -- Birzan, L -- Bonafede, A -- Breitling, F -- Broderick, J -- Bruggen, M -- Butcher, H R -- Ciardi, B -- Duscha, S -- Eisloffel, J -- Falcke, H -- Fender, R -- Ferrari, C -- Frieswijk, W -- Garrett, M A -- de Gasperin, F -- de Geus, E -- Gunst, A W -- Heald, G -- Hoeft, M -- Horneffer, A -- Iacobelli, M -- Kuper, G -- Maat, P -- Macario, G -- Markoff, S -- McKean, J P -- Mevius, M -- Miller-Jones, J C A -- Morganti, R -- Munk, H -- Orru, E -- Paas, H -- Pandey-Pommier, M -- Pandey, V N -- Pizzo, R -- Polatidis, A G -- Rawlings, S -- Reich, W -- Rottgering, H -- Scaife, A M M -- Schoenmakers, A -- Shulevski, A -- Sluman, J -- Steinmetz, M -- Tagger, M -- Tang, Y -- Tasse, C -- ter Veen, S -- Vermeulen, R -- van de Brink, R H -- van Weeren, R J -- Wijers, R A M J -- Wise, M W -- Wucknitz, O -- Yatawatta, S -- Zarka, P -- New York, N.Y. -- Science. 2013 Jan 25;339(6118):436-9. doi: 10.1126/science.1230960.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands. w.hermsen@sron.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23349288" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
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    An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory (2013)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2013-05-25
    Description: Dwarf novae are white dwarfs accreting matter from a nearby red dwarf companion. Their regular outbursts are explained by a thermal-viscous instability in the accretion disc, described by the disc instability model that has since been successfully extended to other accreting systems. However, the prototypical dwarf nova, SS Cygni, presents a major challenge to our understanding of accretion disc theory. At the distance of 159 +/- 12 parsecs measured by the Hubble Space Telescope, it is too luminous to be undergoing the observed regular outbursts. Using very long baseline interferometric radio observations, we report an accurate, model-independent distance to SS Cygni that places the source substantially closer at 114 +/- 2 parsecs. This reconciles the source behavior with our understanding of accretion disc theory in accreting compact objects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Miller-Jones, J C A -- Sivakoff, G R -- Knigge, C -- Kording, E G -- Templeton, M -- Waagen, E O -- New York, N.Y. -- Science. 2013 May 24;340(6135):950-2. doi: 10.1126/science.1237145.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉International Centre for Radio Astronomy Research, Curtin University, Perth, WA 6845, Australia. james.miller-jones@curtin.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23704566" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
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    Bright radio emission from an ultraluminous stellar-mass microquasar in M 31 (2012)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2012-12-14
    Description: A subset of ultraluminous X-ray sources (those with luminosities of less than 10(40) erg s(-1); ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of approximately 5-20M cicled dot, probably by means of an accretion disk. The X-ray and radio emission are coupled in such Galactic sources; the radio emission originates in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium hinders the determination of the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source in the nearby galaxy M 31, whose peak luminosity exceeded 10(39) erg s(-1). The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a black hole of stellar mass. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Middleton, Matthew J -- Miller-Jones, James C A -- Markoff, Sera -- Fender, Rob -- Henze, Martin -- Hurley-Walker, Natasha -- Scaife, Anna M M -- Roberts, Timothy P -- Walton, Dominic -- Carpenter, John -- Macquart, Jean-Pierre -- Bower, Geoffrey C -- Gurwell, Mark -- Pietsch, Wolfgang -- Haberl, Frank -- Harris, Jonathan -- Daniel, Michael -- Miah, Junayd -- Done, Chris -- Morgan, John S -- Dickinson, Hugh -- Charles, Phil -- Burwitz, Vadim -- Della Valle, Massimo -- Freyberg, Michael -- Greiner, Jochen -- Hernanz, Margarita -- Hartmann, Dieter H -- Hatzidimitriou, Despina -- Riffeser, Arno -- Sala, Gloria -- Seitz, Stella -- Reig, Pablo -- Rau, Arne -- Orio, Marina -- Titterington, David -- Grainge, Keith -- England -- Nature. 2013 Jan 10;493(7431):187-90. doi: 10.1038/nature11697. Epub 2012 Dec 12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physics Department, University of Durham, Durham DH1 3LE, UK. m.j.middleton@durham.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23235823" 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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  • 4
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    Two stellar-mass black holes in the globular cluster M22 (2012)
    Nature Publishing Group (NPG)
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    Publication Date: 2012-10-06
    Description: Hundreds of stellar-mass black holes probably form in a typical globular star cluster, with all but one predicted to be ejected through dynamical interactions. Some observational support for this idea is provided by the lack of X-ray-emitting binary stars comprising one black hole and one other star ('black-hole/X-ray binaries') in Milky Way globular clusters, even though many neutron-star/X-ray binaries are known. Although a few black holes have been seen in globular clusters around other galaxies, the masses of these cannot be determined, and some may be intermediate-mass black holes that form through exotic mechanisms. Here we report the presence of two flat-spectrum radio sources in the Milky Way globular cluster M22, and we argue that these objects are black holes of stellar mass (each approximately 10-20 times more massive than the Sun) that are accreting matter. We find a high ratio of radio-to-X-ray flux for these black holes, consistent with the larger predicted masses of black holes in globular clusters compared to those outside. The identification of two black holes in one cluster shows that ejection of black holes is not as efficient as predicted by most models, and we argue that M22 may contain a total population of approximately 5-100 black holes. The large core radius of M22 could arise from heating produced by the black holes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Strader, Jay -- Chomiuk, Laura -- Maccarone, Thomas J -- Miller-Jones, James C A -- Seth, Anil C -- England -- Nature. 2012 Oct 4;490(7418):71-3. doi: 10.1038/nature11490.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA. strader@pa.msu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23038466" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
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    Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47 (2013)
    Nature Publishing Group (NPG)
    Details
    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
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  • 6
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    A radio jet from the optical and x-ray bright stellar tidal disruption flare ASASSN-14li (2015)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2015-11-28
    Description: The tidal disruption of a star by a supermassive black hole leads to a short-lived thermal flare. Despite extensive searches, radio follow-up observations of known thermal stellar tidal disruption flares (TDFs) have not yet produced a conclusive detection. We present a detection of variable radio emission from a thermal TDF, which we interpret as originating from a newly launched jet. The multiwavelength properties of the source present a natural analogy with accretion-state changes of stellar mass black holes, which suggests that all TDFs could be accompanied by a jet. In the rest frame of the TDF, our radio observations are an order of magnitude more sensitive than nearly all previous upper limits, explaining how these jets, if common, could thus far have escaped detection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉van Velzen, S -- Anderson, G E -- Stone, N C -- Fraser, M -- Wevers, T -- Metzger, B D -- Jonker, P G -- van der Horst, A J -- Staley, T D -- Mendez, A J -- Miller-Jones, J C A -- Hodgkin, S T -- Campbell, H C -- Fender, R P -- New York, N.Y. -- Science. 2016 Jan 1;351(6268):62-5. doi: 10.1126/science.aad1182. Epub 2015 Nov 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA. sjoert@jhu.edu. ; Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK. International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth WA 6845, Australia. ; Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA. ; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK. ; Department of Astrophysics, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands. ; Department of Astrophysics, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands. SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands. ; Department of Physics, The George Washington University, 725 21st Street NW, Washington, DC 20052, USA. ; Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK. ; Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA. ; International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth WA 6845, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26612833" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
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  • 7
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    Rapid compact jet quenching in the Galactic black hole candidate X-ray binary MAXI J1535−571 (2020)
    Oxford University Press
    Details
    Publication Date: 2020-09-01
    Description: We present results from six epochs of quasi-simultaneous radio, (sub-)millimetre, infrared, optical, and X-ray observations of the black hole X-ray binary MAXI J1535−571. These observations show that as the source transitioned through the hard–intermediate X-ray state towards the soft–intermediate X-ray state, the jet underwent dramatic and rapid changes. We observed the frequency of the jet spectral break, which corresponds to the most compact region in the jet where particle acceleration begins (higher frequencies indicate closer to the black hole), evolves from the infrared band into the radio band (decreasing by ≈3 orders of magnitude) in less than a day. During one observational epoch, we found evidence of the jet spectral break evolving in frequency through the radio band. Estimating the magnetic field and size of the particle acceleration region shows that the rapid fading of the high-energy jet emission was not consistent with radiative cooling; instead, the particle acceleration region seems to be moving away from the black hole on approximately dynamical time-scales. This result suggests that the compact jet quenching is not caused by local changes to the particle acceleration, rather we are observing the acceleration region of the jet travelling away from the black hole with the jet flow. Spectral analysis of the X-ray emission shows a gradual softening in the few days before the dramatic jet changes, followed by a more rapid softening ∼1–2 d after the onset of the jet quenching.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 8
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    VLT spectroscopy of the black hole candidate Swift J1357.2-0933 in quiescence (2015)
    Oxford University Press
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    Publication Date: 2015-05-23
    Description: We present time-resolved optical spectroscopy of the counterpart to the high-inclination black hole low-mass X-ray binary Swift J1357.2–0933 in quiescence. Absorption features from the mass donor star were not detected. Instead the spectra display prominent broad double-peaked H α emission and weaker He i emission lines. From the H α peak-to-peak separation, we constrain the radial velocity semi-amplitude of the donor star to K 2  〉 789 km s –1 . Further analysis through radial velocity and equivalent width measurements indicates that the H α line is free of variability due to S-wave components or disc eclipses. From our data and previous observations during outburst, we conclude that long-term radial velocity changes ascribed to a precessing disc were of low amplitude or not present. This implies that the centroid position of the line should closely represent the systemic radial velocity, . Using the derived  = –150 km s –1 and the best available limits on the source distance, we infer that the black hole is moving towards the plane in its current Galactic orbit unless the proper motion is substantial. Finally, the depth of the central absorption in the double-peaked profiles adds support for Swift J1357.2–0933 as a high-inclination system. On the other hand, we argue that the low hydrogen column density inferred from X-ray fitting suggests that the system is not seen edge-on.
    Print ISSN: 0035-8711
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    Topics: Physics
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  • 9
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    Erratum: Disc-jet coupling in the Terzan 5 neutron star X-ray binary EXO 1745-248 (2016)
    Oxford University Press
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    Publication Date: 2016-07-22
    Print ISSN: 0035-8711
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    Topics: Physics
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  • 10
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    Disc reflection and a possible disc wind during a soft X-ray state in the neutron star low-mass X-ray binary 1RXS J180408.9-342058 (2016)
    Oxford University Press
    Details
    Publication Date: 2016-07-29
    Description: 1RXS J180408.9–342058 is a transient neutron star low-mass X-ray binary that exhibited a bright accretion outburst in 2015. We present NuSTAR , Swift , and Chandra observations obtained around the peak brightness of this outburst. The source was in a soft X-ray spectral state and displayed an X-ray luminosity of L X ~= (2–3)  x  10 37 ( D /5.8 kpc) 2 erg s –1 (0.5–10 keV). The NuSTAR data reveal a broad Fe–K emission line that we model as relativistically broadened reflection to constrain the accretion geometry. We found that the accretion disc is viewed at an inclination of i ~= 27°–35° and extended close to the neutron star, down to R in ~= 5–7.5 gravitational radii (~=11–17 km). This inner disc radius suggests that the neutron star magnetic field strength is B 2  x  10 8  G. We find a narrow absorption line in the Chandra /HEG data at an energy of ~=7.64 keV with a significance of ~=4.8. This feature could correspond to blueshifted Fe  xxvi and arise from an accretion disc wind, which would imply an outflow velocity of v out ~= 0.086 c (~=25 800 km s –1 ). However, this would be extreme for an X-ray binary and it is unclear if a disc wind should be visible at the low inclination angle that we infer from our reflection analysis. Finally, we discuss how the X-ray and optical properties of 1RXS J180408.9–342058 are consistent with a relatively small ( P orb 3 h) binary orbit.
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    Topics: Physics
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