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12 results on '"Luke O'c. Drury"'

1. Divergent Perspectives on Expert Disagreement: Preliminary Evidence from Climate Science, Climate Policy, Astrophysics, and Public Opinion

Author

Maria Baghramian, James R. Beebe, Finnur Dellsén, and Luke O'c. Drury

Subjects
Physics - Physics and Society, 010504 meteorology & atmospheric sciences, business.industry, Global warming, Exploratory research, Climate change, Public policy, FOS: Physical sciences, 06 humanities and the arts, Physics and Society (physics.soc-ph), Management, Monitoring, Policy and Law, Environmental Science (miscellaneous), Climate science, 0603 philosophy, ethics and religion, Climate policy, Public opinion, 01 natural sciences, Physics - Atmospheric and Oceanic Physics, Political science, 060302 philosophy, Atmospheric and Oceanic Physics (physics.ao-ph), Regional science, business, 0105 earth and related environmental sciences
Abstract

We report the results of an exploratory study that examines the judgments of climate scientists, climate policy experts, astrophysicists, and non-experts (N = 3,367) about the factors that contribute to the creation and persistence of disagreement within climate science and astrophysics. We found that, as compared to educated non-experts, climate experts believe that there is less disagreement within climate science about climate change and that methodological factors and personal or institutional biases play less significant roles in generating existing disagreements than is commonly reported or assumed. We also found that, commensurate with the greater inherent uncertainty and data lacunae in their field, astrophysicists working on cosmic rays were generally more willing to acknowledge expert disagreement, more open to the idea that a set of data can have multiple valid interpretations, and generally less quick to dismiss someone articulating a non-standard view as non-expert, than climate scientists., Comment: Community peer review solicited

Published
2018
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2. Origin of cosmic rays

Author

Luke O'c. Drury

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Shock wave, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Magnetic field, Particle acceleration, Supernova, Acceleration, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

It is argued that there are three `origins' of cosmic rays; the origin of the particles, the origin of the energy, and the site of the acceleration. The evidence for each origin is discussed and a plausible synthesis outlined for the particles of Galactic origin where the energy comes mainly (but not exclusively) from supernova explosions, the site of the acceleration is at strong collisionless shock waves, and the accelerated particles come from the interstellar and circumstellar material swept over by these shocks. If these shocks are capable (as indicated by recent observations and theoretical work) of significantly amplifying magnetic fields this picture appears capable of explaining the cosmic ray particles at all energies below the `ankle' at $3\times10^{18}\,\rm eV$. The particles above this energy are generally taken to be of extra-galactic origin and possible acceleration sites for these UHE particles are briefly discussed., Comment: Review article to appear in special issue of Astroparticle Physics

Published
2012

3. Power requirements for cosmic ray propagation models involving diffusive reacceleration; estimates and implications for the damping of interstellar turbulence

Author

Andrew W. Strong and Luke O'c. Drury

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, 010308 nuclear & particles physics, Turbulence, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Fermi acceleration, Astrophysics, 01 natural sciences, Power (physics), Interstellar medium, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We make quantitative estimates of the power supplied to the Galactic cosmic ray population by second-order Fermi acceleration in the interstellar medium, or as it is usually termed in cosmic ray propagation studies, diffusive reacceleration. Using recent results on the local interstellar spectrum from the Voyager missions we show that for parameter values, in particular the Alfv\'en speed, typically used in propagation codes such as Galprop to fit the B/C ratio, the power contributed by diffusive reacceleration is significant and can be of order 50\% of the total Galactic cosmic ray power. The implications for the damping of interstellar turbulence are briefly considered., Comment: Accepted by A&A; discussion of LIS added at suggestions of referee, extra references and minor corrections incorporated

Published
2016
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4. FIELD AMPLIFICATION, VORTEX FORMATION, AND ELECTRON ACCELERATION IN A PLASMA PROTOSHOCK: EFFECT OF ASYMMETRIC DENSITY PROFILE

Author

Mark E Dieckmann, Luke O'c. Drury, and G. C. Murphy

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Lorentz transformation, Population, FOS: Physical sciences, Plasma, Electron, Vortex, Magnetic field, symbols.namesake, Astrophysical jet, symbols, Atomic physics, Astrophysics - High Energy Astrophysical Phenomena, education, Lorentz force, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Gamma ray bursts (GRBs) are thought to originate from highly relativistic jets. The fireball model predicts internal shocks in the jets, causing magnetic field to be amplified and particles to be accelerated. We model the effects of an asymmetric density configuration for an internal plasma collision in a quasi-parallel magnetic field. We measured electron acceleration and found that a tenuous population of electrons is accelerated to Lorentz factors of \sim 300 - close to energy equipartition with ions. We found that the filaments did not remain static, but were deflected by the Lorentz force and rolled up into small vortices, which themselves merge to form a larger current vortex., Comment: 4 pages, 5 figures; Procceedings of the workshop "High Energy Phenomena in Relativistic Outflows III" (HEPRO III), Barcelona, June 27 - July 1, 2011

Published
2012

5. Power requirements for cosmic ray propagation models involving re-acceleration and a comment on second-order Fermi acceleration theory

Author

Luke O'c. Drury and Andrew Thornbury

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Heuristic (computer science), Turbulence, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Order (ring theory), Astronomy and Astrophysics, Cosmic ray, Fermi acceleration, Computational physics, Power (physics), Acceleration, Classical mechanics, Space and Planetary Science, Physics::Accelerator Physics, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

We derive an analytic expression for the power transferred from interstellar turbulence to the Galactic cosmic rays in propagation models which include re-acceleration. This is used to estimate the power required in such models and the relative importance of the primary acceleration as against re-acceleration. The analysis provides a formal mathematical justification for Fermi's heuristic account of second order acceleration in his classic 1949 paper., Comment: 3 pages, submitted to MNRAS. some additions as requested by the referee

Published
2014

6. Cosmic-ray diffusive reacceleration: a critical look

Author

Andrew W. Strong and Luke O'c. Drury

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Diffusion (acoustics), Scattering, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Position and momentum space, Cosmic ray, Astrophysics, Space (mathematics), Interstellar medium, Momentum, Supernova, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Cosmic-ray scattering on magnetic turbulence leads to spatial diffusive propagation; if the scattering medium is moving, this will inevitably also cause changes in the momentum of the particles, so-called diffusive reacceleration. This can be described as diffusion in momentum space. Diffusive reacceleration has often been invoked to explain the peak observed in secondary-to-primary ratios at a few GeV, in particular Boron-to-Carbon. This avoids the necessity to postulate an ad-hoc break in the spatial diffusive coefficient, and has become almost a standard in modelling cosmic-ray spectra. However, at the levels invoked, the process implies a significant input of energy from the interstellar medium into cosmic rays, so that in such models interstellar space competes with the usual accelerators like supernova remnants. The questions arise: is reacceleration really occurring at the high level required to explain secondary-to-primary ratios? and are the energy requirements physically plausible? We address this issue using both analytical and numerical models of cosmic-ray propagation., Presented at the ICRC2015 in Den Haag

Published
2015

7. HESS and Fermi-LAT discovery of gamma-rays from the blazar 1ES 1312-423

Author

J. Biteau, Michael Punch, G. Fontaine, Mateusz Janiak, S. J. Fegan, M. Weidinger, Svenja Carrigan, E. Birsin, Gilles Henri, André Schulz, Christian Farnier, G. Lamanna, D. Goering, Dieter Horns, Anna Zajczyk, P. Wagner, K. Dutson, A. Woernlein, Emmanuel Moulin, F. Stinzing, B. Giebels, Alexandre Marcowith, C. L. Naumann, A. A. Zdziarski, M. J. Vorster, A. Jacholkowska, P. Willmann, Michal Dyrda, Thomas Lohse, G. Puehlhofer, T. Garrigoux, Christo Venter, J. Brucker, Gavin Rowell, Dirk Lennarz, R. de los Reyes, Denis Wouters, V. Sahakian, Christoph Deil, Jamie Stevens, M. K. Daniel, Elisabetta Bissaldi, T. Kneiske, J. S. Perkins, S. Haeffner, C. Jahn, U. F. Katz, R. Moderski, A. Zech, Vincent Marandon, D. Klochkov, S. Schwarzburg, H. J. Voelk, P. Espigat, C. Stegmann, Nu. Komin, K. Stycz, F. Schuessler, Tanya Edwards, Luke O'c. Drury, Andreas Quirrenbach, C. Couturier, M. Gajdus, Guillaume Dubus, J. F. Glicenstein, K. Bernloehr, Catherine Boisson, Stefan Ohm, I. Oya, Jacek Niemiec, M. Kieffer, S. Pita, M. Holler, Michael Zacharias, M. Dalton, A. Cheesebrough, Pierre Brun, J. Perez, Philip G. Edwards, Olaf Reimer, S. Schwemmer, Jan Conrad, Matthias Kadler, N. Maxted, Manuel Meyer, J. Dyks, E. de Oña Wilhelmi, A. Reimer, Fabio Acero, Andrea Santangelo, Francois Brun, M. Chrétien, L. Rob, A. Fiasson, D. Fernandez, Matteo Cerruti, M. Panter, M. de Naurois, G. Maurin, Thomas Murach, U. Menzler, F. Krayzel, S. Klepser, Anna Barnacka, B. Khélifi, Roopesh Ojha, G. Hermann, M. A. Kastendieck, Regis Terrier, M. Tluczykont, G. Vasileiadis, M. V. Fernandes, M. Paz Arribas, Francesca Volpe, C. Trichard, M. Fuessling, Werner Hofmann, Michał Ostrowski, P. P. Krueger, F. Feinstein, G. Cologna, C. van Eldik, Jim Hinton, Andreas Hillert, J. D. Hague, M. C. Medina, Y. A. Gallant, H.-S. Zechlin, Felix Jankowsky, Peter Eger, Ullrich Schwanke, C-C Lu, A. Djannati-Ataï, L. Oakes, Henning Gast, M. Renaud, Martin Raue, A. G. Akhperjanian, O. Hervet, R. Steenkamp, I. D. Davids, Iurii Sushch, R. D. Parsons, S. Rosier-Lees, P. deWilt, K. Katarzyński, Marek Jamrozy, M. Mohamed, Helene Sol, J. Harris, Sabrina Casanova, Karl Kosack, Frank M. Rieger, J. Mehault, F. Spiess, S. Raab, A. Abramowski, J.-P. Tavernet, W. Kluzniak, T. J. L. McComb, P-O. Petrucci, B. Peyaud, R. White, S. Colafrancesco, I. Jung, B. Rudak, Kathrin Egberts, P. M. Chadwick, B. Degrange, Marianne Lemoine-Goumard, R. Chalme-Calvet, R. C. G. Chaves, Yvonne Becherini, Anna Szostek, Petter Hofverberg, Aion Viana, B. Opitz, A. Foerster, E. O. Anguener, D. Kolitzus, G. Heinzelmann, J. Bolmont, Guy Pelletier, Alicja Wierzcholska, S. Kaufmann, M. H. Grondin, Helen Poon, A. Lopatin, J.-P. Lenain, Reinhard Schlickeiser, Pol Bordas, Hugh Dickinson, J. Becker Tjus, Daniel Sánchez, M. Grudzińska, N. W. Pekeur, Tomasz Bulik, G. Spengler, S. J. Nolan, Joachim Hahn, W. Domainko, A. Balzer, Stefan Wagner, Gisela Anton, M. Mayer, Cameron B Rulten, S. Balenderan, Felix Aharonian, H. Laffon, K. Valerius, Julien Lefaucheur, D. Nedbal, L. Stawarz, P. Vincent, S. Krakau, Martin Ward, Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), FERMI, Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), APC - Astrophysique des Hautes Energies (APC - AHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), HESS, Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), 10103449 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 12006653 - Venter, Christo, 12792322 - Vorster, Michael Johannes, 24922986 - Sushch, Iurii, 23909196 - Casanova, Sabrina, A., Abramowski, F., Acero, F., Aharonian, A. G., Akhperjanian, E., Anguener, G., Anton, S., Balenderan, A., Balzer, A., Barnacka, Y., Becherini, J. B., Tju, K., Bernloehr, E., Birsin, Bissaldi, Elisabetta, J., Biteau, C., Boisson, J., Bolmont, P., Borda, J., Brucker, F., Brun, P., Brun, T., Bulik, S., Carrigan, S., Casanova, M., Cerruti, P. M., Chadwick, R., Chalme Calvet, R. C., G., A., Cheesebrough, M., Chretien, S., Colafrancesco, G., Cologna, J., Conrad, C., Couturier, M., Dalton, M. K., Daniel, I. D., David, B., Degrange, C., Deil, P., Dewilt, H. J., Dickinson, A., Djannati Atai, W., Domainko, L. O., '., G., Dubu, K., Dutson, J., Dyk, M., Dyrda, T., Edward, K., Egbert, P., Eger, P., Espigat, C., Farnier, S., Fegan, F., Feinstein, M. V., Fernande, D., Fernandez, A., Fiasson, G., Fontaine, A., Foerster, M., Fuessling, M., Gajdu, Y. A., Gallant, T., Garrigoux, H., Gast, B., Giebel, J. F., Glicenstein, D., Goering, M. . ., H., M., Grudzinska, S., Haeffner, J. D., Hague, J., Hahn, J., Harri, G., Heinzelmann, G., Henri, G., Hermann, O., Hervet, A., Hillert, J. A., Hinton, W., Hofmann, P., Hofverberg, M., Holler, D., Horn, A., Jacholkowska, C., Jahn, M., Jamrozy, M., Janiak, F., Jankowsky, I., Jung, M. A., Kastendieck, K., Katarzynski, U., Katz, S., Kaufmann, B., Khelifi, M., Kieffer, S., Klepser, D., Klochkov, W., Kluzniak, T., Kneiske, D., Kolitzu, N., Komin, K., Kosack, S., Krakau, F., Krayzel, P. P., Krueger, H., Laffon, G., Lamanna, J., Lefaucheur, M., Lemoine Goumard, J. . ., P., D., Lennarz, T., Lohse, A., Lopatin, C. . ., C., V., Marandon, A., Marcowith, G., Maurin, N., Maxted, M., Mayer, T. J., L., M. C., Medina, J., Mehault, U., Menzler, M., Meyer, R., Moderski, M., Mohamed, E., Moulin, T., Murach, C. L., Naumann, M. d., Nauroi, D., Nedbal, J., Niemiec, S. J., Nolan, L., Oake, S., Ohm, E. d., Ona, B., Opitz, M., Ostrowski, I., Oya, M., Panter, R. D., Parson, M. P., Arriba, N. W., Pekeur, G., Pelletier, J., Perez, P. . ., O., B., Peyaud, S., Pita, H., Poon, G., Puehlhofer, M., Punch, A., Quirrenbach, S., Raab, M., Raue, A., Reimer, O., Reimer, M., Renaud, R. d., Lo, F., Rieger, L., Rob, S., Rosier Lee, G., Rowell, B., Rudak, C. B., Rulten, V., Sahakian, D. A., Sanchez, A., Santangelo, R., Schlickeiser, F., Schuessler, A., Schulz, U., Schwanke, S., Schwarzburg, S., Schwemmer, H., Sol, G., Spengler, F., Spie, L., Stawarz, R., Steenkamp, C., Stegmann, F., Stinzing, K., Stycz, I., Sushch, A., Szostek, R., Terrier, M., Tluczykont, C., Trichard, K., Valeriu, C. v., Eldik, G., Vasileiadi, C., Venter, A., Viana, P., Vincent, H. J., Voelk, F., Volpe, M., Vorster, S. J., Wagner, P., Wagner, M., Ward, M., Weidinger, R., White, A., Wierzcholska, P., Willmann, A., Woernlein, D., Wouter, M., Zacharia, A., Zajczyk, A. A., Zdziarski, A., Zech, H. . ., S., J. S., Perkin, R., Ojha, J., Steven, P. G., Edward, and M., Kadler

Subjects
[PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], gamma-rays: galaxies, Radio galaxy, BL Lacertae objects: individual: 1ES 1312-423, Astrophysics::High Energy Astrophysical Phenomena, Centaurus A, galaxies: active, jets [galaxies], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, radiation mechanisms: non-thermal, galaxies: jets, 0103 physical sciences, High Energy Stereoscopic System, Blazar, 010303 astronomy & astrophysics, individual: 1ES 1312-423 [BL Lacertae objects], Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, non-thermal [radiation mechanisms], Crab Nebula, galaxies [gamma-rays], jet [galaxies], 13. Climate action, Space and Planetary Science, individual: 1ES 1312–423 [BL Lacertae objects], active [galaxies], ddc:520, Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Bl Lacertae objects: individual: 1ES 1312-423, Galaxies: active, Galaxies: jets, Gamma-rays: galaxies, Radiation mechanisms: non-thermal, Fermi Gamma-ray Space Telescope
Abstract

A deep observation campaign carried out by the High Energy Stereoscopic System (H.E.S.S.) on Centaurus A enabled the discovery of gamma rays from the blazar 1ES 1312-423, two degrees away from the radio galaxy. With a differential flux at 1 TeV of (1.9 +/-0.6(stat) +/-0.4(sys)) x 10^{-13} /cm^2 /s /TeV corresponding to 0.5% of the Crab nebula differential flux and a spectral index of 2.9 +/- 0.5 (stat) +/- 0.2 (sys), 1ES 1312-423 is one of the faintest sources ever detected in the very high energy (E>100 GeV) extragalactic sky. A careful analysis using three and a half years of Fermi-LAT data allows the discovery at high energies (E>100 MeV) of a hard spectrum (index of 1.4 +/- 0.4 (stat) +/- 0.2 (sys)) source coincident with 1ES 1312-423. Radio, optical, UV and X-ray observations complete the spectral energy distribution of this blazar, now covering 16 decades in energy. The emission is successfully fitted with a synchrotron self Compton model for the non-thermal component, combined with a black-body spectrum for the optical emission from the host galaxy., 12 pages, 10 figures, accepted in MNRAS

Published
2013

8. Multidimensional simulations of magnetic field amplification and electron acceleration to near-energy equipartition with ions by a mildly relativistic quasi-parallel plasma collision

Author

Luke O'c. Drury, G. C. Murphy, and Mark E Dieckmann

Subjects
Nuclear and High Energy Physics, Field (physics), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, gamma-ray-bursts, Electron, 01 natural sciences, 7. Clean energy, law.invention, Ion, Fusion, plasma och rymdfysik, symbols.namesake, law, PIC simulation, 0103 physical sciences, plasma shock, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Plasma, Condensed Matter Physics, Fusion, Plasma and Space Physics, Synchrotron, Physics - Plasma Physics, Shock (mechanics), Computational physics, Magnetic field, Plasma Physics (physics.plasm-ph), Lorentz factor, symbols, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The energetic electromagnetic eruptions observed during the prompt phase of gamma-ray bursts are attributed to synchrotron emissions. The internal shocks moving through the ultrarelativistic jet, which is ejected by an imploding supermassive star, are the likely source of this radiation. Synchrotron emissions at the observed strength require the simultaneous presence of powerful magnetic fields and highly relativistic electrons. We explore with one and three-dimensional relativistic particle-in-cell simulations the transition layer of a shock, that evolves out of the collision of two plasma clouds at a speed 0.9c and in the presence of a quasi-parallel magnetic field. The cloud densities vary by a factor of 10. The number densities of ions and electrons in each cloud, which have the mass ratio 250, are equal. The peak Lorentz factor of the electrons is determined in the 1D simulation, as well as the orientation and the strength of the magnetic field at the boundary of the two colliding clouds. The relativistic masses of the electrons and ions close to the shock transition layer are comparable as in previous work. The 3D simulation shows rapid and strong plasma filamentation behind the transient precursor. The magnetic field component orthogonal to the initial field direction is amplified in both simulations to values that exceed those expected from the shock compression by over an order of magnitude. The forming shock is quasi-perpendicular due to this amplification. The simultaneous presence of highly relativistic electrons and strong magnetic fields will give rise to significant synchrotron emissions., 8 pages, 5 figures. This work was presented at 21st International Conference on Numerical Simulation of Plasmas (ICNSP'09). Accepted for publication IEEE Trans. on Plasma Science

Published
2010

9. Particle-in-cell simulation of a mildly relativistic collision of an electron-ion plasma carrying a quasi-parallel magnetic field: Electron acceleration and magnetic field amplification at supernova shocks

Author

Luke O'c. Drury, Athina Meli, G. C. Murphy, and Mark E Dieckmann

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Shock wave, FOS: Physical sciences, Astronomy and Astrophysics, Plasma, Astrophysics, 01 natural sciences, Electromagnetic radiation, Relativistic particle, Magnetic field, Computational physics, Alfvén wave, Particle acceleration, Space and Planetary Science, Physics::Plasma Physics, 0103 physical sciences, Physics::Space Physics, Magnetic cloud, 010306 general physics, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract

Plasma processes close to SNR shocks result in the amplification of magnetic fields and in the acceleration of electrons, injecting them into the diffusive acceleration mechanism. The acceleration of electrons and the B field amplification by the collision of two plasma clouds, each consisting of electrons and ions, at a speed of 0.5c is investigated. A quasi-parallel guiding magnetic field, a cloud density ratio of 10 and a plasma temperature of 25 keV are considered. A quasi-planar shock forms at the front of the dense plasma cloud. It is mediated by a circularly left-hand polarized electromagnetic wave with an electric field component along the guiding magnetic field. Its propagation direction is close to that of the guiding field and orthogonal to the collision boundary. It has a low frequency and a wavelength that equals several times the ion inertial length, which would be indicative of a dispersive Alfven wave close to the ion cyclotron resonance frequency of the left-handed mode (ion whistler), provided that the frequency is appropriate. However, it moves with the super-alfvenic plasma collision speed, suggesting that it is an Alfven precursor or a nonlinear MHD wave such as a Short Large-Amplitude Magnetic Structure (SLAMS). The growth of the magnetic amplitude of this wave to values well in excess of those of the quasi-parallel guiding field and of the filamentation modes results in a quasi-perpendicular shock. We present evidence for the instability of this mode to a four wave interaction. The waves developing upstream of the dense cloud give rise to electron acceleration ahead of the collision boundary. Energy equipartition between the ions and the electrons is established at the shock and the electrons are accelerated to relativistic speeds., 16 pages, 18 figures, Accepted for publication by Astron & Astrophys

Published
2009

10. The puzzling MILAGRO hot spots

Author

Luke O'c. Drury and Felix Aharonian

Subjects
Physics, Magnetic trap, Astrophysics::High Energy Astrophysical Phenomena, Milagro, Astrophysics (astro-ph), Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Ultra-high-energy cosmic ray, Secondary neutron
Abstract

We discuss the reported detection by the MILAGRO experiment of localised hot spots in the cosmic ray arrival distribution and the difficulty of interpreting these observations. A model based on secondary neutron production in the heliotail is shown to fail. An alternative model based on loss-cone leakage through a magnetic trap from a local source region is proposed., Comment: Accepted for publication in Astroparticle physics - reformatted to use journal style and with some minor changes at the request of the referee

Published
2008
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11. HESS observations of the galactic center region and their possible dark matter interpretation

Author

J.F. Glicenstein, L. Costamante, Nu. Komin, A. Djannati-Ataï, P. M. Chadwick, P. Goret, Luke O'c. Drury, A. Noutsos, M. Hauser, O. Bolz, M. de Naurois, A. Konopelko, Catherine Boisson, Wystan Benbow, Michael Punch, L. Rolland, Konrad Bernlöhr, G. Superina, Y. A. Gallant, C. van Eldik, J. L. Osborne, F. Feinstein, V. Borrel, P. Espigat, D. Hauser, M. Beilicke, Werner Hofmann, G. Pelletier, M. Holleran, A. Reimer, S. Schlenker, M. Ouchrif, L.-M. Chounet, S. J. Nolan, S. Pita, R. Cornils, F. Breitling, Dieter Horns, A. Marcowith, I. Büsching, Christo Venter, G. Heinzelmann, Gilles Henri, M. Tluczykont, D. Spangler, C. Stegmann, J. Ripken, L. Saugé, Olaf Reimer, R. Steenkamp, Stefan Funk, Kathrin Egberts, Svenja Carrigan, M. Raue, B. Degrange, Olivier Martineau-Huynh, E. Ferrero, Jean Michel Martin, Anne Lemiere, S. M. Rayner, M. Lemoine-Goumard, G. Vasileiadis, David Berge, A. Jacholkowska, B. Giebels, I. J. Latham, O. C. de Jager, Reinhard Schlickeiser, Ilana M. Braun, Hugh Dickinson, Gerd Pühlhofer, U. Schwanke, Thomas Lohse, M. Panter, B. Khélifi, Stefan Wagner, Regis Terrier, Felix Spanier, B. C. Raubenheimer, German Hermann, Jim Hinton, L. Rob, J.-P. Tavernet, C. Hadjichristidis, Guillaume Dubus, K. J. Orford, G. Fontaine, V. Sahakian, Rolf Bühler, Heinrich J. Völk, A. Fiasson, Gavin Rowell, R. Le Gallou, C. Masterson, Dimitrios Emmanoulopoulos, A. R. Bazer-Bachi, A. G. Akhperjanian, C. G. Théoret, Seb. Funk, A. M. Brown, Helene Sol, Felix Aharonian, Karl Kosack, T. J. L. McComb, P. Vincent, Martin Ward, D. Nedbal, Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), HESS, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Photon, Point source, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Astrophysics::High Energy Astrophysical Phenomena, Dark matter, 98.70.Rz, 95.35.+d, 95.85.Pw, 98.35.Jk, FOS: Physical sciences, General Physics and Astronomy, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Cherenkov radiation, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astrophysics (astro-ph), Galactic Center, Gamma ray, Astronomy, High Energy Physics::Experiment, Gamma-ray burst
Abstract

The detection of gamma-rays from the source HESS J1745-290 in the Galactic Center (GC) region with the H.E.S.S. array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point-source with spatial extent less than 1.2'(stat.) (95% CL). The measured energy spectrum above 160 GeV is compatible with a power-law with photon index of 2.25 +/- 0.04(stat.) +/- 0.10 (syst.) and no significant flux variation is detected. These measurements are discussed in the framework of dark matter annihilation. It is found that the bulk of the VHE emission must have non-dark-matter origin. Loose constraints on the velocity-weighted annihilation cross section are derived assuming the presence of an astrophysical non-dark-matter gamma-ray contribution., Comment: 5 pages, 2 figures, published in Physical Review Letters Correct some references The accepted version set on astro-ph was slightly too long for publication. This is a slightly shorter version

Published
2005

12. Two-dimensional PIC simulations of ion beam instabilities in Supernova-driven plasma flows

Author

Mark E Dieckmann, Athina Meli, Luke O'c. Drury, Padma Kant Shukla, and Apostolos Mastichiadis

Subjects
Physics, Shock (fluid dynamics), Ion beam, Astrophysics (astro-ph), FOS: Physical sciences, Plasma, Astrophysics, Electron, Condensed Matter Physics, Magnetic field, Nuclear Energy and Engineering, Electric field, Magnetic pressure, Atomic physics, Supernova remnant
Abstract

Supernova remnant (SNR) blast shells can reach the flow speed $v_s = 0.1 c$ and shocks form at its front. Instabilities driven by shock-reflected ion beams heat the plasma in the foreshock, which may inject particles into diffusive acceleration. The ion beams can have the speed $v_b \approx v_s$. For $v_b \ll v_s$ the Buneman or upper-hybrid instabilities dominate, while for $v_b \gg v_s$ the filamentation and mixed modes grow faster. Here the relevant waves for $v_b \approx v_s$ are examined and how they interact nonlinearly with the particles. The collision of two plasma clouds at the speed $v_s$ is modelled with particle-in-cell (PIC) simulations, which convect with them magnetic fields oriented perpendicular to their flow velocity vector. One simulation models equally dense clouds and the other one uses a density ratio of 2. Both simulations show upper-hybrid waves that are planar over large spatial intervals and that accelerate electrons to $\sim$ 10 keV. The symmetric collision yields only short oscillatory wave pulses, while the asymmetric collision also produces large-scale electric fields, probably through a magnetic pressure gradient. The large-scale fields destroy the electron phase space holes and they accelerate the ions, which facilitates the formation of a precursor shock., Comment: 15 pages, 11 figures, accepted for publication in Plasma Physics and Controlled Fusion

Published
2008

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