Publications


High Orbital Angular Momentum Harmonic Generation

Physical Review Letters 117 (2016)

J Vieira, RMGM Trines, EP Alves, RA Fonseca, JT Mendonça, R Bingham, P Norreys, LO Silva

© 2016 American Physical Society.We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.


Laboratory analogue of a supersonic accretion column in a binary star system.

Nature communications 7 (2016) ncomms11899-

JE Cross, G Gregori, JM Foster, P Graham, JM Bonnet-Bidaud, C Busschaert, N Charpentier, CN Danson, HW Doyle, RP Drake, J Fyrth, ET Gumbrell, M Koenig, C Krauland, CC Kuranz, B Loupias, C Michaut, M Mouchet, S Patankar, J Skidmore, C Spindloe, ER Tubman, N Woolsey, R Yurchak, É Falize

Astrophysical flows exhibit rich behaviour resulting from the interplay of different forms of energy-gravitational, thermal, magnetic and radiative. For magnetic cataclysmic variable stars, material from a late, main sequence star is pulled onto a highly magnetized (B>10 MG) white dwarf. The magnetic field is sufficiently large to direct the flow as an accretion column onto the poles of the white dwarf, a star subclass known as AM Herculis. A stationary radiative shock is expected to form 100-1,000 km above the surface of the white dwarf, far too small to be resolved with current telescopes. Here we report the results of a laboratory experiment showing the evolution of a reverse shock when both ionization and radiative losses are important. We find that the stand-off position of the shock agrees with radiation hydrodynamic simulations and is consistent, when scaled to AM Herculis star systems, with theoretical predictions.


The prompt atmospheric neutrino flux in the light of LHCb

JOURNAL OF HIGH ENERGY PHYSICS (2016) ARTN 130

R Gauld, J Rojo, L Rottoli, S Sarkar, J Talbert


Raman scattering for intense high orbital angular momentum harmonic generation

2016 Conference on Lasers and Electro-Optics, CLEO 2016 (2016)

J Vieira, RMGM Trines, EP Alves, RA Fonseca, JT Mendonca, R Bingham, P Norreys, LO Silva

© 2016 OSA.We identify a mechanism, based on Raman scattering, to endow near-infrared laser beams with high orders of orbital angular momentum (OAM). In combination with high-harmonic generation, this could lead to very high OAM harmonics in the soft x-ray region.


Model experiment of magnetic field amplification in laser-produced plasmas via the Richtmyer-Meshkov instability

Physics of Plasmas 23 (2016)

Y Kuramitsu, N Ohnishi, Y Sakawa, T Morita, H Tanji, T Ide, K Nishio, CD Gregory, JN Waugh, N Booth, R Heathcote, C Murphy, G Gregori, J Smallcombe, C Barton, A Dizière, M Koenig, N Woolsey, Y Matsumoto, A Mizuta, T Sugiyama, S Matsukiyo, T Moritaka, T Sano, H Takabe

© 2016 AIP Publishing LLC.A model experiment of magnetic field amplification (MFA) via the Richtmyer-Meshkov instability (RMI) in supernova remnants (SNRs) was performed using a high-power laser. In order to account for very-fast acceleration of cosmic rays observed in SNRs, it is considered that the magnetic field has to be amplified by orders of magnitude from its background level. A possible mechanism for the MFA in SNRs is stretching and mixing of the magnetic field via the RMI when shock waves pass through dense molecular clouds in interstellar media. In order to model the astrophysical phenomenon in laboratories, there are three necessary factors for the RMI to be operative: a shock wave, an external magnetic field, and density inhomogeneity. By irradiating a double-foil target with several laser beams with focal spot displacement under influence of an external magnetic field, shock waves were excited and passed through the density inhomogeneity. Radiative hydrodynamic simulations show that the RMI evolves as the density inhomogeneity is shocked, resulting in higher MFA.


THE FIRST COMBINED SEARCH for NEUTRINO POINT-SOURCES in the SOUTHERN HEMISPHERE with the ANTARES and ICECUBE NEUTRINO TELESCOPES

Astrophysical Journal 823 (2016)

S Adrián-Martínez, A Albert, M André, G Anton, M Ardid, JJ Aubert, B Baret, J Barrios-Martí, S Basa, V Bertin, S Biagi, R Bormuth, MC Bouwhuis, R Bruijn, J Brunner, J Busto, A Capone, L Caramete, J Carr, T Chiarusi, M Circella, R Coniglione, H Costantini, P Coyle, A Creusot, I Dekeyser, A Deschamps, G De Bonis, C Distefano, C Donzaud, D Dornic, D Drouhin, A Dumas, T Eberl, D Elsässer, A Enzenhöfer, K Fehn, I Felis, P Fermani, F Folger, LA Fusco, S Galatà, P Gay, S Geißelsöder, K Geyer, V Giordano, A Gleixner, R Gracia-Ruiz, K Graf, S Hallmann, H Van Haren, AJ Heijboer, Y Hello, JJ Hernández-Rey, J Hößl, J Hofestädt, C Hugon, CW James, MD Jong, M Kadler, O Kalekin, U Katz, D Kießling, P Kooijman, A Kouchner, M Kreter, I Kreykenbohm, V Kulikovskiy, R Lahmann, D Lefèvre, E Leonora, S Loucatos, M Marcelin, A Margiotta, A Marinelli, JA Martínez-Mora, A Mathieu, T Michael, P Migliozzi, A Moussa, C Mueller, E Nezri, GE PǍvǍlaş

© 2016. The American Astronomical Society. All rights reserved.We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E -2.5 and E -2 power-law spectra with different energy cut-offs.


Turbulent dynamo in a collisionless plasma.

Proceedings of the National Academy of Sciences of the United States of America 113 (2016) 3950-3953

F Rincon, F Califano, AA Schekochihin, F Valentini

Magnetic fields pervade the entire universe and affect the formation and evolution of astrophysical systems from cosmological to planetary scales. The generation and dynamical amplification of extragalactic magnetic fields through cosmic times (up to microgauss levels reported in nearby galaxy clusters, near equipartition with kinetic energy of plasma motions, and on scales of at least tens of kiloparsecs) are major puzzles largely unconstrained by observations. A dynamo effect converting kinetic flow energy into magnetic energy is often invoked in that context; however, extragalactic plasmas are weakly collisional (as opposed to magnetohydrodynamic fluids), and whether magnetic field growth and sustainment through an efficient turbulent dynamo instability are possible in such plasmas is not established. Fully kinetic numerical simulations of the Vlasov equation in a 6D-phase space necessary to answer this question have, until recently, remained beyond computational capabilities. Here, we show by means of such simulations that magnetic field amplification by dynamo instability does occur in a stochastically driven, nonrelativistic subsonic flow of initially unmagnetized collisionless plasma. We also find that the dynamo self-accelerates and becomes entangled with kinetic instabilities as magnetization increases. The results suggest that such a plasma dynamo may be realizable in laboratory experiments, support the idea that intracluster medium turbulence may have significantly contributed to the amplification of cluster magnetic fields up to near-equipartition levels on a timescale shorter than the Hubble time, and emphasize the crucial role of multiscale kinetic physics in high-energy astrophysical plasmas.


Suppression of phase mixing in drift-kinetic plasma turbulence

Physics of Plasmas 23 (2016)

JT Parker, EG Highcock, AA Schekochihin, PJ Dellar

© 2016 Author(s).Transfer of free energy from large to small velocity-space scales by phase mixing leads to Landau damping in a linear plasma. In a turbulent drift-kinetic plasma, this transfer is statistically nearly canceled by an inverse transfer from small to large velocity-space scales due to "anti-phase-mixing" modes excited by a stochastic form of plasma echo. Fluid moments (density, velocity, and temperature) are thus approximately energetically isolated from the higher moments of the distribution function, so phase mixing is ineffective as a dissipation mechanism when the plasma collisionality is small.


Dynamic X-ray diffraction observation of shocked solid iron up to 170 GPa.

Proc Natl Acad Sci U S A 113 (2016) 7745-7749

A Denoeud, N Ozaki, A Benuzzi-Mounaix, H Uranishi, Y Kondo, R Kodama, E Brambrink, A Ravasio, M Bocoum, JM Boudenne, M Harmand, F Guyot, S Mazevet, D Riley, M Makita, T Sano, Y Sakawa, Y Inubushi, G Gregori, M Koenig, G Morard

Investigation of the iron phase diagram under high pressure and temperature is crucial for the determination of the composition of the cores of rocky planets and for better understanding the generation of planetary magnetic fields. Here we present X-ray diffraction results from laser-driven shock-compressed single-crystal and polycrystalline iron, indicating the presence of solid hexagonal close-packed iron up to pressure of at least 170 GPa along the principal Hugoniot, corresponding to a temperature of 4,150 K. This is confirmed by the agreement between the pressure obtained from the measurement of the iron volume in the sample and the inferred shock strength from velocimetry deductions. Results presented in this study are of the first importance regarding pure Fe phase diagram probed under dynamic compression and can be applied to study conditions that are relevant to Earth and super-Earth cores.


Residual zonal flows in tokamaks and stellarators at arbitrary wavelengths

PLASMA PHYSICS AND CONTROLLED FUSION 58 (2016) ARTN 045018

P Monreal, I Calvo, E Sanchez, FI Parra, A Bustos, A Koenies, R Kleiber, T Goerler


Transport coefficients of a relativistic plasma.

Physical review. E 93 (2016) 053208-

OJ Pike, SJ Rose

In this work, a self-consistent transport theory for a relativistic plasma is developed. Using the notation of Braginskii [S. I. Braginskii, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 174], we provide semianalytical forms of the electrical resistivity, thermoelectric, and thermal conductivity tensors for a Lorentzian plasma in a magnetic field. This treatment is then generalized to plasmas with arbitrary atomic number by numerically solving the linearized Boltzmann equation. The corresponding transport coefficients are fitted by rational functions in order to make them suitable for use in radiation-hydrodynamic simulations and transport calculations. Within the confines of linear transport theory and on the assumption that the plasma is optically thin, our results are valid for temperatures up to a few MeV. By contrast, classical transport theory begins to incur significant errors above k_{B}T∼10 keV, e.g., the parallel thermal conductivity is suppressed by 15% at k_{B}T=20 keV due to relativistic effects.


Sherlock et al. Reply:

Physical Review Letters 116 (2016)

M Sherlock, W Rozmus, EG Hill, SJ Rose


Bursty star formation feedback and cooling outflows

Monthly Notices of the Royal Astronomical Society 462 (2016) 994-1001

T Suarez, A Pontzen, HV Peiris, A Slyz, J Devriendt

© 2016 The Authors.We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circum-galactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disc can be modelled as a rapidly moving bubble of hot gas at ~1 kpc above disc, then ask what happens as it moves out further into the halo around the galaxy on ~100 kpc scales. To do this, we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the 'burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in the CGMmay therefore change in response to the detailed historical pattern of star formation. For instance, outflows generated by star formation with short, intense bursts contain up to 60 per cent of their gas mass at temperatures <5 × 104 K; for near-continuous star formation, the figure is < ≈ 5 per cent. Further study of cosmological simulations, and of idealized simulations with e.g. metal-cooling, magnetic fields and/or thermal conduction, will help to understand the precise signature of bursty outflows on observed ion abundances.


SEARCH for SOURCES of HIGH-ENERGY NEUTRONS with FOUR YEARS of DATA from the ICETOP DETECTOR

Astrophysical Journal 830 (2016)

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, K Andeen, T Anderson, I Ansseau, G Anton, M Archinger, C Argüelles, J Auffenberg, S Axani, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, JB Tjus, KH Becker, S Benzvi, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, S Blot, C Bohm, M Börner, F Bos, D Bose, S Böser, O Botner, J Braun, L Brayeur, HP Bretz, A Burgman, T Carver, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, GH Collin, JM Conrad, DF Cowen, R Cross, M Day, JPAMD André, CD Clercq, EDP Rosendo, H Dembinski, SD Ridder, P Desiati, KDD Vries, GD Wasseige, MD With, T Deyoung, JC Díaz-Vélez, VD Lorenzo, H Dujmovic, JP Dumm, M Dunkman, B Eberhardt, T Ehrhardt, B Eichmann, P Eller, S Euler, PA Evenson, S Fahey, AR Fazely, J Feintzeig, J Felde, K Filimonov, C Finley, S Flis, CC Fösig, A Franckowiak, E Friedman, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, K Ghorbani, W Giang, L Gladstone, M Glagla

© 2016. The American Astronomical Society. All rights reserved..IceTop is an air-shower array located on the Antarctic ice sheet at the geographic South Pole. IceTop can detect an astrophysical flux of neutrons from Galactic sources as an excess of cosmic-ray air showers arriving from the source direction. Neutrons are undeflected by the Galactic magnetic field and can typically travel 10 (E/PeV) pc before decay. Two searches are performed using 4 yr of the IceTop data set to look for a statistically significant excess of events with energies above 10 PeV (1016 eV) arriving within a small solid angle. The all-sky search method covers from -90° to approximately -50° in declination. No significant excess is found. A targeted search is also performed, looking for significant correlation with candidate sources in different target sets. This search uses a higher-energy cut (100 PeV) since most target objects lie beyond 1 kpc. The target sets include pulsars with confirmed TeV energy photon fluxes and high-mass X-ray binaries. No significant correlation is found for any target set. Flux upper limits are determined for both searches, which can constrain Galactic neutron sources and production scenarios.


Ultra-stripped supernovae: progenitors and fate

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 451 (2015) 2123-2144

TM Tauris, N Langer, P Podsiadlowski


Search for features in the spectrum of primordial perturbations using Planck and other datasets

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2015) ARTN 052

P Hunt, S Sarkar


Gas flow in barred potentials - III. Effects of varying the quadrupole

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 454 (2015) 1818-1839

MC Sormani, J Binney, J Magorrian


A detailed study of feedback from a massive star

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 448 (2015) 3248-3264

S Geen, J Rosdahl, J Blaizot, J Devriendt, A Slyz


Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube.

Physical review letters 114 (2015) 171102-

MG Aartsen, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, T Anderson, C Arguelles, TC Arlen, J Auffenberg, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, J Becker Tjus, KH Becker, S BenZvi, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, F Bos, D Bose, S Böser, O Botner, L Brayeur, HP Bretz, AM Brown, N Buzinsky, J Casey, M Casier, E Cheung, D Chirkin, A Christov, B Christy, K Clark, L Classen, F Clevermann, S Coenders, DF Cowen, AH Cruz Silva, J Daughhetee, JC Davis, M Day, JP de André, C De Clercq, H Dembinski, S De Ridder, P Desiati, KD de Vries, M de With, T DeYoung, JC Díaz-Vélez, JP Dumm, M Dunkman, R Eagan, B Eberhardt, T Ehrhardt, B Eichmann, J Eisch, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, J Felde, K Filimonov, C Finley, T Fischer-Wasels, S Flis, K Frantzen, T Fuchs, TK Gaisser, R Gaior, J Gallagher, L Gerhardt, D Gier, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, D Grant, P Gretskov, JC Groh, A Groß, C Ha, C Haack, A Haj Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Hebecker, D Heereman, D Heinen, K Helbing, R Hellauer, D Hellwig, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, F Huang, W Huelsnitz, PO Hulth, K Hultqvist, A Ishihara, E Jacobi, J Jacobsen, GS Japaridze, K Jero, M Jurkovic, B Kaminsky, A Kappes, T Karg, A Karle, M Kauer, A Keivani, JL Kelley, A Kheirandish, J Kiryluk, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, A Koob, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, A Kriesten, K Krings, G Kroll, M Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, JL Lanfranchi, DT Larsen, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Lünemann, J Madsen, G Maggi, R Maruyama, K Mase, HS Matis, R Maunu, F McNally, K Meagher, M Medici, A Meli, T Meures, S Miarecki, E Middell, E Middlemas, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, A Olivas, A Omairat, A O'Murchadha, T Palczewski, L Paul, Ö Penek, JA Pepper, C Pérez de los Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, J Pütz, M Quinnan, L Rädel, M Rameez, K Rawlins, P Redl, I Rees, R Reimann, M Relich, E Resconi, W Rhode, M Richman, B Riedel, S Robertson, JP Rodrigues, M Rongen, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, HG Sander, J Sandroos, M Santander, S Sarkar, K Schatto, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, Y Sestayo, S Seunarine, R Shanidze, MW Smith, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, NA Stanisha, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, NL Strotjohann, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, A Terliuk, G Tešić, S Tilav, PA Toale, MN Tobin, D Tosi, M Tselengidou, E Unger, M Usner, S Vallecorsa, N van Eijndhoven, J Vandenbroucke, J van Santen, S Vanheule, M Vehring, M Voge, M Vraeghe, C Walck, M Wallraff, C Weaver, M Wellons, C Wendt, S Westerhoff, BJ Whelan, N Whitehorn, C Wichary, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, M Zoll

A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fμ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.


Milking the spherical cow - on aspherical dynamics in spherical coordinates

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 451 (2015) 1366-1379

A Pontzen, JI Read, R Teyssier, F Governato, A Gualandris, N Roth, J Devriendt

Pages