Publications


Energy Reconstruction Methods in the IceCube Neutrino Telescope

ArXiv (2013)

I Collaboration, MG Aartsen, R Abbasi, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, C Arguelles, J Auffenberg, X Bai, M Baker, 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, J Blumenthal, DJ Boersma, C Bohm, D Bose, S Böser, O Botner, L Brayeur, HP Bretz, AM Brown, R Bruijn, J Casey, M Casier, D Chirkin, A Christov, B Christy, K Clark, L Classen, F Clevermann, S Coenders, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, M Day, CD Clercq, SD Ridder, P Desiati, KDD Vries, MD With, T DeYoung, JCD' iaz-Vélez, M Dunkman, R Eagan, B Eberhardt, B Eichmann, J Eisch, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, DT Grandmont, D Grant, P Gretskov, JC Groh, A Groß, C Ha, AH Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Hebecker, D Heereman, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, F Huang, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, S Jackson, E Jacobi, J Jacobsen, K Jagielski, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, M Kauer, JL Kelley, J Kiryluk, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, A Kriesten, K Krings, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leute, J Lünemann, O Macías, J Madsen, G Maggi, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, A Omairat, A O'Murchadha, L Paul, JA Pepper, CPDL Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, M Quinnan, L Rädel, M Rameez, K Rawlins, P Redl, R Reimann, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, S Robertson, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, HG Sander, 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, C Sheremata, MWE 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, A Tepe, S Ter-Antonyan, G Tešić, S Tilav, PA Toale, MN Tobin, S Toscano, M Tselengidou, E Unger, M Usner, S Vallecorsa, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, C Weaver, M Wellons, C Wendt, S Westerhoff, B Whelan, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, M Zoll

Accurate measurement of neutrino energies is essential to many of the scientific goals of large-volume neutrino telescopes. The fundamental observable in such detectors is the Cherenkov light produced by the transit through a medium of charged particles created in neutrino interactions. The amount of light emitted is proportional to the deposited energy, which is approximately equal to the neutrino energy for $\nu_e$ and $\nu_\mu$ charged-current interactions and can be used to set a lower bound on neutrino energies and to measure neutrino spectra statistically in other channels. Here we describe methods and performance of reconstructing charged-particle energies and topologies from the observed Cherenkov light yield, including techniques to measure the energies of uncontained muon tracks, achieving average uncertainties in electromagnetic-equivalent deposited energy of $\sim 15\%$ above 10 TeV.


Radiative shocks produced from spherical cryogenic implosions at the National Ignition Facility

Physics of Plasmas 20 (2013)

A Pak, L Divol, G Gregori, S Weber, J Atherton, R Bennedetti, DK Bradley, D Callahan, DT Casey, E Dewald, T Döppner, MJ Edwards, JA Frenje, S Glenn, GP Grim, D Hicks, WW Hsing, N Izumi, OS Jones, MG Johnson, SF Khan, JD Kilkenny, JL Kline, GA Kyrala, J Lindl, OL Landen, S Le Pape, T Ma, A Macphee, BJ Macgowan, AJ Mackinnon, L Masse, NB Meezan, JD Moody, RE Olson, JE Ralph, HF Robey, H-S Park, BA Remington, JS Ross, R Tommasini, RPJ Town, V Smalyuk, SH Glenzer, EI Moses

Spherically expanding radiative shock waves have been observed from inertially confined implosion experiments at the National Ignition Facility. In these experiments, a spherical fusion target, initially 2 mm in diameter, is compressed via the pressure induced from the ablation of the outer target surface. At the peak compression of the capsule, x-ray and nuclear diagnostics indicate the formation of a central core, with a radius and ion temperature of ∼20 μm and ∼ 2 keV, respectively. This central core is surrounded by a cooler compressed shell of deuterium-tritium fuel that has an outer radius of ∼40 μm and a density of >500 g/cm3. Using inputs from multiple diagnostics, the peak pressure of the compressed core has been inferred to be of order 100 Gbar for the implosions discussed here. The shock front, initially located at the interface between the high pressure compressed fuel shell and surrounding in-falling low pressure ablator plasma, begins to propagate outwards after peak compression has been reached. Approximately 200 ps after peak compression, a ring of x-ray emission created by the limb-brightening of a spherical shell of shock-heated matter is observed to appear at a radius of ∼100 μm. Hydrodynamic simulations, which model the experiment and include radiation transport, indicate that the sudden appearance of this emission occurs as the post-shock material temperature increases and upstream density decreases, over a scale length of ∼10 μm, as the shock propagates into the lower density (∼1 g/cc), hot (∼250 eV) plasma that exists at the ablation front. The expansion of the shock-heated matter is temporally and spatially resolved and indicates a shock expansion velocity of ∼300 km/s in the laboratory frame. The magnitude and temporal evolution of the luminosity produced from the shock-heated matter was measured at photon energies between 5.9 and 12.4 keV. The observed radial shock expansion, as well as the magnitude and temporal evolution of the luminosity from the shock-heated matter, is consistent with 1-D radiation hydrodynamic simulations. Analytic estimates indicate that the radiation energy flux from the shock-heated matter is of the same order as the in-flowing material energy flux, and suggests that this radiation energy flux modifies the shock front structure. Simulations support these estimates and show the formation of a radiative shock, with a precursor that raises the temperature ahead of the shock front, a sharp μ m-scale thick spike in temperature at the shock front, followed by a post-shock cooling layer. © 2013 AIP Publishing LLC.


Simulation of X-ray scattering diagnostics in multi-dimensional plasma

High Energy Density Physics 9 (2013) 510-515

I Golovkin, JJ MacFarlane, P Woodruff, I Hall, G Gregori, J Bailey, E Harding, T Ao, S Glenzer

X-ray scattering is a powerful diagnostic technique that has been used in a variety of experimental settings to determine the temperature, density, and ionization state of warm dense matter. In order to maximize the intensity of the scattered signal, the x-ray source is often placed in close proximity to the target plasma. Therefore, the interpretation of the experimental data can become complicated by the fact that the detector records photons scattered at different angles from points within the plasma volume. In addition, the target plasma that is scattering the x-rays can have significant temperature and density gradients. To address these issues, we have developed the capability to simulate x-ray scattering for realistic experimental configurations where the effects of plasma non-uniformities and a range of x-ray scattering angles are included. We will discuss the implementation details and show results relevant to previous and ongoing experimental investigations. © 2013 Elsevier B.V.


The wobbly Galaxy: Kinematics north and south with RAVE red-clump giants

Monthly Notices of the Royal Astronomical Society 436 (2013) 101-121

MEK Williams, M Steinmetz, J Binney, A Siebert, H Enke, B Famaey, I Minchev, RS de Jong, C Boeche, KC Freeman, O Bienaymé, J Bland-Hawthorn, BK Gibson, GF Gilmore, EK Grebel, A Helmi, G Kordopatis, U Munari, JF Navarro, QA Parker, W Reid, GM Seabroke, S Sharma, A Siviero, FG Watson, RFG Wyse, T Zwitter

TheRAdialVelocity Experiment survey, combined with proper motions and distance estimates, can be used to study in detail stellar kinematics in the extended solar neighbourhood (solar suburb). Using 72 365 red-clump stars, we examine the mean velocity components in 3D between 6 < R < 10 kpc and -2 < Z < 2 kpc, concentrating on north-south differences. Simple parametric fits to the (R, Z) trends for Vφ and the velocity dispersions are presented. We confirm the recently discovered gradient in mean Galactocentric radial velocity, VR, finding that the gradient is marked below the plane (δ(VR)/δR=-8 kms-1 kpc-1 for Z<0, vanishing to zero above the plane), with a Z gradient thus also present. The vertical velocity, VZ, also shows clear, large-amplitude (|VZ| = 17 km s-1) structure, with indications of a rarefaction- compression pattern, suggestive of wave-like behaviour. We perform a rigorous error analysis, tracing sources of both systematic and random errors. We confirm the north-south differences in VR and VZ along the line of sight, with the VR estimated independent of the proper motions. The complex three-dimensional structure of velocity space presents challenges for future modelling of the Galactic disc, with the Galactic bar, spiral arms and excitation of wave-like structures all probably playing a role. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Plasmoid and Kelvin-Helmholtz instabilities in Sweet-Parker current sheets

ArXiv (2012)

NF Loureiro, AA Schekochihin, DA Uzdensky

A 2D linear theory of the instability of Sweet-Parker (SP) current sheets is developed in the framework of Reduced MHD. A local analysis is performed taking into account the dependence of a generic equilibrium profile on the outflow coordinate. The plasmoid instability [Loureiro et al, Phys. Plasmas {\bf 14}, 100703 (2007)] is recovered, i.e., current sheets are unstable to the formation of a large-wave-number chain of plasmoids ($k_{\rm max}\Lsheet \sim S^{3/8}$, where $k_{\rm max}$ is the wave-number of fastest growing mode, $S=\Lsheet V_A/\eta$ is the Lundquist number, $\Lsheet$ is the length of the sheet, $V_A$ is the Alfv\'en speed and $\eta$ is the plasma resistivity), which grows super-Alfv\'enically fast ($\gmax\tau_A\sim S^{1/4}$, where $\gmax$ is the maximum growth rate, and $\tau_A=\Lsheet/V_A$). For typical background profiles, the growth rate and the wave-number are found to {\it increase} in the outflow direction. This is due to the presence of another mode, the Kelvin-Helmholtz (KH) instability, which is triggered at the periphery of the layer, where the outflow velocity exceeds the Alfv\'en speed associated with the upstream magnetic field. The KH instability grows even faster than the plasmoid instability, $\gmax \tau_A \sim k_{\rm max} \Lsheet\sim S^{1/2}$. The effect of viscosity ($\nu$) on the plasmoid instability is also addressed. In the limit of large magnetic Prandtl numbers, $Pm=\nu/\eta$, it is found that $\gmax\sim S^{1/4}Pm^{-5/8}$ and $k_{\rm max} \Lsheet\sim S^{3/8}Pm^{-3/16}$, leading to the prediction that the critical Lundquist number for plasmoid instability in the $Pm\gg1$ regime is $\Scrit\sim 10^4Pm^{1/2}$. These results are verified via direct numerical simulation of the linearized equations, using a new, analytical 2D SP equilibrium solution.


IceCube search for dark matter annihilation in nearby galaxies and galaxy clusters

Physical Review D - Particles, Fields, Gravitation and Cosmology 88 (2013)

MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, JJ Beatty, S Bechet, J Becker Tjus, K-H Becker, ML Benabderrahmane, S Benzvi, P Berghaus, D Berley, E Bernardini, A Bernhard, D Bertrand, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose, S Böser, O Botner, L Brayeur, H-P Bretz, AM Brown, R Bruijn, J Brunner, M Carson, J Casey, M Casier, D Chirkin, A Christov, B Christy, K Clark, F Clevermann, S Coenders, S Cohen, DF Cowen, AH Cruz Silva, M Danninger, J Daughhetee, JC Davis, M Day, C De Clercq, S De Ridder, P Desiati, KD De Vries, M De With, T Deyoung, JC Díaz-Vélez, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, DT Grandmont, D Grant, A Groß, C Ha, A Haj Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Heereman, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, K Jagielski, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, JL Kelley, J Kiryluk, J Kläs, SR Klein, J-H Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, K Krings, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leute, J Lünemann, O Macías, J Madsen, G Maggi, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, A Omairat, A O'Murchadha, L Paul, JA Pepper, C Pérez De Los Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, L Rädel, M Rameez, K Rawlins, P Redl, R Reimann, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, H-G Sander, 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, C Sheremata, MWE Smith, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, A Tepe, S Ter-Antonyan, G Tešić, S Tilav, PA Toale, S Toscano, E Unger, M Usner, S Vallecorsa, N Van Eijndhoven, A Van Overloop, J Van Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, C Weaver, M Wellons, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, M Zoll

We present the results of a first search for self-annihilating dark matter in nearby galaxies and galaxy clusters using a sample of high-energy neutrinos acquired in 339.8 days of live time during 2009/10 with the IceCube neutrino observatory in its 59-string configuration. The targets of interest include the Virgo and Coma galaxy clusters, the Andromeda galaxy, and several dwarf galaxies. We obtain upper limits on the cross section as a function of the weakly interacting massive particle mass between 300 GeV and 100 TeV for the annihilation into bb̄, W+W-, τ+τ -, μ+μ-, and νν̄. A limit derived for the Virgo cluster, when assuming a large effect from subhalos, challenges the weakly interacting massive particle interpretation of a recently observed GeV positron excess in cosmic rays. © 2013 American Physical Society.


Searches for high-energy neutrino emission in the Galaxy with the combined IceCube-AMANDA detector

ArXiv (2012)

I collaboration, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, K Andeen, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, K Beattie, JJ Beatty, S Bechet, JB Tjus, KH Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, D Bertrand, DZ Besson, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, D Bose, S Böser, O Botner, L Brayeur, AM Brown, R Bruijn, J Brunner, S Buitink, M Carson, J Casey, M Casier, D Chirkin, B Christy, F Clevermann, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, F Descamps, P Desiati, GDV Uiterweerd, T DeYoung, JC Díaz-Vélez, J Dreyer, JP Dumm, M Dunkman, R Eagan, J Eisch, RW Ellsworth, O Engdegård, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, JA Goodman, D Góra, D Grant, A Groß, S Grullon, M Gurtner, C Ha, AH Ismail, A Hallgren, F Halzen, K Hanson, D Heereman, P Heimann, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, GS Japaridze, O Jlelati, A Kappes, T Karg, A Karle, J Kiryluk, F Kislat, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, K Laihem, H Landsman, MJ Larson, R Lauer, M Lesiak-Bzdak, J Lünemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, SM Movit, R Nahnhauer, U Naumann, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, S Panknin, L Paul, JA Pepper, CPDL Heros, D Pieloth, N Pirk, J Posselt, PB Price, GT Przybylski, L Rädel, K Rawlins, P Redl, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, F Rothmaier, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, HG Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, L Schönherr, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, SH Seo, Y Sestayo, S Seunarine, MWE Smith, M Soiron, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, C Walck, T Waldenmaier, M Wallraff, M Walter, R Wasserman, C Weaver, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, A Zilles, M Zoll

We report on searches for neutrino sources at energies above 200 GeV in the Northern sky of the galactic plane, using the data collected by the South Pole neutrino telescopes IceCube and AMANDA. The galactic region considered here includes the Local Arm towards the Cygnus region and our closest approach to the Perseus Arm. The data have been collected between 2007 and 2009 when AMANDA was an integrated part of IceCube, which was still under construction and operated with 22-strings (2007-8) and 40-strings (2008-9) of optical modules deployed in the ice. By combining the larger IceCube detector with the lower energy threshold of the more compact AMANDA detector, we obtain an improved sensitivity at energies below $\sim$10 TeV with respect to previous searches. The analyses presented here are: a scan for point sources within the galactic plane; a search optimized for multiple and extended sources in the Cygnus region, which might be below the sensitivity of the point source scan; and studies of seven pre-selected neutrino source candidates. For one of them, Cygnus X-3, a time-dependent search for neutrinos in coincidence with observed radio and X-ray flares has been performed. No evidence of a signal is found, and upper limits are reported for each of the searches. We investigate neutrino spectra proportional to E$^{-2}$ and E$^{-3}$ to cover the entire range of possible spectra. The soft E$^{-3}$ spectrum results in an energy distribution similar to a source with cut-off below $\sim$50 TeV. For the considered region of the galactic plane, the 90% confidence level muon neutrino flux upper limits are in the range E$^3$dN/dE$\sim 5.4 - 19.5 \times 10^{-11} \rm{TeV^{2} cm^{-2} s^{-1}}$ for point-like neutrino sources in the energy region [180.0 GeV - 20.5 TeV]. These represent the most stringent upper limits for soft-spectra neutrino sources within the Galaxy reported to date.


Pair plasma cushions in the hole-boring scenario

Plasma Physics and Controlled Fusion 55 (2013)

JG Kirk, AR Bell, CP Ridgers

Pulses from a 10 PW laser are predicted to produce large numbers of gamma-rays and electron-positron pairs on hitting a solid target. However, a pair plasma, if it accumulates in front of the target, may partially shield it from the pulse. Using stationary, one-dimensional solutions of the two-fluid (electron-positron) and Maxwell equations, including a classical radiation reaction term, we examine this effect in the hole-boring scenario. We find the collective effects of a pair plasma 'cushion' substantially reduce the reflectivity, converting the absorbed flux into high-energy gamma-rays. There is also a modest increase in the laser intensity needed to achieve threshold for a non-linear pair cascade. © 2013 IOP Publishing Ltd.


Search for Relativistic Magnetic Monopoles with IceCube

ArXiv (2012)

I Collaboration, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, K Andeen, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, K Beattie, JJ Beatty, S Bechet, JB Tjus, KH Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, D Bertrand, DZ Besson, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, D Bose, S Böser, O Botner, L Brayeur, AM Brown, R Bruijn, J Brunner, S Buitink, M Carson, J Casey, M Casier, D Chirkin, B Christy, F Clevermann, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, F Descamps, P Desiati, GD Vries-Uiterweerd, T DeYoung, JC Díaz-Vélez, J Dreyer, JP Dumm, M Dunkman, R Eagan, J Eisch, RW Ellsworth, O Engdegård, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, JA Goodman, D Góra, D Grant, A Groß, S Grullon, M Gurtner, C Ha, AH Ismail, A Hallgren, F Halzen, K Hanson, D Heereman, P Heimann, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, GS Japaridze, O Jlelati, A Kappes, T Karg, A Karle, J Kiryluk, F Kislat, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, K Laihem, H Landsman, MJ Larson, R Lauer, M Lesiak-Bzdak, J Lünemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, SM Movit, R Nahnhauer, U Naumann, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, S Panknin, L Paul, JA Pepper, CPDL Heros, D Pieloth, N Pirk, J Posselt, PB Price, GT Przybylski, L Rädel, K Rawlins, P Redl, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, F Rothmaier, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, HG Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, L Schönherr, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, SH Seo, Y Sestayo, S Seunarine, MWE Smith, M Soiron, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, C Walck, T Waldenmaier, M Wallraff, M Walter, R Wasserman, C Weaver, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, A Zilles, M Zoll

We present the first results in the search for relativistic magnetic monopoles with the IceCube detector, a subsurface neutrino telescope located in the South Polar ice cap containing a volume of 1 km$^{3}$. This analysis searches data taken on the partially completed detector during 2007 when roughly 0.2 km$^{3}$ of ice was instrumented. The lack of candidate events leads to an upper limit on the flux of relativistic magnetic monopoles of $\Phi_{\mathrm{90%C.L.}}\sim 3\e{-18}\fluxunits$ for $\beta\geq0.8$. This is a factor of 4 improvement over the previous best experimental flux limits up to a Lorentz boost $\gamma$ below $10^{7}$. This result is then interpreted for a wide range of mass and kinetic energy values.


Measurement of the Atmospheric $ν_e$ flux in IceCube

ArXiv (2012)

I Collaboration, MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, K Andeen, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, K Beattie, JJ Beatty, S Bechet, JB Tjus, KH Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, D Bertrand, DZ Besson, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose1, S Boser, O Botner, L Brayeur, AM Brown, R Bruijn, J Brunner, S Buitink, M Carson, J Casey, M Casier, D Chirkin, B Christy, K Clark, F Clevermann, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, SD Ridder, F Descamps, P Desiati, GD Vries-Uiterweerd, T DeYoung, JC Diaz-Velez, J Dreyer, JP Dumm, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, O Engdegard, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glusenkamp, A Goldschmidt, G Golup, JA Goodman, D Gora, D Grant, A Gross, S Grullon, M Gurtner, C Ha, AH Ismail, A Hallgren, F Halzen, K Hanson, D Heereman, P Heimann, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, GS Japaridze, O Jlelati, A Kappes, T Karg, A Karle, J Kiryluk, F Kislat, J Klas, SR Klein, JH Kohne, G Kohnen, H Kolanoski, L Kopke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, R Lauer, M Lesiak-Bzdak, J Lunemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Meszaros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, S Panknin, L Paul, JA Pepper, CPDL Heros, D Pieloth, N Pirk, J Posselt, PB Price, GT Przybylski, L Radel, K Rawlins, P Redl, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, HG Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schoneberg, L Schonherr, A Schonwald, A Schukraft, L Schulte, O Schulz, D Seckel, SH Seo, Y Sestayo, S Seunarine, C Sheremata, MWE Smith, M Soiron, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stoss, EA Strahler, R Strom, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge1, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, M Walter, R Wasserman, C Weaver, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, A Zilles, M Zoll

We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube's DeepCore low energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496 $\pm$ 66(stat.) $\pm$ 88(syst.) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.


The IceCube Neutrino Observatory Part VI: Ice Properties, Reconstruction and Future Developments

ArXiv (2013)

I Collaboration, MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, JJ Beatty, S Bechet, JB Tjus, KH Becker, M Bell, ML Benabderrahmane, S BenZvi, P Berghaus, D Berley, E Bernardini, A Bernhard, D Bertrand, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose, S Böser, O Botner, L Brayeur, HP Bretz, AM Brown, R Bruijn, J Brunner, M Carson, J Casey, M Casier, D Chirkin, A Christov, B Christy, K Clark, F Clevermann, S Coenders, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, SD Ridder, P Desiati, KDD Vries, MD With, T DeYoung, JC Díaz-Vélez, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, DT Grandmont, D Grant, A Groß, C Ha, AH Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Heereman, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, K Jagielski, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, JL Kelley, J Kiryluk, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, K Krings, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leute, J Lünemann, J Madsen, G Maggi, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, L Paul, JA Pepper, CPDL Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, L Rädel, M Rameez, K Rawlins, P Redl, R Reimann, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, HG Sander, M Santander, S Sarkar, K Schatto, M Scheel, 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, C Sheremata, MWE Smith, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, A Tepe, S Ter-Antonyan, G Tešić, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, R Wasserman, C Weaver, M Wellons, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, M Zoll

Papers on ice properties, reconstruction and future developments submitted to the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013) by the IceCube Collaboration.


Measurement of South Pole ice transparency with the IceCube LED calibration system

ArXiv (2013)

I Collaboration, MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, JJ Beatty, S Bechet, JB Tjus, KH Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, A Bernhard, D Bertrand, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose, S Böser, O Botner, L Brayeur, AM Brown, R Bruijn, J Brunner, S Buitink, M Carson, J Casey, M Casier, D Chirkin, B Christy, K Clark, F Clevermann, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, SD Ridder, P Desiati, MD With, T DeYoung, JC Díaz-Vélez, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JA Goodman, D Góra, D Grant, A Groß, M Gurtner, C Ha, AH Ismail, A Hallgren, F Halzen, K Hanson, D Heereman, P Heimann, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, JL Kelley, J Kiryluk, F Kislat, J Kläs, SR Klein, JH Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, J Leute, J Lünemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, L Paul, JA Pepper, CPDL Heros, C Pfendner, D Pieloth, N Pirk, J Posselt, PB Price, GT Przybylski, L Rädel, K Rawlins, P Redl, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, HG Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, L Schönherr, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, SH Seo, Y Sestayo, S Seunarine, C Sheremata, MWE Smith, M Soiron, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, R Wasserman, C Weaver, M Wellons, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, A Zilles, M Zoll

The IceCube Neutrino Observatory, approximately 1 km^3 in size, is now complete with 86 strings deployed in the Antarctic ice. IceCube detects the Cherenkov radiation emitted by charged particles passing through or created in the ice. To realize the full potential of the detector, the properties of light propagation in the ice in and around the detector must be well understood. This report presents a new method of fitting the model of light propagation in the ice to a data set of in-situ light source events collected with IceCube. The resulting set of derived parameters, namely the measured values of scattering and absorption coefficients vs. depth, is presented and a comparison of IceCube data with simulations based on the new model is shown.


Simulation of laser-driven, ablated plasma flows in collisionless shock experiments on OMEGA and the NIF

High Energy Density Physics 9 (2013) 192-197

MJ Grosskopf, RP Drake, CC Kuranz, EM Rutter, JS Ross, NL Kugland, C Plechaty, BA Remington, A Spitkovsky, L Gargate, G Gregori, A Bell, CD Murphy, J Meinecke, B Reville, Y Sakawa, Y Kuramitsu, H Takabe, DH Froula, G Fiksel, F Miniati, M Koenig, A Ravasio, E Liang, W Fu, N Woolsey, H-S Park

Experiments investigating the physics of interpenetrating, collisionless, ablated plasma flows have become an important area of research in the high-energy-density field. In order to evaluate the feasibility of designing experiments that will generate a collisionless shock mediated by the Weibel instability on the National Ignition Facility (NIF) laser, computer simulations using the Center for Radiative Shock Hydrodynamics (CRASH) radiation-hydrodynamics model have been carried out. This paper reports assessment of whether the experiment can reach the required scale size while maintaining the low interflow collisionality necessary for the collisionless shock to form. Comparison of simulation results with data from Omega experiments shows the ability of the CRASH code to model these ablated systems. The combined results indicate that experiments on the NIF are capable of reaching the regimes necessary for the formation of a collisionless shock in a laboratory experiment. © 2013.


Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers

EPJ Web of Conferences 59 (2013)

H Shiraga, S Fujioka, M Nakai, T Watari, H Nakamura, Y Arikawa, H Hosoda, T Nagai, M Koga, H Kikuchi, Y Ishii, T Sogo, K Shigemori, H Nishimura, Z Zhang, M Tanabe, S Ohira, Y Fujii, T Namimoto, Y Sakawa, O Maegawa, T Ozaki, KA Tanaka, H Habara, T Iwawaki, K Shimada, M Key, P Norreys, J Pasley, H Nagatomo, T Johzaki, A Sunahara, M Murakami, H Sakagami, T Taguchi, T Norimatsu, H Homma, Y Fujimoto, A Iwamoto, N Miyanaga, J Kawanaka, T Kanabe, T Jitsuno, Y Nakata, K Tsubakimoto, K Sueda, R Kodama, K Kondo, N Morio, S Matsuo, T Kawasaki, K Sawai, K Tsuji, H Murakami, N Sarukura, T Shimizu, K Mima, H Azechi

The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53- μm Gekko-XII, and the 1.053- μm beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (γ rays) and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (γ,n) reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 × 107 was observed. Heating efficiency was estimated to be 10-20% assuming a uniform temperature rise model. © Owned by the authors, published by EDP Sciences, 2013.


Cosmological growth and feedback from supermassive black holes

ArXiv (2013)

P Mocz, KM Blundell, AC Fabian

We develop a simple evolutionary scenario for the growth of supermassive black holes (BHs), assuming growth due to accretion only, to learn about the evolution of the BH mass function from $z=3$ to 0 and from it calculate the energy budgets of different modes of feedback. We tune the parameters of the model by matching the derived X-ray luminosity function (XLF) with the observed XLF of active galactic nuclei. We then calculate the amount of comoving kinetic and bolometric feedback as a function of redshift, derive a kinetic luminosity function and estimate the amount of kinetic feedback and $PdV$ work done by classical double Fanaroff-Riley II (FR II) radio sources. We also derive the radio luminosity function for FR IIs from our synthesized population and set constraints on jet duty cycles. Around 1/6 of the jet power from FR II sources goes into $PdV$ work done in the expanding lobes during the time the jet is on. Anti hierarchical growth of BHs is seen in our model due to addition of an amount of mass being accreted on to all BHs independent of the BH mass. The contribution to the total kinetic feedback by active galaxies in a low accretion, kinetically efficient mode is found to be the most significant at $z<1.5$. FR II feedback is found to be a significant mode of feedback above redshifts $z\sim 1.5$, which has not been highlighted by previous studies.


Blowing cold flows away: the impact of early AGN activity on the formation of a brightest cluster galaxy progenitor

ArXiv (2012)

Y Dubois, C Pichon, J Devriendt, J Silk, M Haehnelt, T Kimm, A Slyz

Supermassive black holes (BH) are powerful sources of energy that are already in place at very early epochs of the Universe (by z=6). Using hydrodynamical simulations of the formation of a massive M_vir=5 10^11 M_sun halo by z=6 (the most massive progenitor of a cluster of M_vir=2 10^15 M_sun at z=0), we evaluate the impact of Active Galactic Nuclei (AGN) on galaxy mass content, BH self-regulation, and gas distribution inside this massive halo. We find that SN feedback has a marginal influence on the stellar structure, and no influence on the mass distribution on large scales. In contrast, AGN feedback alone is able to significantly alter the stellar-bulge mass content by quenching star formation when the BH is self-regulating, and by depleting the cold gas reservoir in the centre of the galaxy. The growth of the BH proceeds first by a rapid Eddington-limited period fed by direct cold filamentary infall. When the energy delivered by the AGN is sufficiently large to unbind the cold gas of the bulge, the accretion of gas onto the BH is maintained both by smooth gas inflow and clump migration through the galactic disc triggered by merger-induced torques. The feedback from the AGN has also a severe consequence on the baryon mass content within the halo, producing large-scale hot superwinds, able to blow away some of the cold filamentary material from the centre and reduce the baryon fraction by more than 30 per cent within the halo's virial radius. Thus in the very young universe, AGN feedback is likely to be a key process, shaping the properties of the most massive galaxies.


Numerical modeling of the sensitivity of x-ray driven implosions to low-mode flux asymmetries

Physical Review Letters 110 (2013)

RHH Scott, DS Clark, DK Bradley, DA Callahan, MJ Edwards, SW Haan, OS Jones, BK Spears, MM Marinak, RPJ Town, PA Norreys, LJ Suter

The sensitivity of inertial confinement fusion implosions, of the type performed on the National Ignition Facility (NIF), to low-mode flux asymmetries is investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P4), resulting from low-order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the deuterium and tritium (DT) "ice" layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of implosion kinetic energy to internal energy of the central hot spot, thus reducing the neutron yield. Furthermore, synthetic gated x-ray images of the hot spot self-emission indicate that P4 shapes may be unquantifiable for DT layered capsules. Instead the positive P4 asymmetry "aliases" itself as an oblate P2 in the x-ray images. Correction of this apparent P2 distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of NIF DT implosions relative to detailed postshot two-dimensional simulations. © 2013 American Physical Society.


Powering of cool filaments in cluster cores by buoyant bubbles - I. Qualitative model

Monthly Notices of the Royal Astronomical Society 436 (2013) 526-530

E Churazov, M Ruszkowski, A Schekochihin

Cool-core clusters (e.g. Perseus or M87) often possess a network of bright gaseous filaments, observed in radio, infrared, optical and X-ray bands. We propose that these filaments are powered by the reconnection of the magnetic field in the wakes of buoyant bubbles. Active galactic nucleus (AGN)-inflated bubbles of relativistic plasma rise buoyantly in the cluster atmosphere, stretching and amplifying the field in the wake to values of β = 8πP/B ~ 1. The field lines in thewake have opposite directions and are forced together as the bubble motion stretches the filament. This setup bears strong similarity to the coronal loops on the Sun or to the Earth's magnetotail. The reconnection process naturally explains both the required level of local dissipation rate in filaments and the overall luminosity of filaments. The original source of power for the filaments is the potential energy of buoyant bubbles, inflated by the central AGN. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


A New Era in Gamma-Ray Astronomy with the Cherenkov Telescope Array

ASTROPARTICLE PHYSICS 43 (2013) 1-2

J Hinton, S Sarkar, D Torres, J Knapp


The role of collisions on mode competition between the two-stream and Weibel instabilities

Journal of Plasma Physics 79 (2013) 987-989

KA Humphrey, DC Speirs, R Bingham, RMGM Trines, P Norreys

We present results from numerical simulations conducted to investigate a potential method for realizing the required fusion fuel heating in the fast ignition scheme to achieving inertial confinement fusion. A comparison will be made between collisionless and collisional particle-in-cell simulations of the relaxation of a non-thermal electron beam through the two-stream instability. The results presented demonstrate energy transfer to the plasma ion population from the laser-driven electron beam via the nonlinear wave-wave interaction associated with the two-stream instability. Evidence will also be provided for the effects of preferential damping of competing instabilities such as the Weibel mode found to be detrimental to the ion heating process. © Cambridge University Press 2013.