Publications


The ATLAS3D project - XXII. Low-efficiency star formation in early-type galaxies: Hydrodynamic models and observations

Monthly Notices of the Royal Astronomical Society 432 (2013) 1914-1927

M Martig, AF Crocker, F Bournaud, E Emsellem, JM Gabor, K Alatalo, L Blitz, M Bois, M Bureau, M Cappellari, RL Davies, TA Davis, A Dekel, PT de Zeeuw, P-A Duc, J Falcón-Barroso, S Khochfar, D Krajnović, H Kuntschner, R Morganti, RM McDermid, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, KS Griffin, R Teyssier, A-M Weijmans, LM Young

We study the global efficiency of star formation in high-resolution hydrodynamical simulations of gas discs embedded in isolated early-type and spiral galaxies. Despite using a universal local law to form stars in the simulations, we find that the early-type galaxies are offset from the spirals on the large-scale Kennicutt relation, and form stars two to five times less efficiently. This offset is in agreement with previous results on morphological quenching: gas discs are more stable against star formation when embedded in early-type galaxies due to the lower disc self-gravity and increased shear. As a result, these gas discs do not fragment into dense clumps and do not reach as high densities as in the spiral galaxies. Even if some molecular gas is present, the fraction of very dense gas (typically above 104 cm-3) is significantly reduced, which explains the overall lower star formation efficiency. We also analyse a sample of local early-type and spiral galaxies, measuring their CO and HI surface densities and their star formation rates as determined by their non-stellar 8 μm emission. As predicted by the simulations, we find that the early-type galaxies are offset from the Kennicutt relation compared to the spirals, with a twice lower efficiency. Finally, we validate our approach by performing a direct comparison between models and observations. We run a simulation designed to mimic the stellar and gaseous properties of NGC 524, a local lenticular galaxy, and find a gas disc structure and global star formation rate in good agreement with the observations. Morphological quenching thus seems to be a robust mechanism, and is also consistent with other observations of a reduced star formation efficiency in early-type galaxies in the COLD GASS survey. This lower efficiency of star formation is not enough to explain the formation of the whole red sequence, but can contribute to the reddening of some galaxies. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Evidence for high-energy extraterrestrial neutrinos at the icecube detector

Science 342 (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, B Eichmann, 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, 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 O'Murchadha, L Paul, JA Pepper, C De Pérez 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, 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 report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4σ level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.


Dense electron-positron plasmas and bursts of gamma-rays from laser-generated quantum electrodynamic plasmas

Physics of Plasmas 20 (2013)

CP Ridgers, CS Brady, R Duclous, JG Kirk, K Bennett, TD Arber, AR Bell

In simulations of a 12.5 PW laser (focussed intensity I = 4 × 10 23 Wcm - 2) striking a solid aluminum target, 10% of the laser energy is converted to gamma-rays. A dense electron-positron plasma is generated with a maximum density of 10 26 m - 3, seven orders of magnitude denser than pure e- e+ plasmas generated with 1PW lasers. When the laser power is increased to 320 PW (I = 10 25 Wcm - 2), 40% of the laser energy is converted to gamma-ray photons and 10% to electron-positron pairs. In both cases, there is strong feedback between the QED emission processes and the plasma physics, the defining feature of the new "QED-plasma" regime reached in these interactions. © 2013 AIP Publishing LLC.


Linear structures in the core of the Coma cluster of galaxies

Science 341 (2013) 1365-1368

JS Sanders, AC Fabian, E Churazov, AA Schekochihin, A Simionescu, SA Walker, N Werner

The hot x-ray-emitting plasma in galaxy clusters is predicted to have turbulent motion, which can contribute around 10% of the cluster's central energy density. We report deep Chandra X-ray Observatory observations of the Coma cluster core, showing the presence of quasi-linear high-density arms spanning 150 kiloparsecs, consisting of low-entropy material that was probably stripped from merging subclusters. Two appear to be connected with a subgroup of galaxies at a 650-kiloparsec radius that is merging into the cluster, implying coherence over several hundred million years. Such a long lifetime implies that strong isotropic turbulence and conduction are suppressed in the core, despite the unrelaxed state of the cluster. Magnetic fields are presumably responsible. The structures seen in Coma present insight into the past billion years of subcluster merger activity.


Search for time-independent neutrino emission from astrophysical sources with 3 years of IceCube data

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, 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, M Day, CD Clercq, SD Ridder, P Desiati, KDD Vries, MD With, T DeYoung, JCD iaz-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 Kolanosk, 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, 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, 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, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge1, 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 search for neutrino point sources using the IceCube data collected between April 2008 and May 2011 with three partially completed configurations of the detector: the 40-, 59- and 79-string configurations. The live-time of this data set are 1,040 days. An unbinned maximum likelihood ratio test was used to search for an excess of neutrinos above the atmospheric background at any given direction in the sky. By adding two more years of data with improved event selection and reconstruction techniques, the sensitivity was improved by a factor 3.5 or more with respect to the previously published results obtained with the 40-string configuration of IceCube. We performed an all-sky survey and a dedicated search using a catalog of \textit{a priori} selected objects observed by other telescopes. In both searches, the data are compatible with the background-only hypothesis. In the absence of evidence for a signal, we set upper limits on the flux of muon neutrinos. For an E$^{-2}$ neutrino spectrum, the observed limits are between 0.9 and $23.2\times 10^{-12}$ TeV$^{-1}$ cm$^{-2}$s$^{-1}$. We also report upper limits for neutrino emission from groups of sources which were selected according to theoretical models or observational parameters and analysed with a stacking approach.


The IceCube Neutrino Observatory Part V: Neutrino Oscillations and Supernova Searches

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 neutrino oscillation and supernova searches submitted to the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013) by the IceCube Collaboration.


The unbearable lightness of being: CDMS versus XENON

ArXiv (2013)

MT Frandsen, F Kahlhoefer, C McCabe, S Sarkar, K Schmidt-Hoberg

The CDMS-II collaboration has reported 3 events in a Si detector, which are consistent with being nuclear recoils due to scattering of Galactic dark matter particles with a mass of about 8.6 GeV and a cross-section on neutrons of about 2 x 10^-41 cm^2. While a previous result from the XENON10 experiment has supposedly ruled out such particles as dark matter, we find by reanalysing the XENON10 data that this is not the case. Some tension remains however with the upper limit placed by the XENON100 experiment, independently of astrophysical uncertainties concerning the Galactic dark matter distribution. We explore possible ways of ameliorating this tension by altering the properties of dark matter interactions. Nevertheless, even with standard couplings, light dark matter is consistent with both CDMS and XENON10/100.


Fast collisionless reconnection and electron heating in strongly magnetized plasmas

Physical Review Letters 111 (2013)

NF Loureiro, AA Schekochihin, A Zocco

Magnetic reconnection in strongly magnetized (low-beta), weakly collisional plasmas is investigated by using a novel fluid-kinetic model [Zocco and Schekochihin, Phys. Plasmas 18, 102309 (2011)] which retains nonisothermal electron kinetics. It is shown that electron heating via Landau damping (linear phase mixing) is the dominant dissipation mechanism. In time, electron heating occurs after the peak of the reconnection rate; in space, it is concentrated along the separatrices of the magnetic island. For sufficiently large systems, the peak reconnection rate is ≈0.2vABy,0, where v A is the Alfvén speed based on the reconnecting field B y,0. The island saturation width is the same as in magnetohydrodynamics models except for small systems, when it becomes comparable to the kinetic scales. © 2013 American Physical Society.


Fast and slow rotators in the densest environments: a FLAMES/GIRAFFE IFS study of galaxies in Abell 1689 at z=0.183

ArXiv (2012)

F D'Eugenio, RCW Houghton, RL Davies, ED Bontà

We present FLAMES/GIRAFFE integral field spectroscopy of 30 galaxies in the massive cluster Abell 1689 at z = 0.183. Conducting an analysis similar to that of ATLAS3D, we extend the baseline of the kinematic morphology-density relation by an order of magnitude in projected density and show that it is possible to use existing instruments to identify slow and fast rotators beyond the local Universe. We find 4.5 +- 1.0 slow rotators with a distribution in magnitude similar to those in the Virgo cluster. The overall slow rotator fraction of our Abell 1689 sample is 0.15 +- 0.03, the same as in Virgo using our selection criteria. This suggests that the fraction of slow rotators in a cluster is not strongly dependent on its density. However, within Abell 1689, we find that the fraction of slow rotators increases towards the centre, as was also found in the Virgo cluster.


Introducing the CTA concept

ASTROPARTICLE PHYSICS 43 (2013) 3-18

BS Acharya, M Actis, T Aghajani, G Agnetta, J Aguilar, F Aharonian, M Ajello, A Akhperjanian, M Alcubierre, J Aleksic, R Alfaro, E Aliu, AJ Allafort, D Allan, I Allekotte, E Amato, J Anderson, EO Anguener, LA Antonelli, P Antoranz, A Aravantinos, T Arlen, T Armstrong, H Arnaldi, L Arrabito, K Asano, T Ashton, HG Asorey, Y Awane, H Baba, A Babic, N Baby, J Baehr, A Bais, C Baixeras, S Bajtlik, M Balbo, D Balis, C Balkowski, A Bamba, R Bandiera, A Barber, C Barbier, M Barcelo, A Barnacka, J Barnstedt, U Barres de Almeida, JA Barrio, A Basili, S Basso, D Bastieri, C Bauer, A Baushev, J Becerra, Y Becherini, KC Bechtol, JB Tjus, V Beckmann, W Bednarek, B Behera, M Belluso, W Benbow, J Berdugo, K Berger, F Bernard, T Bernardino, K Bernloehr, N Bhat, S Bhattacharyya, C Bigongiari, A Biland, S Billotta, T Bird, E Birsin, E Bissaldi, J Biteau, M Bitossi, S Blake, O Blanch Bigas, P Blasi, A Bobkov, V Boccone, M Boettcher, L Bogacz, J Bogart, M Bogdan, C Boisson, J Boix Gargallo, J Bolmont, G Bonanno, A Bonardi, T Bonev, P Bonifacio, G Bonnoli, P Bordas, A Borgland, J Borkowski, R Bose, O Botner, A Bottani, L Bouchet, M Bourgeat, C Boutonnet, A Bouvier, S Brau-Nogue, I Braun, T Bretz, M Briggs, T Bringmann, P Brook, P Brun, L Brunetti, T Buanes, J Buckley, R Buehler, V Bugaev, A Bulgarelli, T Bulik, G Busetto, S Buson, K Byrum, M Cailles, R Cameron, J Camprecios, R Canestrari, S Cantu, M Capalbi, P Caraveo, E Carmona, A Carosi, J Carr, P-H Carton, S Casanova, M Casiraghi, O Catalano, S Cavazzani, S Cazaux, M Cerruti, E Chabanne, P Chadwick, C Champion, A Chen, J Chiang, L Chiappetti, M Chikawa, VR Chitnis, F Chollet, J Chudoba, M Cieslar, A Cillis, J Cohen-Tanugi, S Colafrancesco, P Colin, J Calome, S Colonges, M Compin, P Conconi, V Conforti, V Connaughton, J Conrad, JL Contreras, P Coppi, P Corona, D Corti, J Cortina, L Cossio, H Costantini, G Cotter, B Courty, S Couturier, S Covino, G Crimi, SJ Criswell, J Croston, G Cusumano, M Dafonseca, O Dale, M Daniel, J Darling, I Davids, F Dazzi, A De Angelis, V De Caprio, F De Frondat, EM de Gouveia Dal Pino, I de la Calle, GA De La Vega, RDLR Lopez, B De Lotto, A De Luca, JRT de Mello Neto, M de Naurois, Y de Oliveira, E de Ona Wilhelmi, V de Souza, G Decerprit, G Decock, C Deil, E Delagnes, G Deleglise, C Delgado, D Della Volpe, P Demange, G Depaola, A Dettlaff, A Di Paola, F Di Pierro, C Diaz, J Dick, R Dickherber, H Dickinson, V Diez-Blanco, S Digel, D Dimitrov, G Disset, A Djannati-Atai, M Doert, M Dohmke, W Domainko, DD Prester, A Donat, D Dorner, M Doro, J-L Dournaux, G Drake, D Dravins, L Drury, F Dubois, R Dubois, G Dubus, C Dufour, D Dumas, J Dumm, D Durand, J Dyks, M Dyrda, J Ebr, E Edy, K Egberts, P Eger, S Einecke, C Eleftheriadis, S Elles, D Emmanoulopoulos, D Engelhaupt, R Enomoto, J-P Ernenwein, M Errando, A Etchegoyen, P Evans, A Falcone, D Fantinel, K Farakos, C Farnier, G Fasola, B Favill, E Fede, S Federici, S Fegan, F Feinstein, D Ferenc, P Ferrando, M Fesquet, A Fiasson, E Fillin-Martino, D Fink, C Finley, JP Finley, M Fiorini, R Firpo Curcoll, H Flores, D Florin, W Focke, C Foehr, E Fokitis, L Font, G Fontaine, M Fornasa, A Foerster, L Fortson, N Fouque, A Franckowiak, C Fransson, G Fraser, R Frei, IFM Albuquerque, L Fresnillo, C Fruck, Y Fujita, Y Fukazawa, Y Fukui, S Funk, W Gaebele, S Gabici, R Gabriele, A Gadola, N Galante, D Gall, Y Gallant, J Gamez-Garcia, B Garcia, R Garcia Lopez, D Gardiol, D Garrido, L Garrido, D Gascon, M Gaug, J Gaweda, L Gebremedhin, N Geffroy, L Gerard, A Ghedina, M Ghigo, E Giannakaki, F Gianotti, S Giarrusso, G Giavitto, B Giebels, V Gika, P Giommi, N Girard, E Giro, A Giuliani, T Glanzman, J-F Glicenstein, N Godinovic, V Golev, M Gomez Berisso, J Gomez-Ortega, MM Gonzalez, A Gonzalez, F Gonzalez, A Gonzalez Munoz, KS Gothe, M Gougerot, R Graciani, P Grandi, F Granena, J Granot, G Grasseau, R Gredig, A Green, T Greenshaw, T Gregoire, O Grimm, J Grube, M Grudzinska, V Gruev, S Gruenewald, J Grygorczuk, V Guarino, S Gunji, G Gyuk, D Hadasch, R Hagiwara, J Hahn, N Hakansson, A Hallgren, N Hamer Heras, S Hara, MJ Hardcastle, J Harris, T Hassan, K Hatanaka, T Haubold, A Haupt, T Hayakawa, M Hayashida, R Heller, F Henault, G Henri, G Hermann, R Hermel, A Herrero, N Hidaka, J Hinton, D Hoffmann, W Hofmann, P Hofverberg, J Holder, D Horns, D Horville, J Houles, M Hrabovsky, D Hrupec, H Huan, B Huber, J-M Huet, G Hughes, TB Humensky, J Huovelin, A Ibarra, JM Illa, D Impiombato, S Incorvaia, S Inoue, Y Inoue, K Ioka, E Ismailova, C Jablonski, A Jacholkowska, M Jamrozy, M Janiak, P Jean, C Jeanney, JJ Jimenez, T Jogler, T Johnson, L Journet, C Juffroy, I Jung, P Kaaret, S Kabuki, M Kagaya, J Kakuwa, C Kalkuhl, R Kankanyan, A Karastergiou, K Kaercher, M Karczewski, S Karkar, A Kasperek, D Kastana, H Katagiri, J Kataoka, K Katarzynski, U Katz, N Kawanaka, B Kellner-Leidel, H Kelly, E Kendziorra, B Khelifi, DB Kieda, T Kifune, T Kihm, T Kishimoto, K Kitamoto, W Kluzniak, C Knapic, JW Knapp, J Knoedlseder, F Koeck, J Kocot, K Kodani, J-H Koehne, K Kohri, K Kokkotas, D Kolitzus, N Komin, I Kominis, Y Konno, H Koeppel, P Korohoda, K Kosack, G Koss, R Kossakowski, P Kostka, R Koul, G Kowal, S Koyama, J Koziol, T Kraehenbuehl, J Krause, H Krawzcynski, F Krennrich, A Krepps, A Kretzschmann, R Krobot, P Krueger, H Kubo, VA Kudryavtsev, J Kushida, A Kuznetsov, A La Barbera, N La Palombara, V La Parola, G La Rosa, K Lacombe, G Lamanna, J Lande, D Languignon, J Lapington, P Laporte, C Lavalley, T Le Flour, A Le Padellec, S-H Lee, WH Lee, MA Leigui de Oliveira, D Lelas, J-P Lenain, DJ Leopold, T Lerch, L Lessio, B Lieunard, E Lindfors, A Liolios, A Lipniacka, H Lockart, T Lohse, S Lombardi, A Lopatin, M Lopez, R Lopez-Coto, A Lopez-Oramas, A Lorca, E Lorenz, P Lubinski, F Lucarelli, H Luedecke, J Ludwin, PL Luque-Escamilla, W Lustermann, O Luz, E Lyard, MC Maccarone, TJ Maccarone, GM Madejski, A Madhavan, M Mahabir, G Maier, P Majumdar, G Malaguti, S Maltezos, A Manalaysay, A Mancilla, D Mandat, G Maneva, A Mangano, P Manigot, K Mannheim, I Manthos, N Maragos, A Marcowith, M Mariotti, M Marisaldi, S Markoff, A Marszalek, C Martens, J Marti, J-M Martin, P Martin, G Martinez, F Martinez, M Martinez, A Masserot, A Mastichiadis, A Mathieu, H Matsumoto, F Mattana, S Mattiazzo, G Maurin, S Maxfield, J Maya, D Mazin, L Mc Comb, N McCubbin, I McHardy, R McKay, C Medina, C Melioli, D Melkumyan, S Mereghetti, P Mertsch, M Meucci, J Michalowski, P Micolon, A Mihailidis, T Mineo, M Minuti, N Mirabal, F Mirabel, JM Miranda, R Mirzoyan, T Mizuno, B Moal, R Moderski, I Mognet, E Molinari, M Molinaro, T Montaruli, I Monteiro, P Moore, A Moralejo Olaizola, M Mordalska, C Morello, K Mori, F Mottez, Y Moudden, E Moulin, I Mrusek, R Mukherjee, P Munar-Adrover, H Muraishi, K Murase, A Murphy, S Nagataki, T Naito, D Nakajima, T Nakamori, K Nakayama, C Naumann, D Naumann, M Naumann-Godo, P Nayman, D Nedbal, D Neise, L Nellen, V Neustroev, N Neyroud, L Nicastro, J Nicolau-Kuklinski, A Niedzwiecki, J Niemiec, D Nieto, A Nikolaidis, K Nishijima, S Nolan, R Northrop, D Nosek, N Nowak, A Nozato, P O'Brien, Y Ohira, M Ohishi, S Ohm, H Ohoka, T Okuda, A Okumura, J-F Olive, RA Ong, R Orito, M Orr, J Osborne, M Ostrowski, LA Otero, N Otte, E Ovcharov, I Oya, A Ozieblo, L Padilla, S Paiano, D Paillot, A Paizis, S Palanque, M Palatka, J Pallota, K Panagiotidis, J-L Panazol, D Paneque, M Panter, R Paoletti, A Papayannis, G Papyan, JM Paredes, G Pareschi, G Parks, J-M Parraud, D Parsons, MP Arribas, M Pech, G Pedaletti, V Pelassa, D Pelat, MDC Perez, M Persic, P-O Petrucci, B Peyaud, A Pichel, S Pita, F Pizzolato, L Platos, R Platzer, L Pogosyan, M Pohl, G Pojmanski, JD Ponz, W Potter, J Poutanen, E Prandini, J Prast, R Preece, F Profeti, H Prokoph, M Prouza, M Proyetti, I Puerto-Gimenez, G Puehlhofer, I Puljak, M Punch, R Pyziol, EJ Quel, J Quinn, A Quirrenbach, E Racero, PJ Rajda, P Ramon, R Rando, RC Rannot, M Rataj, M Raue, P Reardon, O Reimann, A Reimer, O Reimer, K Reitberger, M Renaud, S Renner, B Reville, W Rhode, M Ribo, M Ribordy, MG Richer, J Rico, J Ridky, F Rieger, P Ringegni, J Ripken, PR Ristori, A Riviere, S Rivoire, L Rob, U Roeser, R Rohlfs, G Rojas, P Romano, W Romaszkan, GE Romero, S Rosen, SR Lees, D Ross, G Rouaix, J Rousselle, S Rousselle, AC Rovero, F Roy, S Royer, B Rudak, C Rulten, M Rupinski, F Russo, F Ryde, B Sacco, EO Saemann, A Saggion, V Safiakian, K Saito, T Saito, Y Saito, N Sakaki, R Sakonaka, A Salini, F Sanchez, M Sanchez-Conde, A Sandoval, H Sandaker, E Sant'Ambrogio, A Santangelo, EM Santos, A Sanuy, L Sapozhnikov, S Sarkar, N Sartore, H Sasaki, K Satalecka, M Sawada, V Scalzotto, V Scapin, M Scarcioffolo, J Schafer, T Schanz, S Schlenstedt, R Schlickeiser, T Schmidt, J Schmoll, P Schovanek, M Schroedter, C Schultz, J Schultze, A Schulz, K Schure, T Schwab, U Schwanke, J Schwarz, S Schwarzburg, T Schweizer, S Schwemmer, A Segreto, J-H Seiradakis, GH Sembroski, K Seweryn, M Sharma, M Shayduk, RC Shellard, J Shi, T Shibata, A Shibuya, E Shum, L Sidoli, M Sidz, J Sieiro, M Sikora, J Silk, A Sillanpaa, BB Singh, J Sitarek, C Skole, R Smareglia, A Smith, D Smith, J Smith, N Smith, D Sobczynska, H Sol, G Sottile, M Sowinski, F Spanier, D Spiga, S Spyrou, V Stamatescu, A Stamerra, R Starling, L Stawarz, R Steenkamp, C Stegmann, S Steiner, N Stergioulas, R Sternberger, M Sterzel, F Stinzing, M Stodulski, U Straumann, E Strazzeri, L Stringhetti, A Suarez, M Suchenek, R Sugawara, K-H Sulanke, S Sun, AD Supanitsky, T Suric, P Sutcliffe, J Sykes, M Szanecki, T Szepieniec, A Szostek, G Tagliaferri, H Tajima, H Takahashi, K Takahashi, L Takalo, H Takami, C Talbot, J Tammi, M Tanaka, S Tanaka, J Tasan, M Tavani, J-P Tavernet, LA Tejedor, I Telezhinsky, P Temnikov, C Tenzer, Y Terada, R Terrier, M Teshima, V Testa, D Tezier, D Thuermann, L Tibaldo, O Tibolla, A Tiengo, M Tluczykont, CJ Todero Peixoto, F Tokanai, M Tokarz, K Toma, K Torii, M Tornikoski, DF Torres, M Torres, G Tosti, T Totani, C Toussenel, G Tovmassian, P Travnicek, M Trifoglio, I Troyano, K Tsinganos, H Ueno, K Umehara, SS Upadhya, T Usher, M Uslenghi, JF Valdes-Galicia, P Vallania, G Vallejo, W van Driel, C van Eldik, J Vandenbrouke, J Vanderwalt, H Vankov, G Vasileiadis, V Vassiliev, D Veberic, I Vegas, S Vercellone, S Vergani, C Veyssiere, JP Vialle, A Viana, M Videla, P Vincent, S Vincent, J Vink, N Vlahakis, L Vlahos, P Vogler, A Vollhardt, H-P von Gunten, S Vorobiov, C Vuerli, V Waegebaert, R Wagner, RG Wagner, S Wagner, SP Wakely, R Walter, T Walther, K Warda, R Warwick, P Wawer, R Wawrzaszek, N Webb, P Wegner, A Weinstein, Q Weitzel, R Welsing, M Werner, H Wetteskind, R White, A Wierzcholska, S Wiesand, M Wilkinson, DA Williams, R Willingale, K Winiarski, R Wischnewski, L Wisniewski, M Wood, A Woernlein, Q Xiong, KK Yadav, H Yamamoto, T Yamamoto, R Yamazaki, S Yanagita, JM Yebras, D Yelos, A Yoshida, T Yoshida, T Yoshikoshi, V Zabalza, M Zacharias, A Zajczyk, R Zanin, A Zdziarski, A Zech, A Zhao, X Zhou, K Zietara, J Ziolkowski, P Ziolkowski, V Zitelli, C Zurbach, P Zychowski, CTA Consortium


Laminar shocks in high power laser interactions

40th EPS Conference on Plasma Physics, EPS 2013 European Physical Society (EPS) 2 (2013) 850-853

RA Cairns, R Bingham, PA Norreys, RMGM Trines


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.


Ultrahigh Energy Neutrinos at the Pierre Auger Observatory

ArXiv (2013)

PA Collaboration

The observation of ultrahigh energy (UHE) neutrinos has become a priority in experimental astroparticle physics. UHE neutrinos can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going neutrinos) or in the Earth crust (Earth-skimming neutrinos), producing air showers that can be observed with arrays of detectors at the ground. With the Surface Detector Array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e. after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHE neutrinos in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHE neutrinos in the EeV range and above.


Fast and slow rotators in the densest environments: A FLAMES/GIRAFFE integral field spectroscopy study of galaxies in a1689 at z = 0.183

Monthly Notices of the Royal Astronomical Society 429 (2013) 1258-1266

F D'Eugenio, RCW Houghton, RL Davies, E Dalla Bontà

We present FLAMES/GIRAFFE integral field spectroscopy of 30 galaxies in the massive cluster A1689 at z = 0.183. Conducting an analysis similar to that of ATLAS3D, we extend the baseline of the kinematic morphology-density relation by an order of magnitude in projected density and show that it is possible to use existing instruments to identify slow and fast rotators beyond the local Universe. We find 4.5 ± 1.0 slow rotators with a distribution in magnitude similar to those in the Virgo cluster. The overall slow rotator fraction of our A1689 sample is 0.15 ± 0.03, the same as in Virgo using our selection criteria. This suggests that the fraction of slow rotators in a cluster is not strongly dependent on its density. However, within A1689, we find that the fraction of slow rotators increases towards the centre, as was also found in the Virgo cluster. © 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.


The IceProd Framework: Distributed Data Processing for the IceCube Neutrino Observatory

ArXiv (2013)

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, JC Díaz-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, 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, G Merino, 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, LR ädel, I Rae, 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, HG Sander, M Santander, S Sarkar, K Schatto, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, A Schönwald, A Schukraft, L Schulte, D Schultz, 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, 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

IceCube is a one-gigaton instrument located at the geographic South Pole, designed to detect cosmic neutrinos, iden- tify the particle nature of dark matter, and study high-energy neutrinos themselves. Simulation of the IceCube detector and processing of data require a significant amount of computational resources. IceProd is a distributed management system based on Python, XML-RPC and GridFTP. It is driven by a central database in order to coordinate and admin- ister production of simulations and processing of data produced by the IceCube detector. IceProd runs as a separate layer on top of other middleware and can take advantage of a variety of computing resources, including grids and batch systems such as CREAM, Condor, and PBS. This is accomplished by a set of dedicated daemons that process job submission in a coordinated fashion through the use of middleware plugins that serve to abstract the details of job submission and job management from the framework.


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.


Universal behaviour of shock precursors in the presence of efficient cosmic ray acceleration

Monthly Notices of the Royal Astronomical Society 430 (2013) 2873-

B Reville, AR Bell


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.


Cosmic-ray acceleration and escape from supernova remnants

Monthly Notices of the Royal Astronomical Society 431 (2013) 415-429

AR Bell, KM Schure, B Reville, G Giacinti

Galactic cosmic-ray (CR) acceleration to the knee in the spectrum at a few PeV is only possible if the magnetic field ahead of a supernova remnant (SNR) shock is strongly amplified by CRs escaping the SNR. A model formulated in terms of the electric charge carried by escaping CRs predicts the maximum CR energy and the energy spectrum of CRs released into the surrounding medium. We find that historical SNRs such as Cas A, Tycho and Kepler may be expanding too slowly to accelerate CRs to the knee at the present time. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.


Gamma-ray emission in near critical density plasmas

Plasma Physics and Controlled Fusion 55 (2013)

CS Brady, CP Ridgers, TD Arber, AR Bell

Previous work on the interaction of high power lasers with high density targets have identified that emission is primarily from interaction within the skin layer at the target front (e.g. Ridgers et al 2012 Phys. Rev. Lett. 108 165006). This mechanism is inefficient when compared to Reinjected Electron Synchrotron Emission (RESE) for laser interaction with low density solids (Brady et al 2012 Phys. Rev. Lett. 109 245006). However, these detailed analyses of the emission mechanisms were mainly based on 1D simulations and so did not incorporate some important 2D effects. In this paper these 1D emission mechanisms are confirmed to still exist in 2D with comparable properties and a new, intrinsically 2D, emission mechanism, termed edgeglow, is described which can convert 4-5% of the laser energy into gamma-ray energy. © 2013 IOP Publishing Ltd.