Publications

2015

• Stability in exponential time of Minkowski space-time with a space-like translation symmetry
  
  • Huneau Cécile
  • Huneau Cecile
  , 2014, pp.1 - 14. (10.5802/slsedp.77)
  DOI : 10.5802/slsedp.77
• The Diffusion Approximation for the Linear Boltzmann Equation with Vanishing Scattering Coefficient
  
  • Bardos Claude
  • Bernard Etienne
  • Golse François
  • Sentis Remi
  Communications in Mathematical Sciences, International Press, 2015, 13 (3), pp.pp. 641-671. The present paper discusses the diffusion approximation of the linear Boltzmann equation in cases where the collision frequency is not uniformly large in the spatial domain. Our results apply for instance to the case of radiative transfer in a composite medium with optically thin inclusions in an optically thick background medium. The equation governing the evolution of the approximate particle density coincides with the limit of the diffusion equation with infinite diffusion coefficient in the optically thin inclusions. (10.4310/CMS.2015.v13.n3.a3)
  DOI : 10.4310/CMS.2015.v13.n3.a3
• Countability properties of some Berkovich spaces
  
  • Favre Charles
  , 2015. We prove that any compact Berkovich space over the field of Laurent series over an arbitrary field is angelic. In particular, is it sequentially compact.
• Measuring a Cherenkov ring in the radio emission from air showers at 110–190MHz with LOFAR
  
  • Nelles A.
  • Schellart P.
  • Buitink S.
  • Corstanje A.
  • de Vries K.D.
  • Enriquez J.E.
  • Falcke H.
  • Frieswijk W.
  • Hörandel J.R.
  • Scholten O.
  • ter Veen S.
  • Thoudam S.
  • van den Akker M.
  • Anderson J.
  • Asgekar A.
  • Bell M.E.
  • Bentum M.J.
  • Bernardi G.
  • Best P.
  • Bregman J.
  • Breitling F.
  • Broderick J.
  • Brouw W.N.
  • Brüggen M.
  • Butcher H.R.
  • Ciardi B.
  • Deller A.
  • Duscha S.
  • Eislöffel J.
  • Fallows R.A.
  • Garrett M.A.
  • Gunst A.W.
  • Hassall T.E.
  • Heald G.
  • Horneffer A.
  • Iacobelli M.
  • Juette E.
  • Karastergiou A.
  • Kondratiev V.I.
  • Kramer M.
  • Kuniyoshi M.
  • Kuper G.
  • Maat P.
  • Mann G.
  • Mevius M.
  • Norden M.J.
  • Paas H.
  • Pandey-Pommier M.
  • Pietka G.
  • Pizzo R.
  • Polatidis A.G.
  • Reich W.
  • Röttgering H.
  • Scaife A.M.M.
  • Schwarz D.
  • Smirnov O.
  • Stappers B.W.
  • Steinmetz M.
  • Stewart A.
  • Tagger Michel
  • Tang Y.
  • Tasse C.
  • Vermeulen R.
  • Vocks C.
  • van Weeren R.J.
  • Wijnholds S.J.
  • Wucknitz O.
  • Yatawatta S.
  • Zarka P.
  Astroparticle Physics, Elsevier, 2015, 65, pp.11–21. Measuring radio emission from air showers offers a novel way to determine properties of the primary cosmic rays such as their mass and energy. Theory predicts that relativistic time compression effects lead to a ring of amplified emission which starts to dominate the emission pattern for frequencies above ∼100∼100 MHz. In this article we present the first detailed measurements of this structure. Ring structures in the radio emission of air showers are measured with the LOFAR radio telescope in the frequency range of 110–190 MHz. These data are well described by CoREAS simulations. They clearly confirm the importance of including the index of refraction of air as a function of height. Furthermore, the presence of the Cherenkov ring offers the possibility for a geometrical measurement of the depth of shower maximum, which in turn depends on the mass of the primary particle. (10.1016/j.astropartphys.2014.11.006)
  DOI : 10.1016/j.astropartphys.2014.11.006