Garay Elizondo, Luis Javier

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First Name
Luis Javier
Last Name
Garay Elizondo
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Física Teórica
Física Teórica
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Now showing 1 - 2 of 2
  • Publication
    The trans-Planckian problem as a guiding principle
    (Int School Advanced Studies, 2011-11) Barbado, L. C.; Barceló, C.; Garay Elizondo, Luis Javier; Jannes, Gil
    We use the avoidance of the trans-Planckian problem of Hawking radiation as a guiding principle in searching for a compelling scenario for the evaporation of black holes or black-hole-like objects. We argue that there exist only three possible scenarios, depending on whether the classical notion of long-lived horizon is preserved by high-energy physics and on whether the dark and compact astrophysical objects that we observe have long-lived horizons in the first place. Along the way, we find that i) a theory with high-energy superluminal signalling and a long-lived trapping horizon would be extremely unstable in astrophysical terms and that i i) stellar pulsations of objects hovering right outside but extremely close to their gravitational radius can result in a mechanism for Hawking-like emission.
  • Publication
    Two faces of quantum sound
    (Amer Physical Soc, 2010-08-25) Barceló, C.; Garay Elizondo, Luis Javier; Jannes, G.
    Fluctuations around a Bose-Einstein condensate can be described by means of Bogolubov theory leading to the notion of quasiparticle and antiquasiparticle familiar to nonrelativistic condensed-matter practitioners. On the other hand, we already know that these perturbations evolve according to a relativistic Klein-Gordon equation in the long-wavelength approximation. For shorter wavelengths, we show that this equation acquires nontrivial corrections which modify the Klein-Gordon product. In this approach, quasiparticles can also be defined (up to the standard ambiguities due to observer dependence). We demonstrate that-in the low-energy as well as in the high-energy regimes-both concepts of quasiparticle are actually the same, regardless of the formalism (Bogolubov or Klein-Gordon) used to describe them. These results also apply to any barotropic, inviscid, irrotational fluid, with or without quantum potential. Finally, we illustrate how the quantization of these systems of quasiparticles proceeds by analyzing a stationary configuration containing an acoustic horizon. We show that there are several possible choices of a regular vacuum state, including a regular generalization of the Boulware vacuum. Issues such us Hawking radiation crucially depend on this vacuum choice.