Can dark energy viscosity be detected with the Euclid survey
D. S. acknowledges support from the JAEDoc program with Grant No. JAEDoc074 and the Spanish MICINN under Project No. AYA2009-13936-C06-06. D. S. also acknowledges financial support from the Madrid Regional Government (CAM) under the program HEPHACOS P-ESP-00346, Consolider-Ingenio 2010 PAU (CSD2007-00060), as well as the European Union Marie Curie Network ‘‘UniverseNet’’ under Contract No. MRTN-CT-2006-035863. E. M. was supported by the Spanish MICINNs Juan de la Cierva programme (Grant No. JCI-2010-08112), by CICYT through Project No. FPA-2009 09017, by the Community of Madrid through the project HEPHACOS (Grant No. S2009/ESP- 1473) under Grant No. P-ESP-00346 and by the European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITNGA-2011-289442). M. K. acknowledges funding by the Swiss NSF