TY - JOUR
T1 - Silk damping at a redshift of a billion
T2 - New limit on small-scale adiabatic perturbations
AU - Jeong, Donghui
AU - Pradler, Josef
AU - Chluba, Jens
AU - Kamionkowski, Marc
PY - 2014/8/5
Y1 - 2014/8/5
N2 - We study the dissipation of small-scale adiabatic perturbations at early times when the Universe is hotter than T≃0.5keV. When the wavelength falls below the damping scale kD-1, the acoustic modes diffuse and thermalize, causing entropy production. Before neutrino decoupling, kD is primarily set by the neutrino shear viscosity, and we study the effect of acoustic damping on the relic neutrino number, primordial nucleosynthesis, dark-matter freeze-out, and baryogenesis. This sets a new limit on the amplitude of primordial fluctuations of ΔR2<0.007 at 104Mpc-1k105Mpc-1 and a model-dependent limit of ΔR20.3 at k1020-25Mpc-1.
AB - We study the dissipation of small-scale adiabatic perturbations at early times when the Universe is hotter than T≃0.5keV. When the wavelength falls below the damping scale kD-1, the acoustic modes diffuse and thermalize, causing entropy production. Before neutrino decoupling, kD is primarily set by the neutrino shear viscosity, and we study the effect of acoustic damping on the relic neutrino number, primordial nucleosynthesis, dark-matter freeze-out, and baryogenesis. This sets a new limit on the amplitude of primordial fluctuations of ΔR2<0.007 at 104Mpc-1k105Mpc-1 and a model-dependent limit of ΔR20.3 at k1020-25Mpc-1.
UR - http://www.scopus.com/inward/record.url?scp=84905671246&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84905671246&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.113.061301
DO - 10.1103/PhysRevLett.113.061301
M3 - Article
AN - SCOPUS:84905671246
SN - 0031-9007
VL - 113
JO - Physical review letters
JF - Physical review letters
IS - 6
M1 - 061301
ER -