Gravitational wave background from neutron star phase transition
  We study the generation of a stochastic gravitational wave (GW) background
produced by a population of neutron stars (NSs) which go over a hadron-quark
phase transition in its inner shells. We obtain, for example, that the NS phase
transition, in cold dark matter scenarios, could generate a stochastic GW
background with a maximum amplitude of $h_{\rm BG} \sim 10^{-24}$, in the
frequency band $\nu_{\rm{obs}} \simeq 20-2000 {\rm Hz}$ for stars forming at
redshifts of up to $z\simeq 20.$ We study the possibility of detection of this
isotropic GW background by correlating signals of a pair of Advanced LIGO
observatories.
