Fluctuating dark energy and the luminosity distance

Abstract The origin of dark energy driving the accelerated expansion universe is still mysterious. We explore possibility that fluctuates, resulting in spatial correlations. Due to these fluctuations, Hubble rate itself becomes a fluctuating quantity. discuss effect this has on measurements type Ia supernovae, which are used constrain luminosity distance. show distance affected by correlations several ways. First, dressed thereby differing from standard ΛCDM. Second, angular become visible two-point correlation function To investigate latter we construct power spectrum fluctuations. then perform forecast for two supernova surveys, ongoing Dark Energy Survey (DES) and upcoming Legacy Space Time (LSST), compare with relativistic lensing effects perturbed find signal can rise above LSST could test large part parameter space. As an example, specific realisation such scenario quantum fluctuations some field early imprint predictable form density today. In case, fluctuates due intrinsic nature field. study whether model would be measurable, conclude testing challenging. However, taking into account speed sound c s < 1 fluid make observable.