W. Zimdahl et D. Pavon, COVARIANT COSMOLOGICAL PERTURBATION DYNAMICS IN THE LARGE-SCALE LIMIT, Physical review. D. Particles and fields, 57(12), 1998, pp. 7607-7610
Using the existence of a covariant conserved quantity on large perturb
ation scales in a spatially flat perfect fluid or scalar field univers
e, we present a general formula for gauge-invariantly defined comoving
energy density perturbations which encodes the entire linear perturba
tion dynamics in a closed time integral. On this basis we discuss pert
urbation modes in different cosmological epochs.