Impact of galactic and intergalactic dust on the stellar EBL
  Current theories assume that the low intensity of the stellar extragalactic
background light (stellar EBL) is caused primarily by finite age of the
Universe because the finite age limits the number of photons pumped into the
space by galaxies and thus the sky is dark in the night. We oppose this opinion
and show that two main factors are responsible for the extremely low intensity
of the observed stellar EBL: (1) a low mean surface brightness of galaxies,
which causes a low luminosity density in the local Universe, and (2) light
extinction due to absorption by galactic and intergalactic dust. Dust produces
a partial opacity of galaxies and of the Universe. The galactic opacity reduces
the intensity of light from more distant background galaxies obscured by
foreground galaxies. The effective extinction AV for light passing through a
galaxy is 0.2 mag. This causes that distant background galaxies do not
contribute to the EBL significantly. In addition, light of distant galaxies is
dimmed due to absorption by intergalactic dust. Even a minute intergalactic
opacity of 1x10^(-2) mag per Gpc is high enough to produce significant effects
on the EBL. The absorbed starlight heats up the galactic and intergalactic dust
and is further re-radiated at the IR, FIR and micro-wave spectrum. Assuming
static infinite universe with no galactic and intergalactic dust, the stellar
EBL should be as high as the surface brightness of stars. However, if dust is
considered, the predicted stellar EBL is about 290 nWm^(-2)sr^(-1), which is
only 5 times higher than the observed value. Hence, the presence of dust has
higher impact on the EBL than currently assumed. In the expanding universe, the
calculated value of the EBL is further decreased, because the obscuration
effect and intergalactic absorption become more pronounced at high redshifts
when the matter was concentrated at smaller volume than at present.
