The energy output of the Universe from 0.1 micron to 1000 micron

TL;DR

This paper quantifies the universe's stellar energy output across 0.1 to 1000 microns, revealing how dust attenuates starlight and estimating the total energy emitted and escaping into intergalactic space.

Contribution

It introduces a calibrated galactic dust model combined with galaxy observations to accurately measure starlight attenuation and energy output across a broad wavelength range.

Findings

Only 11% of 0.1 micron photons escape galaxies.

Up to 87% of light escapes at 2.1 microns.

Total stellar energy output is approximately 1.6 x 10^{35} W Mpc^{-3}.

Abstract

The dominant source of electromagnetic energy in the Universe today (over ultraviolet, optical and near-infrared wavelengths) is starlight. However, quantifying the amount of starlight produced has proven difficult due to interstellar dust grains which attenuate some unknown fraction of the light. Combining a recently calibrated galactic dust model with observations of 10,000 nearby galaxies we find that (integrated over all galaxy types and orientations) only (11 +/- 2)% of the 0.1 micron photons escape their host galaxies; this value rises linearly (with log(lambda)) to (87 +/- 3)% at 2.1 micron. We deduce that the energy output from stars in the nearby Universe is (1.6+/-0.2) x 10^{35} W Mpc^{-3} of which (0.9+/-0.1) x 10^{35} W Mpc^{-3} escapes directly into the inter-galactic medium. Some further ramifications of dust attenuation are discussed, and equations that correct individual galaxy flux measurements for its effect are provided.