[Paper Review] Implications of the cosmic infrared background for light production and the star formation history in the Universe

R. Gispert, G. Lagache+1 more|arXiv (Cornell University)|May 29, 2000

Astronomy and Astrophysical Research2 references18 citations

TL;DR

This paper analyzes the cosmic infrared background (CIB) to constrain the star formation history and light production in the universe, using observed CIB spectra to infer the redshift evolution of far-infrared radiation from dust-reprocessed starlight. It finds that the far-IR background requires a radiation production rate increasing by a factor >10 from z=0 to z=1, followed by a plateau at higher redshifts, indicating a peak in star formation activity at z≈1–2, with infrared galaxies dominating the background and implying a strong evolution in galactic dust properties over cosmic time.

ABSTRACT

The Cosmic Background due to the integrated radiation from galaxies over the whole life of the Universe is reviewed. We find that this background is well constrained by measurements. The total power in the background is in the range 60-93 nW/m2/sr. The data show the existence of a minimum separating the direct stellar radiation from the infrared part due to radiation reemitted by dust. This reemitted dust radiation is about 1-2.6 time the background power in the optical/near-IR thus much larger than the same ratio measured locally (30%). The far-infrared and submillimeter background is likely to be dominated by redshifted infrared galaxies. The long wavelength spectrum of the background being significantly flatter than the spectrum of these galaxies it strongly constrains the far-infrared radiation production rate history which must increase by a factor larger than 10 between the present time and a redshift 1 and then stays rather constant at higher redshift, contrary to the ultraviolet radiation production rate which decreases rapidly. Several models of galaxy evolution have been proposed to explain the submillimeter background. In this paper we do not propose a new model; we systematically explore the allowed range of evolution histories allowed by the data. If infrared galaxies are mostly powered by starbursts as indicated by recent observations, this infrared production history reflects the history of starbursts in the Universe.

Motivation & Objective

• To determine the redshift evolution of far-infrared radiation production from galaxies using constraints from the cosmic infrared background (CIB).
• To explore the range of possible evolution histories of infrared galaxies consistent with observed CIB fluxes and spectral shapes.
• To infer the star formation history from the inferred infrared radiation production rate, assuming dust-reprocessed starlight dominates the CIB.
• To compare the inferred radiation production history with other observational constraints on star formation and galaxy evolution.
• To avoid model-dependent assumptions by systematically analyzing possible spectral energy distributions (SEDs) and observational uncertainties.

Proposed method

• The paper uses the observed CIB spectrum from UV to submillimeter wavelengths as the primary constraint, integrating deep extragalactic source counts and diffuse background upper limits.
• It applies a formalism to invert the CIB spectrum into the comoving radiation production rate φ(z) per unit redshift, assuming a single-frequency emission model for simplicity.
• The method uses the relation φν₀(z) ∝ (νIν / 10⁻⁸ Wm⁻²sr⁻¹) × (ν/ν₀)⁻⁵/² to derive the radiation production rate at a reference frequency ν₀ = 310 THz.
• The analysis assumes a Euclidean geometry for the background calculation and applies power-law approximations to the CIB spectrum in different wavelength bands.
• It derives the redshift evolution of the radiation production rate by fitting the observed CIB slope to the expected spectral shape from evolving galaxies.
• The method systematically explores the range of SEDs and redshift evolution histories consistent with observational uncertainties, avoiding reliance on a single SED model.

Experimental results

Research questions

• RQ1 What is the redshift evolution of the far-infrared radiation production rate required to reproduce the observed cosmic infrared background?
• RQ2 How does the inferred radiation production history compare with the observed star formation rate density in the local universe?
• RQ3 To what extent must the luminosity function of infrared galaxies evolve with redshift to explain the CIB spectrum?
• RQ4 What constraints does the CIB spectrum place on the contribution of dust-reprocessed starlight versus active galactic nuclei to the background?
• RQ5 How do the observed CIB spectral shape and minimum near 3–10 μm inform the physical properties and evolution of the dominant sources?

Key findings

• The total cosmic infrared background power is constrained to 60–93 nWm⁻²sr⁻¹, with a significant excess in the far-IR relative to the optical, indicating strong dust reprocessing.
• The ratio of far-IR to optical background energy is 1–2.6, significantly higher than the local value of ~30%, implying a change in galactic properties over cosmic time.
• The far-IR and submillimeter background is likely dominated by high-redshift, dust-enshrouded infrared galaxies, particularly those undergoing starbursts.
• The radiation production rate must increase by a factor >10 between z=0 and z=1, then remain nearly constant at higher redshifts, contrary to the declining UV production rate.
• The observed CIB spectrum is flatter than the spectrum of individual IR galaxies, indicating that the dominant sources must have evolved significantly in luminosity and spectral shape.
• The inferred radiation production rate at z≈1–4 is independent of the assumed emission frequency (ν₀) due to the spectral slope matching the no-evolution case, confirming robustness in that redshift range.