# Galaxy And Mass Assembly: the evolution of the cosmic spectral energy distribution from z = 1 to z = 0

## TL;DR

This study tracks the evolution of the cosmic spectral energy distribution from redshift 1 to 0, revealing a significant decline in the universe's energy output and changes in dust attenuation and stellar populations.

## Contribution

It provides the first comprehensive measurement of the evolving cosmic spectral energy distribution using stacked SED fits from GAMA and COSMOS datasets across multiple redshifts.

## Key findings

- The universe's bolometric energy output decreased by a factor of four since z=1.
- Dust attenuation has decreased, increasing photon escape fraction at 150 nm.
- The CSED accounts for over 60% of the cosmic optical and infrared backgrounds.

## Abstract

We present the evolution of the Cosmic Spectral Energy Distribution (CSED) from $z = 1 - 0$. Our CSEDs originate from stacking individual spectral energy distribution fits based on panchromatic photometry from the Galaxy and Mass Assembly (GAMA) and COSMOS datasets in ten redshift intervals with completeness corrections applied. Below $z = 0.45$, we have credible SED fits from 100 nm to 1 mm. Due to the relatively low sensitivity of the far-infrared data, our far-infrared CSEDs contain a mix of predicted and measured fluxes above $z = 0.45$. Our results include appropriate errors to highlight the impact of these corrections. We show that the bolometric energy output of the Universe has declined by a factor of roughly four -- from $5.1 \pm 1.0$ at $z \sim 1$ to $1.3 \pm 0.3 \times 10^{35}~h_{70}$~W~Mpc$^{-3}$ at the current epoch. We show that this decrease is robust to cosmic variance, SED modelling and other various types of error. Our CSEDs are also consistent with an increase in the mean age of stellar populations. We also show that dust attenuation has decreased over the same period, with the photon escape fraction at 150~nm increasing from $16 \pm 3$ at $z \sim 1$ to $24 \pm 5$ per cent at the current epoch, equivalent to a decrease in $A_\mathrm{FUV}$ of 0.4~mag. Our CSEDs account for $68 \pm 12$ and $61 \pm 13$ per cent of the cosmic optical and infrared backgrounds respectively as defined from integrated galaxy counts and are consistent with previous estimates of the cosmic infrared background with redshift.