Modelling and interpreting spectral energy distributions of galaxies
  with BEAGLE
  We present a new-generation tool to model and interpret spectral energy
distributions (SEDs) of galaxies, which incorporates in a consistent way the
production of radiation and its transfer through the interstellar and
intergalactic media. This flexible tool, named BEAGLE (for BayEsian Analysis of
GaLaxy sEds), allows one to build mock galaxy catalogues as well as to
interpret any combination of photometric and spectroscopic galaxy observations
in terms of physical parameters. The current version of the tool includes
versatile modeling of the emission from stars and photoionized gas, attenuation
by dust and accounting for different instrumental effects, such as
spectroscopic flux calibration and line spread function. We show a first
application of the BEAGLE tool to the interpretation of broadband SEDs of a
published sample of ${\sim}10^4$ galaxies at redshifts $0.1 \lesssim
z\lesssim8$. We find that the constraints derived on photometric redshifts
using this multi-purpose tool are comparable to those obtained using public,
dedicated photometric-redshift codes and quantify this result in a rigorous
statistical way. We also show how the post-processing of BEAGLE output data
with the Python extension PYP-BEAGLE allows the characterization of systematic
deviations between models and observations, in particular through posterior
predictive checks. The modular design of the BEAGLE tool allows easy extensions
to incorporate, for example, the absorption by neutral galactic and
circumgalactic gas, and the emission from an active galactic nucleus, dust and
shock-ionized gas. Information about public releases of the BEAGLE tool will be
maintained on http://www.jacopochevallard.org/beagle.
