Metal enrichment in a semi-analytical model, fundamental scaling relations, and the case of Milky Way galaxies

Gas flows play a fundamental role in galaxy formation and evolution, providing the fuel for the star formation process. These mechanisms leave an imprint in the amount of heavy elements. Thus, the analysis of this metallicity signature provides additional constraint on the galaxy formation scenario. We aim to discriminate between four different galaxy formation models based on two accretion scenarios and two different star formation recipes. We address the impact of a bimodal accretion scenario and a strongly regulated star formation recipe. We present a new extension of the eGalICS model, which allows us to track the metal enrichment process. Our new chemodynamical model is applicable for situations ranging from metal-free primordial accretion to very enriched interstellar gas contents. We use this new tool to predict the metallicity evolution of both the stellar populations and gas phase. We also address the evolution of the gas metallicity with the star formation rate (SFR). We then focus on a sub-sample of Milky Way-like galaxies. We compare both the cosmic stellar mass assembly and the metal enrichment process of such galaxies with observations and detailed chemical evolution models. Our models, based on a strong star formation regulation, allow us to reproduce well the stellar mass to gas-phase metallicity relation observed in the local universe. However, we observe a systematic shift towards high masses. Our $Mstar-Zg-SFR relation is in good agreement with recent measurements: our best model predicts a clear dependence with the SFR. Both SFR and metal enrichment histories of our Milky Way-like galaxies are consistent with observational measurements and detailed chemical evolution models. We finally show that Milky Way progenitors start their evolution below the observed main sequence and progressively reach this observed relation at z = 0.Comment: 22 pages, 11 figure

XID+ a new prior-based extraction tool for Herschel-SPIRE maps

International audienceWe present XID+, a new generation of software for prior-based photometryextraction in the Herschel SPIRE maps. Based on a Bayesian framework, XID+allows the inclusion of prior information and gives access to the full posteriorprobability distribution of fluxes. XID+ is developed within the HerschelExtragalactic Legacy Project (HELP) and is available athttps://github.com/H-E-L-P/XID_plus

The emission of galaxies over the whole electromagnetic spectrum

International audienceThe Spectral Energy Distributions (SEDs) of galaxies contain a wealth of information on the physical processes at play in galaxies and on their components: gas, stars, dust, Active Galactic Nuclei (AGN). Many of the fundamental properties which shape stellar population ensembles are encoded in their SEDs. In this paper, we will try to keep track of the main properties, e.g. star formation history, total mass in stars, characteristics of the AGN, but also the physical state and amount of gas and dust. We will also see how to use modern tools to collect information on the source of the emission in a way consistent with the observed data from the observed far-ultraviolet to far-infrared ranges

The emission of galaxies over the whole electromagnetic spectrum

International audienceThe Spectral Energy Distributions (SEDs) of galaxies contain a wealth of information on the physical processes at play in galaxies and on their components: gas, stars, dust, Active Galactic Nuclei (AGN). Many of the fundamental properties which shape stellar population ensembles are encoded in their SEDs. In this paper, we will try to keep track of the main properties, e.g. star formation history, total mass in stars, characteristics of the AGN, but also the physical state and amount of gas and dust. We will also see how to use modern tools to collect information on the source of the emission in a way consistent with the observed data from the observed far-ultraviolet to far-infrared ranges

The emission of galaxies over the whole electromagnetic spectrum

International audienceThe Spectral Energy Distributions (SEDs) of galaxies contain a wealth of information on the physical processes at play in galaxies and on their components: gas, stars, dust, Active Galactic Nuclei (AGN). Many of the fundamental properties which shape stellar population ensembles are encoded in their SEDs. In this paper, we will try to keep track of the main properties, e.g. star formation history, total mass in stars, characteristics of the AGN, but also the physical state and amount of gas and dust. We will also see how to use modern tools to collect information on the source of the emission in a way consistent with the observed data from the observed far-ultraviolet to far-infrared ranges

HELP: A catalogue of 170 million objects, selected at 0.36-4.5 μ\mum, from 1270 deg.2^{2} of prime extragalactic fields

International audienceWe present an optical to near-infrared selected astronomical catalogue covering 1270 deg.$^2$. This is the first attempt to systematically combine data from 23 of the premier extragalactic survey fields - the product of a vast investment of telescope time. The fields are those imaged by the Herschel Space Observatory which form the Herschel Extragalactic Legacy Project (HELP). Our catalogue of 170 million objects is constructed by a positional cross match of 51 public surveys. This high resolution optical, near-infrared, and mid-infrared catalogue is designed for photometric redshift estimation, extraction of fluxes in lower resolution far-infrared maps, and spectral energy distribution modelling. It collates, standardises, and provides value added derived quantities including corrected aperture magnitudes and astrometry correction over the Herschel extragalactic wide fields for the first time. $grizy$ fluxes are available on all fields with $g$ band data reaching $5\sigma$ point-source depths in a 2 arcsec aperture of 23.5, 24.4, and 24.6 (AB) mag at the 25th, 50th, and 75th percentiles, by area covered, across all HELP fields. It has $K$ or $K_s$ coverage over 1146 deg.$^2$ with depth percentiles of 20.2, 20.4, and 21.0 mag respectively. The IRAC Ch 1 band is available over 273 deg.$^2$ with depth percentiles of 17.7, 21.4, and 22.2 mag respectively. This paper defines the ``masterlist'' objects for the first data release (DR1) of HELP. This large sample of standardised total and corrected aperture fluxes, uniform quality flags, and completeness measures provides large well understood statistical samples over the full Herschel extragalactic sky