Rubin-LSST

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We present <jats:monospace>CoLoRe</jats:monospace>, a public software package to efficiently generate synthetic realisations of multiple cosmological surveys. <jats:monospace>CoLoRe</jats:monospace> can simulate the growth of structure with different degrees of accuracy, with the current implementation supporting lognormal fields, first, and second order Lagrangian perturbation theory. <jats:monospace>CoLoRe</jats:monospace> simulates the density field on an all-sky light-cone up to a desired maximum redshift, and uses it to generate multiple 2D and 3D maps: galaxy positions and velocities, lensing (shear, magnification, convergence), integrated Sachs-Wolfe effect, line intensity mapping, and line of sight skewers for simulations of the Lyman-<jats:italic>α</jats:italic> forest. We test the accuracy of the simulated maps against analytical theoretical predictions, and showcase its performance with a multi-survey simulation including DESI galaxies and quasars, LSST galaxies and lensing, and SKA intensity mapping and radio galaxies. We expect <jats:monospace>CoLoRe</jats:monospace> to be particularly useful in studies aiming to characterise the impact of systematics in multi-experiment analyses, quantify the covariance between different datasets, and test cross-correlation pipelines for near-future surveys.</jats:p>

Abstract:

We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, λRe⁠, drawn from the SAMI Galaxy Survey. We fit a global [α/Fe]–σ relation, finding that [α/Fe]=(0.395±0.010)log10(σ)−(0.627±0.002)⁠. We observe an anti-correlation between the residuals Δ[α/Fe] and the inclination-corrected λeoRe⁠, which can be expressed as Δ[α/Fe]=(−0.057±0.008)λeoRe+(0.020±0.003)⁠. The anti-correlation appears to be driven by star-forming galaxies, with a gradient of Δ[α/Fe]∼(−0.121±0.015)λeoRe⁠, although a weak relationship persists for the subsample of galaxies for which star formation has been quenched. We take this to be confirmation that disc-dominated galaxies have an extended duration of star formation. At a reference velocity dispersion of 200 km s−1, we estimate an increase in half-mass formation time from ∼0.5 Gyr to ∼1.2 Gyr from low- to high-λeoRe galaxies. Slow rotators do not appear to fit these trends. Their residual α-enhancement is indistinguishable from other galaxies with λeoRe⪅0.4⁠, despite being both larger and more massive. This result shows that galaxies with λeoRe⪅0.4 experience a similar range of star formation histories, despite their different physical structure and angular momentum.