The ALHAMBRA survey: tight dependence of the optical mass-to-light ratio on galaxy colour up to z = 1.5

TL;DR

This study establishes a tight, redshift-independent relation between galaxy optical mass-to-light ratio and colour up to z=1.5, enabling reliable mass estimates from optical colours over a significant cosmic time span.

Contribution

It extends the known mass-to-light ratio versus colour relation to higher redshifts up to 1.5, demonstrating its stability and providing a tool for galaxy mass estimation.

Findings

The mass-to-light ratio correlates linearly with colour for quiescent galaxies.

The relation is quadratic for star-forming galaxies.

No significant evolution of the relation with redshift up to 1.5.

Abstract

Our goal is to characterise the dependence of the optical mass-to-light ratio on galaxy colour up to z = 1.5, expanding the redshift range explored in previous work. From the ALHAMBRA redshifts, stellar masses, and rest-frame luminosities provided by the MUFFIT code, we derive the mass-to-light ratio vs. colour relation (MLCR) both for quiescent and star-forming galaxies. The intrinsic relation and its physical dispersion are derived with a Bayesian inference model. The rest-frame i-band mass-to-light ratio of quiescent and star-forming galaxies presents a tight correlation with the rest-frame (g - i) colour up to z = 1.5. Such MLCR is linear for quiescent galaxies and quadratic for star-forming galaxies. The intrinsic dispersion in these relations is 0.02 dex for quiescent galaxies and 0.06 dex for star-forming ones. The derived MLCRs do not present a significant redshift evolution and are compatible with previous local results in the literature. Finally, these tight relations also hold for g- and r-band luminosities. The derived MLCRs in ALHAMBRA can be used to predict the mass-to-light ratio from a rest-frame optical colour up to z = 1.5. These tight correlations do not change with redshift, suggesting that galaxies have evolved along the derived relations during the last 9 Gyr.