Age-dating the tully-fisher relation at moderate redshift*

Abstract

We analyse the Tully-Fisher relation at moderate redshift from the point of view of the underlying stellar populations, by comparing optical and NIR photometry with a phenomenological model that combines population synthesis with a simple prescription for chemical enrichment. The sample comprises 108 late-type galaxies extracted from the FORS Deep Field and William Herschel Deep Field surveys at z ≲ 1 (median redshift z = 0.45). A correlation is found between stellar mass and the parameters that describe the star formation history, with massive galaxies forming their populations early (zFOR ~ 3), with star formation timescales, τ1 ~ 4 Gyr, although with very efficient chemical enrichment time-scales (τ2 ~ 1Gyr). In contrast, the stellar-to-dynamical mass ratio - which, in principle, would track the efficiency of feedback in the baryonic processes driving galaxy formation - does not appear to correlate with the model parameters. On the Tully-Fisher plane, no significant age segregation is found at fixed circular speed, whereas at fixed stellar-to-dynamical mass fraction, age splits the sample, with older galaxies having faster circular speeds at fixed Ms/Mdyn. Although our model does not introduce any prior constraint on dust reddening, we obtain a strong correlation between colour excess and stellar mass. © 2013 The Authors.