paper

The Munich Near--Infrared Cluster Survey (MUNICS) -- VI. The stellar masses of K-band selected field galaxies to z ~ 1.2

arXiv:astro-ph/0403041 · doi:10.1086/420781

Abstract

We present a measurement of the evolution of the stellar mass function in four redshift bins at 0.4 < z < 1.2 using a sample of more than 5000 K-selected galaxies drawn from the MUNICS dataset. Our data cover the stellar mass range 10^10 < M/Msun < 10^12. We derive K-band mass-to-light ratios by fitting a grid of composite stellar population models of varying star formation history, age, and dust extinction to BVRIJK photometry. We discuss the evolution of the average mass-to-light ratio as a function of galaxy stellar mass in the K-band and in the B-band. We compare our stellar mass function at z > 0 to estimates obtained similarly at z=0. We find that the mass-to-light ratios in the K-band decline with redshift. This decline is similar for all stellar masses above $1 0^{1} 0 M s u n . L o w er ma ss g a l a x i es ha v e l o w er ma ss - t o - l i g h t r a t i os a t a l l r e d s hi f t s . T h es t e l l a r ma ss f u n c t i o n e v o l v ess i g ni f i c an tl y t oz = 1.2. T h e t o t a l n or ma l i z a t i o n d ecr e a ses b y a f a c t or o f 2, t h ec ha r a c t er i s t i c ma ss (t h e k n ee) s hi f t s t o w a r d s l o w er ma sses an d t h e b r i g h t e n d t h er e f or es t ee p e n s w i t h r e d s hi f t . T h e am o u n t o f n u mb er d e n s i t y e v o l u t i o ni s a s t r o n g f u n c t i o n o f s t e l l a r ma ss, w i t hm or e ma ss i v esy s t e m ss h o w in g f a s t er e v o l u t i o n t han l ess ma ss i v esy s t e m s . W e d i sc u ss t h e t o t a l s t e l l a r ma ss d e n s i t y o f t h e u ni v er se an d co m p a r eo u r r es u l t s t o t h e v a l u es f r o m t h e l i t er a t u r e b o t ha tl o w er an d hi g h er r e d s hi f t . W e f in d t ha tt h es t e l l a r ma ss d e n s i t y a t z 1 i sr o ug h l y 50$ z \sim 1$. Our data favor a scenario in which the growth of the most massive galaxies is dominated by accretion and merging rather than star formation which plays a larger role in the growth of less massive systems.

Accepted for publication in ApJ, issues of style and typos corrected to match printed version (proofs)