The Ultraviolet Upturn in field Luminous Red Galaxies at $0.3<z<0.7$

Abstract

We derive the evolution of the ultraviolet upturn colour from a sample of field luminous red galaxies at $0.3<z<0.7$ with $-24<M_r<-21.5$. No individual objects are securely detected, so we stack several hundred galaxies within absolute magnitude and redshift intervals. We find that the colour of the ultraviolet upturn (in observed $NUV-i$ which is approximately equivalent to the classical $FUV-V$ at the redshifts of our targets) does not change strongly with redshift to $z=0.7$. This behaviour is similar to that observed in cluster ellipticals over this same mass range and at similar redshifts and we speculate that the processes involved in the origin of the UV upturn are the same. The observations are most consistent with spectral synthesis models containing a fraction of a helium rich stellar population with abundances between 37\% and 42\%, although we cannot formally exclude a contribution due to residual star formation at the $\sim 0.5\%$ level (however, this appears unlikely for cluster galaxies that are believed to be more quenched). This suggests that the ultraviolet upturn is a primordial characteristic of early type galaxies at all redshifts and that an unexpected nucleosynthesis channel may lead to nearly complete chemical evolution at early times.

8 pages, accepted by MNRAS

References in corpus (14)

• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• UV-extended E-MILES stellar population models: young components in massive early-type galaxies
• A binary model for the UV-upturn of elliptical galaxies (MNRAS version)
• The 2dF-SDSS LRG and QSO (2SLAQ) Luminous Red Galaxy Survey
• Mass loss on the red giant branch: the value and metallicity dependence of Reimers' η in globular clusters
• Comparing dynamical and photometric-stellar masses of early-type galaxies at z ~ 1
• Sub one percent mass fractions of young stars in red massive galaxies
• The Look-back Time Evolution of Far-Ultraviolet Flux from the Brightest Cluster Elliptical Galaxies at z < 0.2
• Binary stars and the UVX in early type galaxies
• Stellar population properties of individual massive early-type galaxies at 1.4 < z < 2
• Clues on the history of early-type galaxies from SDSS spectra and GALEX photometry
• Properties of Luminous Red Galaxies in the Sloan Digital Sky Survey
• Galaxy And Mass Assembly (GAMA): Defining Passive Galaxy Samples and Searching for the UV Upturn
• Environmental Effects on the UV Upturn in Local Clusters of Galaxies