The Evolution of the Far-UV Luminosity Function and Star Formation Rate Density of the Chandra Deep Field South from z=0.2-1.2 with Swift/UVOT

TL;DR

This study measures the evolution of the far-UV luminosity function and star formation rate density in the Chandra Deep Field South from z=0.2 to 1.2 using Swift/UVOT data, revealing significant luminosity evolution and higher star formation rates than previously reported.

Contribution

It provides new measurements of the far-UV luminosity function and star formation rate density evolution using deep UVOT imaging, with improved estimates accounting for dust attenuation.

Findings

Luminosity function shows M* fades by ~2 magnitudes from z~1 to z~0.3.

Star formation rate density increases as (1+z)^1.9 up to z~1.

Star formation rates are about twice as high as previous measurements.

Abstract

We use deep Swift UV/Optical Telescope (UVOT) near-ultraviolet (1600A to 4000A) imaging of the Chandra Deep Field South to measure the rest-frame far-UV (FUV; 1500A) luminosity function (LF) in four redshift bins between z=0.2 and 1.2. Our sample includes 730 galaxies with u < 24.1 mag. We use two methods to construct and fit the LFs: the traditional V_max method with bootstrap errors and a maximum likelihood estimator. We observe luminosity evolution such that M* fades by ~2 magnitudes from z~1 to z~0.3 implying that star formation activity was substantially higher at z~1 than today. We integrate our LFs to determine the FUV luminosity densities and star formation rate densities from z=0.2 to 1.2. We find evolution consistent with an increase proportional to (1+z)^1.9 out to z~1. Our luminosity densities and star formation rates are consistent with those found in the literature, but are, on average, a factor of ~2 higher than previous FUV measurements. In addition, we combine our UVOT data with the MUSYC survey to model the galaxies' ultraviolet-to-infrared spectral energy distributions and estimate the rest-frame FUV attenuation. We find that accounting for the attenuation increases the star formation rate densities by ~1 dex across all four redshift bins.