The GALEX-SDSS NUV & FUV Flux Density and Local Star-Formation Rate

TL;DR

This paper calculates local UV flux densities and star formation rates using GALEX and SDSS data, providing improved estimates that account for dust attenuation and cosmic variance, aligning with recent Halpha-based measurements.

Contribution

It introduces a new method for measuring local UV flux densities and SFRs over larger volumes, with dust correction, improving agreement with other indicators.

Findings

Calculated UV flux densities at low redshift with dust correction.

Derived a star formation rate density of 0.0312±0.0045 h M⊙ yr^-1 Mpc^-3.

Found that accounting for cosmic variance reconciles most low-redshift SFR estimates.

Abstract

We calculate the local UV flux density in the GALEX MIS FUV and NUV bands using redshifts provided by SDSS DR7. Luminosity functions are calculated for the overlapping MIS and SDSS sample, allowing flux densities to be measured and the local star formation rate (SFR) to be calculated using volumes much larger than previous FUV based estimates. We calculate flux densities for a dust corrected low redshift (0.013 < z < 0.1) sample of f[FUV] = 22.24 \pm 3.13 \times 10^25 h ergs s^-1 Hz^-1 Mpc^-3, f[NUV] = 38.54 \pm 5.30 \times 10^25 h ergs s^-1 Hz^-1 Mpc^-3. The star formation rate density found is 0.0312\pm0.0045 h M\odot yr^-1 Mpc^-3. This is larger than published rates recently found using the UV implied SFR, though the major discrepancy is the correction made for dust attenuation and once this is dealt with consistently the results agree well. These values are also consistent with recent Halpha derived SFRs. Once cosmic variance is taken into account most of the recent SFRs at low redshift (z < 0.3) found in the literature can be brought into agreement, however the lowest redshift values (z < 0.045) do appear to be significantly lower.