The HerMES submillimetre local and low-redshift luminosity functions
2016
We used wide-area surveys over 39 deg2 by the HerMES (Herschel Multi-tiered Extragalactic
Survey) collaboration, performed with the Herschel Observatory SPIRE multiwavelength
camera, to estimate the low-redshift, 0.02 < z < 0.5, monochromatic luminosity functions
(LFs) of galaxies at 250, 350 and 500 μm. Within this redshift interval, we detected 7087
sources in five independent sky areas, ∼40 per cent of which have spectroscopic redshifts,
while for the remaining objects photometric redshifts were used. The SPIRE LFs in different
fields did not show any field-to-field variations beyond the small differences to be expected
from cosmic variance. SPIRE flux densities were also combined with Spitzer photometry
and multiwavelength archival data to perform a complete spectral energy distribution fitting
analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric
infrared (IR; 8–1000 μm) LFs and their low-z evolution from a combination of statistical
estimators. Integration of the latter prompted us to also compute the local luminosity density
and the comoving star formation rate density (SFRD) for our sources, and to compare them
with theoretical predictions of galaxy formation models. The LFs show significant and rapid
luminosity evolution already at low redshifts, 0.02 < z < 0.2, with L∗
IR
∝ (1 + z)6.0±0.4 and
�
∗
IR
∝ (1 + z)−2.1±0.4, L∗
250
∝ (1 + z)5.3±0.2 and �
∗
250
∝ (1 + z)−0.6±0.4 estimated using the IR
bolometric and the 250 μm LFs, respectively. Converting our IR LD estimate into an SFRD
assuming a standard Salpeter initial mass function and including the unobscured contribution
based on the UV dust-uncorrected emission from local galaxies, we estimate an SFRD scaling
of SFRD0 + 0.08z, where SFRD0 � (1.9 ± 0.03) × 10−2 [M� Mpc−3] is our total SFRD
estimate at z ∼ 0.02.
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