HerMES: Herschel-SPIRE observations of Lyman Break Galaxies

TL;DR

This study uses Herschel-SPIRE observations to analyze the submillimetre properties of high-redshift Lyman Break Galaxies, revealing their infrared luminosities and differences from lower-redshift counterparts through stacking analysis.

Contribution

It provides the first submillimetre detection of UV-selected high-redshift galaxies using stacking, and compares their infrared properties to lower-redshift galaxies, highlighting evolutionary differences.

Findings

LBGs at z~3 have median infrared luminosity of 2.8x10^{12} Lsun.

Stacked submm detection confirms Herschel-SPIRE's effectiveness for high-redshift galaxy studies.

Infrared luminosity estimates from UV data agree for z~2 BX/BM galaxies but not for z~3 LBGs.

Abstract

We present first results of a study of the submillimetre (rest frame far-infrared) properties of z~3 Lyman Break Galaxies (LBGs) and their lower-redshift counterparts BX/BM galaxies, based on Herschel-SPIRE observations of the Northern field of the Great Observatories Origins Deep Survey (GOODS-N). We use stacking analysis to determine the properties of LBGs well below the current limit of the survey. Although LBGs are not detected individually, stacking the infrared luminous LBGs (those detected with Spitzer at 24 microns yields a statistically significant submm detection with mean flux <S_{250}>= 5.9+/-1.4 mJy confirming the power of SPIRE in detecting UV-selected high-redshift galaxies at submillimetre wavelengths. In comparison, the Spitzer 24 microns detected BX/BM galaxies appear fainter with a stacked value of <S_{250}> = 2.7 +/-0.8 mJy. By fitting the Spectral Energy Distributions (SEDs) we derive median infrared luminosities, L_{IR}, of 2.8x10^{12} Lsun and 1.5x10^{11} Lsun for z~3 LBGs and BX/BMs, respectively. We find that $L_{IR} estimates derived from present measurements are in good agreement with those based on UV data for z~2 BX/BM galaxies, unlike the case for z~3 infrared luminous LBGs where the UV underestimates the true $L_{IR}. Although sample selection effects may influence this result we suggest that differences in physical properties (such as morphologies, dust distribution and extent of star-forming regions) between z ~3 LBGs and z~2 BX/BMs may also play a significant role.