The far-infrared/submillimeter properties of galaxies located behind the Bullet cluster

TL;DR

This study uses Herschel observations of the Bullet cluster to analyze the far-infrared properties of high-redshift galaxies, revealing they are scaled-up versions of local lower luminosity galaxies with extended star formation.

Contribution

First detailed spectral energy distribution analysis of lensed high-redshift galaxies behind the Bullet cluster using Herschel data.

Findings

Galaxies have lower infrared luminosities than local ULIRGs.

Star formation occurs on larger scales than in local ultra-luminous infrared galaxies.

Spectral energy distributions are best fit with templates of less luminous local galaxies.

Abstract

The Herschel Lensing Survey (HLS) takes advantage of gravitational lensing by massive galaxy clusters to sample a population of high-redshift galaxies which are too faint to be detected above the confusion limit of current far-infrared/submillimeter telescopes. Measurements from 100-500 micron bracket the peaks of the far-infrared spectral energy distributions of these galaxies, characterizing their infrared luminosities and star formation rates. We introduce initial results from our science demonstration phase observations, directed toward the Bullet cluster (1E0657-56). By combining our observations with LABOCA 870 micron and AzTEC 1.1 mm data we fully constrain the spectral energy distributions of 19 MIPS 24 micron selected galaxies which are located behind the cluster. We find that their colors are best fit using templates based on local galaxies with systematically lower infrared luminosities.This suggests that our sources are not like local ultra-luminous infrared galaxies in which vigorous star formation is contained in a compact highly dust-obscured region. Instead, they appear to be scaled up versions of lower luminosity local galaxies with star formation occurring on larger physical scales.