The Link Between SCUBA and Spitzer: Cold Galaxies at z<1

TL;DR

This study reveals that distant IR-luminous galaxies at z<1 have colder dust properties than local counterparts, suggesting significant evolution in their dust and star formation characteristics, and potentially linking them to high-redshift submillimetre galaxies.

Contribution

It identifies a population of cold, high-redshift IR galaxies with shifted SED peaks, bridging local IR galaxies and high-redshift submillimetre sources, highlighting their evolutionary significance.

Findings

Distant IR galaxies have longer wavelength SED peaks than local ones.

These galaxies exhibit lower dust temperatures, indicating evolution in dust properties.

They may serve as the missing link between local IR sources and high-redshift SMGs.

Abstract

We show that the far-IR properties of distant Luminous and Ultraluminous InfraRed Galaxies (LIRGs and ULIRGs) are on average divergent from analogous sources in the local Universe. Our analysis is based on Spitzer MIPS and IRAC data of L_IR>10^10 L_solar, 70um-selected objects in the 0.1<z<2 redshift range and supported by a comparison with the IRAS Bright Galaxy Sample. The majority of the objects in our sample are described by Spectral Energy Distributions (SEDs) which peak at longer wavelengths than local sources of equivalent total infrared luminosity. This shift in SED peak wavelength implies a noticeable change in the dust and/or star-forming properties from z~0 to the early Universe, tending towards lower dust temperatures, indicative of strong evolution in the cold dust, `cirrus', component. We show that these objects are potentially the missing link between the well-studied local IR-luminous galaxies, Spitzer IR populations and SCUBA sources -- the z<1 counterparts of the cold z>1 SubMillimetre Galaxies (SMGs) discovered in blank-field submillimetre surveys. The Herschel Space Observatory is well placed to fully characterise the nature of these objects, as its coverage extends over a major part of the far-IR/submm SED for a wide redshift range.