The Herschel-PACS North Ecliptic Pole Survey

TL;DR

This paper presents a comprehensive Herschel-PACS survey of the North Ecliptic Pole, producing high-quality maps and catalogues that extend previous data, and analyzing galaxy counts to understand infrared galaxy evolution and their contribution to the cosmic infrared background.

Contribution

It provides the deepest Herschel-PACS source catalogues for the North Ecliptic Pole and compares observed galaxy counts with evolution models to identify key galaxy populations.

Findings

Catalogues contain 1384 and 630 sources at 100 and 160 microns.

Detected sources extend to flux densities of 6mJy and 19mJy.

Galaxy counts align with previous models and suggest luminous infrared galaxies dominate evolution.

Abstract

A detailed analysis of Herschel-PACS observations at the North Ecliptic Pole is presented. High quality maps, covering an area of 0.44 square degrees, are produced and then used to derive potential candidate source lists. A rigorous quality control pipeline has been used to create final legacy catalogues in the PACS Green 100 micron and Red 160 micron bands, containing 1384 and 630 sources respectively. These catalogues reach to more than twice the depth of the current archival Herschel/PACS Point Source Catalogue, detecting 400 and 270 more sources in the short and long wavelength bands respectively. Galaxy source counts are constructed that extend down to flux densities of 6mJy and 19mJy (50% completeness) in the Green 100 micron and Red 160 micron bands respectively. These source counts are consistent with previously published PACS number counts in other fields across the sky. The source counts are then compared with a galaxy evolution model identifying a population of luminous infrared galaxies as responsible for the bulk of the galaxy evolution over the flux range (5-100mJy) spanned by the observed counts, contributing approximate fractions of 50% and 60% to the cosmic infrared background (CIRB) at 100 microns and 160 microns respectively.