Confusion of extragalactic sources in the far infrared: a baseline assessment of the performance of PRIMAger in intensity and polarization

Abstract

Because of their limited angular resolution, far-infrared telescopes are usually affected by confusion phenomenon. Since several galaxies can be located in the same instrumental beam, only the brightest objects emerge from the fluctuations caused by fainter sources. The probe far-infrared mission for astrophysics imager (PRIMAger) will observe the mid- and far-infrared (25-235 $\mu$m) sky both in intensity and polarization. We aim to provide predictions of the confusion level and its consequences for future surveys. We produced simulated PRIMAger maps affected only by the confusion noise using the simulated infrared extragalactic sky (SIDES) semi-empirical simulation. We then estimated the confusion limit in these maps and extracted the sources using a basic blind extractor. By comparing the input galaxy catalog and the extracted source catalog, we derived various performance metrics as completeness, purity, and the accuracy of various measurements. In intensity, we predict that the confusion limit increases rapidly with increasing wavelength. The confusion limit in polarization is more than 100x lower. The measured flux density is dominated by the brightest galaxy in the beam, but other objects also contribute at longer wavelength (~30% at 235 $\mu$m). We also show that galaxy clustering has a mild impact on confusion in intensity (up to 25%), while it is negligible in polarization. In intensity, a basic blind extraction will be sufficient to detect galaxies at the knee of the luminosity function up to z~3 and 10${}^{11}$ M${}_{\odot }$ main-sequence galaxies up to z~5. In polarization for a conservative sensitivity, we expect ~8 000 detections up to z=2.5 opening a totally new window on the high-z dust polarization. Finally, we show that intensity surveys at short wavelength and polarization surveys at long wavelength tend to reach confusion at similar depth. There is thus a strong synergy.

24 pages, 18 figures, 6 tables, Accepted by A&A

References in corpus (15)

• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• The Cosmic Infrared Background Resolved by Spitzer. Contributions of Mid-Infrared Galaxies to the Far-Infrared Background
• The 0.4 < z < 1.3 star formation history of the Universe as viewed in the far-infrared
• Evolution of the dust emission of massive galaxies up to z=4 and constraints on their dominant mode of star formation
• An ALMA survey of submillimetre galaxies in the Extended Chandra Deep Field South: High resolution 870um source counts
• Intrinsic alignments of SDSS-III BOSS LOWZ sample galaxies
• The Astrodust+PAH Model: A Unified Description of the Extinction, Emission, and Polarization from Dust in the Diffuse Interstellar Medium
• Simulated observations of sub-millimetre galaxies: the impact of single-dish resolution and field variance
• CONCERTO: High-fidelity simulation of millimeter line emissions of galaxies and [CII] intensity mapping
• Polarized thermal emission from dust in a galaxy at redshift 2.6
• NIKA2 Cosmological Legacy Survey: Survey Description and Galaxy Number Counts
• Super-resolving Herschel imaging: a proof of concept using Deep Neural Networks
• The magnetic fields of starburst galaxies. I. Identification and characterization of the thermal polarization in the galactic disk and outflow
• The polarized spectral energy distribution of NGC 4151
• Disentangling the co-evolution of galaxies and supermassive black holes with PRIMA

Cited by in corpus (2)

• Synergy between Roman and PRIMA imaging capabilities for large extragalactic surveys
• The NIKA2 cosmological legacy survey at 2 mm: catalogs, colors, redshift distributions, and implications for deep surveys