NIKA2 Cosmological Legacy Survey. First measurement of the confusion noise at the IRAM 30 m telescope

Year: 2025

Type: article

Abstract: The NIKA2 Cosmological Legacy Survey (N2CLS) is a large programme using the NIKA2 dual-band camera on the IRAM 30 m telescope. Its goal is to improve our understanding of the physics of distant Dusty Star Forming Galaxies (DSFGs) by carrying out deep surveys of two fields, GOODS-North and COSMOS. This work is focussed on GOODS-North, which was observed for 78.2 hours, simultaneously at 1.2 and 2 mm, with a field of view of ∼240 arcmin 2 . With such a deep integration, we were able to measure, for the first time, the confusion noise limits at the 30 m telescope using the best sampled ∼62 arcmin 2 and masking sources with a flux greater than 0.54 or 0.17 mJy at 1.2 or 2 mm, respectively. We found a confusion noise of 139.1 −19.2 +15.9 ±11.9 μJy/beam at 1.2 mm and 38.6 −13.1 +9.6 ±3.7 μJy/beam at 2 mm (the first uncertainty is statistical, the second is the cosmic variance). In this region, this corresponds to half the instrumental noise. To derive these estimates, we devised a novel estimator, referred to as the cross variance, which also enabled us to estimate the correlated confusion noise between the two bands. Thus, we obtained a result of 49.6 −24.8 +15.9 ±6.4 μJy/beam. These values are consistent with the state of the art Simulated Infrared Dusty Extragalactic Sky (SIDES) model.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202554530

Institutions: Centre National de la Recherche Scientifique, Aix-Marseille Université, Laboratoire d’Astrophysique de Marseille, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur, Cardiff University, Université Paris Cité, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Astrophysique, Instrumentation et Modélisation, Institut de Radioastronomie Millimétrique, Instituto de Radioastronomía Milimétrica, Institut Néel, Observatoire astronomique de Strasbourg, Université de Strasbourg, University of Sussex, Institut polytechnique de Grenoble, Institut National de Physique Nucléaire et de Physique des Particules, Sapienza University of Rome, Institute for Research in Fundamental Sciences, Consejo Superior de Investigaciones Científicas, Centro de Astrobiología, National and Kapodistrian University of Athens, National Observatory of Athens, Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, Argonne National Laboratory, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères, Université Pierre-et-Marie-Curie, Institució Catalana de Recerca i Estudis Avançats, Institute of Space Sciences, Université Toulouse III - Paul Sabatier, Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, University of Rome Tor Vergata, University of Leeds, Institut d'Astrophysique de Paris, Lyon 1 Université, Université de Lyon, Institut de Physique des 2 Infinis de Lyon

Language: English

Topic: Radio Astronomy Observations and Technology

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,865

Funders: Aix-Marseille Université, European Commission, Agence Nationale de la Recherche, Centre National d’Etudes Spatiales, Max-Planck-Gesellschaft, Centre National de la Recherche Scientifique, Institut National de Physique Nucléaire et de Physique des Particules

Awards: G1190173965, G2121614283, G292453335, G3527965702, Des détecteurs pour Observer l'Univers, G434337789, G5753977096, G5850839165, Observing the millimeter sky with the NIKA2 camera, G7321284446, Better Accuracy and robusTness for Mass Assessment of Neutrino, G8800819381, G880779785, G8963277490, G8964069747, G994248709

OpenAlex ID: W4417466920