NIKA2 Cosmological Legacy Survey. First measurement of the confusion noise at the IRAM 30 m telescope
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.
Authors
- Á. Bongiovanni (ORCID: https://orcid.org/0000-0002-3557-3234)
- Arlene Moore Sievers
- F. Ruppin (ORCID: https://orcid.org/0000-0002-0955-8954)
- F. Kéruzoré (ORCID: https://orcid.org/0000-0002-9605-5588)
- S. Leclercq
- P. A. R. Ade (ORCID: https://orcid.org/0000-0002-5127-0401)
- A. Maury (ORCID: https://orcid.org/0000-0002-3801-8754)
- C. Hanser (ORCID: https://orcid.org/0009-0002-9656-9025)
- Stergios Amarantidis (ORCID: https://orcid.org/0000-0001-7948-5714)
- A. J. Rigby (ORCID: https://orcid.org/0000-0002-3351-2200)
- N. Ponthieu
- A. Gómez (ORCID: https://orcid.org/0000-0002-8752-1401)
- K. Schuster
- M. Muñoz-Echeverría (ORCID: https://orcid.org/0000-0002-5375-9083)
- G. Lagache (ORCID: https://orcid.org/0000-0003-1492-2519)
- I. Myserlis (ORCID: https://orcid.org/0000-0003-3025-9497)
- G. Ejlali (ORCID: https://orcid.org/0000-0002-4010-5793)
- E. F. C. Driessen (ORCID: https://orcid.org/0000-0002-7540-1103)
- H. Ajeddig
- V. Revéret (ORCID: https://orcid.org/0000-0002-5461-2462)
- C. Tucker (ORCID: https://orcid.org/0000-0002-1851-3918)
- S. Savorgnano (ORCID: https://orcid.org/0009-0008-6617-7972)
- M. De Petris (ORCID: https://orcid.org/0000-0001-7859-2139)
- M. Calvo Gomez (ORCID: https://orcid.org/0000-0001-5588-1448)
- S. C. Madden
- O. Bourrion
- B. Ladjelate
- M. Béthermin (ORCID: https://orcid.org/0000-0002-3915-2015)
- S. Katsioli (ORCID: https://orcid.org/0000-0001-7095-8933)
- C. Krämer (ORCID: https://orcid.org/0000-0002-4908-4925)
- R. Adam (ORCID: https://orcid.org/0009-0000-5380-1109)
- L. Bing (ORCID: https://orcid.org/0000-0002-0440-7129)
- F. Mayet
- R. Zylka
- A. Beelen (ORCID: https://orcid.org/0000-0003-3201-0185)
- F. -X. Désert
- G. Pisano (ORCID: https://orcid.org/0000-0003-4302-5681)
- J. Goupy (ORCID: https://orcid.org/0000-0003-4497-4002)
- L. Perotto (ORCID: https://orcid.org/0000-0001-6937-5052)
- A. Paliwal (ORCID: https://orcid.org/0000-0001-9337-3938)
- A. Monfardini
- A. Ferragamo
- J. Bounmy
- A. Moyer-Anin
- H. Roussel
- S. Berta
- M. Sánchez-Portal
- A. Ritacco
- A. Benoît
- A. Catalano
- S. Doyle
- J.F. Macías-Pérez (ORCID: https://orcid.org/0000-0002-5385-2763)
- P. André
- J. F. Lestrade
- R. Neri
- D. Chérouvrier
Institutions
- Université Claude Bernard Lyon 1 (FR)
- Institut polytechnique de Grenoble (FR)
- University of Rome Tor Vergata (IT)
- Institució Catalana de Recerca i Estudis Avançats (ES)
- Argonne National Laboratory (US)
- Centre National de la Recherche Scientifique (FR)
- University of Leeds (GB)
- Université Toulouse III - Paul Sabatier (FR)
- University of Sussex (GB)
- Université Fédérale de Toulouse Midi-Pyrénées (FR)
- Lyon College (US)
- National and Kapodistrian University of Athens (GR)
- Université Côte d'Azur (FR)
- Université Paris Cité (FR)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris Sciences et Lettres (FR)
- Université Paris-Saclay (FR)
- Institut d'Astrophysique de Paris (FR)
- Observatoire astronomique de Strasbourg (FR)
- Sorbonne Université (FR)
- Astrophysique, Instrumentation et Modélisation (FR)
- Institut de Radioastronomie Millimétrique (FR)
- Laboratoire d’Astrophysique de Marseille (FR)
- Institute of Space Sciences (ES)
- National Observatory of Athens (GR)
- Observatoire de la Côte d’Azur (FR)
- CEA Paris-Saclay (FR)
- Centro de Astrobiología (ES)
- Institut National de Physique Nucléaire et de Physique des Particules (FR)
- Institut Néel (FR)
- Institute for Research in Fundamental Sciences (IR)
- Cardiff University (GB)
- Sapienza University of Rome (IT)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2025-12-19
- DOI
- https://doi.org/10.1051/0004-6361/202554530
- Citations
- 1
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 1.15
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