NIKA2 cosmological legacy survey: Blind detection of galaxy clusters in the COSMOS field via the Sunyaev-Zel’dovich effect

Chérouvrier, D., Macías-Pérez, J. F., Désert, F. X., Adam, R., Ade, P. ORCID: https://orcid.org/0000-0002-5127-0401, Ajeddig, H., Amarantidis, S., André, P., Aussel, H., Barrena, R., Beelen, A., Benoît, A., Berta, S., Béthermin, M., Bongiovanni, A., Bounmy, J., Bourrion, O., Bing, L.-J., Calvo, M., Catalano, A., De Petris, M., Doyle, S. ORCID: https://orcid.org/0000-0002-9054-986X, Driessen, E. F. C., Ejlali, G., Ferragamo, A., Fernández-Torreiro, M., Gomez, A., Goupy, J., Hanser, C., Katsioli, S., Kéruzoré, F., Kramer, C., Ladjelate, B., Lagache, G., Leclercq, S., Lestrade, J.-F., Madden, S. C., Maury, A., Mayet, F., Melin, J.-B., Monfardini, A., Moyer-Anin, A., Muñoz-Echeverría, M., Myserlis, I., Neri, R., Paliwal, A., Perotto, L., Pisano, G., Pointecouteau, E., Ponthieu, N., Pratt, G. W., Revéret, V., Rigby, A. J., Ritacco, A., Roussel, H., Ruppin, F., Sánchez-Portal, M., Savorgnano, S., Schuster, K., Sievers, A., Tucker, C. and Zylka, R. 2025. NIKA2 cosmological legacy survey: Blind detection of galaxy clusters in the COSMOS field via the Sunyaev-Zel’dovich effect. Astronomy & Astrophysics 700 , A30. 10.1051/0004-6361/202554450

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Abstract

Clusters of galaxies, formed in the latest stages of structure formation, are unique cosmological probes. With the advent of large CMB surveys like those from the Planck satellite, the ACT and SPT telescopes, we now have access to a large number of galaxy clusters detected at millimeter wavelengths via the thermal Sunyaev-Zel’dovich (tSZ) effect. Nevertheless, it is interesting to complement them with high-angular-resolution (tens of arcseconds) observations to target the lowest-mass and highest-redshift clusters. This is the case of observations with the NIKA2 camera, which is installed on the IRAM 30-m telescope in Pico Veleta, Spain. We used the existing 150 GHz (2 mm) data from the NIKA2 Cosmological Legacy Survey (N2CLS) Large Program to blindly search for galaxy clusters in the well-known COSMOS field, across a 877 arcmin2 region centered on (RA, Dec)J2000 = (10h00m28.81s, +02d17m30.44s). We first developed a dedicated data reduction pipeline to construct NIKA2 maps at 2 mm. We then used a matched-filter algorithm to extract cluster candidates assuming a universal pressure profile to model the expected cluster tSZ signal. We computed the purity and completeness of the sample by applying the previous algorithm to simulated maps of the sky signal in the COSMOS field, including tSZ contribution, point sources and instrumental noise. We find a total of 16 cluster candidates at S/N > 4, from which eight have either an optical or X-ray cluster (or group of galaxies) counterpart. This is the first blind detection of clusters of galaxies at mm wavelengths at 18″ angular resolution. For candidates with available redshift estimates, we derived their mass by modeling the cluster tSZ signal with a universal pressure profile via a MCMC analysis. From this analysis, we confirm that NIKA2 and the IRAM 30-m telescope should be sensitive to low-mass clusters at intermediate and high redshift, complementing current and planned large tSZ-based cluster surveys.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	EDP Sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	29 August 2025
Date of Acceptance:	2 June 2025
Last Modified:	29 Aug 2025 15:15
URI:	https://orca.cardiff.ac.uk/id/eprint/180745

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