PRIN 2022: PROGETTI DI RICERCA DI RILEVANTE INTERESSE NAZIONALE

                               Prot. 2022KCS97B - CUP: J53D23001620006                                      

Research Unit 1: Matteo Costanzi (UniTs) - finanziamento 139.050 Euro di cui 125.644 Euro di contributo MUR

Research Unit 2: Emiliano Munari (INAF-Trieste) - CUP C53D23001140006 - finanziamento 122.836 euro di cui 98.779 euro di contributo MUR

Galaxy clusters are one of the main cosmological probes of the next coming wide field photometric surveys, such as Euclid or LSST, with the promise of helping shedding light on many fundamental questions in cosmology such as the nature of dark matter and dark energy.

Yet, despite the huge progress made over the last decade, a sizable amount of the cosmological information encoded in this data risks to remain unexploited due to our limited capability of connecting the observed properties of the large scale structure to our theoretical models.

Photometric cluster catalogs exemplify this limitation: different sources of systematics hamper our capability of calibrating cluster masses from observable mass proxies, and thus, of interpreting the data within our theoretical framework. This is especially true for low to intermediate mass systems (13.5≲log(M)≲14.5): these objects outnumber by orders of magnitudes the number of massive clusters in photometric cluster catalogs, but the low signal-to-noise (S/N) of these detections makes these systems especially prone to systematics which hinder their cosmological utility.

The EMC2 proposal aims at unlocking the full cosmological utility of the forthcoming Euclid cluster catalog by a careful characterization of the sample over the whole mass range probed by the survey with particular emphasis on the poorly understood low S/N detections which limit the statistical power of ongoing and future photometric cluster surveys. 

We plan to achieve our goal by pursuing three main lines of investigation:

1) the optimization of the cluster finder algorithms and mass proxy definition used to build the cosmological sample;

2) the development of a model to accurately describe the relation between the photometric mass proxies and underlying halo mass over the whole mass range probed by the survey;

3) the development of a methodology to optimally exploit the sparse cluster member galaxies’ spectroscopic data that will be available from the Euclid survey for cluster mass calibration.

Publications:

• Euclid: Exploring observational systematics in cluster cosmology -- a comprehensive analysis of cluster counts and clustering - Fumagalli, A., et al. (2025), submitted to AA, arXiv e-prints, DOI: 10.48550/arXiv.2510.13509 

• Selection function of clusters in Dark Energy Survey year 3 data from cross-matching with South Pole Telescope detections - Grandis, S., et al. (2025), Astronomy and Astrophysics, DOI: 10.1051/0004-6361/202554177 

• Euclid preparation: LXV. Determining the weak lensing mass accuracy and precision for galaxy clusters - Euclid Collaboration, et al. (2025), Astronomy and Astrophysics, DOI: 10.1051/0004-6361/202452122 

• Optical galaxy cluster mock catalogs with realistic projection effects: Validations with the SDSS clusters - Lee, A., et al. (2025), Physical Review D, DOI: 10.1103/PhysRevD.111.063502 

• A forward analytical model for the optical selection bias on galaxy cluster lensing profiles - Costanzi, M., et al. (2026), submitted to PRD

• CosmoPostProcess a simulation calibrated framework for weak lensing selection bias in richness-selected galaxy clusters - Ingrao, R., et al (in prep)

• Euclid preparation: Spectroscopy constrains the cluster mass-richness relation - Ho, M. et al (in prep), submitted to Euclid editorial board

• CLASH-VLT: Galaxy cluster MACS J0329–0211 and its surroundings using galaxies as kinematic tracers - Girardi, M.,  et al. (2024), Astronomy and Astrophysics, Vol. 692, A175, DOI: 10.1051/0004-6361/202451286 

• The final WaZP galaxy cluster catalog of the Dark Energy Survey and comparison with SZE data - Benoist, C., et al 2026, submitted to AA and accepted, arXiv e-prints, doi:10.48550/arXiv.2507.05360

• Impact of weak-lensing mass-mapping algorithms on cosmology inference - Tersenov, Baumont et al.  A&A, 698, A25 (2025) doi: 10.1051/0004-6361/202553707

• Euclid Quick Data Release (Q1) - First detections from the Euclid galaxy cluster workflow - Euclid Collaboration, et al. (2025), A&A Special Issue 'Euclid Quick Data Release (Q1) DOI: 10.1051/0004-6361/202554937