B. Epinat, T. Contini, W. Mercier, L. Ciesla, B. C. Lemaux, Sean D. Johnson, J. Richard, J. Brinchmann, L. A. Boogaard, D. Carton, L. Michel-Dansac, R. Bacon, D. Krajnović, H. Finley, I. Schroetter, E. Ventou, V. Abril-Melgarejo, A. Boselli, N. F. Bouché, W. Kollatschny, K. Kovač, M. Paalvast, G. Soucail, T. Urrutia, P. M. Weilbacher

Abstract
Context. Galaxies migrate along filaments of the cosmic web from small groups to clusters, which creates the appearance that the evolution of their properties speeds up as environments get denser.

Aims. We introduce the MUSE gAlaxy Groups in COSMOS (MAGIC) survey, which was built to study the impact of environment on galaxy evolution down to low stellar masses over the last 8 Gyr.

Methods. The MAGIC survey consists of 17 Multi-Unit Spectrocopic Exporer (MUSE) fields targeting 14 massive, known structures at intermediate redshift (0.3 < z < 0.8) in the COSMOS area, with a total on-source exposure of 67 h. We securely measured the redshifts for 1419 sources and identified 76 galaxy pairs and 67 groups of at least three members using a friends-of-friends algorithm. The environment of galaxies is quantified from group properties, as well as from global and local density estimators.

Results. The MAGIC survey has increased the number of objects with a secure spectroscopic redshift over its footprint by a factor of about 5 compared to previous extensive spectroscopic campaigns on the COSMOS field. Most of the new redshifts have apparent magnitudes in the z++ band z_app++ > 21.5. The spectroscopic redshift completeness is high: in the redshift range of [O II] emitters (0.25 ≤ z < 1.5), where most of the groups are found, it globally reaches a maximum of 80% down to z_app++ = 25.9, and locally decreases from ∼100% to ∼50% in magnitude bins from z_app++ = 23−24 to z_app++ = 25.5. We find that the fraction of quiescent galaxies increases with local density and with the time spent in groups. A morphological dichotomy is also found between bulge-dominated quiescent and disk-dominated star-forming galaxies. As environment gets denser, the peak of the stellar mass distribution shifts towards M⋆ > 10¹⁰ M_⊙, and the fraction of galaxies with M⋆ < 10⁹ M_⊙ decreases significantly, even for star-forming galaxies. We also highlight peculiar features such as close groups, extended nebulae, and a gravitational arc.

Conclusions. Our results suggest that galaxies are preprocessed in groups of increasing mass before entering rich groups and clusters. We publicly release two catalogs containing the properties of galaxies and groups, respectively.

Keywords
catalogs / galaxies: clusters: general / galaxies: distances and redshifts / galaxies: evolution / galaxies: groups: general / galaxies: high-redshift

Notes
- Based on observations made with ESO telescopes at the Paranal Observatory under programs 094.A-0247, 095.A-0118, 096.A-0596, 097.A-0254, 098.A-0017, 099.A-0246, 0100.A-0607, 0101.A-0282, 0102.A-0327, 0103.A-0563.
- Catalogs described in Appendix A are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/683/A205

Astronomy & Astrophysics
Volume 683, Article Number A205, Number of pages 27
2024 March

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