A wealth of interacting galaxies in the interacting cluster A2670
Fecha
2023
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Universidad de Valparaíso
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Facultad
Facultad de Ciencias
Departamento o Escuela
Facultad de Ciencias. Instituto de Física y Astronomía
Determinador
Recolector
Especie
Nota general
Magíster en Astrofísica. Universidad de Valparaíso. 2023.
Resumen
Galaxy clusters are among the largest and most massive known gravitationally bound structures in the Universe, that continue growing through the accretion of galaxies from field, groups and even other clusters. It is thus expected that the evolution of galaxies depends on interactions with their evolving environments and that cluster mergers accelerate galaxy evolution as they present violent environments where ram-pressure and galaxy-galaxy interactions can be enhanced. To understand how galaxies evolve across cosmic environment, we study in great detail the growth of the interacting system A2670, a massive nearby galaxy cluster (ꓟ₂₀₀= 8.5 ± 1.2 × 10¹⁴M, z = 0.0763, ꓣ₂₀₀= 1.91 ± 0.1 Mpc), with clear evidences of past interactions. We built a complete and homogeneous photometric catalogue using public data from Legacy Survey (LS) DR9 for galaxies within the cluster and out to its infall region (5× ꓣ₂₀₀) and public spectroscopic data from Sloan Digital Sky Survey (SDSS) were also collected, available for some galaxies in this large area explored. We use 2D and 3D methods to identify substructures using the positions collected and velocities when these were available. We find a wealth of substructures, including the main cluster core, a large infalling group at the same velocity and several other smaller substructures. Then, to study the impact of these substructures on the evolution of member galaxies, we visually examine the optical morphologies of 843 galaxies brighter than ꓟᵣ= −20 in and around the cluster through custom-made codes and algorithms. We found 236 interacting galaxies, with ∼ 42 − 63% of those being ram-pressure stripping (RPS) candidates and ∼ 31 − 37% possible gravitational interactions (GRAV). Interestingly, the interacting galaxies follow the substructures found, with the richest structures having more interacting galaxies, with a mild indication that RPS is dominant at the cluster core but also clearly present at the outskirts, close to 5 × ꓣ₂₀₀. Overall, the fraction of RPS candidates found is the largest to date for a single system, making A2670 a unique environment to study pre and post-processing. Finally, we measured the visible tails angle in RPS candidates (a.k.a “jellyfish” galaxies) to use it as a proxy of the direction of motion. We find a not as clear trend as seen in regular clusters, likely due to the combined effect of pre- and post-processing, revealing a complex dynamical behavior, with a mixture of radial and non-radial infall into the main cluster.
Descripción
Lugar de Publicación
Valparaíso
Auspiciador
Palabras clave
CUMULO DE GALAXIAS, EVOLUCION
Licencia
Atribución-NoComercial-CompartirIgual 3.0 Chile (CC BY-NC-SA 3.0 CL)