Starburst galaxies in the Hydra i cluster
Journal article, 2025
Studying the impact of environment on star formation and quenching pathways requires statistically relevant samples of galaxies in a wide mass range. We present a new catalog of 196 galaxies of the nearby Hydra I cluster out to ∼1.75r200, consisting of broad u,g,r,i,z along with narrowband Hα measurements. These deep optical images were obtained with the DECam camera (CTIO) and reach down to a surface brightness limit of μ(3σ 10″ × 10″) = 26.9 mag arcsec2 in the g band. We also report the HI properties for 89 cluster members detected with MeerKAT. A color magnitude diagram (CMD) shows a bimodal distribution typical of a cluster population, more evolved than those found in isolation. We combined optical Hα and WISE infrared data to compare the star formation history at two distinct timescales. Differences in the star-forming activity depicted by both populations manifest as a starburst in 24 found members. Of these, 18 starburst galaxies have neutral gas measurements, and they show disturbed HI disks that suggest an environmentally triggered boost in star formation within the last 107 yrs. Processes such as ram pressure stripping or tidal interactions may underlie their enhanced star-forming activity and asymmetric disks. Since Hydra s dynamical history is unclear, we examine the spatial and velocity distribution of the sample. We reveal a possible link between the large-scale structure feeding the Hydra I cluster and the heightened star-forming activity of the starburst galaxies. This feeding pattern matches the few substructures that have been identified in Hydra in previous works, and this may explain their origin. Our results portray a picture of a cluster with an evolved nature, plus a population of new infalling galaxies that manifest the impact of their first contact with the cluster environment through star formation, color, morphology, and gas content transformations.
Galaxies: interactions
Galaxies: evolution
Galaxies: starburst
Galaxies: clusters: general
Galaxies: star formation
Author
C. C. De La Casa
Spanish National Research Council (CSIC)
Kelley Michelle Hess
Spanish National Research Council (CSIC)
Netherlands Institute for Radio Astronomy (ASTRON)
Chalmers, Space, Earth and Environment, Onsala Space Observatory
L. Verdes-Montenegro
Spanish National Research Council (CSIC)
R. Kotulla
University of Wisconsin Madison
Hao Chen
University of Cape Town
Zhejiang Lab
T. H. Jarrett
University of Cape Town
Western Sydney University
University of Hawaii
M. E. Cluver
Swinburne University of Technology
University of the Western Cape
Simon B. De Daniloff
Universidad de Granada
Institut de Radioastronomie Millimétrique (IRAM)
Marie Lou Gendron-Marsolais
Spanish National Research Council (CSIC)
Universite Laval
C. Carignan
Université de Montréal
Université Joseph Ki-Zerbo
University of Cape Town
John S. Gallagher
University of Wisconsin Madison
R. C. Kraan-Korteweg
University of Cape Town
R. Ianjamasimanana
Spanish National Research Council (CSIC)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 704 A264Infrastructure
Onsala Space Observatory
Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202553831