Early results from GLASS-JWST. XX: Unveiling a population of "red-excess'' galaxies in Abell2744 and in the coeval field

分类： 天文学 >> 天文学 提交时间： 2023-02-19

Benedetta Vulcani Tommaso Treu Antonello Calabro Jacopo Fritz Bianca Poggianti Pietro Bergamini Andrea Bonchi Kit Boyett Gabriel Caminha Marco Castellano Alan Dressler Adriano Fontana Karl Glazebrook Claudio Grillo Matthew Malkan Sara Mascia Amata Mercurio Emiliano Merlin Benjamin Metha Takahiro Morishita

摘要： We combine the superior JWST/NIRCam imaging and MUSE data to characterize the properties of galaxies in different environmental conditions in the cluster Abell2744 (z=0.3064) and in its immediate surroundings. Our most striking result is the discovery of a ``red-excess'' population in F200W-F444W colors both in the cluster regions and the field. These galaxies have normal F115W-F150W colors, but are up to 0.8 mag redder than red sequence galaxies in F200W-F444W. They also have rather blue rest frame B-V colors. Galaxies with the largest color deviations are found in the field and at the cluster virial radius, suggesting that mechanisms taking place in these regions might be more effective in producing these colors. Looking at their morphology, many cluster galaxies show signatures consistent with ram pressure stripping, while field galaxies have features resembling interactions and mergers. Our hypothesis is that these galaxies are characterized by dust enshrouded star formation: a JWST/NIRSpec spectrum for one of the galaxies is dominated by a strong PAH at 3.3mu m, suggestive of dust obscured star formation. Larger spectroscopic samples are needed to understand if the color excess is due exclusively to dust-obscured star formation, and the role of environment in triggering it.

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