Abstract
Abstract Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) observations of a sample of distant (z ∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift (z ∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (Hα and even more astonishing [O ii](3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved [O ii]/Hα line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low-z galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.
Highlights
Clusters of galaxies are among the densest regions of the Universe, and are characterized by a peculiar morphological mix of their galaxy population that results in the prevalence of early type galaxies over the late type ones
In this paper we will present the characterization of 13 galaxies with ionized gas tails due to ongoing rampressure stripping in two massive intermediate redshift (∼ 0.3−0.4) clusters made possible by the MUSE Guaranteed Time Observations (GTO) data (Bacon et al 2017; Richard et al 2021)
In this paper we have presented the characterization of 13 RPS galaxies located in the central region of the two intermediate redshift (∼ 0.3) clusters A2744 and A370
Summary
Clusters of galaxies are among the densest regions of the Universe, and are characterized by a peculiar morphological mix of their galaxy population that results in the prevalence of early type galaxies over the late type ones (see Dressler 1980; Fasano et al 2015, for the nearest clusters). The first spectroscopic evidence of ram-pressure events in a z=0.7 cluster, detected using the MUSE IFU spectrograph, is reported in Boselli et al (2019) where two long tails of ionized gas departing from two galaxies close to the cluster center have been revealed through their [OII] emission These two galaxies show a very large line-of-sight velocity with respect to the host cluster, and still display a tail in the plane of the sky, due to an edge-on stripping. In this paper we will present the characterization of 13 galaxies with ionized gas tails due to ongoing rampressure stripping in two massive intermediate redshift (∼ 0.3−0.4) clusters made possible by the MUSE Guaranteed Time Observations (GTO) data (Bacon et al 2017; Richard et al 2021) This is part of an ongoing, systematic search of tailed ram pressure stripped galaxies in a large sample of intermediate redshift clusters (0.3-0.6). We will use in the paper a standard cosmology of (H0=70 km s−1 Mpc−1, ΩM =0.3, Ωλ=0.7)
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