Abstract
Abstract Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram pressure stripping (RPS) and spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail, as a function of the cluster velocity dispersion, galaxy stellar mass, clustercentric distance, and speed in the intracluster medium. Our model provides a good description of the observed gas truncation radius and of the fraction of SFR observed in the stripped tails, once we take into account the fact that the star formation efficiency in the tails is a factor of ∼5 lower than in the galaxy disk, in agreement with GASP ongoing H i and CO observations. Finally, we estimate the contribution of RPS to the intracluster light (ICL) and find that the average SFR in the tails of ram pressure stripped gas is per cluster. By extrapolating this result to evaluate the contribution to the ICL at different epochs, we compute an integrated average value per cluster of ∼4 × 109 M ☉ of stars formed in the tails of RPS galaxies since z ∼ 1.
Highlights
Environmental effects play a primary role in galaxy evolution and in particular in shaping the star formation (SF) history of galaxies in groups and even more so in clusters
This paper is organised as follow: in Sect. 2 we present our data and in Sect. 3 we describe our measurements methods and analysis; in Sect. 4 we presents our observational results; in Sect. 5 we propose a simple analytical approach to estimate the fraction of star formation rate (SFR) in the tails and we compare the results with our observations; in Sect. 6 we use our data to estimate the total contribution to the intracluster light (ICL) due to ram-pressure stripping; in Sect. 7 we summarise our work and conclusions
The correlation between SFRTOT and galaxy stellar mass is shown in the upper panel in Fig. 3; a detailed analysis of this correlation is presented in Vulcani et al (2018), which demonstrates a statistically significant enhancement of the SFR in both the discs and the tails of GASP ram-pressure stripped galaxies compared to undisturbed galaxies
Summary
Environmental effects play a primary role in galaxy evolution and in particular in shaping the star formation (SF) history of galaxies in groups and even more so in clusters (see e.g. Boselli & Gavazzi 2006; Guglielmo et al 2015). RPS is the result of the interaction between the galaxy interstellar medium and the hot and dense intracluster medium (ICM); it affects only the gas in a galaxy with no direct effect on its stellar component but it has dramatic consequences on the formation of new stars. In the vast majority of the ram-pressure stripped tails that have been studied so far there is evidence of ongoing star formation (see Poggianti et al 2019a for a literature review) in agreement with theoretical predictions of models and numerical simulations (e.g. Kapferer et al 2009; Tonnesen & Bryan 2012). The only known case of a well studied jellyfish galaxy showing an extended Hα tail but no reported evidence of ongoing SF is NGC4569 in the Virgo cluster, which is affected both by ram pressure and a strong close interaction. The only known case of a well studied jellyfish galaxy showing an extended Hα tail but no reported evidence of ongoing SF is NGC4569 in the Virgo cluster, which is affected both by ram pressure and a strong close interaction. Boselli et al (2016) suggested than mechanisms other than photoionisation, –such as shocks, heat conduction or magnetohydrodynamic waves– are responsible for the gas ionisation
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