GASP – XVII. H i imaging of the jellyfish galaxy JO206: gas stripping and enhanced star formation

Abstract

We present VLA H I observations of JO206, a prototypical ram-pressure stripped galaxy in the GASP sample. This massive galaxy (M * = 8.5 × 10 10 M ) is located at a redshift of z = 0.0513, near the centre of the low-mass galaxy cluster, IIZw108 (σ ∼ 575 km s −1 ). JO206 is characterised by a long tail (≥90 kpc) of ionised gas stripped away by ram-pressure. We find a similarly long H I tail in the same direction as the ionised gas tail and measure a total H I mass of 3.2 × 10 9 M . This is about half the expected H I mass given the stellar mass and surface density of JO206. A total of 1.8 × 10 9 M (60%) of the detected H I is in the gas stripped tail. An analysis of the star formation rate shows that the galaxy is forming more stars compared to galaxies with the same stellar and H I mass. On average we find a H I gas depletion time of ∼0.5 Gyr which is about four times shorter than that of "normal" spiral galaxies. We performed a spatially resolved analysis of the relation between star formation rate density and gas density in the disc and tail of the galaxy at the resolution of our H I data. The star formation efficiency of the disc is about 10 times higher than that of the tail at fixed H I surface densities. Both the inner and outer parts of JO206 show an enhanced star formation compared to regions of similar H I surface density in field galaxies. The enhanced star formation is due to ram-pressure stripping during the galaxy's first infall into the cluster.

AlFoCS + Fornax3D: resolved star formation in the Fornax cluster with ALMA and MUSE

“…In the gas tail, on the other hand, depletion times are 10 times longer. This is in agreement with what is found in other gas tails caused by RPS (Moretti et al 2018;Ramatsoku et al 2019;Jachym et al 2019).…”

“…Depletion times in its gas tail, however, are much larger, typically around 10 times those in the galaxy body, or longer. This is in line with results from Moretti et al (2018Moretti et al ( , 2019; Ramatsoku et al (2019); Jachym et al (2019).…”

“…The GAs Stripping Phenomena in galaxies (GASP) with the Multi Unit Spectroscopic Explorer (MUSE) survey targeted 114 RPS galaxies, specifically to study gas removal processes in galaxies in different environments (Poggianti et al 2017). In this context, studies by Vulcani et al (2018), Ramatsoku et al (2019), and Moretti et al (2018) have found that RPS can enhance the SFR in galaxy disks by 0.2 dex, and that depletion times in the disks of RPS galaxies are decreased, while they are increased in their tails (with a difference of a factor ∼10).…”

MUSE Analysis of Gas around Galaxies (MAGG) – II: metal-enriched halo gas around z ∼ 1 galaxies

“…As galaxies undergo complex encounters, the gas in their CGM, being more diffuse and extended, should be even more susceptible to the effects of gravitational interactions like tidal stripping, or to hydrodynamic interactions. Indeed at low redshifts (z < 0.1), the effects of galaxy interactions within groups and clusters are manifested on the cool neutral hydrogen and molecular gas in the form of tidal streams, plumes, fountains, high-velocity clouds and warped discs (Fraternali et al 2002;Sancisi et al 2008;Mihos et al 2012;Jáchym et al 2014;Ramatsoku et al 2019;Moretti et al 2020), as well as on the ionized gas (Fumagalli et al 2014;Poggianti et al 2017;Vulcani et al 2018;Fossati et al 2019a). Galaxy mergers are also more likely in denser environments, and merger-driven outflows could affect the gas content and distribution in the CGM (Hani et al 2018).…”

The role of environment on quenching, star formation and AGN activity

“…7 for three example galaxies), and the kinematical decoupling of HI and Hα can be Figure 7. HI contours on top of the MUSE Hα image (plus the optical broad band image outside of the inset in the right panel) of three GASP jellyfish galaxies (from left to right, Ramatsoku et al 2019and Deb et al 2020. In the right panel, the black contour is HI in emission and the white contour in absorption.…”