Constraining the duration of ram pressure stripping features in the optical from the direction of jellyfish galaxy tails

TL;DR

This study analyzes the orientation and lifespan of optical tails in jellyfish galaxies caused by ram pressure stripping, revealing their dynamics and duration during galaxy infall into clusters.

Contribution

It provides the first comprehensive measurement of tail directions relative to cluster centers and constrains the lifespan of optical tails using Bayesian analysis and simulations.

Findings

33% of tails point away from cluster centers

Tails appear around 1.16 R200 from cluster center

Tails last approximately 660 million years after pericenter

Abstract

Ram pressure stripping is perhaps the most efficient mechanism for removing gas and quenching galaxies in dense environments as they move through the intergalactic medium. Extreme examples of on-going ram pressure stripping are known as jellyfish galaxies, characterized by a tail of stripped material that can be directly observed in multiple wavelengths. Using the largest homogeneous broad-band optical jellyfish candidate sample in local clusters known to date, we measure the angle between the direction of the tails visible in the galaxies, and the direction towards the host cluster center. We find that $33\%$ of the galaxy tails point away from the cluster center, $18\%$ point towards the cluster center, and $49\%$ point elsewhere. Moreover, we find stronger signatures of ram pressure stripping happening on galaxies with a tail pointing away and towards the cluster center, and larger velocity dispersion profiles for galaxies with tails pointing away. These results are consistent with a scenario where ram pressure stripping has a stronger effect for galaxies following radial orbits on first infall. The results also suggest that in many cases, radially infalling galaxies are able to retain their tails after pericenter and continue to experience significant on-going ram pressure stripping. We further constrain the lifespan of the optical tails from the moment they first appear to the moment they disappear, by comparing the observed tail directions with matched N-body simulations through Bayesian parameter estimation. We obtain that galaxy tails appear for the first time at $\sim 1.16$ R$_{200}$ and disappear $\sim660$ Myr after pericenter.