# Deep Chandra observations of the stripped galaxy group falling into Abell 2142

## TL;DR

This study uses deep Chandra X-ray observations to analyze the complex gas dynamics and magnetic effects in a galaxy group falling into Abell 2142, revealing slow thermalization and turbulence.

## Contribution

It provides detailed insights into the morphology, magnetic draping, and turbulence in the infalling galaxy group using high-resolution X-ray data.

## Key findings

- Magnetic draping shields the gas in the inner tail.
- Surface brightness fluctuations indicate inhibited thermal conduction.
- Turbulence in the tail is mild with Mach number 0.1-0.25.

## Abstract

In the local Universe, the growth of massive galaxy clusters mainly operates through the continuous accretion of group-scale systems. The infalling group in Abell 2142 is the poster child of such an accreting group, and as such, it is an ideal target to study the astrophysical processes induced by structure formation. We present the results of a deep (200 ks) observation of this structure with Chandra, which highlights the complexity of this system in exquisite detail. In the core of the group, the spatial resolution of Chandra reveals the presence of a leading edge and a complex AGN-induced activity. The morphology of the stripped gas tail appears straight in the innermost 250 kpc, suggesting that magnetic draping efficiently shields the gas from its surroundings. However, beyond $\sim300$ kpc from the core, the tail flares and the morphology becomes strongly irregular, which could be explained by a breaking of the drape, e.g. because of turbulent motions. The power spectrum of surface-brightness fluctuations is relatively flat ($P_{2D}\propto k^{-2.3}$), which indicates that thermal conduction is strongly inhibited even beyond the region where magnetic draping is effective. The amplitude of density fluctuations in the tail is consistent with a mild level of turbulence with a Mach number $M_{3D}\sim0.1-0.25$. Overall, our results show that the processes leading to the thermalization and mixing of the infalling gas are slow and relatively inefficient.