Spiraling into the `snail' cluster MCXC J0157.4-0550
Abstract
We present a deep Chandra (130 ks) study of a striking, tidally induced cold front in a subcluster merging with the galaxy cluster MCXC J0157.4-0550. The subcluster, nicknamed the `snail' (J0157), displays an extensive spiral structure that extends to ∼ 260 kpc --- one of the largest spiral cold fronts identified to date. Surface brightness and spectral analysis across four sectors reveal a consistent density jump of a factor of ∼ 3 across the front, together with significant temperature discontinuities, and thermodynamic mapping further delineates the coherent, low-entropy structure of the stripped gas. Unlike classical sloshing cold fronts, the spiral in J0157 arises not from oscillation of a displaced cool core, but from subcluster gas that has been ram pressure stripped and tidally wound into a spiral by orbital rotation. Applying Gaussian Gradient Magnitude filtering and azimuthal surface-brightness analysis, we identify quasi-periodic corrugations along the front consistent with candidate Kelvin-Helmholtz (KH) instabilities, with a characteristic scale of ∼ 90 kpc. The presence of these KH rolls constrains the effective ICM viscosity to ≲ 0.59 times the Spitzer value and the magnetic field strength at the interface to ≲ 5.9 μG. These results establish J0157 as a useful laboratory for probing macro-scale merger-induced gas dynamics and micro-scale plasma transport processes in the intracluster medium.
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BibTeX
@misc{geng2026spiraling,
title = {{Spiraling into the `snail' cluster MCXC J0157.4-0550}},
author = {Chao Geng and Chong Ge and Ming Sun and Li Ji and Guilin Liu and Zhicheng He and Haiguang Xu and John ZuHone and Paul Nulsen and Craig Sarazin and Nobuhiro Okabe},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24360},
eprint = {2610.24360},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24360},
}
RIS
TY - UNPB
TI - Spiraling into the `snail' cluster MCXC J0157.4-0550
AU - Chao Geng
AU - Chong Ge
AU - Ming Sun
AU - Li Ji
AU - Guilin Liu
AU - Zhicheng He
AU - Haiguang Xu
AU - John ZuHone
AU - Paul Nulsen
AU - Craig Sarazin
AU - Nobuhiro Okabe
PY - 2026
DA - 2026/10/17
PB - arXiv
DO - 10.48550/arxiv.2610.24360
UR - https://arxiv.org/abs/2610.24360
AB - We present a deep Chandra (130 ks) study of a striking, tidally induced cold front in a subcluster merging with the galaxy cluster MCXC J0157.4-0550. The subcluster, nicknamed the `snail' (J0157), displays an extensive spiral structure that extends to ∼ 260 kpc --- one of the largest spiral cold fronts identified to date. Surface brightness and spectral analysis across four sectors reveal a consistent density jump of a factor of ∼ 3 across the front, together with significant temperature discontinuities, and thermodynamic mapping further delineates the coherent, low-entropy structure of the stripped gas. Unlike classical sloshing cold fronts, the spiral in J0157 arises not from oscillation of a displaced cool core, but from subcluster gas that has been ram pressure stripped and tidally wound into a spiral by orbital rotation. Applying Gaussian Gradient Magnitude filtering and azimuthal surface-brightness analysis, we identify quasi-periodic corrugations along the front consistent with candidate Kelvin-Helmholtz (KH) instabilities, with a characteristic scale of ∼ 90 kpc. The presence of these KH rolls constrains the effective ICM viscosity to ≲ 0.59 times the Spitzer value and the magnetic field strength at the interface to ≲ 5.9 μG. These results establish J0157 as a useful laboratory for probing macro-scale merger-induced gas dynamics and micro-scale plasma transport processes in the intracluster medium.
ER -