---
title: "Ram pressure and returning gas"
description: "Follow ram pressure and gas binding, recompute fixed slices, and distinguish disk fuel from global stellar light."
canonical_url: "https://sandboxphysics.com/stories/ram-pressure-stripping/"
language: "en"
page_type: "story"
alternate_languages:
  zh-CN: "https://sandboxphysics.com/zh/stories/ram-pressure-stripping/"
last_modified: "2026-11-12"
---

Ram pressure and returning gas

# Ram pressure and returning gas

Sandbox Physics · 2026-11-11

Gas can leave a galaxy disk while remaining bound. Start with its motion, then follow the wind pulse, the fuel counted inside the disk and the light of successive stellar generations.

1. L1

   ## [Why cluster galaxies become redder](https://sandboxphysics.com/stories/ram-pressure-stripping/why-cluster-galaxies-become-redder/)

   A cluster can reduce a galaxy’s cold fuel or its future supply. Follow how fewer young blue stars change the combined light, and how dust can mimic that change.

2. L1

   ## [Why a galaxy tail can fall back](https://sandboxphysics.com/stories/ram-pressure-stripping/why-a-galaxy-tail-can-fall-back/)

   A cluster wind can lift gas that still belongs to its galaxy. Follow the difference between a visible tail, gravitational binding and permanent fuel loss.

3. L2

   ## [From a wind pulse to a restoring force](https://sandboxphysics.com/stories/ram-pressure-stripping/from-a-wind-pulse-to-restoring-force/)

   Derive ram acceleration from a gas column, compare impulse with vertical gravity, and see when a static pressure threshold is useful.

4. L2

   ## [Follow fuel across the disk boundary](https://sandboxphysics.com/stories/ram-pressure-stripping/follow-fuel-across-the-disk-boundary/)

   Derive how a moving gas population changes disk star formation, while the global rate can remain identical across different wind paths.

5. L3

   ## [Recompute five fixed gas slices](https://sandboxphysics.com/stories/ram-pressure-stripping/recompute-five-fixed-gas-slices/)

   Use an independent offline package to recompute disk mass, binding, star formation and the static restoring-force reference from five exact synthetic slices.

6. L3

   ## [Why global colour needs a history](https://sandboxphysics.com/stories/ram-pressure-stripping/why-global-colour-needs-a-history/)

   Build stellar light from populations of different ages, then separate a specified shutdown, dust reddening and the location of stripped gas.

7. L4

   ## [Read exposure histories and multiphase tail physics](https://sandboxphysics.com/stories/ram-pressure-stripping/read-exposure-and-multiphase-tail-physics/)

   Read pressure and exposure statistics in a fixed GAEA–TNG paper, then connect their limits to cooling and magnetic fields in gas-tail research.

## Independent scientific materials

[Download the offline scientific ZIP](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/ram-pressure-science-v1.zip) · [Read units and calculation scope](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/README.md)

Python, NumPy and SciPy recompute the five fixed synthetic slices, the local static restoring-force reference and four-age global colour ratios. This package evaluates saved scientific data; original gas integration and native SSP convolution are separate calculations.

Files, sizes and SHA-256

- [README.md](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/README.md) (4173 B)
  `963ce7a0921c497a5556558faa685310a3ad424db826831c794f031492b7ad90`
- [requirements.txt](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/requirements.txt) (27 B)
  `39b93fa1b8397265839a510ca7601608248a7f3524067b61667e977bf4351475`
- [criterion.py](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/criterion.py) (4267 B)
  `ab0ce3a9e95a01ca886e3a9f997e162cee4c7d9081d36c7e1cec2ae5d1c1b2e0`
- [recompute.py](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/recompute.py) (2612 B)
  `47b44c4dd30ddecb64226dc6f1b0c59c6e25e769ec8e8885f38b581b77b68a5f`
- [fixed-slices.json](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/fixed-slices.json) (82090 B)
  `e536102615f5fc2bfdda56b4374dc63fc0307229a0a248c6e84a7ab8ad2638ca`
- [expected.json](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/expected.json) (19249 B)
  `4816379eba85e94a8477f6268b8186cba5b23f8ee2f079075cff31fcf7ef7d0e`
- [ram-pressure-science-v1.zip](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/ram-pressure-science-v1.zip) (45741 B)
  `979dbcbd25d63a9a9f79e85f921976d051c46a57eac82f21713dee288297a2f2`

## Sources and calculation scope

1. [Köppen, Jáchym, Taylor & Palouš, Ram Pressure Stripping Made Easy, arXiv:1806.05887v1 (2018)](https://arxiv.org/abs/1806.05887v1)

   Sections2.1–2.2 and5.4 explain the slow-pressure/impulse limits and re-accretable gas. Our fixed three-component potential, equal-mass sheets and consuming gas are specified independently; the own static comparison does not reproduce every published simulation or observational sample.

2. [Xie et al., The impact of ram pressure on cluster galaxies, arXiv:2504.12863v1 / A&A 698, A73 (2025)](https://arxiv.org/html/2504.12863v1)

   Fixed 17 April 2025 scientific text: sections 2.4/3.1, Figures 1–2 and 5–7. The v1 body has received/accepted placeholders; the current arXiv bibliographic page lists A&A 698, A73 and acceptance. The guide reads pressure definitions and aggregate exposure statistics; it does not join summary tables into an individual TNG trajectory.

3. [Gronke & Oh, The growth and entrainment of cold gas in a hot wind, arXiv:1806.02728v2 (2018)](https://arxiv.org/abs/1806.02728v2)

   Controlled three-dimensional cloud-in-wind cooling study. Mixed-gas cooling, material origin, downstream domain and resolution are the relevant reading questions. It is not a self-gravitating star-forming disk or a calibration of this gas-sheet model.

4. [Dursi & Pfrommer, Draping of Cluster Magnetic Fields over Bullets and Bubbles, arXiv:0711.0213v2 (2008)](https://arxiv.org/abs/0711.0213v2)

   Three-dimensional magnetic draping around an initially unmagnetized projectile, including analytic and MHD arguments. Explicit thermal conduction is omitted; a geometric heat-flow inference is distinguished from a simulated conductivity. The gas-sheet Lab does not evolve this field.

5. [Bruzual & Charlot, Stellar population synthesis at the resolution of 2003, astro-ph/0309134v1](https://arxiv.org/abs/astro-ph/0309134v1)

   Section 2.3 supplies the initially formed-mass convention and population convolution. The fixed numerical input is easyGalaxy commit 133c62b383fae964701b673e62517293161b41d5, tests/data/bc03\_ssp\_z\_0.02\_salp.model, SHA5b2e2f9f2ecdbbd329ff4993f84a5d4bd7f8bfef6877b38d2042e9a0cf96e1fd. Its Salpeter label is retained; an unspecified track release is not invented.

6. [Calzetti et al., The Dust Content and Opacity of Actively Star-Forming Galaxies, astro-ph/9911459v1 / ApJ533 (2000)](https://arxiv.org/abs/astro-ph/9911459v1)

   Empirical attenuation context for the separately specified screens. The own calculation restricts the prescription to 1200–22000 Angstrom; it does not fit a measured dust parameter or solve infrared re-emission.

7. [Bianconi et al., LoCuSS pre-processing in infalling galaxy groups, arXiv:1710.04230v1 (2017)](https://arxiv.org/html/1710.04230v1)

   Focused primary HTML reading of sections 2–4 and Figure 2 caption: X-ray group selection, spectroscopic members, massive-galaxy cut and infrared formation threshold. The comparison is of selected populations at projected cluster radius; no object-by-object gas-loss history or causal intervention is reproduced.

8. [Dou, Yu & Hou, Pre-processing and protection during cluster infall, arXiv:2605.23314v1 (2026)](https://arxiv.org/html/2605.23314v1)

   Fixed 22 May 2026 paper, accepted by A&A according to its bibliographic page. Focused reading: sections 2.1–2.4, 3.1–3.2, 5.3–5.5 and summary. A 25-cluster sample, full spectroscopic structure labels and 7092 mass-complete galaxies support a statistical environment comparison. Its projected infall proxy is phenomenological; pre-processing and apparent protection are distinguished from individual timing or demonstrated gas shielding.

9. [Original fixed-slice and static-restoring-force materials](https://sandboxphysics.com/stories/ram-pressure-stripping/materials/ram-pressure-science-v1.zip)

   Our five exact synthetic slices with sixty-four sheets and thirteen fields, initial common arrays, two global-light histories/three screens/four-age band subset, independent Python static maxima and mask/energy/colour diagnostics. Original trajectory and native SSP production are distinct earlier calculations; this offline package repeats diagnostics and band ratios. No browser Engine, original FITS/SED, paper, author code or observed-galaxy data is included.