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Asymmetric eROSITA bubbles as the evidence of a circumgalactic medium wind
Guobin Mou1,2, Dongze Sun3, Taotao Fang4
1School of Physics and Technology, Wuhan University, 430072, Wuhan, China. gbmou@whu.edu.cn.
Nature Communications
|February 11, 2023
Summary
Asymmetric eROSITA bubbles suggest a dynamic circumgalactic medium wind model explains their formation. This wind reshapes the galactic halo, influencing the bubbles' observed morphology and brightness.
Area of Science:
- Astrophysics
- Cosmic Microwave Background Radiation
- Galactic Astronomy
Background:
- The eROSITA bubbles, observed by the eROSITA instrument, exhibit complex asymmetric features.
- The origin of these large-scale structures in the Milky Way's halo remains a subject of ongoing scientific debate.
Purpose of the Study:
- To investigate the formation mechanisms of the asymmetric eROSITA bubbles.
- To test the validity of different astrophysical models in explaining observed bubble morphology and brightness.
Main Methods:
- Hydrodynamic simulations were employed to model gas dynamics within the galactic halo.
- Simulations explored scenarios including circumgalactic medium winds, non-axisymmetric halo gas, and tilted nuclear outflows.
Main Results:
- Asymmetric eROSITA bubbles are best explained by a dynamic circumgalactic medium wind model.
- This model, with wind originating from the east-by-north direction, successfully reproduces the observed distortions and brightness variations.
- Other proposed mechanisms, such as non-axisymmetric halo gas or tilted outflows, were disfavored by the simulation results.
Conclusions:
- A unidirectional circumgalactic medium wind provides a compelling explanation for the observed eROSITA bubble asymmetry.
- The Milky Way appears to be accreting material from one side while expelling feedback through outflows.
- This dynamic interplay shapes the galactic halo's density and metallicity distribution.
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