Temperature asymmetry in the Milky Way's hot circumgalactic medium induced by the Magellanic Clouds
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| author | Oprea, Alexandru Fraternali, Filippo Starkenburg, Else Tepper-Garcia, Thor Bland-Hawthorn, Joss |
| author_facet | Oprea, Alexandru Fraternali, Filippo Starkenburg, Else Tepper-Garcia, Thor Bland-Hawthorn, Joss |
| contents | The Milky Way is surrounded by a hot diffuse circumgalactic medium (CGM) with temperatures of millions of degrees. Recent X-ray observations with the eROSITA satellite discovered a significant temperature asymmetry of this hot CGM, with the southern hemisphere being on average hotter than the northern one by a relative difference of $Δ T/T \approx 12\%$, where $T$ is averaged over the entire CGM. In this Letter, we investigate whether the passage of the Magellanic Clouds can be responsible for this asymmetry by means of a hydrodynamical/N-body simulation. In the simulation, the Magellanic Clouds induce a relative motion of the Milky Way's disc of up to 40 km/s. This motion leads to compression of the CGM gas in the southern hemisphere, resulting in an overall temperature increase in that region. We estimate a south-north temperature difference of $Δ T/T \approx 13-20\%$, consistent with the observations. We find that this temperature asymmetry is a recent phenomenon that began ~100 Myr ago. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_08652 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Temperature asymmetry in the Milky Way's hot circumgalactic medium induced by the Magellanic Clouds Oprea, Alexandru Fraternali, Filippo Starkenburg, Else Tepper-Garcia, Thor Bland-Hawthorn, Joss Astrophysics of Galaxies The Milky Way is surrounded by a hot diffuse circumgalactic medium (CGM) with temperatures of millions of degrees. Recent X-ray observations with the eROSITA satellite discovered a significant temperature asymmetry of this hot CGM, with the southern hemisphere being on average hotter than the northern one by a relative difference of $Δ T/T \approx 12\%$, where $T$ is averaged over the entire CGM. In this Letter, we investigate whether the passage of the Magellanic Clouds can be responsible for this asymmetry by means of a hydrodynamical/N-body simulation. In the simulation, the Magellanic Clouds induce a relative motion of the Milky Way's disc of up to 40 km/s. This motion leads to compression of the CGM gas in the southern hemisphere, resulting in an overall temperature increase in that region. We estimate a south-north temperature difference of $Δ T/T \approx 13-20\%$, consistent with the observations. We find that this temperature asymmetry is a recent phenomenon that began ~100 Myr ago. |
| title | Temperature asymmetry in the Milky Way's hot circumgalactic medium induced by the Magellanic Clouds |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2604.08652 |