A disk-dominated and clumpy circumgalactic medium of the Milky Way seen in X-ray emission
Résumé
The Milky Way galaxy is surrounded by a circumgalactic medium that may play a key role in galaxy evolution as the source of gas for star formation and a repository of metals and energy produced by star formation and nuclear activity. The circumgalactic medium may also be a repository for baryons seen in the early universe, but undetected locally3. The circumgalactic medium has an ionized component at temperatures near 2 × 106 K studied primarily in the soft-X-ray band. Here we report a survey of the southern Galactic sky with a soft-X-ray spectrometer optimized to study diffuse soft-X-ray emission6. The X-ray emission is best fitted with a disk-like model based on the radial profile of the surface density of molecular hydrogen, a tracer of star formation, suggesting that the X-ray emission is predominantly from hot plasma produced via stellar feedback. Strong variations in the X-ray emission on angular scales of ~10° indicate that the circumgalactic medium is clumpy. Addition of an extended, and possibly massive, halo component is needed to match the halo density inferred from other observations
Domaines
Planète et Univers [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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