Séminaire/Seminar Galaxies |
| « A high-resolution view of the molecular gas in Stephan's Quintet with JWST and ALMA » |
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Pierre Guillard |
| We combine JWST and HST imaging with ALMA CO(2-1) spectroscopy to study the highly turbulent multi-phase intergalactic medium (IGM) in Stephan’s Quintet on 25-150 pc scales. Previous Spitzer observations revealed luminous H2 line cooling across a 45 kpc-long filament, created by a giant shock-wave, following the collision with an intruder galaxy NGC 7318b. We demonstrate that the MIRI/F1000W/F770W filters are dominated by 0-0 S(3) H2 and a combination of PAH and 0-0 S(5) H2 emission. They reveal the dissipation of kinetic energy as massive clouds experience collisions, interactions and likely destruction/re-cycling within different phases of the IGM. In one kpc-scaled structure, warm H2 formed a triangular-shaped head and tail of compressed and stripped gas behind a narrow shell of cold H2. In another region, two cold molecular clumps with very different velocities are connected by an arrow-shaped stream of warm, probably shocked, H2 suggesting a cloud-cloud collision is occurring. In both regions, a high warm-to-cold molecular gas fraction indicates that the cold clouds are being disrupted and converted into warm gas. We also map gas associated with an apparently forming dwarf galaxy. We suggest that the primary mechanism for exciting strong mid-IR H2 lines throughout Stephan’s Quintet is through a fog of warm gas created by the shattering of denser cold molecular clouds and mixing/recycling in the post-shocked gas. Without spectroscopy, JWST cannot provide a complete picture of the kinematics and excitation of the shocked warm gas, but it reveals the rich variety of ways that different gas phases interact with one another in Stephan’s Quintet. |
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jeudi 1 juin 2023 - 11:30 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |