Extended high-ionization [MgIV] emission tracing widespread shocks in starbursts seen by JWST /NIRSpec
| Autor: | Pereira-Santaella, Miguel, García-Bernete, Ismael, González-Alfonso, Eduardo, Alonso-Herrero, Almudena, Colina, Luis, García-Burillo, Santiago, Rigopoulou, Dimitra, Arribas, Santiago, Perna, Michele |
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| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | A&A 685, L13 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202449982 |
| Popis: | We report the detection of extended (>0.5-1kpc) high-ionization [MgIV] 4.487 $\mu$m (80 eV) emission in four local luminous infrared galaxies observed with JWST/NIRSpec. Excluding the nucleus and outflow of the Type 1 active galactic nucleus (AGN) in the sample, we find that the [MgIV] luminosity is well correlated with that of H recombination lines, which mainly trace star forming clumps in these objects, and that the [ArVI] 4.530 $\mu$m (75 eV), usually seen in AGN, is undetected. On 100-400pc scales, the [MgIV] line profiles are broader (sigma([MgIV])=90 +- 25 km/s) and shifted (Delta_v up to +- 50 km/s) compared to those of the H recombination lines and lower ionization transitions (e.g., sigma(Hu-12)=57 +- 15 km/s). The [MgIV] kinematics follow the large scale rotating velocity field of these galaxies and the broad [MgIV] profiles are compatible with the broad wings detected in the H recombination lines. Based on these observational results, extended highly ionized gas more turbulent than the ambient interstellar medium, possibly as a result of ionizing shocks associated with star-formation, is the most likely origin of the [MgIV] emission. We also computed new grids of photoionization and shock models to investigate where the [MgIV] line originates. Shocks with velocities of 100-130 km/s reproduce the observed line ratios and the [MgIV] luminosity agrees with that expected from the mechanical energy released by supernove (SNe) in these regions. Therefore, these models support shocks induced by SNe as the origin of the [MgIV] line. Future studies on the stellar feedback from SNe will benefit from the [MgIV] line that is little affected by obscuration and, in absence of an AGN, can only be produced by shocks due to its high ionization potential. Comment: Accepted for publication in A&A Letters. 6 pages, 6 figures. Appendix: 8 pages, 10 figures |
| Databáze: | arXiv |
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