Velocity dispersion in the interstellar medium of early galaxies
| Autor: | S. Carniani, Andrea Ferrara, A. Zanella, Simona Gallerani, Christoph Behrens, Andrea Pallottini, Livia Vallini, M. Kohandel |
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| Přispěvatelé: | Kohandel, M, Pallottini, A, Ferrara, A, Carniani, S, Gallerani, S, Vallini, L, Zanella, A, Behrens, C |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
FOS: Physical sciences
Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences high-redshift [Galaxies] Settore FIS/05 - Astronomia e Astrofisica 0103 physical sciences ISM [Galaxies] 010303 astronomy & astrophysics Reionization Astrophysics::Galaxy Astrophysics Line (formation) Physics numerical [Methods] 010308 nuclear & particles physics Sigma Velocity dispersion Astronomy and Astrophysics evolution [Galaxies] Astrophysics - Astrophysics of Galaxies formation [Galaxies] Galaxy Redshift Interstellar medium general [Infrared] Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Earth and Planetary Astrophysics Energy (signal processing) |
| Zdroj: | Monthly Notices of the Royal Astronomical Society, 499(1), 1250-1265 |
| Popis: | We study the structure of spatially resolved, line-of-sight velocity dispersion for galaxies in the Epoch of Reionization (EoR) traced by [CII] $158\mu\rm{m}$ line emission. Our laboratory is a simulated prototypical Lyman-break galaxy, "Freesia", part of the SERRA suite. The analysis encompasses the redshift range 6 < z < 8, when Freesia is in a very active assembling phase. We build velocity dispersion maps for three dynamically distinct evolutionary stages (Spiral Disk at z=7.4, Merger at z=8.0, and Disturbed Disk at z=6.5) using [CII] hyperspectral data cubes. We find that, at a high spatial resolution of 0.005" ($\simeq 30 pc$), the luminosity-weighted average velocity dispersion is $\sigma_{\rm{CII}}$~23-38 km/s with the highest value belonging to the highly-structured Disturbed Disk stage. Low resolution observations tend to overestimate $\sigma_{\rm CII}$ values due to beam smearing effects that depend on the specific galaxy structure. For an angular resolution of 0.02" (0.1"), the average velocity dispersion is 16-34% (52-115%) larger than the actual one. The [CII] emitting gas in Freesia has a Toomre parameter $\mathcal{Q}$~0.2 and a rotational-to-dispersion ratio of $v_{\rm c}/\sigma$~ 7 similar to that observed in z=2-3 galaxies. The primary energy source for the velocity dispersion is due to gravitational processes, such as merging/accretion events; energy input from stellar feedback is generally subdominant (< 10%). Finally, we find that the resolved $\sigma_{\rm{CII}} - {\Sigma}_{\rm SFR}$ relation is relatively flat for $0.02 Comment: Accepted for publication in MNRAS; 16 pages (plus appendix), 8 figures, 3 tables |
| Databáze: | OpenAIRE |
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