Early galaxy growth: mergers or gravitational instability?
| Autor: | Andrea Ferrara, Christoph Behrens, A. Zanella, Simona Gallerani, M. Kohandel, S. Carniani, Andrea Pallottini |
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| Přispěvatelé: | Zanella, A, Pallottini, A, Ferrara, A, Gallerani, S, Carniani, S, Kohandel, M, Behrens, C |
| Rok vydání: | 2020 |
| Předmět: |
Effective radius
Physics 010308 nuclear & particles physics Infrared FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Photoionization Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Galaxy Redshift Wavelength Settore FIS/05 - Astronomia e Astrofisica Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Halo 10. No inequality 010303 astronomy & astrophysics Lyman-break galaxy Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 500:118-137 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/staa2776 |
| Popis: | We investigate the spatially-resolved morphology of galaxies in the early Universe. We consider a typical redshift z = 6 Lyman Break galaxy, "Althaea" from the SERRA hydrodynamical simulations. We create mock rest-frame ultraviolet, optical, and far-infrared observations, and perform a two-dimensional morphological analysis to de-blend the galaxy disk from substructures (merging satellites or star-forming regions). We find that the [CII]158um emitting region has an effective radius 1.5 - 2.5 times larger than the optical one, consistent with recent observations. This [CII] halo in our simulated galaxy arises as the joint effect of stellar outflows and carbon photoionization by the galaxy UV field, rather than from the emission of unresolved nearby satellites. At the typical angular resolution of current observations (> 0.15") only merging satellites can be detected; detection of star-forming regions requires resolutions of < 0.05". The [CII]-detected satellite has a 2.5 kpc projected distance from the galaxy disk, whereas the star-forming regions are embedded in the disk itself (distance < 1 kpc). This suggests that multi-component systems reported in the literature, which have separations > 2 kpc, are merging satellites, rather than galactic substructures. Finally, the star-forming regions found in our mock maps follow the local L[CII] - SFR_UV relation of galaxy disks, although sampling the low-luminosity, low-SFR tail of the distribution. We show that future JWST observations, bridging UV and [CII] datasets, will be exceptionally suited to characterize galaxy substructures thanks to their exquisite spatial resolution and sensitivity to both low-metallicity and dust-obscured regions that are bright at infrared wavelengths. Accepted for publication in MNRAS; 17 pages (plus appendix), 7 figures, 4 tables |
| Databáze: | OpenAIRE |
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