Zooming on the internal structure of $z\simeq6$ galaxies
Publication Date
2017-03-01Journal Title
Monthly Notices of the Royal Astronomical Society
ISSN
0035-8711
Publisher
Oxford University Press
Volume
465
Issue
3
Pages
2540-2558
Language
English
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Pallottini, A., Ferrara, A., Gallerani, S., Vallini, L., Maiolino, R., & Salvadori, S. (2017). Zooming on the internal structure of $z\simeq6$ galaxies. Monthly Notices of the Royal Astronomical Society, 465 (3), 2540-2558. https://doi.org/10.1093/mnras/stw2847
Abstract
We present zoom-in, AMR, high-resolution ($\simeq 30$ pc) simulations of high-redshift ($z \simeq 6$) galaxies with the aim of characterizing their internal properties and interstellar medium. Among other features, we adopt a star formation model based on a physically-sound molecular hydrogen prescription, and introduce a novel scheme for supernova feedback, stellar winds and dust-mediated radiation pressure. In the zoom-in simulation the target halo hosts "Dahlia", a galaxy with a stellar mass $M_*=1.6\times 10^{10}$M$_\odot$, representative of a typical $z\sim 6$ Lyman Break Galaxy. Dahlia has a total H2 mass of $10^{8.5}$M$_\odot$, that is mainly concentrated in a disk-like structure of effective radius $\simeq 0.6$ kpc and scale height $\simeq 200$ pc. Frequent mergers drive fresh gas towards the center of the disk, sustaining a star formation rate per unit area of $\simeq 15 $M$_\odot$ yr$^{-1}$ kpc$^{-2}$. The disk is composed by dense ($n \gtrsim 25$ cm$^{-3}$), metal-rich ($Z \simeq 0.5 $ Z$_\odot$) gas, that is pressure-supported by radiation. We compute the $158\mu$m [CII] emission arising from Dahlia, and find that $\simeq 95\%$ of the total [CII] luminosity ($L_{[CII]}\simeq10^{7.5}$ L$_\odot$) arises from the H2 disk. Although $30\%$ of the CII mass is transported out of the disk by outflows, such gas negligibly contributes to [CII] emission, due to its low density ($n \lesssim 10$ cm$^{-3}$) and metallicity ($Z\lesssim 10^{-1}$Z$_\odot$). Dahlia is under-luminous with respect to the local [CII]-SFR relation; however, its luminosity is consistent with upper limits derived for most $z\sim6$ galaxies.
Keywords
methods: numerical, galaxies: evolution, galaxies: formation, galaxies: highredshift, galaxies: ISM, infrared: general
Sponsorship
This research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915. SS was supported by the European Research Council through a Marie–Skodolowska–Curie Fellowship, project PRIMORDIAL-700907. RM acknowledges support from the ERC Advanced Grant 695671 ‘QUENCH’ and from the Science and Technology Facilities Council (STFC).
Funder references
STFC (ST/K003119/1)
STFC (ST/M001172/1)
ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (695671)
Embargo Lift Date
2100-01-01
Identifiers
External DOI: https://doi.org/10.1093/mnras/stw2847
This record's URL: https://www.repository.cam.ac.uk/handle/1810/262085
Rights
Licence:
http://www.rioxx.net/licenses/all-rights-reserved