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ABSTRACT We study specific star formation rate (sSFR) and gas profiles of star-forming (SF) and green valley (GV) galaxies in the simba cosmological hydrodynamic simulation. SF galaxy half-light radii (Rhalf) at z = 0 and their evolution (∝(1 + z)−0.78) agree with observations. Passive galaxy Rhalf agree with observations at high redshift, but by z = 0 are too large, owing to numerical heating. We compare simbaz = 0 sSFR radial profiles for SF and GV galaxies to observations. simba shows strong central depressions in star formation rate (SFR), sSFR, and gas fraction in GV galaxies and massive SF systems, qualitatively as observed, owing to black hole X-ray feedback, which pushes central gas outwards. Turning off X-ray feedback leads to centrally peaked sSFR profiles as in other simulations. In conflict with observations, simba yields GV galaxies with strongly dropping sSFR profiles beyond ≳Rhalf, regardless of active galactic nucleus feedback. The central depression owes to lowering molecular gas content; the drop in the outskirts owes to reduced star formation efficiency. simba’s satellites have higher central sSFR and lower outskirts sSFR than centrals, in qualitative agreement with observations. At z = 2, simba does not show central depressions in massive SF galaxies, suggesting simba’s X-ray feedback should be more active at high-z. High-resolution tests indicate central sSFR suppression is not sensitive to numerical resolution. Reproducing the central sSFR depression in z = 0 GV galaxies represents a unique success of simba. The remaining discrepancies highlight the importance of SFR and gas profiles in constraining quenching mechanisms.
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simba-EoR : early galaxy formation in the simba simulation including a new sub-grid interstellar medium model
ABSTRACT We update the dust model present within the simba galaxy simulations with a self-consistent framework for the co-evolution of dust and molecular hydrogen populations in the interstellar medium, and use this to explore $$z \ge 6$$ galaxy evolution. In addition to tracking the evolution of dust and molecular hydrogen abundances, our model fully integrates these species into the simba simulation, explicitly modelling their impact on physical processes such as star formation and cooling through the inclusion of a novel two-phase sub-grid model for interstellar gas. Running two cosmological simulations down to $$z \sim 6$$ we find that our simba-EoR model displays a generally tighter concordance with observational data than fiducial simba. Additionally we observe that our simba-EoR models increase star formation activity at early epochs, producing larger dust-to-gas ratios consequently. Finally, we discover a significant population of hot dust at $$\sim 100$$ K, aligning with contemporaneous observations of high-redshift dusty galaxies, alongside the large $$\sim 20$$ K population typically identified.
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- Award ID(s):
- 1909153
- PAR ID:
- 10554344
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 535
- Issue:
- 2
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 1293-1314
- Size(s):
- p. 1293-1314
- Sponsoring Org:
- National Science Foundation
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