AstraeusIV : Quantifying the star formation histories of galaxies in the Epoch of Reionization

Abstract

We use the \textsc{astraeus} framework, that couples an N-body simulation with a semi-analytic model for galaxy formation and a semi-numerical model for reionization, to quantify the star formation histories (SFHs) of galaxies in the first billion years. Exploring four models of radiative feedback, we fit the SFH of each galaxy at $z>5$ as $\log (\mathrm{SFR}(z))=-\alpha (1+z)+\beta$; star formation is deemed stochastic if it deviates from this fit by more than ${\Delta }_{\mathrm{SFR}}=0.6$dex. Our key findings are: (i) The fraction of stellar mass formed and time spent in the stochastic phase decrease with increasing stellar mass and redshift $z$. While galaxies with stellar masses of $M_{\star }\sim 10^7{M}_{\odot }$ at $z\sim 5(10)$ form $\sim 70\%(20\%)$ of their stellar mass in the stochastic phase, this reduces to $<10\%$ at all redshifts for galaxies with $M_{\star }>10^{10}{M}_{\odot }$; (ii) the fractional mass assembled and lifetime spent in the stochastic phase do not significantly change with the radiative feedback model used; (iii) at all redshifts, $\alpha$ increases (decreases for the strongest radiative feedback model) with stellar mass for galaxies with $M_{\star }\lesssim 10^{8.5}{M}_{\odot }$ and converges to $\sim 0.18$ for more massive galaxies; $\beta$ always increases with stellar mass. Our proposed fits can reliably recover the stellar masses and mass-to-light ratios for galaxies with $M_{\star }\sim 10^{8-10.5}{M}_{\odot }$ and $M_{UV}\sim -17\mathrm{to}-23$ at $z\sim 5-9$. This physical model can therefore be used to derive the SFHs for galaxies observed by a number of forthcoming instruments.

19 pages, 14 figures, accepted for publication in MNRAS

References in corpus (15)

• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• Constraining the properties of AGN host galaxies with Spectral Energy Distribution modeling
• Firefly (Fitting IteRativEly For Likelihood analYsis): a full spectral fitting code
• How Well Can We Measure the Stellar Mass of a Galaxy: The Impact of the Assumed Star Formation History Model in SED Fitting
• Essential physics of early galaxy formation
• Minihalo photoevaporation during cosmic reionization: evaporation times and photon consumption rates
• On the SFR-M${}_{\ast }$ main sequence archetypal star-formation history and analytical models
• Astraeus I: The interplay between galaxy formation and reionization
• Cosmic Reionization On Computers II. Reionization History and Its Back Reaction on Early Galaxies
• Stochastic modeling of star-formation histories I: the scatter of the star-forming main sequence
• Improving $z\sim 7-11$ Galaxy Property Estimates with JWST/NIRCam Medium-Band Photometry
• The Escape Fraction of Ionizing Photons During the Epoch of Reionization: observability with the Square Kilometre Array
• Exploring the Dust Content of Galactic Halos with Herschel III. NGC 891
• Astraeus III: The environment and physical properties of reionization sources

Cited by in corpus (10)

• The brightest galaxies at Cosmic Dawn
• Carbonaceous dust grains seen in the first billion years of cosmic time
• The ALMA REBELS Survey: Specific Star-Formation Rates in the Reionization Era
• Bursty star formation during the Cosmic Dawn driven by delayed stellar feedback
• Quantifying the Effects of Known Unknowns on Inferred High-redshift Galaxy Properties: Burstiness, the IMF, and Nebular Physics
• Identification of a transition from stochastic to secular star formation around $z=9$ with JWST
• The impact of an evolving stellar initial mass function on early galaxies and reionisation
• Astraeus VI: Hierarchical assembly of AGN and their large-scale effect during the Epoch of Reionization
• Astraeus VII: The environmental-dependent assembly of galaxies in the Epoch of Reionization
• POLAR-II: modeling star formation history of galaxies on the 21-cm signal from Epoch of Reionization