arXiv subjects

John H Wise

Publications and source records attributed to John H Wise.

3 recordsLinked to original sources

arXiv2026

JWST Predictions for $z > 10$ Galaxies from the Renaissance Simulations -- I: Photometry and Sizes

JWST has enabled new high redshift observations with 14 spectroscopically confirmed galaxies at $z > 10$ to date, leading to a need for high redshift, high resolution simulations to interpret these observations. We present the physical properties and mock observations of the galaxies in the Renaissance Simulations to add to the growing database of high redshift simulation data to guide and interpret observations. We find that they provide an accurate representation of the formation history of JWST's $z > 10$ discoveries and follow the trends observed in JWST galaxies but extended to lower masses. The stellar masses of the Renaissance galaxies range from $\approx 10^{3}$ to $10^8 M_{\odot}$ and overlap well with the $z > 10$ JWST galaxies with a stellar mass range of about $10^{7}$ to $10^9 M_{\odot}$. The simulated SFRs increase from $10^{-4}$ to $10^1 M_{\odot}yr^{-1}$, overlapping the JWST galaxies' lower SFRs in the range $1 - 20 M_{\odot}yr^{-1}$. These compact galaxies show minimal morphology change as their stellar masses increase with the majority of the half light radii between $1$ and $10$ pc and the majority of the half stellar mass radii around $0.1$ kpc; their Sersic indices vary between $0$ and $4$. The Renaissance galaxies are bluer and generally transition well into the absolute UV magnitudes of the JWST galaxies in the main sequence of galaxies. Overall, our simulations agree well with JWST's discoveries to date, making them a valuable tool in the continued effort to understand the high redshift Universe.

astro-ph.GA↗

arXiv2018

Fully Coupled Simulation of Cosmic Reionization. III. Stochastic Early Reionization by the Smallest Galaxies

Previously we identified a new class of early galaxy that we estimate contributes up to 30\% of the ionizing photons responsible for reionization. These are low mass halos in the range $M_h =10^{6.5}-10^{8} M_{\odot}$ that have been chemically enriched by supernova ejecta from prior Pop III star formation. Despite their low star formation rates, these Metal Cooling halos (MCs) are significant sources of ionizing radiation, especially at the onset of reionization, due to their high number density and ionizing escape fractions. Here we present a fully-coupled radiation hydrodynamic simulation of reionization that includes these MCs as well the more massive hydrogen atomic line cooling halos. Our method is novel: we perform halo finding inline with the radiation hydrodynamical simulation, and assign escaping ionizing fluxes to halos using a probability distribution function (PDF) measured from the galaxy-resolving Renaissance Simulations. The PDF captures the mass dependence of the ionizing escape fraction as well as the probability that a halo is actively forming stars. With MCs, reionization starts earlier than if only halos of $10^8 M_{\odot}$ and above are included, however the redshift when reionization completes is only marginally affected as this is driven by more massive galaxies. Because star formation is intermittent in MCs, the earliest phase of reionization exhibits a stochastic nature, with small H II regions forming and recombining. Only later, once halos of mass $\sim 10^9 M_{\odot}$ and above begin to dominate the ionizing emissivity, does reionization proceed smoothly in the usual manner deduced from previous studies. This occurs at $z\approx 10$ in our simulation.

astro-ph.CO↗

arXiv2016

X-ray Background at High Redshifts from Pop III Remnants: Results from Pop III star formation rates in the Renaissance Simulations

Due to their long mean free paths, X-rays are expected to have many significant impacts globally on the properties of the intergalactic medium (IGM) by their heating and ionizing processes on large scales. At high redshifts, X-rays from Population (Pop) III binaries might have important effects on cosmic reionization and the Lyman alpha forest. As a continuation of our previous work on Pop III binary X-rays (Xu et al. 2014), we use the Pop III distribution and evolution from the Renaissance Simulations, a suite of self-consistent cosmological radiation hydrodynamics simulations of the formation of the first galaxies, to calculate the X-ray luminosity density and background over the redshift range 20 > z > 7.6. As we find that Pop III star formation continues at a low, nearly constant rate to the end of reionization, X-rays are being continuously produced at significant rates compared to other possible X-ray sources, such as AGNs and normal X-ray binaries during the same period of time. We estimate that Pop III binaries produce approximately 6 eV of energy in the X-rays per hydrogen atom. We calculate the X-ray background for different monochromatic photon energies. KeV X-rays redshift and accumulate to produce a strong X-ray background spectrum extending to roughly 500 eV. The X-ray background is strong enough to heat the IGM to ~ 1000 K and to ionize a few percent of the neutral hydrogen. These effects are important for an understanding of the neutral hydrogen hyperfine transition 21-cm line signatures, the Ly alpha forest, and optical depth of the CMB to Thomson scattering.

astro-ph.GA↗