Search

The recent launch of JWST has ushered in a new era of high-redshift astronomy by providing detailed insights into the gas and stellar populations of galaxies in the epoch of reionization. Interpreting these observations and translating them into constraints on the physics of early galaxy formation is a complex challenge that requires sophisticated models of star formation and the interstellar medium (ISM) in high-redshift galaxies. To this end, we present Version 1 of the ${\rm SPHINX^{20}}$ public data release. ${\rm SPHINX^{20}}$ is a full box cosmological radiation hydrodynamics simulation that simultaneously models the large-scale process of cosmic reionization and the detailed physics of a multiphase ISM, providing a statistical sample of galaxies akin to those currently being observed by JWST. The data set contains $\sim14,000$ mock images and spectra of the stellar continuum, nebular continuum, and 52 nebular emission lines, including Ly$\alpha$, for each galaxy in ${\rm SPHINX^{20}}$ with a star formation rate $\geq0.3\ {\rm M_{\odot}\ yr^{-1}}$. All galaxy emission has been processed with dust radiative transfer and/or resonant line radiative transfer, and data is provided for ten viewing angles for each galaxy. Additionally, we provide a comprehensive set of intrinsic galaxy properties, including halo masses, stellar masses, star formation histories, and ISM characteristics (e.g., metallicity, ISM gas densities, LyC escape fractions). This paper outlines the data generation methods, presents a comparative analysis with JWST ERS and Cycle 1 observations, and addresses data set limitations. The ${\rm SPHINX^{20}}$ data release can be downloaded at the following URL: https://github.com/HarleyKatz/SPHINX-20-data.

We compare mock ultraviolet C ii and Si ii absorption and emission line features generated using a ∼10 ^9 M _⊙ virtual galaxy with observations of 131 z ∼ 3 galaxies from the vandels survey. We find that the mock spectra reproduce reasonably well a large majority (83%) of the vandels spectra ( χ ^2 < 2), but do not resemble the most massive objects (⪆10 ^10 M _⊙ ), which exhibit broad absorption features. Interestingly, the best-matching mock spectra originate from periods of intense star formation in the virtual galaxy, where its luminosity is 4 times higher than in periods of relative quiescence. Furthermore, for each galaxy, we predict the Lyman continuum (LyC) escape fractions ( ${f}_{\mathrm{esc}\ (\mathrm{pred})}^{\mathrm{LyC}}$ ) using the environment of the virtual galaxy. We derive an average ${f}_{\mathrm{esc}\ (\mathrm{pred})}^{\mathrm{LyC}}$ of 0.01 ± 0.02, consistent with other estimates from the literature. The ${f}_{\mathrm{esc}\ (\mathrm{pred})}^{\mathrm{LyC}}$ are tightly correlated with the Ly α escape fractions and highly consistent with observed empirical trends. Additionally, galaxies with larger ${f}_{\mathrm{esc}\ (\mathrm{pred})}^{\mathrm{LyC}}$ exhibit bluer β slopes, more Ly α flux, and weaker low-ionization absorption lines. Building upon the good agreement between ${f}_{\mathrm{esc}\ (\mathrm{pred})}^{\mathrm{LyC}}$ and observationally established LyC diagnostics, we examine the LyC leakage mechanisms in the simulation. We find that LyC photon leakage is enhanced in directions where the observed flux dominantly emerges from compact regions depleted of neutral gas and dust, mirroring the scenario inferred from observational data. In general, this study further highlights the potential of high-resolution radiation hydrodynamics simulations in analyzing UV absorption and emission line features and providing valuable insights into the LyC leakage of star-forming galaxies.

Observations of low-ionization state metal lines provide crucial insights into the interstellar medium (ISM) of galaxies, yet, disentangling the physical processes responsible for the emerging line profiles is difficult. This work investigates how mock spectra generated using a single galaxy in a radiation-hydrodynamical simulation can help us interpret observations of a real galaxy. We create 22,500 C ii and Si ii spectra from the virtual galaxy at different times and through multiple lines of sight and compare them with the 45 observations of low-redshift star-forming galaxies from the COS Legacy Spectroscopic SurveY ( classy ). We find that the mock profiles provide accurate replicates of the observations of 38 galaxies with a broad range of stellar masses (10 ^6 –10 ^9 M _⊙ ) and metallicities (0.02–0.55 Z _⊙ ). Additionally, we highlight that aperture losses explain the weakness of the fluorescent emission in several classy spectra and must be accounted for when comparing simulations to observations. Overall, we show that the evolution of a single simulated galaxy can produce a large diversity of spectra whose properties are representative of galaxies of comparable or smaller masses. Building upon these results, we explore the origin of the continuum, residual flux, and fluorescent emission in the simulation. We find that these different spectral features all emerge from distinct regions in the galaxy’s ISM, and their characteristics can vary as a function of the viewing angle. While these outcomes challenge simplified interpretations of down-the-barrel spectra, our results indicate that high-resolution simulations provide an optimal framework to interpret these observations.