Towards precise galaxy evolution: a comparison between spectral indices of $z\sim 1$ galaxies in the IllustrisTNG simulation and the LEGA-C survey

Abstract

We present the first comparison of observed stellar continuum spectra of high-redshift galaxies and mock galaxy spectra generated from hydrodynamical simulations. The mock spectra are produced from the IllustrisTNG TNG100 simulation combined with stellar population models and take into account dust attenuation and realistic observational effects (aperture effects and noise). We compare the simulated $D_{n}4000$ and EW(H$\delta$) of galaxies with $10.5\le \log (M_{\ast }/M_{\odot })\le 11.5$ at $0.6\le z\le 1.0$ to the observed distributions from the LEGA-C survey. TNG100 globally reproduces the observed distributions of spectral indices, implying that the age distribution of galaxies in TNG100 is generally realistic. Yet there are small but significant differences. For old galaxies, TNG100 shows small $D_{n}4000$ when compared to LEGA-C, while LEGA-C galaxies have larger EW(H$\delta$) at fixed $D_{n}4000$. There are several possible explanations: 1) LEGA-C galaxies have overall older ages combined with small contributions (a few percent in mass) from younger ($<1$~Gyr) stars, while TNG100 galaxies may not have such young sub-populations; 2) the spectral mismatch could be due to systematic uncertainties in the stellar population models used to convert stellar ages and metallicities to observables. In conclusion, the latest cosmological galaxy formation simulations broadly reproduce the global age distribution of galaxies at $z\sim 1$ and, at the same time, the high quality of the latest observed and simulated datasets help constrain stellar population synthesis models as well as the physical models underlying the simulations.

17 pages, 12 figures, accepted by AJ

References in corpus (19)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• Evolution of asymptotic giant branch stars I. Updated synthetic TP-AGB models and their basic calibration
• Charting the evolution of the ages and metallicities of massive galaxies since z=0.7
• The Assembly Histories of Quiescent Galaxies Since z=0.7 from Absorption Line Spectroscopy
• A Large Stellar Evolution Database for Population Synthesis Studies. III. Inclusion of the full Asymptotic Giant Branch phase and Web tools for stellar population analyses
• The Cosmic Evolution Survey (COSMOS): a large-scale structure at z=0.73 and the relation of galaxy morphologies to local environment
• Sub one percent mass fractions of young stars in red massive galaxies
• Resolving the age bimodality of galaxy stellar populations on kpc scales
• Galaxy populations in massive z=0.2-0.9 clusters: I. Analysis of spectroscopy
• A few StePS forward in unveiling the complexity of galaxy evolution: light-weighted stellar ages of intermediate redshift galaxies with WEAVE
• Recent Star-formation in a Massive Slowly-Quenched Lensed Quiescent Galaxy at z=1.88

Cited by in corpus (5)

• An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS field (AS2COSPEC): Survey Description and First Results
• WEAVE-StePS. A stellar population survey using WEAVE at WHT
• The LEGA-C of nature and nurture in stellar populations of galaxies at z~0.6-1.0: D4000 and H-delta reveal different assembly histories for quiescent galaxies in different environments
• The connection between stellar mass, age and quenching timescale in massive quiescent galaxies at $z\simeq 1$
• Passive spiral galaxies deeply captured by Subaru Hyper Suprime-Cam