iMaNGA: mock MaNGA galaxies based on IllustrisTNG and MaStar SSPs. I. Construction and analysis of the mock data cubes

TL;DR

This paper introduces a method to create realistic mock galaxy data cubes from IllustrisTNG simulations, enabling direct comparison with MaNGA observations by matching instrumental effects and spectral properties.

Contribution

The paper presents a novel approach to generate MaNGA-like mock data cubes from simulations, incorporating instrumental effects and stellar population models based on MaStar.

Findings

Intrinsic and recovered age and metallicity gradients agree within 1σ.

Star formation histories closely match between input and recovered data.

Mock data analysis demonstrates the method's effectiveness for comparison with real observations.

Abstract

Galaxy formation and evolution simulations are essential tools to probe poorly known astrophysics processes, but particular care is needed to compare simulations with galaxy observations, as observed data need to be modelled as well. We present a method to generate mock galaxies from the hydro-dynamical IllustrisTNG simulations which are suited to compare with integral field spectroscopic observation of galaxies from the SDSS-IV/MaNGA survey. Firstly, we include the same instrumental effects and procedures as adopted in the acquisition and analysis of real data. Furthermore, we generate the galaxy spectra from the simulations using new stellar population models based on the MaNGA stellar library (MaStar). In this way, our mock data cubes have the same spatial sampling, cover the same wavelength range (3600-10300 \r{A}), and share the same spectral resolution ($R\approx1800$) and flux calibration of real MaNGA galaxy spectra. In this first paper, we demonstrate the method over an early-type and a late-type simulated galaxy from TNG50. We analyse the correspondent mock MaNGA-like data cubes with the same full spectral fitting code, \textsc{FIREFLY}, which was used for the observed spectra. We find that the intrinsic and recovered age and metallicity gradients are consistent within 1${\sigma}$, with residuals over all tassels consistent with $0$ at the 68$\%$ confidence level. We also perform the challenging test at comparing intrinsic and recovered star formation histories, finding a close resemblance between input and output. In follow-up papers, we will present a full simulated MaNGA-like catalogue ($\approx10,000$ galaxies) with a comprehensive comparison of TNG50 simulations to MaNGA observational results.