Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS

Abstract

The upcoming generation of optical spectrographs on four meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide high-quality spectra for thousands of galaxies. These data will allow us to examine of the stellar population properties at intermediate redshift, an epoch that remains unexplored by large and deep surveys. We assess our capability to retrieve the mean stellar metallicity in galaxies at different redshifts and S/N, while simultaneously exploiting the UV and optical rest-frame wavelength coverage. The work is based on a comprehensive library of spectral templates of stellar populations, covering a wide range of age and metallicity values and built assuming various SFHs. We simulated realistic observations of a large sample of galaxies carried out with WEAVE at the WHT at different redshifts and S/N values. We measured all the reliable indices on the simulated spectra and on the comparison library. We then adopted a Bayesian approach to obtain the probability distribution of stellar metallicity. The analysis of the spectral indices has shown how some mid-UV indices can provide reliable constraints on stellar metallicity, along with optical indicators. The analysis of the mock observations has shown that even at S/N=10, the metallicity can be derived within 0.3 dex, in particular, for stellar populations older than 2 Gyr. Our results are in good agreement with other theoretical and observational works in the literature and show how the UV indicators can be advantageous in constraining metallicities. This is very promising for the upcoming surveys carried out with new, highly multiplexed, large-field spectrographs, such as StePS at the WEAVE and 4MOST, which will provide spectra of thousands of galaxies covering large spectral ranges at relatively high S/N.

16 pages, 14 figures. Submitted 31/03/2023, Accepted 20/07/2023

References in corpus (24)

• UV-extended E-MILES stellar population models: young components in massive early-type galaxies
• The 1% Concordance Hubble Constant
• Evidence for TP-AGB stars in high redshift galaxies, and their effect on deriving stellar population parameters
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
• 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
• SDSS-IV MaNGA: pyPipe3D analysis release for 10,000 galaxies
• An optimized H_βindex for disentangling stellar population ages
• IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies
• Stellar populations and evolution of early-type cluster galaxies: Constraints from optical imaging and spectroscopy of z=0.5-0.9 galaxy clusters
• Sub one percent mass fractions of young stars in red massive galaxies
• Integral-field kinematics and stellar populations of early-type galaxies out to three half-light radii
• Inverse stellar population age gradients of post-starburst galaxies at z=0.8 with LEGA-C
• Synthetic Mid-UV Spectroscopic Indices of Stars
• A few StePS forward in unveiling the complexity of galaxy evolution: light-weighted stellar ages of intermediate redshift galaxies with WEAVE
• Stellar population properties of individual massive early-type galaxies at 1.4 < z < 2
• Scaling relations and baryonic cycling in local star-forming galaxies. III. Outflows, effective yields and metal loading factors
• Strong CO Absorption Features in Massive ETGs
• WEAVE-StePS. A stellar population survey using WEAVE at WHT
• Young stellar population gradients in central cluster galaxies from NUV and optical spectroscopy
• Do galaxies die? Different views from simulations and observations in the Local Universe
• A tale of a rich cluster at z$\sim$0.8 as seen by the Star Formation Histories of its ETGs
• Lessons from the massive relic NGC 1277: remaining in-situ star formation in the cores of massive galaxies

Cited by in corpus (3)

• The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
• Euclid preparation. LXVIII. Extracting physical parameters from galaxies with machine learning
• From simulations to observations. Methodology and data release of mock TNG50 galaxies at 0.3 < z < 0.7 for WEAVE-StePS