Fingerprints of Stellar Populations in the Near-Infrared: An Optimised Set of Spectral Indices in the JHK-Bands

Abstract

Stellar population studies provide unique clues to constrain galaxy formation models. So far, detailed studies based on absorption line strengths have mainly focused on the optical spectral range although many diagnostic features are present in other spectral windows. In particular, the near-infrared (NIR) can provide a wealth of information about stars, such as evolved giants, that have less evident optical signatures. Due to significant advances in NIR instrumentation and extension of spectral libraries and stellar population synthesis (SPS) models to this domain, it is now possible to perform in-depth studies of spectral features in the NIR to a high level of precision. In the present work, taking advantage of state-of-the-art SPS models covering the NIR spectral range, we introduce a new set of NIR indices constructed to be maximally sensitive to the main stellar population parameters, namely age, metallicity and initial mass function (IMF). We fully characterize the new indices against these parameters as well as their sensitivity to individual elemental abundance variations, velocity dispersion broadening, wavelength shifts, signal-to-noise ratio and flux calibration. We also present, for the first time, a method to ensure that the analysis of spectral indices is not affected by sky contamination, which is a major challenge when dealing with NIR spectroscopy. Moreover, we discuss two main applications: (i) the ability of some NIR spectral indices to constrain the shape of the low-mass IMF and (ii) current issues in the analysis of NIR spectral indices for future developments of SPS modelling.

38 pages, 23 figures, published in MNRAS

References in corpus (26)

• Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
• UV-extended E-MILES stellar population models: young components in massive early-type galaxies
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• Radial variations in the stellar initial mass function of early-type galaxies
• The Assembly Histories of Quiescent Galaxies Since z=0.7 from Absorption Line Spectroscopy
• Probing the near infrared stellar population of Seyfert galaxies
• The initial mass function of a massive relic galaxy
• IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies
• The X-Shooter Spectral Library (XSL): Data Release 2
• The first detection of near-infrared CN bands in active galactic nuclei: signature of star formation
• A New Approach to the Study of Stellar Populations in Early-Type Galaxies: K-band Spectral Indices and an Application to the Fornax Cluster
• MILES extended: Stellar population synthesis models from the optical to the infrared
• Stellar population synthesis models between 2.5 and 5 μm based on the empirical IRTF stellar library
• The Fornax 3D project: a two-dimensional view of the stellar initial mass function in the massive lenticular galaxy FCC 167
• A new stellar library in the region of the CO index at 2.3 $\mu$m. New index definition and empirical fitting functions
• Comparison of Stellar Population Model Predictions Using Optical and Infrared Spectroscopy
• Sub one percent mass fractions of young stars in red massive galaxies
• SPIDER X - Environmental effects in central and satellite early-type galaxies through the stellar fossil record
• The Stellar Populations of Starburst Galaxies Through near infrared spectroscopy
• The Initial Mass Function of Early-type Galaxies: no correlation with [Mg/Fe]
• Optical/NIR stellar absorption and emission-line indices from luminous infrared galaxies
• The puzzling interpretation of NIR indices: The case of NaI2.21
• Young stellar population gradients in central cluster galaxies from NUV and optical spectroscopy
• Evidence of a Bottom-heavy Initial Mass Function in Massive Early-type Galaxies from Near-infrared Metal Lines
• The APOGEE Library of Infrared SSP Templates (A-LIST): High-Resolution Simple Stellar Population Spectral Models in the H-Band
• Infrared Telescope Facility (IRTF) spectral library II: New indices in Y, J, H, and L atmospheric windows

Cited by in corpus (10)

• Modelling simple stellar populations in the near-ultraviolet to near-infrared with the X-shooter Spectral Library (XSL)
• Stellar Mass-to-light Ratios: Composite Bulge+Disk Models and the Baryonic Tully-Fisher Relation
• Strong CO Absorption Features in Massive ETGs
• The relic galaxy NGC~1277 rules out intermediate-age stellar populations origin of CO-strong absorptions in massive early-type galaxies
• CO radial gradients in the bulge of M31
• TP-AGB stars and stellar population properties of a post-starburst galaxy at $z\sim 2$ through optical and NIR spectroscopy with JWST
• Puzzling radial gradients of K-band absorption features in the giant elliptical galaxy M87
• Extragalactic globular cluster near-infrared spectroscopy: I. Integrated near-infrared spectra of Centaurus A/NGC 5128
• J-PAS: A Neural Network Approach to Single Stellar Population Characterization
• SMARTY: The mileS Moderate resolution neAr-infRared sTellar librarY