The stellar initial mass function at 0.9<z<1.5

Abstract

We explore the stellar initial mass function (IMF) of a sample of 49 massive quiescent galaxies (MQGs) at 0.9$<$z$<$1.5. We base our analysis on intermediate resolution spectro-photometric data in the GOODS-N field taken in the near-infrared and optical with the HST/WFC3 G141 grism and the Survey for High-z Absorption Red and Dead Sources (SHARDS). To constrain the slope of the IMF, we have measured the TiO${}_2$ spectral feature, whose strength depends strongly on the content of low-mass stars, as well as on stellar age. Using ultraviolet to near-infrared individual and stacked spectral energy distributions, we have independently estimated the stellar ages of our galaxies. Knowing the age of the stellar population, we interpret the strong differences in the TiO${}_2$ feature as an IMF variation. In particular, for the heaviest z$\sim$1 MQGs (M$>$10${}^{11}$Msun) we find an average age of 1.7$\pm$0.3 Gyr and a bottom-heavy IMF (${\Gamma }_b$=3.2$\pm$0.2). Lighter MQGs (2$\times$10${}^{10}$$<$M$<$10${}^{11}$ Msun) at the same redshift are younger on average (1.0$\pm$0.2 Gyr) and present a shallower IMF slope (${\Gamma }_b=2.7_{-0.4}^{+0.3}$). Our results are in good agreement with the findings about the IMF slope in early-type galaxies of similar mass in the present-day Universe. This suggests that the IMF, a key characteristic of the stellar populations in galaxies, is bottom-heavier for more massive galaxies and has remained unchanged in the last $\sim$8 Gyr.

6 pages, 5 figures, accepted for publication in ApJL

References in corpus (43)

• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
• CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey - The Hubble Space Telescope Observations, Imaging Data Products and Mosaics
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• A Simple Model for the Absorption of Starlight by Dust in Galaxies
• The epochs of early-type galaxy formation as a function of environment
• Dust Absorption And The Ultraviolet Luminosity Density At z \approx 3 As Calibrated By Local Starburst Galaxies
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
• The stellar mass assembly of galaxies from z=0 to z=4. Analysis of a sample selected in the rest-frame near-infrared with Spitzer
• A systematic variation of the stellar initial mass function in early-type galaxies
• A Substantial Population of Low Mass Stars in Luminous Elliptical Galaxies
• The NEWFIRM Medium-band Survey: Photometric Catalogs, Redshifts and the Bimodal Color Distribution of Galaxies out to z~3
• STELIB: a library of stellar spectra at R~2000
• Stellar Population Diagnostics of Elliptical Galaxy Formation
• The initial mass function of early-type galaxies
• A new chemo-evolutionary population synthesis model for early-type galaxies. I: Theoretical basis
• The galaxy stellar mass-star formation rate relation: Evidence for an evolving stellar initial mass function?
• SPIDER VIII - Constraints on the Stellar Initial Mass Function of Early-type Galaxies from a Variety of Spectral Features
• Evidence for a Non-Uniform Initial Mass Function in the Local Universe
• Evidence of Cosmic Evolution of the Stellar Initial Mass Function
• Stellar Kinematics of z~2 Galaxies and the Inside-Out Growth of Quiescent Galaxies
• Systematic variation of the stellar Initial Mass Function with velocity dispersion in early-type galaxies
• Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios
• The stellar IMF determined in early-type galaxies from a non-degenerate set of optical line indices
• Near-IR line-strengths in elliptical galaxies: evidence for IMF variations?
• Evidence for a non-universal stellar initial mass function from the integrated properties of SDSS galaxies
• Deep near-infrared spectroscopy of passively evolving galaxies at z>1.4
• Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at z~2
• The Assembly Histories of Quiescent Galaxies Since z=0.7 from Absorption Line Spectroscopy
• SHARDS: an optical spectro-photometric survey of distant galaxies
• Velocity Dispersions and Dynamical Masses for a Large Sample of Quiescent Galaxies at z > 1: Improved Measures of the Growth in Mass and Size
• UV-to-FIR analysis of Spitzer/IRAC sources in the Extended Groth Strip II: Photometric redshifts, Stellar masses and Star formation rates
• Uv-to-fir analysis of spitzer/irac sources in the extended groth strip i: Multi-wavelength photometry and spectral energy distributions
• Keck Spectroscopy of z>1 Field Spheroidals: Dynamical Constraints on the Growth Rate of Red "Nuggets"
• The Progenitors of Local Ultra-massive Galaxies Across Cosmic Time: from Dusty Star-bursting to Quiescent Stellar Populations
• Dynamical Versus Stellar Masses in Compact Early-Type Galaxies: Further Evidence for Systematic Variation in the Stellar Initial Mass Function
• Salpeter normalization of the Stellar Initial Mass Function for massive galaxies at z~1
• SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65<z<1.1 galaxies
• HST/WFC3 Near-Infrared spectroscopy of quenched galaxies at z~1.5 from the WISP Survey: Stellar population properties

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• Observed trend in the star formation history and the dark matter fraction of galaxies at redshift $z\approx 0.8$
• Implications of a Temperature Dependent IMF I: Photometric Template Fitting
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• Calibrated, cosmological hydrodynamical simulations with variable IMFs III: Spatially-resolved properties and evolution
• Revisiting the bulge-halo conspiracy II: Towards explaining its puzzling dependence on redshift
• Evidence of a Bottom-heavy Initial Mass Function in Massive Early-type Galaxies from Near-infrared Metal Lines
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• Implications of galaxy buildup for putative IMF variations in massive galaxies
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• Constraints on the evolutionary mechanisms of massive galaxies since $z\sim 1$ from their velocity dispersions
• Stellar Initial Mass Function (IMF) Probed with Supernova Rates and Neutrino Background: Cosmic Average IMF Slope is $\simeq 2-3$ Similar to the Salpeter IMF
• SEW: A full-spectrum linear fitting with stellar population synthesis method Based on "Equivalent Widths spectrum"
• Growing in number, passive in nature: tracing the evolution of the most massive quiescent galaxies since z ~ 0.8 with BOSS and DESI