Revisiting the classics: Is [Mg/Fe] a good proxy for galaxy formation time-scales?

Abstract

In the local Universe, massive early-type galaxies exhibit enhanced [Mg/Fe] ratios, which has been traditionally interpreted as the result of a rapid ($\tau \lesssim 1$ Gyr) collapse. However, recent claims of a non-universal, steep initial mass function call for a revision of this standard interpretation. In the present work we show how the simultaneous consideration of a high [Mg/Fe] and a steep IMF slope would imply unreasonably short ($\tau \sim 7$ Myr) and intense (SFR $\sim 10^5$ Msun yr${}^{-1}$) formation events for massive early-type galaxies. We discuss possible caveats and explanations to this apparent inconsistency, and we suggest that further IMF determinations, both in the local Universe and at high redshift, are necessary to better understand the problem.

5 pages, MNRAS Letters accepted

References in corpus (10)

• A systematic variation of the stellar initial mass function in early-type galaxies
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
• A unified multi-wavelength model of galaxy formation
• 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
• Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results
• Radial constraints on the Initial Mass Function from TiO features and Wing-Ford band in Early-type Galaxies
• A calibration of the stellar mass fundamental plane at z ~ 0.5 using the micro-lensing induced flux ratio anomalies of macro-lensed quasars
• Further evidence for a time-dependent initial mass function in massive early-type galaxies

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• The impact of the metallicity and star formation rate on the time-dependent galaxy-wide stellar initial mass function
• The Dawes Review 8: Measuring the Stellar Initial Mass Function
• SDSS-IV MaNGA: The Spatially Resolved Stellar Initial Mass Function in $\sim$400 Early-Type Galaxies
• Timing the formation and assembly of early-type galaxies via spatially resolved stellar populations analysis
• IMF shape constraints from stellar populations and dynamics from CALIFA
• The Fornax 3D project: a two-dimensional view of the stellar initial mass function in the massive lenticular galaxy FCC 167
• The Fornax 3D project: Thick disks in a cluster environment
• The hELENa project - I. Stellar populations of early-type galaxies linked with local environment and galaxy mass
• Chemical evolution of elliptical galaxies with a variable IMF -- A publicly available code
• Calibrated, cosmological hydrodynamical simulations with variable IMFs I: Method and effect on global galaxy scaling relations
• Initial Mass Function Variability (or not) Among \\ Low-Velocity Dispersion, Compact Stellar Systems
• Stellar populations across the black hole mass - velocity dispersion relation
• Calibrated, cosmological hydrodynamical simulations with variable IMFs III: Spatially-resolved properties and evolution
• Extreme Variation in Star Formation Efficiency Across a Compact, Starbursting Disk Galaxy
• Massive High-Redshift Quiescent Galaxies With JWST
• Self-similarity in the chemical evolution of galaxies and the delay time distribution of SNe Ia
• The initial mass function of stars and the star-formation rates of galaxies
• Implications of galaxy buildup for putative IMF variations in massive galaxies
• Recovery of the low- and high-mass end slopes of the IMF in massive early-type galaxies using detailed elemental abundances
• Black hole feedback and the evolution of massive early-type galaxies
• ZF-UDS-7329: A relic galaxy in the early Universe
• The star formation timescale of elliptical galaxies -- Fitting [Mg/Fe] and total metallicity simultaneously
• Fornax 3D project: assessing the diversity of IMF and stellar population maps within the Fornax Cluster