RECONSTRUCTING THE STELLAR MASS DISTRIBUTIONS OF GALAXIES USING S4G IRAC 3.6 AND 4.5 μm IMAGES. II. THE CONVERSION FROM LIGHT TO MASS

By S. Meidt, E. Schinnerer, G. van de Ven, Dennis Zaritsky, Reynier Peletier, Johan H. Knapen, K. Sheth, M. Regan, M. Querejeta, J. Muńoz-Mateos and 19 more. 2014

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We present a new approach for estimating the 3.6 μm stellar mass-to-light (M/L) ratio ϒ3.6 in terms of the [3.6]–[4.5] colors of old stellar populations. Our approach avoids several of the largest sources of uncertainty in existing techniques using population synthesis models. By focusing on mid-IR wavelengths, we gain a virtually dust extinction-free tracer of the old stars, avoiding the need to adopt a dust model to correctly interpret optical or optical/near-IR colors normally leveraged to assign the mass-to-light ratio ϒ. By calibrating a new relation between near-IR and mid-IR colors of giant stars observed in GLIMPSE we also avoid the discrepancies in model predictions for the [3.6]–[4.5] colors of old stellar populations due to uncertainties in the molecular line opacities assumed in template spectra. We find that the [3.6]–[4.5] color, which is driven primarily by metallicity, provides a tight constraint on ϒ3.6, which varies intrinsically less than at optical wavelengths. The uncertainty on ϒ3.6 of ∼0.07 dex due to unconstrained age variations marks a significant improvement on existing techniques for estimating the stellar M/L with shorter wavelength data. A single ϒ3.6 = 0.6 (assuming a Chabrier initial mass function (IMF)), independent of [3.6]–[4.5] color, is also feasible because it can be applied simultaneously to old, metal-rich and young, metal-poor populations, and still with comparable (or better) accuracy (∼0.1 dex) than alternatives. We expect our ϒ3.6 to be optimal for mapping the stellar mass distributions in S4G galaxies, for which we have developed an independent component analysis technique to first isolate the old stellar light at 3.6 μm from nonstellar emission (e.g., hot dust and the 3.3 polycyclic aromatic hydrocarbon feature). Our estimate can also be used to determine the fractional contribution of nonstellar emission to global (rest-frame) 3.6 μm fluxes, e.g., in WISE imaging, and establishes a reliable basis for exploring variations in the stellar IMF.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Signal Processing

View Paper: https://www.semanticscholar.org/paper/22fe3fadba5484a98275703181ddf84135e5d778

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Citations in the corpus

A CLASSICAL MORPHOLOGICAL ANALYSIS OF GALAXIES IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S4G) (2015, methodology): “Meidt et al. (2012, 2014) and Querajeta et al. (2014) use [3.6]−[4.5] colors and a technique known as “independent component analysis” to locate and remove young contaminants and derive stellar mass maps.”
One Law to Rule Them All: The Radial Acceleration Relation of Galaxies (2016, methodology): “They are in agreement with independent estimates from different SPS models (Meidt et al. 2014; Norris et al. 2016) and resolved stellar populations in the LMC (Eskew et al. 2012).”
HIGH-RESOLUTION MASS MODELS OF DWARF GALAXIES FROM LITTLE THINGS (2015, background): “Although there is some contamination by PAH emission extending into the 3.6µm band (Meidt et al. 2014) this is reduced in dIrr galaxies which, by virtue of having low heavy element abundances, have a correspondingly lower dust content.”
Fitting the radial acceleration relation to individual SPARC galaxies (2018, background): “ESO Fellow Assuming that the stellar mass-to-light ratio Υ? does not vary strongly at [3.6] (McGaugh & Schombert 2014, 2015; Meidt et al. 2014; Schombert & McGaugh 2014), it is found that the RAR has an observed rms scatter of only 0.13 dex (McGaugh et al. 2016; Lelli et al. 2017a).”
THE SMALL SCATTER OF THE BARYONIC TULLY–FISHER RELATION (2015, methodology): “We assume δΥ∗ = 0.11 dex, as suggested by stellar population models (Meidt et al. 2014; McGaugh & Schombert 2014).”
SPARC: MASS MODELS FOR 175 DISK GALAXIES WITH SPITZER PHOTOMETRY AND ACCURATE ROTATION CURVES (2016, background): “If we adopt the customary 12 definition of maximum disk as Vbar/Vobs = 0.85 (Sackett 1997), then the mean maximum-disk value of Υ? is ∼0.5 M /L , which is similar to the predictions of SPS models with standard IMFs (e.g., McGaugh & Schombert 2014; Meidt et al. 2014; Schombert & McGaugh 2014a).”
The dark nemesis of galaxy formation : why hot haloes trigger black hole growth and bring star formation to an end (2016, methodology): “To plot total galaxy mass, rather than than bulge mass alone, we convert the mid-IR photometry given by Savorgnan et al. (2016) to stellar mass using the calibration of Meidt et al. (2014).”
A z = 0 Multiwavelength Galaxy Synthesis. I. A WISE and GALEX Atlas of Local Galaxies (2019, background): “WISE3 and WISE4 measurements, and often NUV and FUV, should now be available for almost all galaxies, including the S4G sample (but were not available to Meidt et al. 2014; Querejeta et al. 2015, and earlier work).”
The lifecycle of molecular clouds in nearby star-forming disc galaxies (2019, methodology): “, in a similar way as presented in Meidt et al. (2012, 2014); Querejeta et al. (2014).”
STELLAR MASSES AND STAR FORMATION RATES FOR 1 M GALAXIES FROM SDSS+WISE (2015, background): “…Germany; e-mail: yu-yen.chang@cea.fr 2 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia rate and precise stellar mass estimates, even in the absence of any other photometric or spectroscopic information (Meidt et al. 2014).”