RECONSTRUCTING THE STELLAR MASS DISTRIBUTIONS OF GALAXIES USING S4G IRAC 3.6 AND 4.5 μm IMAGES. I. CORRECTING FOR CONTAMINATION BY POLYCYCLIC AROMATIC HYDROCARBONS, HOT DUST, AND INTERMEDIATE-AGE…

By S. Meidt, E. Schinnerer, Johan H. Knapen, A. Bosma, E. Athanassoula, K. Sheth, R. Buta, Dennis Zaritsky, E. Laurikainen, D. Elmegreen and 16 more. 2011

136 citations recorded by the source corpus.

With the aim of constructing accurate two-dimensional maps of the stellar mass distribution in nearby galaxies from Spitzer Survey of Stellar Structure in Galaxies 3.6 and 4.5 μm images, we report on the separation of the light from old stars from the emission contributed by contaminants. Results for a small sample of six disk galaxies (NGC 1566, NGC 2976, NGC 3031, NGC 3184, NGC 4321, and NGC 5194) with a range of morphological properties, dust content, and star formation histories are presented to demonstrate our approach. To isolate the old stellar light from contaminant emission (e.g., hot dust and the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature) in the IRAC 3.6 and 4.5 μm bands we use an independent component analysis (ICA) technique designed to separate statistically independent source distributions, maximizing the distinction in the [3.6]–[4.5] colors of the sources. The technique also removes emission from evolved red objects with a low mass-to-light ratio, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, revealing maps of the underlying old distribution of light with [3.6]–[4.5] colors consistent with the colors of K and M giants. The contaminants are studied by comparison with the non-stellar emission imaged at 8 μm, which is dominated by the broad PAH feature. Using the measured 3.6 μm/8 μm ratio to select individual contaminants, we find that hot dust and PAHs together contribute between ∼5% and 15% to the integrated light at 3.6 μm, while light from regions dominated by intermediate-age (AGB and RSG) stars accounts for only 1%–5%. Locally, however, the contribution from either contaminant can reach much higher levels; dust contributes on average 22% to the emission in star-forming regions throughout the sample, while intermediate-age stars contribute upward of 50% in localized knots. The removal of these contaminants with ICA leaves maps of the old stellar disk that retain a high degree of structural information and are ideally suited for tracing stellar mass, as will be the focus in a companion paper.

Subfields: Analytical Chemistry, Astronomy and Astrophysics, Signal Processing

View Paper: https://www.semanticscholar.org/paper/b8b808a83c67cb3545ca6d1709423682c0455158

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In Astronomy and Astrophysics

In Signal Processing

Benjamin D. Johnson

Citations in the corpus

GALAXY AND MASS ASSEMBLY (GAMA): MID-INFRARED PROPERTIES AND EMPIRICAL RELATIONS FROM WISE (2014, background): “In the local Universe, the 3.4 μm (W1) and 4.6 μm (W2) bands chiefly trace the continuum emission from evolved stars (see, for example, Meidt et al. 2012).”
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.”
THE PdBI ARCSECOND WHIRLPOOL SURVEY (PAWS). I. A CLOUD-SCALE/MULTI-WAVELENGTH VIEW OF THE INTERSTELLAR MEDIUM IN A GRAND-DESIGN SPIRAL GALAXY (2013, methodology): “Given the possibly large contribution from younger stellar clusters, the contaminant-corrected 3.6µm map of Meidt et al. (2012) provides a better view of the old stellar population alone and its spatial relation to the molecular gas (Fig.”
COLOR–MASS-TO-LIGHT-RATIO RELATIONS FOR DISK GALAXIES (2014, unknown): “This is small at 3.6µm (Kim et al. 2012; Meidt et al. 2012).”
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).”
THE CO-TO-H2 CONVERSION FACTOR AND DUST-TO-GAS RATIO ON KILOPARSEC SCALES IN NEARBY GALAXIES (2012, background): “This provides only a rough tracer of stellar mass surface density, since we do not take into account corrections for various contaminants in the 3.6 2 Data available at http://www.caha.es/sanchez/orion/ 6 Sandstrom et al. µm band (Zibetti & Groves 2011; Meidt et al. 2012).”
MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES (2013, methodology): “We estimate the stellar surface density, Σ∗, for each kpc-sized element from the contaminant-corrected 3.6µm maps of Meidt et al. (2012).”
CONVERTING FROM 3.6 AND 4.5 μm FLUXES TO STELLAR MASS (2012, background): “Even with sophisticated treatments, such as that described by Meidt et al. (2012), one might at best be able to exclude all of these outliers from the analysis, at which point one would return to our estimate of the scatter of ∼ 0.12 (or 30% in mass for the regions considered here).”
RECONSTRUCTING THE STELLAR MASS DISTRIBUTIONS OF GALAXIES USING S4G IRAC 3.6 AND 4.5 μm IMAGES. II. THE CONVERSION FROM LIGHT TO MASS (2014, background): “Whereas old stars typically exhibit blue colors in the range -0.15<[3.6]-[4.5]<-0.02, the emission from non-stellar sources are characterized by colors [3.6]- [4.5]∼0.3 and redder (Meidt et al 2012; Querejeta et al. 2014).”
DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES (2012, background): “However, the significant but uncertain stochastic effects of asymptotic giant branch (AGB) stars on the total NIR luminosities of low luminosity galaxies must also be considered (see, e.g., Fouesneau & Lançon 2010; Meidt et al. 2012; Melbourne et al. 2012).”