Resolved stellar mass maps of galaxies. I: method and implications for global mass estimates

By S. Zibetti, S. Charlot, Hans-Walter Rix Mpia Heidelberg, Iap Paris. 2009

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We introduce a novel technique to construct spatially resolved maps of stellar mass surface density in galaxies based on optical and near-infrared (NIR) imaging. We use optical/NIR colour(s) to infer effective stellar mass-to-light ratios (M/L) at each pixel, which are then multiplied by the surface brightness to obtain the local surface stellar mass density. We build look-up tables to express M/L as a function of colour(s) by marginalizing over a Monte Carlo library of 50 000 stellar population synthesis (SPS) models by Charlot & Bruzual, which include a revised prescription for the thermally pulsing asymptotic giant branch (TP-AGB) stellar evolutionary phase. Moreover, we incorporate a wide range of possible dust extinction parameters. In order to extract reliable flux and colour information at any position in the galaxy, we perform a median adaptive smoothing of the images that preserves the highest possible spatial resolution. As the most practical and robust, and hence fiducial method, we express the M/L in the H band as a function of (g−i) and (i−H). Stellar mass maps computed in this way have a typical accuracy of 30 per cent or less at any given pixel, determined from the scatter in the models. We compare maps obtained with our fiducial method with those derived using other combinations of bandpasses: (i) mass maps based on the M/L in NIR bands require one optical and one optical-NIR colour to avoid significant biases as a function of the local physical properties of a galaxy; (ii) maps based on M/L in i band as a function of (g−i) only are generally in excellent agreement with our best optical-NIR set, except for extremely star-forming and dust extincted regions. We further compute stellar mass maps using a model library identical to the previous one except for being based on older SPS models, which assume shorter lived TP-AGB stars. The M/L in the NIR inferred using these old models may be up to 2.5 times larger than the new ones, but this varies strongly as a function of colours and is maximal for the bluest colours. Finally, we compare total stellar mass estimates obtained by integrating resolved mass maps with those obtained with unresolved photometry. In galaxies with evident dust lanes, unresolved estimates may miss up to 40 per cent of the total stellar mass because dusty regions are strongly under-represented in the luminous fluxes.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c724a3a8606470db8b54626febe84994b83dfe09

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Citations in the corpus

THE DISKMASS SURVEY. I. OVERVIEW (2010, methodology): “Unfortunately, independent contraints from SPS models on Υ∗ are rather poor (uncertainties of factors of 4, and possibly much larger are likely) due to uncertainties in the low-mass end of the IMF, late-phases of stellar evolution (especially the TP-AGB), and a wide range of possible star-formation ”
The effect of the environment on the Hi scaling relations (2011, methodology): “Stellar masses M∗ are determined from i-band luminosities Li using the g− i colour-dependent stellar mass-to-light ratio relation from Zibetti et al. (2009), assuming a Chabrier (2003) initial mass function (IMF): log(M∗/Li) = −0.963 + 1.032 ∗ (g − i) (4) The final sample used for the following…”
Stellar Mass—Halo Mass Relation and Star Formation Efficiency in High-Mass Halos (2014, methodology): “We advocate using masses measured within specific apertures for such comparisons and provide such measurements for our BCGs for a range of apertures in Table 4 in the Appendix B.”
Galaxy And Mass Assembly (GAMA): the galaxy stellar mass function at z < 0.06 (2011, background): “Bell et al. (2003) givea = −0.152 andb = 0.518 while reading off from figure 4 of Zibetti et al. (2009) givesa ≃ −1 andb ≃ 1, though the latter is for resolved parts of galaxies.”
Cosmic X-ray surveys of distant active galaxies (2015, background): “The host-galaxy color provides a basic characterization of the galaxy integrated stellar populations and, when combined with the luminosity, a reliable estimate of the mass of the host galaxy (e.g., Bell and de Jong 2001; Zibetti et al 2009; Conroy 2013).”
The star formation history of CALIFA galaxies: Radial structures (2013, methodology): “In a pioneering work, Zibetti et al. (2009) carried out a detailed analysis of nine nearby galaxies using SDSS ugriz plus J, H, K images, devising a method to derive the spatially resolved H band M/L ratio as a function of the g− i color.”
ANGULAR MOMENTUM AND GALAXY FORMATION REVISITED (2012, background): “…variation in Υ⋆,K across our entire sample of late and early-type galaxies is conventionally expected to be no more than ∼ 0.1 dex, based on B − V colors (Bell et al. 2003), although there are recent suggestions of variations at the level of ∼ 0.4 dex (Zibetti et al. 2009; Bershady et al. 2011).”
CONSTRAINTS ON THE ASSEMBLY AND DYNAMICS OF GALAXIES. I. DETAILED REST-FRAME OPTICAL MORPHOLOGIES ON KILOPARSEC SCALE OF z ∼ 2 STAR-FORMING GALAXIES (2010, background): “…that observed colors andM/L ratio of stellar populations are correlated, and this behavior can be used to infer stellar masses (see, e.g., Rudnick et al. 2006; Zibetti et al. 2009, for applications to derive the cosmic stellar mass density or spatially-resolved mass maps of nearby galaxies).”
THE EMISSION BY DUST AND STARS OF NEARBY GALAXIES IN THE HERSCHEL KINGFISH SURVEY (2011, methodology): “The Zibetti et al. (2009) model outputs stellar mass-to-light ratios logM∗/LH(B − V, V − H), and for the LVL galaxies, which have ugriz-band SDSS data, we use logM∗/LH(g − i, i − H).”
THE HERSCHEL REFERENCE SURVEY: DUST IN EARLY-TYPE GALAXIES AND ACROSS THE HUBBLE SEQUENCE (2011, methodology): “We estimate stellar masses for 20 PACS Photometer Point Spread Function Document (2010) 21 PACS Photometer Calibration Document (2011) the sample from the i-band luminosities using the relationship between stellar mass and galaxy color for a Chabrier initial mass function (Zibetti et al. 2009).”
CALIFA, the Calar Alto Legacy Integral Field Area survey - III. Second public data release (2012, methodology): “A mosaiced SDSS image was created for each galaxy using SDSSmosaic , an IRAF 4 package developed by S. Zibetti (Zibetti et al. 2009), which also subtracts the background from each SDSS scan by ﬁtting a plane surface that allows for linear gradient along the scan direction.”
A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA (2013, methodology): “These images were created using the SDSSmosaic tool included in IRAF7 (Zibetti et al. 2009).”
MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES (2013, neutral): “Based on comparison to Zibetti et al. (2009), we use Σ∗ [ M⊙ pc −2 ] = 200 I3.”
The dust scaling relations of the Herschel Reference Survey (2012, methodology): “This approach is similar to what has been done in the past to determine stellar masses from optical and near-infrared luminosities and colours (e.g., Bell et al. 2003; Zibetti et al. 2009).”