%0 Journal Article
%A Gil De Paz, Armando
%T The Spitzer Survey of Stellar Structure in Galaxies (S^4G)
%D 2010
%@ 0004-6280
%U https://hdl.handle.net/20.500.14352/44888
%X The Spitzer Survey of Stellar Structure in Galaxies (S^4G) is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d<40 Mpc, |b| > 30º, m_Bcorr <15.5, D_25 >1’) survey of 2,331 galaxies using the Infrared Array Camera (IRAC) at 3.6 and 4.5μm. Each galaxy is observed for 240 s and mapped to ≤ 1.5×D_25. The final mosaicked images have a typical 1σ rms noise level of 0.0072 and 0.0093 MJy sr^−1 at 3.6 and 4.5μm, respectively. Our azimuthally-averaged surface brightness profile typically traces isophotes at μ_3.6μm(AB)(1σ)~27 mag arcsec^−2, equivalent to a stellar mass surface density of ~ 1 M_⊙pc^−2. S^4G thus provides an unprecedented data set for the study of the distribution of mass and stellar structures in the local Universe. This large, unbiased and extremely deep sample of all Hubble types from dwarfs to spirals to ellipticals will allow for detailed structural studies, not only as a function of stellar mass, but also as a function of the local environment. The data from this survey will serve as a vital testbed for cosmological simulations predicting the stellar mass properties of present-day galaxies. This paper introduces the survey, describes the sample selection, the significance of the 3.6 and 4.5μm bands for this study, and the data collection & survey strategy. We describe the S^4G data analysis pipeline and present measurements for a first set of galaxies, observed in both the cryogenic and warm mission phase of Spitzer. For every galaxy we tabulate the galaxy diameter, position angle, axial ratio, inclination at μ_3.6μm(AB)= 25.5 and 26.5 mag arcsec^−2 (equivalent to ≈ μ_B(AB)=27.2 and 28.2 mag arcsec^−2, respectively). These measurements will form the initial S^4G catalog of galaxy properties. We also measure the total magnitude and the azimuthally-averaged radial profiles of ellipticity, position angle, surface brightness and color. Finally, we deconstruct each galaxy using GALFIT into its main constituent stellar components: the bulge/spheroid, disk, bar, and nuclear point source, where necessary. Together these data products will provide a comprehensive and definitive catalog of stellar structures, mass and properties of galaxies in the nearby Universe and enable a variety of scientific investigations, some of which are highlighted in this introductory S^4G survey paper.
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