The Spitzer Survey of Stellar Structure in Galaxies (S^4G)
2010
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|> 30°,m_(Bcorr) 1') survey of 2331 galaxies using the Infrared Array Camera (IRAC) at 3.6 and
4.5 μm. Each galaxy is observed for 240 s and mapped to ≥ 1:5 × D_(25). The final mosaicked images have a typical
1 σ rms noise level of 0.0072 and 0:0093 MJy sr^-1 at 3.6 and 4.5 μm, 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 article introduces the survey and
describes the sample selection, the significance of the 3.6 and 4.5 μm bands for this study, and the data collection
and survey strategies. 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 phases 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, using the galaxy-fitting code GALFIT, we deconstruct each
galaxy 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 will enable a variety of scientific investigations, some of
which are highlighted in this introductory S^4G survey paper.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
5
Citations
NaN
KQI