The Complete Spitzer Survey of Stellar Structure in Galaxies (CS⁴G)^★

¹ Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
³ Space Physics and Astronomy Research Unit, University of Oulu, Pentti Kaiteran katu 1, 90014 Oulu, Finland
⁴ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, 28040 Madrid, Spain
⁵ Centre of Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield, UK
⁶ Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487, USA
⁷ IPAC, Mail Code 314-6, Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA
⁸ Max-Planck-Institut für Extraterrestriche Physik, Giessenbach-Str. 1, 85748 Garching, Germany
⁹ Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
¹⁰ Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹¹ MMT Observatory, University of Arizona, 933 N Cherry Ave, Tucson, AZ 85721, USA
¹² Kavli Institute for Astronomy and Astrophysics, Peking University, 12 Beijing 100871, PR China
¹³ Department of Astronomy, School of Physics, Peking University, Beijing 100871, PR China
¹⁴ University of Louisville, Department of Physics and Astronomy, 102 Natural Science Building, Louisville, KY 40292, USA
¹⁵ Finnish Centre of Astronomy with ESO (FINCA), Vesilinnantie 5, 20014 University of Turku, Finland
¹⁶ Specim, Spectral Imaging Ltd., Elektroniikkatie 13, 90590 Oulu, Finland
¹⁷ Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea
¹⁸ Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
¹⁹ Normet Oy, Elektroniikkatie 8, 90590 Oulu, Finland
²⁰ The Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101, USA
²¹ Department of Astronomy & Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
²² Observatório do Valongo, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
²³ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
²⁴ Observatorio Astronómico Nacional (IGN), C/Alfonso XII, 3, 28014 Madrid, Spain
²⁵ NASA Headquarters Mary W. Jackson Building, 300 E Street SW, Washington, DC 20546, USA
²⁶ Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA

^★★ Corresponding author: pmsa.astro@gmail.com

Received: 24 July 2024
Accepted: 28 February 2025

Abstract

Context. The Spitzer Survey of Stellar Structure in Galaxies (S⁴G), together with its Early Type Galaxy (ETG) extension, stands as the most extensive dataset of deep uniform mid-infrared (mid-IR; 3.6 and 4.5 μm) imaging for a sample of 2817 nearby (d < 40 Mpc) galaxies. However, the velocity criterion used to select the original sample results in an additional 422 galaxies without H I detection that should have been included in the S⁴G on the basis of their optical recession velocities.

Aims. In order to create a complete magnitude-, size-, and volume-limited sample of nearby galaxies, we collected 3.6 μm and i-band images using archival data from different surveys and complemented it with new observations for the missing galaxies. Since most, but not all, of these galaxies have a Hubble type in Hyperleda T_HL > 0, we denote the sample of these additional galaxies as disc galaxy (DG) extension. We present the Complete Spitzer Survey of Stellar Structure in Galaxies (CS⁴G), encompassing a sample of 3239 galaxies (S⁴G+ETG+DG) with consistent imaging, surface brightness profiles, photometric parameters, and revised morphological classification.

Methods. Following the original strategy of the S⁴G survey, we produced masks, surface brightness profiles, and curves of growth using masked 3.6 μm and i-band images. From these profiles, we derived the integrated quantities, including total magnitude, stellar mass, concentration parameter, and galaxy size, converting between optical i-band and 3.6 μm. We also re-measured these parameters for the S⁴G and ETG to create a homogenous sample. We present new morphologically revised T-types, and we showcase mid-IR scaling relations for the stellar mass, galaxy size, concentration index, and morphological type.

Results. Our new masking procedure increases the number of pixels masked out by a factor of five, improving the masking of fainter regions over previous S⁴G data. Our photometric parameters from i-band imaging yield measurements consistent with the original sample (S⁴G) and its ETG extension in the 3.6 μm band. The new DG extension consists of galaxies with a wide morphological range (−5 < T_HL < 10) and a mass range of 6 < log(M_⋆/M_⊙) < 11. The galaxies in the DG sample have an average mass of log(M_⋆/M_⊙) = 9.21, an average galaxy isophotal radius at 25.5 mag arcsec⁻² of R_25.5 = 7.1 kpc, and an average concentration index of C₈₂ = 2.92.

Conclusions. We completed the S⁴G sample by incorporating 422 galaxies into the original dataset. The new galaxies constitute 15% of the total previous sample (S⁴G+ETG), but in the lower-mass range (M_⋆ < 10⁹ M_⊙), and the disc galaxy extension increases the sample by 36%. The CS⁴G includes at least 99.94% of the complete sample of nearby galaxies, meeting the original selection criteria based on a comparison with the NED database. We make the images and surface brightness profiles available to the community together with the conjunct catalogue of the whole CS⁴G dataset with consistent photometric measurements for 3239 galaxies. The CS⁴G will enable a wide set of investigations into galaxy structure and evolution, and it will complement the optical, near-IR, and mid-IR imaging that will obtained in the coming years with Euclid, Rubin, Roman, and other research projects.