Stellar masses, sizes, and radial profiles for 465 nearby early-type galaxies: An extension to the Spitzer survey of stellar structure in Galaxies (S⁴G)^⋆

¹ Space Physics and Astronomy Research Unit, University of Oulu, Oulu 90014, Finland
e-mail: a.emery.watkins@gmail.com
² Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield AL10 9AB, UK
³ Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
⁴ Finnish Centre of Astronomy with ESO (FINCA), University of Turku, Vesilinnantie 5, 20014 Turku, Finland
⁵ Specim, Spectral Imaging Ltd., Elektroniikkatie 13, 90590 Oulu, Finland
⁶ Departamento de Astrofísica, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain
⁷ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
⁸ Department for Physics, Engineering Physics and Astrophysics, Queen’s University, Kingston, ON K7L 3N6, Canada
⁹ Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487, USA
¹⁰ Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
¹¹ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
¹² Department of Astronomy, School of Physics, Peking University, Beijing 100871, PR China
¹³ University of Louisville, Department of Physics and Astronomy, 102 Natural Science Building, 40292 KY, Louisville, USA
¹⁴ Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 41566, Korea
¹⁵ IPAC, Mail Code 314-6, Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA
¹⁶ Valongo Observatory, Federal University of Rio de Janeiro, Ladeira Pedro Antônio, 43, Saúde CEP, 20080-090 Rio de Janeiro, RJ, Brazil
¹⁷ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
¹⁸ NASA Headquarters Mary W. Jackson Building, 300 E Street SW, Washington, DC 20546, USA
¹⁹ Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA

Received: 9 November 2021
Accepted: 18 January 2022

Abstract

Context. The Spitzer Survey of Stellar Structure in Galaxies (S⁴G) is a detailed study of over 2300 nearby galaxies in the near-infrared (NIR), which has been critical to our understanding of the detailed structures of nearby galaxies. Because the sample galaxies were selected only using radio-derived velocities, however, the survey favored late-type disk galaxies over lenticulars and ellipticals.

Aims. A follow-up Spitzer survey was conducted to rectify this bias, adding 465 early-type galaxies (ETGs) to the original sample, to be analyzed in a manner consistent with the initial survey. We present the data release of this ETG extension, up to the third data processing pipeline (P3): surface photometry.

Methods. We produce curves of growth and radial surface brightness profiles (with and without inclination corrections) using reduced and masked Spitzer IRAC 3.6 μm and 4.5 μm images produced through Pipelines 1 and 2, respectively. From these profiles, we derive the following integrated quantities: total magnitudes, stellar masses, concentration parameters, and galaxy size metrics. We showcase NIR scaling relations for ETGs among these quantities.

Results. We examine general trends across the whole S⁴G and ETG extension among our derived parameters, highlighting differences between ETGs and late-type galaxies (LTGs). The latter are, on average, more massive and more concentrated than LTGs, and subtle distinctions are seen among ETG morphological subtypes. We also derive the following scaling relations and compare them with previous results in visible light: mass-size (both half-light and isophotal), mass-concentration, mass-surface brightness (central, effective, and within 1 kpc), and mass-color.

Conclusions. We find good agreement with previous works, though some relations (e.g., mass-central surface brightness) will require more careful multicomponent decompositions to be fully understood. The relations between mass and isophotal radius and between mass and surface brightness within 1 kpc, in particular, show notably small scatter. The former provides important constraints on the limits of size growth in galaxies, possibly related to star formation thresholds, while the latter–particularly when paired with the similarly tight relation for LTGs–showcases the striking self-similarity of galaxy cores, suggesting they evolve little over cosmic time. All of the profiles and parameters described in this paper will be provided to the community via the NASA/IPAC database on a dedicated website.