DECREASED FREQUENCY OF STRONG BARS IN S0 GALAXIES: EVIDENCE FOR SECULAR EVOLUTION?

Journal Article · Mon Sep 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/721/1/259· OSTI ID:21464871

Buta, R ^[1]; Laurikainen, E; Salo, H ^[2]; Knapen, J H ^[3]

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1. Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States)
2. Department of Physics/Astronomy Division, University of Oulu, FIN-90014 (Finland)
3. Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain)

Using data from the Near-Infrared S0 Survey of nearby, early-type galaxies, we examine the distribution of bar strengths in S0 galaxies as compared to S0/a and Sa galaxies, and as compared to previously published bar strength data for Ohio State University Bright Spiral Galaxy Survey spiral galaxies. Bar strengths based on the gravitational torque method are derived from 2.2 {mu}m K{sub s} -band images for a statistical sample of 138 (98 S0, 40 S0/a,Sa) galaxies having a mean total blue magnitude (B{sub T}) {<=} 12.5 and generally inclined less than 65{sup 0}. We find that S0 galaxies have weaker bars on average than spiral galaxies in general, even compared to their closest spiral counterparts, S0/a and Sa galaxies. The differences are significant and cannot be entirely due to uncertainties in the assumed vertical scale heights or in the assumption of constant mass-to-light ratios. Part of the difference is likely simply due to the dilution of the bar torques by the higher mass bulges seen in S0s. If spiral galaxies accrete external gas, as advocated by Bournaud and Combes, then the fewer strong bars found among S0s imply a lack of gas accretion according to this theory. If S0s are stripped former spirals, or else are evolved from former spirals due to internal secular dynamical processes which deplete the gas as well as grow the bulges, then the weaker bars and the prevalence of lenses in S0 galaxies could further indicate that bar evolution continues to proceed during and even after gas depletion.

• OSTI ID: 21464871
• Journal Information: Astrophysical Journal, Vol. 721, Issue 1; Other Information: DOI: 10.1088/0004-637X/721/1/259; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
GALACTIC EVOLUTION
GALAXIES
IMAGES
MASS
PHOTOMETRY
EVOLUTION