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2000PASP..112..504S - Publ. Astron. Soc. Pac., 112, 504-528 (2000/April-0)

Bias properties of extragalactic distance indicators. IX. Absolute luminosity and line-width distributions for galaxy types along the Hubble sequence based on distance-limited samples from the revised Shapley-Ames catalog.

SANDAGE A.

Abstract (from CDS):

Type-specific luminosity functions on the M0,iB(T) magnitude system of the Revised Shapley-Ames Catalog (RSA) are derived for distance-limited samples of galaxies for all Hubble types and van den Bergh luminosity classes listed in the RSA. The distributions of 21 cm line widths are derived for the Sa to Sd spirals and the Sm/Im types in the same samples. The distance-limited subsamples have been separated from the complete flux-limited listings in the RSA using properties of Spaenhauer diagrams.

Each type-specific luminosity function is bounded on the bright and faint ends. All galaxies in the sample that have an appreciable spiral pattern are brighter than M0,iB(T)=-15 (H0=50). There are no dwarf spirals in this sample. Galaxies on the exponentially rising faint end of ``general'' luminosity functions in the recent literature called ``spirals'' are not galaxies with spiral arms but rather are star-forming galaxies of Sm and Im types. The distinction is crucial in predictions of the morphological mix expected at faint apparent magnitudes and large redshifts. One of the purposes of this paper is to begin to provide the necessary morphological resolution to adjudicate the high-redshift suggestions for an appreciable morphological evolution with look-back time.

The brightest and fastest rotating galaxies along the present-day Hubble sequence are large-bulge Sa types. The faintest and slowest rotators are Sd and Sm/Im galaxies. The luminosity function of E galaxies is appreciably fainter than for all spirals earlier than Sc II-III. S0 galaxies that have pronounced disk characteristics are fainter than those with ``intermediate'' (I) and/or ``subtle'' (S) S0 characteristics.

Bias in the slope and zero point of the Tully-Fisher (TF) relation in flux-limited samples compared with distance-limited subsamples is demonstrated using Sb and Sbc galaxies, similar to that shown for Sc galaxies in Paper VII. A fine structure in the TF correlation that varies with Hubble type and van den Bergh luminosity class is suggested for Sb and Sbc galaxies, also similar to that set out for Sc galaxies in Paper VII. The sense is that at fixed absolute magnitude the later luminosity classes (i.e., larger L numbers) for a fixed Hubble type have higher rotational velocities by ∼4% per luminosity L number. Said differently, the Sb, Sbc, and Sc galaxies with less developed spiral arms rotate faster at a given absolute magnitude. A larger sample is required to prove or disprove the trend seen in the present data.


Abstract Copyright:

Journal keyword(s): Galaxies: Luminosity Function, Mass Function - Methods: Observational

Simbad objects: 4

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