Abstract/Details

HIGH RESOLUTION SURFACE PHOTOMETRY OF ELLIPTICAL GALAXIES

LAUER, TOD RICHARD.   University of California, Santa Cruz ProQuest Dissertations Publishing,  1983. 8406988.

Abstract (summary)

High-resolution CCD surface photometry profiles have been obtained for a sample of 42 nearby elliptical and SO galaxies in order to investigate their central structure and core properties. An analysis of the apparent core radii and seeing profiles indicates that 14 galaxies have resolvable cores between 1".5 and 5".0. Five more galaxies are considered to be only marginally unresolved.

A hybrid Fourier deconvolution procedure has been developed in order to correct the surface photometry for seeing in a model-independent way. Tests of the procedure on simulated galaxy images show that intrinsic cores equal to the seeing radius or larger can be recovered from the observed seeing-convolved photometry. An examination of the deconvolved profiles of the resolved galaxies shows that none of them can be described by isothermal King model cores. Half of the resolved galaxies match the core profile of M87 over an extended radial range, indicating the possible existence of massive nuclear black holes or radially anisotropic velocity fields in these objects. The remaining half show even larger deviations from isothermality.

An examination of the galaxy images finds "boxy" isophote shapes, faint stellar disks, and dust lanes to occur in some galaxies. Deviations of the isophote shapes from perfect ellipses are less than 1% for all but the "boxy" elliptical galaxies, and as small as 0.1% in some cases.

Core radii and central surface brightnesses are measured from the seeing-deconvolved photometry, which in turn yield central mass-to-light ratios. An analysis of the core parameters finds the central luminosity density, (rho)(,c), to act as a second parameter with luminosity, L, in driving the core structure. Parametrization of M/L by L and (rho)(,c) shows M/L to depend on central luminosity density only, as M/L(TURN)(rho)(,c)('-0.17). An analysis of parameters measured from the de Vaucouleurs effective radii finds parallel results for average luminosity densities and mass-to-light ratios derived from the effective radii parameters. The ratio of core radius to effective radius shows large scatter, however, and no dependence on total luminosity.

The present results support the formation of elliptical galaxies from proto-galactic gas clouds rather than as the end products of a dissipationless merger hierarchy of less massive stellar systems. Larson's suggestion that the cores represent the final period of star formation in the cloud, most easily explains the observed independence of the cores from global properties of the galaxies. The dependence of M/L on (rho)(,c) is then explained as a possible dependence of the IMF slope or lower main sequence cutoff on local mass density.

Indexing (details)


Subject
Astrophysics
Classification
0596: Astrophysics
Identifier / keyword
Pure sciences
Title
HIGH RESOLUTION SURFACE PHOTOMETRY OF ELLIPTICAL GALAXIES
Author
LAUER, TOD RICHARD
Number of pages
289
Degree date
1983
School code
0036
Source
DAI-B 44/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
979-8-205-21877-1
University/institution
University of California, Santa Cruz
University location
United States -- California
Degree
Ph.D.
Source type
Dissertation or Thesis
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
8406988
ProQuest document ID
303126469
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
https://www.proquest.com/docview/303126469/