Michele Cappellari's Ph.D. Thesis

Padova, Italy, 31 December 2000

Nuclear Mass Concentrations in Galaxies

Chapter 1 Introduction and Summary

Cover Page + Contents + Chapter 1
cappellari_chapter1.ps.gz (121 KB, 14 pages, no figures)

Chapter 2 The Mini AGN at the Center of the Elliptical Galaxy NGC 4552 with HST

I make use of spectroscopic and photometric HST observations to investigate the nature of an ultraviolet (UV) flare we previously discovered in the nucleus of the normal elliptical galaxy NGC 4552. These observations give strong support to our hypothesis that this phenomenon has been produced by an accretion event onto the nuclear BH in this galaxy.
cappellari_chapter2.ps.gz (688 KB, 34 pages, 12 figures)
Published Paper

Chapter 3 The Cuspy Liner Nucleus of the S0/a Galaxy NGC 2681

I study by means of HST the gas kinematics in the bulge of the spiral galaxy NGC 2681. This object has a low central stellar dispersion and a correspondingly low BH mass has to be expected. The upper limit to the BH mass I determine for this object is consistent with the predictions from the MBH-sigma relation, indeed. In addition, the absence of color gradients and spectral shape variations within this galaxy central regions (R<10"), combined with the very steep photometric profile, suggests that the nucleus of this object formed through a rapid dissipative collapse.
cappellari_chapter3.ps.gz (428 KB, 20 pages, 10 figures)
Published Paper

Chapter 4 Circumnuclear Keplerian Disks in Galaxies

I construct a model of the expected bidimensional appearance of nuclear emission lines, as observed in ground-based long-slit spectra, as a function of the central BH mass. In particular, I show that some of the observed lines---apparently consisting of two kinematically distinct components---can actually be explained as due to the presence of a thin gaseous disk, rotating in the combined potential of the stellar potential and the nuclear BH. In doing so, I notice that this kind of study can be very useful to select good candidates for further HST observations intended to derive accurate BH mass estimates in spiral galaxies.
cappellari_chapter4.ps.gz (306 KB, 12 pages, 5 figures)
Published Paper

Chapter 5 The Counterrotating Core and Nuclear Black Hole in IC 1459

I analyze high S/N spectroscopic observations, along five different slit positions, of the elliptical galaxy IC 1459, the prototype galaxy with a kinematically decoupled core. I present results based on self-consistent three-integral axisymmetric models of the stellar kinematics, obtained with Schwarzschild's numerical orbit superposition method. To fit the observed surface brightness an axisymmetric Multi Gaussian Expansion (MGE) parametrization for the three-dimensional stellar luminosity density has been adopted. The analysis of the internal dynamics of this object indicates that the observed counterrotation is produced by stars lying essentially in a thin disk and having a mass ~1% of the galaxy total mass. The intrinsic shape I derive for the decoupled core strongly favors one of the competing hypotheses for the formation of the nucleus of this galaxy, namely the external acquisition of counterrotating gas, which subsequently settled on a thin disk that later turned into stars. During the acquisition process, the gas could have contributed to the BH growth, an occurrence confirmed by the estimated BH mass, which turns out to be of the same order of magnitude as the counterrotating core.
cappellari_chapter5.ps.gz (1280 KB, 26 pages, 16 figures)
Published Paper

Chapter 6 An Efficient Algorithm for the MGE Fit of Galaxy Images

I develop an efficient, accurate and robust new algorithm, for the determination of the Multi Gaussian Expansion (MGE) parametrization starting from galaxy images. The MGE method is currently the one that can better reproduce the density distribution of real galaxies, i.e. composed of multiple photometric components. The new algorithm presented in this chapter makes the MGE method more generally and easily applicable to dynamical studies of galaxies. Here I apply this algorithm to the MGE fitting of a galaxy sample with HST photometry, which will be used in subsequent work.
cappellari_chapter6.ps.gz (2341 KB, 24 pages, 16 figures)
Published Paper

Chapter 7 The Orthogonally Rotating Core in NGC 4698

I present spectroscopic and photometric observations, from the ground and with HST, of a new kinematically decoupled core, that seems to rotate orthogonally to the disk, in the bulge of the spiral galaxy NGC 4698. I discuss some possible hypotheses for the nature of this object.
cappellari_chapter7.ps.gz (436 KB, 12 pages, 7 figures)
Published Paper

Appendix A

Objects in NGC 205 Resolved into Stellar Associations by HST UV Imaging

cappellari_appendixA.ps.gz (350 KB, 10 pages, 4 figures)
Published Paper

Appendix B

UV Imaging of the Galaxy Cluster Abell 851 at z=0.41

cappellari_appendixB.ps.gz (693 KB, 17 pages, 6 figures)
Published Paper

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