相关论文: The Formation of Galactic Bulges
Most giant spiral galaxies have pseudo or disk-like bulges that are considered to be the result of purely secular processes. This may challenge the hierarchical scenario predicting about one major merger per massive galaxy ($>$$3\times…
I use Spitzer 3.6-8.0 \mu m color profiles to compare the radial structure of star formation in pseudobulges and classical bulges. Pseudobulges are ``bulges'' which form through secular evolution, rather than mergers. In this study,…
We have derived the photometric parameters for the structural components of a sample of fourteen SB0 galaxies by applying a parametric photometric decomposition to their observed $I$-band surface brightness distribution. We find that SB0…
The center of our disk galaxy, the Milky Way, is dominated by a boxy/peanut-shaped bulge. Numerous studies of the bulge based on stellar photometry have concluded that the bulge stars are exclusively old. The perceived lack of young stars…
Properties of normal galactic star formation, including the density dependence, threshold density, turbulent scaling relations, and clustering properties, are applied to the formation of galactic bulges. One important difference is that the…
We use cosmological hydrodynamic simulations to investigate formation of galactic bulges within the framework of hierarchical clustering in a representative CDM cosmological model. We show that largest objects forming at cosmological…
Bulges are commonly believed to form in the dynamical violence of galaxy collisions and mergers. Here we model the stellar kinematics of the Bulge Radial Velocity Assay (BRAVA), and find no sign that the Milky Way contains a classical bulge…
We study nine S0-Sb galaxies with (photometric) bulges consisting of two distinct components. The outer component is a flattened, kinematically cool, disklike structure: a "disky pseudobulge". Embedded inside is a rounder, kinematically hot…
Spiral galaxies comprise three major structural components; thin discs, thick discs, and central bulges. Relative dominance of these components is known to correlate with the total mass of the galaxy, and produces a remarkable morphological…
Photometric scaling relations are studied for S0 galaxies and compared with those for spirals. New 2D K_s-band multi-component decompositions are presented for 122 early-type disk galaxies. Combining with our previous decompositions, the…
We review internal processes of secular evolution in galaxy disks, concentrating on the buildup of dense central features that look like classical, merger-built bulges but that were made slowly out of disk gas. We call these pseudobulges.…
We have obtained surface photometry in U, B, R and I for a complete optically selected sample of 45 early-type spiral galaxies, to investigate the colors and color gradients of spiral bulges. Color profiles in U-R, B-R, U-B and R-I have…
This talk investigates the formation of early-type galaxies from a deliberately observational view point. I begin by reviewing the conclusions that can be reached by comparing the detailed properties of galaxies in present-day clusters,…
We use numerical simulations to examine the structure of merger remnants resulting from collisions of gas-rich spiral galaxies. When the gas fraction of the progenitors is small, the remnants structurally and kinematically resemble…
Nuclear star clusters are among the densest stellar systems known and are common in both early- and late-type galaxies. They exhibit scaling relations with their host galaxy which may be related to those of supermassive black holes. These…
We use deep Hubble Space Telescope images taken with the Advanced Camera for Surveys (ACS) in the F475W and F814W filters to investigate the globular cluster systems in four edge-on Sa spiral galaxies covering a factor of 4 in luminosity.…
Insight into the origin of bulges is saught in this review only from the properties of their stellar populations. Evidence concerning the age of the Galactic bulge stellar population is reviewed first, then the case of the bulge of M31 is…
In some scenarios for the formation of the Milky Way bulge the stellar population at the edges of the boxy bulge may be younger than those on the minor axis, or close to the Galactic center. So far the only bulge region where deep…
The observations and evolution of clumpy, high-redshift galaxies are reviewed. Models suggest that the clumps form by gravitational instabilities in a gas-rich disk, interact with each other gravitationally, and then merge in the center…
A large fraction of bulgeless disk galaxies contain young compact stellar systems at their centers, in spite of the local gravitational stability of these disks. We evaluate two contrasting hypotheses for the origin of the nuclear star…