5 research outputs found
Statistics 301 Bilingual (English/Spanish)
This poster outlining the redesign of STAT 301 (Elementary Statistical Methods) was presented at the IMPACT Symposium 2014
Inside-Out Infall Formation of Disk Galaxies: Do Predictions Differ from Models without Size Evolution?
We develop an idealized inside-out formation model for disk galaxies to
include a realistic mix of galaxy types and luminosities that provides a fair
match to the traditional observables. The predictions of our infall models are
compared against identical models with no-size evolution by generating fully
realistic simulations of the HDF, from which we recover the angular size
distributions. We find that our infall models produce nearly identical angular
size distributions to those of our no-size evolution models in the case of a
Omega = 0 geometry but produce slightly smaller sizes in the case of a Omega =
1 geometry, a difference we associate with the fact that there is a different
amount of cosmic time in our two models for evolving to relatively low
redshifts (z \approx 1-2). Our infall models also predict a slightly smaller
(11% - 29%) number of large (disk scale lengths > 4 h_{50} ^{-1} kpc) galaxies
at z \approx 0.7 for the CFRS as well as different increases in the central
surface brightness of the disks for early-type spirals, the infall model
predicting an increase by 1.2 magnitudes out to z \approx 2 (Omega = 0), 1
(Omega = 1), while our no-size evolution models predict an increase of only 0.5
magnitude. This result suggests that infall models could be important for
explaining the 1.2-1.6 magnitude increase in surface brightness reported by
Schade et al. (1995, 1996a, 1996b).Comment: 12 pages, LaTeX (aaspp4.sty), accepted by ApJ Letter
A Look At Three Different Scenarios for Bulge Formation
In this paper, we present three qualitatively different scenarios for bulge
formation: a secular evolution model in which bulges form after disks and
undergo several central starbursts, a primordial collapse model in which bulges
and disks form simultaneously, and an early bulge formation model in which
bulges form prior to disks. We normalize our models to the local z=0
observations of de Jong & van der Kruit (1994) and Peletier & Balcells (1996)
and make comparisons with high redshift observations. We consider model
predictions relating directly to bulge-to-disk properties. As expected, smaller
bulge-to-disk ratios and bluer bulge colors are predicted by the secular
evolution model at all redshifts, although uncertainties in the data are
currently too large to differentiate strongly between the models.Comment: 19 pages, 6 figures, accepted for publication in the Astrophysical
Journa