Supernova Remnants in the Magellanic Clouds III: An X-ray Atlas of LMC Supernova Remnants

We have used archival ROSAT data to present X-ray images of thirty-one supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). We have classified these remnants according to their X-ray morphologies, into the categories of Shell-Type, Diffuse Face, Centrally Brightened, Point-Source Dominated, and Irregular. We suggest possible causes of the X-ray emission for each category, and for individual features of some of the SNRs.Comment: 27 pages, 6 figures (9 figure files). To appear in the Supplement Series of the Astrophysical Journal, August 1999 Vol. 123 #

The ACS Nearby Galaxy Survey Treasury

The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D<4 Mpc). The survey volume encompasses 69 galaxies in diverse environments, including close pairs, small & large groups, filaments, and truly isolated regions. The galaxies include a nearly complete range of morphological types spanning a factor of ~10^4 in luminosity and star formation rate. The survey data consists of images taken with ACS on HST, supplemented with archival data and new WFPC2 imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m_F475W=28.0 mag, m_F606W=27.3 mag, and m_F814W=27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both the ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.Comment: 54 pages, including 24 pages of figures and 16 pages of tables. Project website and data available at http://www.nearbygalaxies.org/ . Data is also available through MAST. Scheduled to appear in the Astrophysical Journal Supplements. (Replaced to fix several figures that were damaged during compression

Dark matter halo properties of nearby, late-type galaxies.

With the advent of detailed simulations of galaxy formation in a CDM universe, specific predictions are being made on the structure of dark matter halos (DMHs) on galaxy scales. However most DMHs of low surface brightness and dwarf irregular galaxies show some level of disagreement with the predictions. To better test these models, I have embarked on a study of 20 nearby, late-type galaxies, carefully chosen to provide the most consistent tests of model predictions. I have obtained deep broad band BVR and narrow band Halpha imaging of each to better constrain the luminous, baryonic component in these galaxies. To constrain the core kinematics of these systems, I have obtained deep, long-slit spectroscopy observations around the wavelength of Halpha. Using new VLA and WSRT full synthesis HI observations for a subsample of galaxies, I have determined extended rotation curves and HI masses. After accounting for the baryonic mass, I modelled the dark matter contribution using the Psuedo-isothermal, Navarro-Frenk-White or Burkert density profile. Most of the galaxies modelled were better fit by a Pseudo-isothermal DMH as determined by comparing the c2red which were derived from the overall rotation curve fits. Only one galaxy was better fit by a Navarro-Frenk-White DMH. I also compared the circular velocity residuals as a function of radius for each DMH profile. As before, the Puedo-isothermal DMH model yielded the smallest residuals for the same six galaxies referred to above. I have also presented the DMH density profiles inverted from their Dark Matter rotation curves. Out of seven galaxies, four have profiles with obvious constant density cores. Only one galaxy had a steep DMH density profile with a measured inner power law slope of -1.2, which is consistent with that predicted from numerical simulations. I compared these data with a sample of similarly determined density profiles from the literature, and I found the range and distribution of measured inner slopes consistent. I merged the samples and determined there were no trends in the measured inner power law slopes with absolute magnitude or central surface brightness.Ph.D.AstronomyPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124952/2/3163947.pd