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Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Collisionless Models Revisited, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller
Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Collisionless Models Revisited, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller
Department of Physics and Astronomy Faculty Publications
We construct and evolve three one-parameter families and one two-parameter family of steady-state models of stellar disks embedded in live dark matter (DM) halos in order to study the dynamical and secular phases of bar evolution. These models are tested against those published in the literature in order to extend them and to include the gaseous component in the follow-up paper. Specifically, we are interested in the angular momentum, J, redistribution in the disk-halo system during these two evolutionary phases without distinguishing between the resonant and non-resonant effects. We confirm the previous results and quantify for the first time …
Dissecting Galaxy Formation. I. Comparison Between Pure Dark Matter And Baryonic Models, Emilio Romano-Diaz, Isaac Shlosman, Clayton Heller, Yehuda Hoffman
Dissecting Galaxy Formation. I. Comparison Between Pure Dark Matter And Baryonic Models, Emilio Romano-Diaz, Isaac Shlosman, Clayton Heller, Yehuda Hoffman
Department of Physics and Astronomy Faculty Publications
We compare assembly of dark matter (DM) halos with and without baryons from identical initial conditions, within the context of cosmological evolution in the ΛCDM WMAP3 Universe (baryons+DM, hereafter BDM model, and pure DM, PDM model). In representative PDM and BDM models, we find that baryons contribute decisively to the evolution of the central region, leading to an isothermal DM cusp, and thereafter to a flat DM density core—the result of heating by dynamical friction of the DM+baryon substructure during a quiescent evolution epoch. This process ablates the cold gas from an embedded disk, cutting the star formation rate by …
Pah Emission From Ultraluminous Infrared Galaxies, V. Desai, L. Armus, H. W. W. Spoon, Vassilis Charmandaris, J. Bernard-Salas, B. R. Brandl, D. Farrah, B.T. Soifer, H. I. Teplitz, P. M. Ogle, D. Devost, Sarah J.U. Higdon, J. A. Marshall, J. R. Houck
Pah Emission From Ultraluminous Infrared Galaxies, V. Desai, L. Armus, H. W. W. Spoon, Vassilis Charmandaris, J. Bernard-Salas, B. R. Brandl, D. Farrah, B.T. Soifer, H. I. Teplitz, P. M. Ogle, D. Devost, Sarah J.U. Higdon, J. A. Marshall, J. R. Houck
Department of Physics and Astronomy Faculty Publications
We explore the relationships between the Polycyclic Aromatic Hydrocarbon (PAH) feature strengths, mid-infrared continuum luminosities, far-infrared spectral slopes, optical spectroscopic classifications, and silicate optical depths within a sample of 107 ULIRGs observed with the Infrared Spectrograph on the Spitzer Space Telescope. The detected 6.2 µm PAH equivalent widths (EQWs) in the sample span more than two orders of magnitude (∼0.006–0.8 µm), and ULIRGs with HII-like optical spectra or steep far-infrared spectral slopes (S25/S60 < 0.2) typically have 6.2 µm PAH EQWs that are half that of lower-luminosity starbursts. A significant fraction (∼40–60%) of HII-like, LINER-like, and cold ULIRGs have very weak PAH EQWs. Many of these ULIRGs also have large (τ9.7 > 2.3) silicate optical depths. The far-infrared spectral slope is strongly correlated with PAH EQW, but not with silicate optical depth. In addition, the PAH EQW decreases with …
Hubble Space Telescope Morphologies Of Z ~ 2 Dust Obscured Galaxies. I. Power-Law Sources, R.S. Bussman, Arjun Dey, J. Lotz, Lee Armus, Kate Brand, Michael J. I. Brown, Vandana Desai, Peter Eisenhardt, James L. Higdon, Sarah J.U. Higdon, B. T. Jannuzi, Emeric Le Floc'h, J. Melbourne, B. T. Soifer, Daniel Weedman
Hubble Space Telescope Morphologies Of Z ~ 2 Dust Obscured Galaxies. I. Power-Law Sources, R.S. Bussman, Arjun Dey, J. Lotz, Lee Armus, Kate Brand, Michael J. I. Brown, Vandana Desai, Peter Eisenhardt, James L. Higdon, Sarah J.U. Higdon, B. T. Jannuzi, Emeric Le Floc'h, J. Melbourne, B. T. Soifer, Daniel Weedman
Department of Physics and Astronomy Faculty Publications
We present high spatial resolution optical and near-infrared imaging obtained using the ACS, WFPC2 and NICMOS cameras aboard the Hubble Space Telescope of 31 24µm–bright z ≈ 2 Dust Obscured Galaxies (DOGs) identified in the Bo¨otes Field of the NOAO Deep Wide-Field Survey. Although this subset of DOGs have mid-IR spectral energy distributions dominated by a power-law component suggestive of an AGN, all but one of the galaxies are spatially extended and not dominated by an unresolved component at rest-frame UV or optical wavelengths. The observed V − H and I − H colors of the extended components are 0.2−3 …
Book Review: Helping Students Learn In A Learner-Centered Environment By Terry Doyle (Stylus, 2008), Delena Bell Gatch
Book Review: Helping Students Learn In A Learner-Centered Environment By Terry Doyle (Stylus, 2008), Delena Bell Gatch
Department of Physics and Astronomy Faculty Publications
Excerpt: According to Terry Doyle in his book Helping Students Learn in a Learner-Centered Environment, “Most important, this book has been written to answer the single most asked question I hear when working with faculty groups: How do I help my students adjust to a learner-centered practice?” As desired, Doyle has offered some excellent answers for faculty struggling to transform their students into lifelong learners.