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Articles 61 - 63 of 63
Full-Text Articles in Physical Sciences and Mathematics
Constraints On H0 From The Central Velocity Dispersions Of Lens Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Constraints On H0 From The Central Velocity Dispersions Of Lens Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Faculty Publications
We employ Schwarzschild's method of the orbit modeling to constrain the mass profiles of the central lens galaxies in Q0957+561 and PG 1115+080. We combine the measured, central projected stellar velocity dispersions of these galaxies with the self-similar radial profiles of the rms velocity and of the Gauss-Hermite moment h4 observed in nearby galaxies for 0 lesssim R lesssim 2Reff. For Q0957+561, we find a 16% uncertainty in the galaxy mass and formal 2 σ limits on the Hubble constant of H0=61$\mathstrut{^{+13}_{-15}}$ km s-1 Mpc-1. For PG 1115+080, we find that none of the viable lens models can be ruled …
Twisting Of X-Ray Isophotes In Triaxial Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Twisting Of X-Ray Isophotes In Triaxial Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Faculty Publications
We investigate X-ray isophote twists created by triaxiality differences between the luminous stellar distributions and the dark halos in elliptical galaxies. For a typically oblate luminous galaxy embedded in a more prolate halo formed by dissipationless collapse, the triaxiality difference of ΔT simeq 0.7 leads to typical isophote twists of langΔψXrang simeq 16° ± 19° at 3 effective stellar radii. In a model that includes baryonic dissipation, the effect is smaller, with ΔT simeq 0.3 and langΔψXrang simeq 5° ± 8°. Thus, accurate measurements of X-ray isophote twists may be able to set constraints on the interactions between baryons and …
Structural And Dynamical Uncertainties In Modelling Axisymmetric Elliptical Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Structural And Dynamical Uncertainties In Modelling Axisymmetric Elliptical Galaxies, Aaron J. Romanowsky, C. S. Kochanek
Faculty Publications
Quantitative dynamical models of galaxies require deprojection of the observed surface brightness to determine the luminosity density of the galaxy. Existing deprojection methods for axisymmetric galaxies assume that a unique deprojection exists for any given inclination, even though the projected density is known to be degenerate to the addition of ‘konus densities’ that are invisible in projection. We develop a deprojection method based on linear regularization that can explore the range of luminosity densities that are statistically consistent with an observed surface brightness distribution. The luminosity density is poorly constrained at modest inclinations (i ≿ 30°), even in the limit …