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Cosmology, Relativity, and Gravity Commons™

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Dartmouth Scholarship

2008

Articles 1 - 5 of 5

Full-Text Articles in Cosmology, Relativity, and Gravity

Ages And Metallicities Of Early-Type Void Galaxies From Line Strength Measurements, Gary Wegner, Norman A. Grogin May 2008

Ages And Metallicities Of Early-Type Void Galaxies From Line Strength Measurements, Gary Wegner, Norman A. Grogin

Dartmouth Scholarship

We present spectroscopic observations of 26 galaxies of type E and S0, based on their blue morphologies, located in voids by the study of Grogin & Geller in 1999. Measurements of redshift, velocity dispersion, and four Lick line indices, Mg b , Fe5270, Fe5335, and Hβ with their errors are given for all of these galaxies, along with Hβ, [O III], Hα, and [N II] emission line strengths for a subset of these objects. These sources are brighter than M* for low-density regions and tend to be bluer than their counterpart early-type objects in high-density regions. Using the models …

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Large Scale Structure As A Probe Of Gravitational Slip, Scott F. Daniel, Robert R. Caldwell, Asantha Cooray, Alessandro Melchiorri May 2008

Large Scale Structure As A Probe Of Gravitational Slip, Scott F. Daniel, Robert R. Caldwell, Asantha Cooray, Alessandro Melchiorri

Dartmouth Scholarship

A new time-dependent, scale-independent parameter, ϖ, is employed in a phenomenological model of the deviation from general relativity in which the Newtonian and longitudinal gravitational potentials slip apart on cosmological scales as dark energy, assumed to be arising from a new theory of gravitation, appears to dominate the Universe. A comparison is presented between ϖ and other parametrized post-Friedmannian models in the literature. The effect of ϖ on the cosmic microwave background anisotropy spectrum, the growth of large-scale structure, the galaxy weak-lensing correlation function, and cross correlations of cosmic microwave background anisotropy with galaxy clustering are illustrated. Cosmological models with …

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Spatially Resolved Spectroscopy Of Coma Cluster Early‐Type Galaxies. Iv. Completing The Data Set, E. M. Corsini, G. Wegner, R. P. Saglia, J. Thomas Apr 2008

Spatially Resolved Spectroscopy Of Coma Cluster Early‐Type Galaxies. Iv. Completing The Data Set, E. M. Corsini, G. Wegner, R. P. Saglia, J. Thomas

Dartmouth Scholarship

The long-slit spectra obtained along the minor axis, offset major axis, and diagonal axis are presented for 12 E and S0 galaxies of the Coma Cluster drawn from a magnitude-limited sample studied before. The rotation curves, velocity dispersion profiles, and the H3 and H4 coefficients of the Hermite decomposition of the line-of-sight velocity distribution are derived. The radial profiles of the Hβ, Mg, and Fe line strength indices are measured too. In addition, the surface photometry of the central regions of a subsample of four galaxies recently obtained with the Hubble Space Telescope is presented. The data will …

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Lower Limit To The Scale Of An Effective Quantum Theory Of Gravitation, R. R. Caldwell, Daniel Grin Jan 2008

Lower Limit To The Scale Of An Effective Quantum Theory Of Gravitation, R. R. Caldwell, Daniel Grin

Dartmouth Scholarship

An effective quantum theory of gravitation in which gravity weakens at energies higher than ∼10−3  eV is one way to accommodate the apparent smallness of the cosmological constant. Such a theory predicts departures from the Newtonian inverse-square force law on distances below ∼0.05  mm. However, it is shown that this modification also leads to changes in the long-range behavior of gravity and is inconsistent with observed gravitational lenses.

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First Results From Ideal 2-D Mhd Reconstruction: Magnetopause Reconnection Event Seen By Cluster, W. L. Teh, B. U. O. Sonnerup Jan 2008

First Results From Ideal 2-D Mhd Reconstruction: Magnetopause Reconnection Event Seen By Cluster, W. L. Teh, B. U. O. Sonnerup

Dartmouth Scholarship

We have applied a new reconstruction method (Sonnerup and Teh, 2008), based on the ideal single-fluid MHD equations in a steady-state, two-dimensional geometry, to a reconnection event observed by the Cluster-3 (C3) space- craft on 5 July 2001, 06:23 UT, at the dawn-side Northern- Hemisphere magnetopause. The event has been previously studied by use of Grad-Shafranov (GS) reconstruction, per- formed in the deHoffmann-Teller frame, and using the as- sumption that the flow effects were either negligible or the flow was aligned with the magnetic field. Our new method allows the reconstruction to be performed in the frame of reference moving …

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