Open Access. Powered by Scholars. Published by Universities.®

Physical Processes Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 4 of 4

Full-Text Articles in Physical Processes

Structural Properties Of Discs And Bulges Of Early-Type Galaxies, Roelof S. De Jong, Luc Simard, Roger L. Davies, R. P. Saglia, David Burstein, Matthew Colless, Robert Mcmahan, Gary Wegner Dec 2004

Structural Properties Of Discs And Bulges Of Early-Type Galaxies, Roelof S. De Jong, Luc Simard, Roger L. Davies, R. P. Saglia, David Burstein, Matthew Colless, Robert Mcmahan, Gary Wegner

Dartmouth Scholarship

We have used the EFAR sample of galaxies to investigate the light distributions of early-type galaxies. We decompose the two-dimensional light distribution of the galaxies in a flattened spheroidal component with a Sérsic radial light profile and an inclined disc component with an exponential light profile. We show that if we assume that all galaxies can have a spheroidal and a disc component, then the brightest, bulge-dominated elliptical galaxies have a fairly broad distribution in the Sérsic profile shape parameter nB, with a median of approximately 3.7 and with σ∼ 0.9. Other galaxies have smaller nB values. …


Self‐Consistent Diffusive Lifetimes Of Weibel Magnetic Fields In Gamma‐Ray Bursts, C. H. Jaroschek, H. Lesch, R. A. Treumann Dec 2004

Self‐Consistent Diffusive Lifetimes Of Weibel Magnetic Fields In Gamma‐Ray Bursts, C. H. Jaroschek, H. Lesch, R. A. Treumann

Dartmouth Scholarship

Weibel filamentation in relativistic plasma shell collisions has been demonstrated as an efficient and fast mechanism for the generation of near-equipartition magnetic fields in self-consistent particle-in-cell (PIC) simulations. In generic γ-ray burst (GRB) models with kinetically dominated plasma outflow, sufficient strength and lifetime of magnetic fields are essential to validate synchrotron emission as the source of radiative outbursts. In this article we report on self-consistent PIC simulations of pair-plasma shell collisions in the highly relativistic regime with particle ensembles up to 5 × 108. Energy dependence of magnetic field generation in the Weibel process is discussed, and for …


The Oxford-Dartmouth Thirty Degree Survey - I. Observations And Calibration Of A Wide-Field Multiband Survey, Emily C. Macdonald, Paul Allen, Gavin Dalton, Leonidas A. Moustakas, Catherine Heymans, Edward Edmondso N, Chris Blake, Lee Clewley, Molly C. Hammell, Ed Olding, Lance Miller, Steve Rawlings, Jasper Wall, Gary Wegner, Christian Wolf Aug 2004

The Oxford-Dartmouth Thirty Degree Survey - I. Observations And Calibration Of A Wide-Field Multiband Survey, Emily C. Macdonald, Paul Allen, Gavin Dalton, Leonidas A. Moustakas, Catherine Heymans, Edward Edmondso N, Chris Blake, Lee Clewley, Molly C. Hammell, Ed Olding, Lance Miller, Steve Rawlings, Jasper Wall, Gary Wegner, Christian Wolf

Dartmouth Scholarship

The Oxford–Dartmouth Thirty Degree Survey (ODTS) is a deep, wide, multiband imaging survey designed to cover a total of 30 deg2 in BV RiZ, with a subset of U- and K-band data, in four separate fields of 5–10 deg2 centred at 00:18:24 +34:52, 09:09:45 +40:50, 13:40:00 +02:30 and 16:39:30 +45:24. Observations have been made using the Wide Field Camera on the 2.5-m Isaac Newton Telescope (INT) in La Palma to average limiting depths (5σ Vega, aperture magnitudes) of U= 24.8, B= 25.6, V= 25.0, R= 24.6 and i′= …


The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith Jan 2004

The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith

Masters

In every part of the world the rate of map revision is alarmingly low when compared to the rate of change of many human influenced surface features. There is therefore a requirement to regularly gather up-to-date information about surface features and to incorporate changes in maps both quickly and effectively before it becomes history. When an aerial photograph is taken, it contains errors one category of which is caused by the aircraft taking the photograph being tilted. This aerial photograph by itself is of little commercial value. Accurate maps cannot be created from it, its use in GIS (Geographical Information …