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External Galaxies

2005

Articles 1 - 4 of 4

Full-Text Articles in Astrophysics and Astronomy

Neutrosophic Methods In General Relativity, Florentin Smarandache, Dmitri Rabounski, Larissa Borissova Dec 2005

Neutrosophic Methods In General Relativity, Florentin Smarandache, Dmitri Rabounski, Larissa Borissova

Branch Mathematics and Statistics Faculty and Staff Publications

In this work the authors apply concepts of Neutrosophic Logic to the General Theory of Relativity to obtain a generalisation of Einstein’s fourdimensional pseudo-Riemannian differentiable manifold in terms of Smarandache Geometry (Smarandache manifolds), by which new classes of relativistic particles and non-quantum teleportation are developed. Fundamental features of Neutrosophic Logic are its denial of the Law of Excluded Middle, and open (or estimated) levels of truth, falsity and indeterminancy. Both Neutrosophic Logic and Smarandache Geometry were invented some years ago by one of the authors (F. Smarandache). The application of these purely mathematical theories to General Relativity reveals hitherto unknown …

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Noao Fundamental Plane Survey. Ii. Age And Metallicity Along The Red Sequence From Line‐Strength Data, Jenica E. Nelan, Russell J. Smith, Michael J. Hudson, Gary A. Wegner Oct 2005

Noao Fundamental Plane Survey. Ii. Age And Metallicity Along The Red Sequence From Line‐Strength Data, Jenica E. Nelan, Russell J. Smith, Michael J. Hudson, Gary A. Wegner

Dartmouth Scholarship

We present spectroscopic line-strength data for 4097 red-sequence galaxies in 93 low-redshift galaxy clusters and use these to investigate variations in average stellar populations as a function of galaxy mass. Our analysis includes an improved treatment of nebular emission contamination, which affects ~10% of the sample galaxies. Using the stellar population models of D. Thomas and collaborators, we simultaneously fit 12 observed line-strength-σ relations in terms of common underlying trends of age, [Z/H] (total metallicity), and [α/Fe] (α-element enhancement). We find that the observed line-strength-σ relations can be explained only if higher mass red-sequence galaxies are, on average, …

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The Oxford-Dartmouth Thirty Degree Survey - Ii. Clustering Of Bright Lyman Break Galaxies: Strong Luminosity-Dependent Bias At Z = 4, Paul D. Allen, Leonidas A. Moustakas, Gavin Dalton, Emily Macdonald, Chris Blake, Lee Clewley, Catherine Heymans, Gary Wegner Apr 2005

The Oxford-Dartmouth Thirty Degree Survey - Ii. Clustering Of Bright Lyman Break Galaxies: Strong Luminosity-Dependent Bias At Z = 4, Paul D. Allen, Leonidas A. Moustakas, Gavin Dalton, Emily Macdonald, Chris Blake, Lee Clewley, Catherine Heymans, Gary Wegner

Dartmouth Scholarship

We present measurements of the clustering properties of bright (L > L*) z~4 Lyman break galaxies (LBGs) selected from the Oxford-Dartmouth Thirty Degree Survey (ODT). We describe techniques used to select and evaluate our candidates and calculate the angular correlation function, which we find best fitted by a power law, ω(θ) =Awθ−β with Aw= 15.4 (with θ in arcsec), using a constrained slope of β= 0.8. Using a redshift distribution consistent with photometric models, we deproject this correlation function and find a comoving Mpc in a Ωm= 0.3 flat λ cosmology for iAB≤ 24.5. This corresponds to a linear bias value …

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X-Ray Variability During The Quiescent State Of The Neutron Star X-Ray Transient In The Globular Cluster Ngc 6440, Edward M. Cackett, Rudy Wijnands, Craig O. Heinke, Peter D. Edmonds, Walter H. G. Lewin, David Pooley, Jonathan E. Grindlay, Peter G. Jonker, Jon M. Miller Feb 2005

X-Ray Variability During The Quiescent State Of The Neutron Star X-Ray Transient In The Globular Cluster Ngc 6440, Edward M. Cackett, Rudy Wijnands, Craig O. Heinke, Peter D. Edmonds, Walter H. G. Lewin, David Pooley, Jonathan E. Grindlay, Peter G. Jonker, Jon M. Miller

Physics and Astronomy Faculty Research Publications

The globular cluster NGC 6440 is known to harbor a bright neutron star X-ray transient. We observed the globular cluster with Chandra on two occasions when the bright transient was in its quiescent state, in 2000 July and 2003 June (both observations were made nearly 2 yr after the end of their preceding outbursts). The quiescent spectrum during the first observation is well represented by a two-component model (a neutron star atmosphere model plus a power-law component that dominates at energies above 2 keV). During the second observation (which was roughly of equal duration to the first observation) we found …

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