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Astrophysics and Astronomy Commons

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Full-Text Articles in Astrophysics and Astronomy

Dynamical Masses Of Early-Type Galaxies: A Comparison To Lensing Results And Implications For The Stellar Initial Mass Function And The Distribution Of Dark Matter, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner, S. Seitz Jul 2011

Dynamical Masses Of Early-Type Galaxies: A Comparison To Lensing Results And Implications For The Stellar Initial Mass Function And The Distribution Of Dark Matter, J. Thomas, R. P. Saglia, R. Bender, D. Thomas, K. Gebhardt, J. Magorrian, E. M. Corsini, G. Wegner, S. Seitz

Dartmouth Scholarship

This work aims to study the distribution of the luminous and dark matter in Coma early-type galaxies. Dynamical masses obtained under the assumption that mass follows light do not match with the masses of strong gravitational lens systems of similar velocity dispersions. Instead, dynamical fits with dark matter haloes are in good agreement with lensing results. We derive mass-to-light ratios of the stellar populations from Lick absorption line indices, reproducing well the observed galaxy colours. Even in dynamical models with dark matter haloes the amount of mass that follows the light increases more rapidly with the galaxy velocity dispersion than …


Evidence For Particle Acceleration To The Knee Of The Cosmic Ray Spectrum In Tycho’S Supernova Remnant, Kristoffer A. Eriksen, John P. Hughes, Carles Badenes, Robert Fesen Feb 2011

Evidence For Particle Acceleration To The Knee Of The Cosmic Ray Spectrum In Tycho’S Supernova Remnant, Kristoffer A. Eriksen, John P. Hughes, Carles Badenes, Robert Fesen

Dartmouth Scholarship

Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the "knee" of the CR spectrum at 10^15 eV, accelerating particles to relativistic energies in their blast waves by the process of diffusive shock acceleration (DSA). Since cosmic ray nuclei do not radiate efficiently, their presence must be inferred indirectly. Previous theoretical calculations and X-ray observations show that CR acceleration modifies significantly the structure of the SNR and greatly amplifies the interstellar magnetic field. We present new, deep X-ray observations of the remnant of Tycho's supernova (SN 1572, henceforth Tycho), which reveal a …