Practical Approach To Cosmological Perturbations In Modified Gravity,
2013
SISSA - International School for Advanced Studies
Practical Approach To Cosmological Perturbations In Modified Gravity, Alessandra Silvestri, Levon Pogosian, Roman V. Buniy
Mathematics, Physics, and Computer Science Faculty Articles and Research
The next generation of large scale surveys will not only measure cosmological parameters within the framework of general relativity, but will also allow for precision tests of the framework itself. At the order of linear perturbations, departures from the growth in the standard cosmological model can be quantified in terms of two functions of time and Fourier number k. We argue that in local theories of gravity, in the quasistatic approximation, these functions must be ratios of polynomials in k, with the numerator of one function being equal to the denominator of the other. Moreover, the polynomials are even and …
Illuminating The Darkest Gamma-Ray Bursts With Radio Observations,
2013
Roger Williams University
Illuminating The Darkest Gamma-Ray Bursts With Radio Observations, B.A. Zauderer, E. Berger, R. Margutti, A.J. Levan, F. Olivares E., D.A. Perley, W. Fong, A. Horesh, Adria Updike, J. Greiner, N.R. Tanvir, T. Laskar, R. Chornock, A.M. Soderberg, K.M. Menten, E. Nakar, J. Carpenter, P. Chandra, A.J. Castro-Tirado, M. Bremer, J. Gorosabel, S. Guziy, D. P´Erez-Ram´Irez, J.M. Winters
Arts & Sciences Faculty Publications
No abstract provided.
Challenges For Λcdm And Mond,
2013
Case Western Reserve University
Challenges For Λcdm And Mond, Stacy S. Mcgaugh
Faculty Scholarship
The Universe on large scales is well described by the ΛCDM cosmological model. There however remain some heavy clouds on our global understanding, especially on galaxy scales, which we review here. While some of these clouds might perhaps disappear through small compensatory adjustments of the model, such as changing the mass of the dark matter particles or accounting better for baryonic physics, others should rather be taken as strong indications that the physics of the dark sector is, at the very least, much richer and complex than currently assumed, and that our understanding of gravity and dynamics might also be …
Study Of Dynamic Features Of Highly Energetic Reactions By Dsc And High-Speed Temperature Scanner (Hsts),
2013
The University of Texas Rio Grande Valley
Study Of Dynamic Features Of Highly Energetic Reactions By Dsc And High-Speed Temperature Scanner (Hsts), Mkhitar Hobosyan, Kh. G. Kirakosyan, S. L. Kharatyan, Karen S. Martirosyan
Physics & Astronomy Faculty Publications
The dynamic features of Al2O3 - polytetrafluoroethylene (PTFE) and Al - PTFE reactions in non-isothermal conditions are presented. The Differential Scanning Calorimetry (DSC) and High-Speed Temperature Scanner (HSTS) were used to characterize the Al2O3/Al – PTFE reactions at different heating rates. The study shows that the HSTS instrument can give more information about the reaction mechanism and kinetics than the conventional DSC measurements. In this work we show that high heating rates may reveal exothermic reaction between Al2O3 and PTFE that were previously unidentified. The PTFE can potentially remove the oxide layer from aluminum in the initial period of the …
Bayesian Inference Of Polarized Cosmic Microwave Background Power Spectra From Interferometric Data,
2013
University of Richmond
Bayesian Inference Of Polarized Cosmic Microwave Background Power Spectra From Interferometric Data, Ata Karakci, P. M. Sutter, Le Zhang, Emory F. Bunn, Andrei Korotkov, Peter Timbie, Gregory S. Tucker, Benjamin D. Wandelt
Physics Faculty Publications
Detection of B-mode polarization of the cosmic microwave background (CMB) radiation is one of the frontiers of observational cosmology. Because they are an order of magnitude fainter than E-modes, it is quite a challenge to detect B-modes. Having more manageable systematics, interferometers prove to have a substantial advantage over imagers in detecting such faint signals. Here, we present a method for Bayesian inference of power spectra and signal reconstruction from interferometric data of the CMB polarization signal by using the technique of Gibbs sampling. We demonstrate the validity of the method in the flat-sky approximation for a simulation of an …
Analysis Of Mathematical Descriptions Of Gravitational Microlensing,
2013
University of Northern Iowa
Analysis Of Mathematical Descriptions Of Gravitational Microlensing, Sarah Michelle Pearce
Honors Program Theses
This thesis will provide an analysis of some aspects of gravitational microlensing and the quantitative descriptions used to model the astrophysical systems involved. One aspect of the mathematical description of micro lensing events that is investigated in this thesis is the evolution of micro lensing equations from the formalism of general relativity. The derivation of these equations from those governing general relativity and the bending of light rays in geometric optics is explicitly determined. The relationship between the equations used to model events and the light curves produced is investigated. The effect of degeneracies in the mathematical equations used to …
A Study In Merger Induced Galaxy Evolution Through Post-Starburst Systems,
2013
University of Northern Iowa
A Study In Merger Induced Galaxy Evolution Through Post-Starburst Systems, Zachary Dean Griffith
Honors Program Theses
We discuss an optical study of a triple galaxy system at a redshift of 0.06. In optical images from Data Release 7 of the Sloan Digital Sky Survey (SDSS), the system consists of a close pair plus another galaxy at a projected distance of 35 kpc. Tidal features extending at least 30 kpc are visible to the southeast of both the galaxy pair and the third member of the system, suggesting significant interaction. One of the the pair and the more isolated galaxy are low-luminosity radio sources. The lone galaxy appears extended in a radio map from the FIRST survey. …
Ensemble Forecasting Of Coronal Mass Ejections Using The Wsa-Enlil With Coned Model,
2013
Air Force Institute of Technology
Ensemble Forecasting Of Coronal Mass Ejections Using The Wsa-Enlil With Coned Model, D. Emmons, Ariel O. Acebal, A. Pulkkinen, A. Taktakishvili, Peter Macneice, D. Odstrcil
Faculty Publications
The combination of the Wang‐Sheeley‐Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and CONED Model version 1.3 (WSA‐ENLIL with CONED Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (halo CMEs). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the CONED Model. The CONED Model used image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO/LASCO imagery based on techniques described by Pulkkinen et al. (2010). The input parameter distributions were used as input to WSA‐ENLIL to calculate the temporal evolution of the …
Fundamental Limits Of Detection In The Near And Mid Infrared,
2013
Claremont McKenna College
Fundamental Limits Of Detection In The Near And Mid Infrared, Nathan Lenssen
CMC Senior Theses
The construction of the James Webb Space Telescope has brought attention to infrared astronomy and cosmology. The potential information about our universe to be gained by this mission and future infrared telescopes is staggering, but infrared observation faces many obstacles. These telescopes face large amounts of noise by many phenomena, from emission off of the mirrors to the cosmic infrared background. Infrared telescopes need to be designed in such a way that noise is minimized to achieve sufficient signal to noise ratio on high redshift objects. We will investigate current and planned space and ground based telescopes, model the noise …
Galaxy Zoo : A Catalog Of Overlapping Galaxy Pairs For Dust Studies.,
2013
University of Alabama - Tuscaloosa
Galaxy Zoo : A Catalog Of Overlapping Galaxy Pairs For Dust Studies., William C. Keel, Anna M. Manning, Benne W. Holwerda, Massimo Mezzoprete, Chris J. Lintott, Kevin Schawinski, Pamela Gay, Karen L. Masters
Faculty and Staff Scholarship
Analysis of galaxies with overlapping images offers a direct way to probe the distribution of dust extinction and its effects on the background light. We present a catalog of 1990 such galaxy pairs selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the Galaxy Zoo project. We highlight subsamples which are particularly useful for retrieving such properties of the dust distribution as UV extinction, the extent perpendicular to the disk plane, and extinction in the inner parts of disks. The sample spans wide ranges of morphology and surface brightness, opening up the possibility of using this technique to …
Effective Field Theory Approach To Gravitationally Induced Decoherence,
2013
Dartmouth College
Effective Field Theory Approach To Gravitationally Induced Decoherence, M. P. Blencowe
Dartmouth Scholarship
Adopting the viewpoint that the standard perturbative quantization of general relativity provides an effective description of quantum gravity that is valid at ordinary energies, we show that gravity as an environment induces the rapid decoherence of stationary matter superposition states when the energy differences in the superposition exceed the Planck energy scale.
Parameter Estimation For Compact Binary Coalescence Signals With The First Generation Gravitational-Wave Detector Network,
2013
The University of Texas Rio Grande Valley
Parameter Estimation For Compact Binary Coalescence Signals With The First Generation Gravitational-Wave Detector Network, J. Aasi, J. Abadie, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone, Cristina V. Torres
Physics & Astronomy Faculty Publications
Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and …
Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics – Ii. Clues To The Origins Of S0 Galaxies,
2013
University of Nottingham
Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics – Ii. Clues To The Origins Of S0 Galaxies, A. Cortesi, M. R. Merrifield, L. Coccato, M. Arnaboldi, O. Gerhard, Aaron J. Romanowsky, N. G. Douglass, K. Kuiijken, M. Capaccioli, K. C. Freeman, K. Saha, A. L. Chies-Santos
Faculty Publications
The stellar kinematics of the spheroids and discs of S0 galaxies contain clues to their formation histories. Unfortunately, it is difficult to disentangle the two components and to recover their stellar kinematics in the faint outer parts of the galaxies using conventional absorption line spectroscopy. This paper therefore presents the stellar kinematics of six S0 galaxies derived from observations of planetary nebulae, obtained using the Planetary Nebula Spectrograph. To separate the kinematics of the two components, we use a maximum-likelihood method that combines the discrete kinematic data with a photometric component decomposition. The results of this analysis reveal that: the …
The Densest Galaxy,
2013
Michigan State University
The Densest Galaxy, J. Strader, A. C. Seth, J. P. Brodie, D. A. Forbes, G. Fabbiano, Aaron J. Romanowsky, C. Conroy, N. Caldwell, V. Pota, C. Usher, J. A. Arnold
Faculty Publications
We report the discovery of a remarkable ultra-compact dwarf galaxy around the massive Virgo elliptical galaxy NGC 4649 (M60), which we call M60-UCD1. With a dynamical mass of 2.0 × 108 M ☉ but a half-light radius of only ~24 pc, M60-UCD1 is more massive than any ultra-compact dwarfs of comparable size, and is arguably the densest galaxy known in the local universe. It has a two-component structure well fit by a sum of Sérsic functions, with an elliptical, compact (rh = 14 pc; n ~ 3.3) inner component and a round, exponential, extended (rh = 49 pc) outer component. …
The Paucity Of Globular Clusters Around The Field Elliptical Ngc 7507,
2013
CCT La Plata-CONICET-UNLP
The Paucity Of Globular Clusters Around The Field Elliptical Ngc 7507, J. P. Caso, T. Richtler, L. P. Bassino, R. Salinas, R. R. Lane, Aaron J. Romanowsky
Faculty Publications
There is strong evidence that globular cluster systems (GCSs) of massive galaxies are largely assembled by infall/accretion processes. Therefore, we expect the GCSs of isolated elliptical galaxies to be poor. Alhough not completely isolated, NGC 7507 is a massive field elliptical galaxy with an apparently very low dark matter content. Aims: We determine the richness, the colour distribution, and the structural properties of the GCS of NGC 7507. Methods: We perform wide-field Washington photometry with data obtained with the MOSAIC II camera at the 4m-Blanco telescope, CTIO. Results: The GCS is very poor with S_N ~ 0.6. We identify three …
Angular Momentum And Galaxy Formation Revisited: Effects Of Variable Mass-To-Light Ratios,
2013
Space Telescope Science Institute
Angular Momentum And Galaxy Formation Revisited: Effects Of Variable Mass-To-Light Ratios, S. M. Fall, Aaron J. Romanowsky
Faculty Publications
We rederive the relation between the specific angular momentum j sstarf and the mass M sstarf of the stellar matter in galaxies of different morphological types. This is a revision of the j sstarf-M sstarf diagram presented in our recent comprehensive study of galactic angular momentum. In that work, we estimated j sstarf from kinematic and photometric data that extended to large radii and M sstarf from near-infrared luminosities LK with an assumed universal mass-to-light ratio M sstarf/LK . However, recent stellar population models show large variations in M sstarf/LK correlated with B – V color. In the present work, …
Book Review: Weird Worlds: Bizarre Bodies Of The Solar System And Beyond,
2013
Embry-Riddle Aeronautical University
Book Review: Weird Worlds: Bizarre Bodies Of The Solar System And Beyond, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of Weird Worlds : Bizarre Bodies of the Solar System and Beyond by David A. J. Seargent. Springer, 2013 309p, 1461470633 $34.95, 9781461470632 $34.95.
Heteroclinic And Homoclinic Connections Between The Sun-Earth Triangular Points And Quasi-Satellite Orbits For Solar Observations,
2013
G.M.V. Aerospace & Defence S.A.U.
Heteroclinic And Homoclinic Connections Between The Sun-Earth Triangular Points And Quasi-Satellite Orbits For Solar Observations, Pedro J. Llanos, Gerald R. Hintz, Martin W. Lo, James K. Miller
Publications
Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP (circular restricted three-body problem) in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. …
Testing Diagnostics Of Nuclear Activity And Star Formation In Galaxies At Z > 1,
2012
University of California - Santa Cruz
Testing Diagnostics Of Nuclear Activity And Star Formation In Galaxies At Z > 1, Jonathan R. Trump, Nicholas P. Konidaris, Guillermo Barro, David C. Koo, Dale D. Kocevski, Stéphanie Juneau, Benjamin J. Weiner, S. M. Faber, Ian S. Mclean, Renbin Yan, Pablo G. Pérez-González, Victor Villar
Physics and Astronomy Faculty Publications
We present some of the first science data with the new Keck/MOSFIRE instrument to test the effectiveness of different AGN/SF diagnostics at z ~ 1.5. MOSFIRE spectra were obtained in three H-band multi-slit masks in the GOODS-S field, resulting in 2 hr exposures of 36 emission-line galaxies. We compare X-ray data with the traditional emission-line ratio diagnostics and the alternative mass-excitation and color-excitation diagrams, combining new MOSFIRE infrared data with previous HST/WFC3 infrared spectra (from the 3D-HST survey) and multiwavelength photometry. We demonstrate that a high [O III]/Hβ ratio is insufficient as an active galactic nucleus (AGN) indicator …
The Central Molecular Gas Structure In Liners With Low-Luminosity Active Galactic Nuclei: Evidence For Gradual Disappearance Of The Torus,
2012
Instituto de Astrofísica de Canarias, Spain
The Central Molecular Gas Structure In Liners With Low-Luminosity Active Galactic Nuclei: Evidence For Gradual Disappearance Of The Torus, F. Müller-Sánchez, M. A. Prieto, M. Mezcua, R. I. Davies, M. A. Malkan, Moshe Elitzur
Physics and Astronomy Faculty Publications
We present observations of the molecular gas in the nuclear environment of three prototypical low-luminosity active galactic nuclei (LLAGNs), based on VLT/SINFONI AO-assisted integral-field spectroscopy of H2 1-0 S(1) emission at angular resolutions of ~0.''17. On scales of 50-150 pc, the spatial distribution and kinematics of the molecular gas are consistent with a rotating thin disk, where the ratio of rotation (V) to dispersion (σ) exceeds unity. However, in the central 50 pc, the observations reveal a geometrically and optically thick structure of molecular gas (V/σ < 1 and N H > 1023 cm–2 …
