Generation of Curvature Perturbations with Extra Anisotropic Stress (2009)
Kojima, Kazuhiko, Kajino, Toshitaka, Mathews, Grant J.
We study the evolution of curvature perturbations and the cosmic microwave background (CMB) power spectrum in the presence of an hypothesized extra anisotropic stress in the early universe. Such...
Effect of Long-lived Strongly Interacting Relic Particles on Big Bang Nucleosynthesis (2009)
Kusakabe, Motohiko, Kajino, Toshitaka, Yoshida, Takashi, Mathews, Grant J.
It has been suggested that relic long-lived strongly interacting massive particles (SIMPs, or $X$ particles) existed in the early universe. We study effects of such long-lived unstable SIMPs on big...
Constraints on the Primordial Magnetic Field from $\sigma_8$ (2008)
Yamazaki, Dai G., Ichiki, Kiyotomo, Kajino, Toshitaka, Mathews, Grant. J.
A primordial magnetic field (PMF) can affect the evolution of density field fluctuations in the early universe.In this paper we constrain the PMF amplitude $B_\lambda$ and power spectral index...
Grant J. Mathews, P. Maronetti, Jay Salmonson, J. R. Wilson
There are numerous aspects of modern gamma-ray astrophysics which are intimately connected with high precision gamma-ray astronomy. High resolution observations of galactic gamma-ray lines have...
Kojima, Kazuhiko, Ichiki, Kiyotomo, Yamazaki, Dai G., Kajino, Toshitaka, Mathews, Grant J.
If a primordial magnetic field (PMF) is present during photon decoupling and afterward, a finite neutrino mass can affect all modes of the CMB. In this work, we expand on earlier studies of the...
An Axisymmetric Object-Based Search for a Flat Compact Dimension (2008)
Dylan Menzies, Grant J. Mathews
Abstract. A method is presented to search for a hypertorus symmetry axis by the alignment of distant objects. This offers greater sensitivity than previously proposed object-based methods that rely...
Effects of a Primordial Magnetic Field on Low and High Multipoles of the CMB (2008)
Yamazaki, Dai G., Ichiki, Kiyotomo, Kajino, Toshitaka, Mathews, Grant J.
The existence of a primordial magnetic field (PMF) would affect both the temperature and polarization anisotropies of the cosmic microwave background (CMB). It also provides a plausible explanation...
Kusakabe, Motohiko, Kajino, Toshitaka, Boyd, Richard N., Yoshida, Takashi, Mathews, Grant J.
The $^6$Li abundance observed in metal poor halo stars exhibits a plateau similar to that for $^7$Li suggesting a primordial origin. However, the observed abundance of $^6$Li is a factor of $10^3$...
The X^- Solution to the ^6Li and ^7Li Big Bang Nucleosynthesis Problems (2007)
Kusakabe, Motohiko, Kajino, Toshitaka, Boyd, Richard N., Yoshida, Takashi, Mathews, Grant J.
The $^6$Li abundance observed in metal poor halo stars appears to exhibit a plateau as a function of metallicity similar to that for $^7$Li, suggesting a big bang origin. However, the inferred...
THE ASTROPHYSICAL JOURNAL, 561 346363, 2001 November 1 V (2007)
The American Astronomical, Wako Aoki, Sean G. Ryan, John E. Norris, Timothy C. Beers, Hiroyasu Ando, ...
We report abundance estimates for neutron capture elements, including lead (Pb), and nucleosynthesis models for their origin, in two carbon-rich, very metal-poor stars, LP 625-44 and LP 706-7. These...
Comment on the Relativistic Galactic Model by Cooperstock and Tieu (2006)
Menzies, Dylan, Mathews, Grant J.
It has recently been suggested that observed galaxy rotation curves can be accounted for by general relativity without recourse to dark-matter halos. A number of objections have been raised, which...
Yamazaki, Dai G., Ichiki, Kiyotomo, Kajino, Toshitaka, Mathews, Grant J.
The primordial magnetic field (PMF) can strongly affect the cosmic microwave background (CMB) power spectrum and the formation of large scale structure. In this presentation, we calculate the CMB...
Bulk Viscosity, Decaying Dark Matter, and the Cosmic Acceleration (2006)
Wilson, James R., Mathews, Grant J., Fuller, George M.
We discuss a cosmology in which cold dark-matter particles decay into relativistic particles. We argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. For decay...
Two-neutron capture reactions and the r process (2006)
Bartlett, Amy, Görres, Joachim, Mathews, Grant J., Otsuki, Kaori, Wiescher, Michael, Frekers, Dieter, ...
$^6$Li Production by the Radiative Decay of Long-Lived Particles (2006)
Kusakabe, Motohiko, Kajino, Toshitaka, Mathews, Grant J.
Recent spectroscopic observations of metal poor stars have indicated that both $^7$Li and $^6$Li have abundance plateaus with respect to the metallicity. Abundances of $^7$Li are about a factor three...
General Relativistic Galaxy Rotation Curves: Implications for Dark Matter Distribution (2006)
Menzies, Dylan, Mathews, Grant J.
It has recently been suggested that observed galaxy rotation curves can be accounted for by general relativity without recourse to dark-matter halos. Good fits have been produced to observed galatic...
Neutron-capture elements in the metal-poor globular cluster M15 (2006)
Otsuki, Kaori, Honda, Satoshi, Aoki, Wako, Kajino, Toshitaka, Mathews, Grant J.
We report on observations of six giants in the globular cluster M15 (NGC 7078) using the Subaru Telescope to measure neutron-capture elemental abundances. Our abundance analyses based on high-quality...
An Axisymmetric Object-Based Search for a Flat Compact Dimension (2005)
Menzies, Dylan, Mathews, Grant J.
A method is presented to search for a hypertorus symmetry axis by the alignment of distant objects. This offers greater sensitivity than previously proposed object-based methods that rely on accurate...
Early Star Formation and Chemical Evolution in Proto-Galactic Clouds (2004)
Saleh, Lamya, Beers, Timothy C., Mathews, Grant J.
We present numerical simulations to describe the evolution of pre-Galactic clouds in a model which is motivated by cold dark matter simulations of hierarchical galaxy formation. We adopt a SN-induced...
Ashenfelter, Timothy P., Mathews, Grant J., Olive, Keith A.
Evidence from a large sample of quasar absorption-line spectra in damped Lyman-alpha systems has suggested a possible time variation of the fine structure constant alpha. The most statistically...
The Chemical Evolution of Mg Isotopes vs. the Time Variation of the Fine Structure Constant (2003)
Ashenfelter, T., Mathews, Grant J., Olive, Keith A.
The many-multiplet method applied to high redshift quasar absorption spectra has indicated a possible time variation of the fine structure constant. Alternatively, a constant value of alpha is...
Aoki, Wako, Ryan, Sean G., Iwamoto, Nobuyuki, Beers, Timothy C., Norris, John E., Ando, Hiroyasu, ...
We report on the first measurement of the Eu isotope fractions (151Eu and 153Eu) in s-process-element-enhanced, metal-poor stars. We use these ratios to investigate the 151Sm branching of s-process...
r-Process Abundance Universality and Actinide Cosmochronology (2002)
Otsuki, Kaori, Mathews, Grant J., Kajino, Toshitaka
We review recent observational and theoretical results concerning the presence of actinide nuclei on the surfaces of old halo stars and their use as an age determinant. We present model calculations...
s-Process Nucleosynthesis in Low-Metallicity Stars (2002)
Iwamoto, Nobuyuki, Kajino, Toshitaka, Mathews, Grant J., Fujimoto, Masayuki Y., Aoki, Wako
We have made a parametric study of s-process nucleosynthesis in the metal poor ([Fe/H]=-2.7) stars LP625-44 and LP706-7. We find that a high neutron exposure and a small overlap factor are necessary...
LoSecco, John M., Mathews, Grant J., Wang, Yun
Observers have demonstrated that it is now feasible to measure the cosmic microwave background (CMB) temperature at high redshifts. We explore the possible constraints on cosmology which might...
Neutron Capture Elements in s-Process-Rich, Very Metal-Poor Stars (2001)
Aoki, Wako, Ryan, Sean G., Norris, John E., Beers, Timothy C., Ando, Hiroyasu, Iwamoto, Nobuyuki, ...
We report abundance estimates for neutron-capture elements, including lead (Pb), and nucleosynthesis models for their origin, in two carbon-rich, very metal-poor stars, LP625-44 and LP706-7. These...
Wanajo, Shinya, Kajino, Toshitaka, Mathews, Grant J., Otsuki, Kaori
We present calculations of r-process nucleosynthesis in neutrino-driven winds from the nascent neutron stars of core-collapse supernovae. A full dynamical reaction network for both the alpha-rich...
Model Independent Primordial Power Spectrum from Maxima, Boomerang, and DASI Data (2000)
A model-independent determination of the primordial power spectrum of matter density fluctuations could uniquely probe physics of the very early universe, and provide powerful constraints on...
Bardeen-Petterson Effect and Quasi-Periodic Oscillations in X-Ray Binaries (2000)
Fragile, P. Chris, Mathews, Grant J., Wilson, James R.
The Bardeen-Petterson effect around a rapidly-rotating compact object causes a tilted accretion disk to warp into the equatorial plane of the rotating body. Viscous forces cause the accretion flow to...
Impact of Few-Body Reactions on Explosive Nucleosynthesis: The Big-Bang and Supernovae (2000)
Kajino, Toshitaka, Otsuki, Kaori, Wanajo, Shin-ya, Orito, Manabu, Mathews, Grant J.
We study the few body reactions in explosive nucleosynthesis of light-to-heavy mass elements in various astrophysical conditions. In neutrino-driven winds of gravitational core collapse of SNeII,...
Gamma-Ray Bursts via the Neutrino Emission from Heated Neutron Stars (2000)
Salmonson, Jay D., Wilson, James R., Mathews, Grant J.
A model is proposed for gamma-ray bursts based upon a neutrino burst of about 10^52 ergs lasting a few seconds above a heated collapsing neutron star. This type of thermal neutrino burst is suggested...
Gamma-Ray Bursts via Pair Plasma Fireballs from Heated Neutron Stars (2000)
Salmonson, Jay D., Wilson, James R., Mathews, Grant J.
In this paper we model the emission from a relativistically expanding electron-positron pair plasma fireball originating near the surface of a heated neutron star. This pair fireball is deposited via...
Binary Neutron Stars Systems: Irrotational Quasi-Equilibrium Sequences (1999)
Marronetti, Pedro, Mathews, Grant J., Wilson, James R.
We report on numerical results from an independent formalism to describe the quasi-equilibrium structure of nonsynchronous binary neutron stars in general relativity. This is an important independent...
Stochastic Isocurvature Baryon Fluctuations, Baryon Diffusion, and Primordial Nucleosynthesis (1996)
Kurki-Suonio, Hannu, Jedamzik, Karsten, Mathews, Grant J.
We examine effects on primordial nucleosynthesis from a truly random spatial distribution in the baryon-to-photon ratio ($\eta$). We generate stochastic fluctuation spectra characterized by different...
Halo White Dwarfs and the Hot Intergalactic Medium (1996)
Fields, Brian D., Mathews, Grant J., Schramm, David N.
We present a schematic model for the formation of baryonic galactic halos and hot gas in the Local Group and the intergalactic medium. We follow the dynamics, chemical evolution, heat flow and gas...
A Merger Model and Globular Cluster Formation (1994)
Lee, Sangjin, Schramm, David N., Mathews, Grant J.
We propose a self-consistent model for globular cluster formation in, but not limited to, our Galaxy, based on the merger model of Mathews and Schramm (1993). Stars and star clusters form in bursts...
Statistical Constraints on the Inflation Effective Potential from the COBE DMR Results (1994)
Kurki-Suonio, Hannu, Mathews, Grant J.
We explore constraints on various forms for the effective potential during inflation based upon a statistical comparison between inflation-generated fluctuations in the cosmic microwave background...
Production of Li, Be \& B from Baryon Inhomogeneous Primordial Nucleosynthesis (1993)
Thomas, David, Schramm, David N., Olive, Keith A., Mathews, Grant J., Meyer, Bradley S., Fields, Brian D.
We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of \li6, \be9 and B in population II stars. The present work differs from previous...