Accretion process onto super-spinning objects (2009)
Bambi, Cosimo, Freese, Katherine, Harada, Tomohiro, Takahashi, Rohta, Yoshida, Naoki
The accretion process onto spinning objects in Kerr spacetimes is studied with numerical simulations. Our results show that accretion onto compact objects with Kerr parameter (characterizing the...
Is the Carter-Israel conjecture correct? (2009)
Bambi, Cosimo, Freese, Katherine, Takahashi, Rohta
According to the Carter-Israel conjecture, the end-state of the gravitational collapse of matter is a Kerr-Newman black hole. Nevertheless, neither the theory nor observations can confirm that. In...
Are we seeing the beginnings of Inflation? (2009)
Ilie, Cosmin, Biswas, Tirthabir, Freese, Katherine
Phantom Cosmology provides an unique opportunity to "connect" the phantom driven (low en- ergy meV scale) dark energy phase to the (high energy GUT scale) inflationary era. This is possible because...
Kaluza-Klein Dark Matter And Neutrinos From Annihilation In The Sun (2009)
Flacke, Thomas, Menon, Arjun, Hooper, Dan, Freese, Katherine
In models with one universal extra dimension (UED), the first Kaluza-Klein excitations of the hypercharge gauge boson, B^(1), and the neutral component of isospin gauge boson, W^3(1), are each viable...
High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons (2009)
Buckley, Matthew R., Freese, Katherine, Hooper, Dan, Spolyar, Douglas, Murayama, Hitoshi
Decaying dark matter has previously been proposed as a possible explanation for the excess high energy cosmic ray electrons and positrons seen by PAMELA and the Fermi Gamma-Ray Space Telescope...
High Energy Neutrinos As A Test of Leptophilic Dark Matter (2009)
Spolyar, Douglas, Buckley, Matthew, Freese, Katherine, Hooper, Dan, Murayama, Hitoshi
Recently, observations by PAMELA, the Fermi Gamma Ray Space Telescope, and other cosmic ray experiments have generated a great deal of interest in dark matter (DM) particles which annihilate at a...
Dai, De-Chang, Freese, Katherine, Stojkovic, Dejan
In order to accommodate increasingly tighter observational constraints on dark matter, several models have been proposed recently in which dark matter particles are charged under some hidden gauge...
Dark Stars: a new look at the First Stars in the Universe (2009)
Spolyar, Douglas, Bodenheimer, Peter, Freese, Katherine, Gondolo, Palo
We have proposed that the first phase of stellar evolution in the history of the Universe may be Dark Stars (DS), powered by dark matter heating rather than by nuclear fusion, and in this paper we...
Dark Stars: A New Study of the FIrst Stars in the Universe (2009)
Freese, Katherine, Spolyar, Douglas, Bodenheimer, Peter, Gondolo, Paolo
We have proposed that the first phase of stellar evolution in the history of the Universe may be Dark Stars (DS), powered by dark matter heating rather than by nuclear fusion. Weakly Interacting...
Bambi, Cosimo, Freese, Katherine
We reply to the comment "A note on the innocuous implications of a minimum length in quantum gravity" by P.H. Frampton [Class. Quantum Grav. 26 (2009) 018001, arXiv:arXiv:0808.0283] on our paper...
Dark Stars: D\"od och \AA teruppst\aa ndelse (2009)
Spolyar, Douglas, Freese, Katherine, Gondolo, Paolo, Aguirre, Anthony, Bodenheimer, Peter, Sellwood, Jeremy A., ...
The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own...
Dark Stars: Begynnelsen (2009)
Gondolo, Paolo, Freese, Katherine, Spolyar, Douglas, Aguirre, Anthony, Bodenheimer, Peter, Sellwood, Jeremy A., ...
The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own...
Savage, Christopher, Freese, Katherine, Gondolo, Paolo, Spolyar, Douglas
The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted as a signal for the existence of weakly interacting dark matter (WIMPs) in our galactic halo, are re-examined in light of...
Dark Stars: the First Stars in the Universe may be powered by Dark Matter Heating (2008)
Freese, Katherine, Bodenheimer, Peter, Gondolo, Paolo, Spolyar, Douglas
A new line of research on Dark Stars is reviewed, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion. Weakly Interacting Massive...
Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed:...
Apparent shape of super-spinning black holes (2008)
Bambi, Cosimo, Freese, Katherine
We consider the possibility that astrophysical Black Holes (BHs) can violate the Kerr bound; i.e., they can have angular momentum greater than BH mass, $J > M$. We discuss implications on the BH...
Bambi, Cosimo, Spolyar, Douglas, Dolgov, Alexander D., Freese, Katherine, Volonteri, Marta
If the cosmological dark matter has a component made of small primordial black holes, they may have a significant impact on the physics of the first stars and on the subsequent formation of massive...
Gravity Waves from Chain Inflation (2008)
Ashoorioon, Amjad, Freese, Katherine
Chain inflation proceeds through a series of first order phase transitions, which can release considerable gravitational waves (GW). We demonstrate that bubble collisions can leave an observable...
Slow nucleation rates in Chain Inflation with QCD Axions or Monodromy (2008)
Ashoorioon, Amjad, Freese, Katherine, Liu, James T.
The previous proposal (by two of us) of chain inflation with the QCD axion is shown to fail. The proposal involved a series of fast tunneling events, yet here it is shown that tunneling is too slow....
Compatibility of DAMA/LIBRA dark matter detection with other searches (2008)
Savage, Christopher, Gelmini, Graciela, Gondolo, Paolo, Freese, Katherine
The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted as a signal for the existence of weakly interacting dark matter (WIMPs) in our galactic halo, are examined in light of...
Dark Stars: Dark Matter in the First Stars leads to a New Phase of Stellar Evolution (2008)
Freese, Katherine, Spolyar, Douglas, Aguirre, Anthony, Bodenheimer, Peter, Gondolo, Paolo, Sellwood, J. A., ...
The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own...
Freese, Katherine, Bodenheimer, Peter, Spolyar, Douglas, Gondolo, Paolo
Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (typically at redshifts $z \sim 10-50$) are powered by heating from dark matter (DM)...
Dark Matter Densities during the Formation of the First Stars and in Dark Stars (2008)
Freese, Katherine, Gondolo, Paolo, Sellwood, J. A., Spolyar, Douglas
The first stars in the universe form inside $\sim 10^6 M_\odot$ dark matter (DM) haloes whose initial density profiles are laid down by gravitational collapse in hierarchical structure formation...
Dark Matter in the MSSM Golden Region (2008)
Kasahara, Junya, Freese, Katherine, Gondolo, Paolo
Dark matter is examined within the ``golden region'' of the Minimal Supersymmetric Standard Model. This region satisfies experimental constraints, including a lower bound on the Higgs mass of 114...
Dangerous implications of a minimum length in quantum gravity (2008)
Bambi, Cosimo, Freese, Katherine
The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this...
The Phantom Bounce: A New Proposal for an Oscillating Cosmology (2008)
Freese, Katherine, Brown, Matthew G., Kinney, William H.
An oscillating universe cycles through a series of expansions and contractions. We propose a model in which ``phantom'' energy with a supernegative pressure ($p < - \rho$) grows rapidly and dominates...
Dark Matter Capture in the First Stars: a Power Source and Limit on Stellar Mass (2008)
Freese, Katherine, Spolyar, Douglas, Aguirre, Anthony
The annihilation of weakly interacting massive particles can provide an important heat source for the first (Pop. III) stars, potentially leading to a new phase of stellar evolution known as a "Dark...
Natural Inflation: the status after WMAP 3-year data (2008)
Freese, Katherine, Kinney, William H., Savage, Christopher
The model of Natural Inflation is examined in light of recent 3-year data from the Wilkinson Microwave Anisotropy Probe and shown to provide a good fit. The inflaton potential is naturally flat due...
Dark matter capture in the first stars: a power source and limit on stellar mass (2008)
Freese, Katherine, Spolyar, Douglas, Aguirre, Anthony
"The annihilation of weakly interacting massive particles can provide an important heat source for the first (Pop III, 'Pop' standing for 'population') stars, potentially leading to a new phase of...
Dangerous implications of a minimum length in quantum gravity (2008)
Bambi, Cosimo, Freese, Katherine
"The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this...
The phantom bounce: a new oscillating cosmology (2008)
Brown, Matthew G, Freese, Katherine, Kinney, William H
"An oscillating universe cycles through a series of expansions and contractions. We propose a model in which 'phantom' energy with p
Effect of dark matter on the first stars: a new phase of stellar evolution (2008)
Gondolo, Paolo, Freese, Katherine; Spolyar, Douglas
Dark matter (DM) in protostellar halos can dramatically alter the current theoretical framework for the formation of the first stars. Heat from supersymmetric DM annihilation can overwhelm any...
Observational Status Of The Texture Large-Scale Structure Formation Model (2007)
Hideyuki Umeda, Katherine Freese
We reexamined CDM texture large-scale structure (LSS) formation model. We confirmed that texture model is consistent with 4-year COBE data both in an open and a critical matter density(\Omega 0 = 1)...
The Effect of Dark Matter on the First Stars: A New Phase of Stellar Evolution (2007)
Freese, Katherine, Gondolo, Paolo, Spolyar, Douglas
Dark matter (DM) in protostellar halos can dramatically alter the current theoretical framework for the formation of the first stars. Heat from supersymmetric DM annihilation can overwhelm any...
Dark matter and the first stars: a new phase of stellar evolution (2007)
Spolyar, Douglas, Freese, Katherine, Gondolo, Paolo
A mechanism is identified whereby dark matter (DM) in protostellar halos dramatically alters the current theoretical framework for the formation of the first stars. Heat from neutralino DM...
Chain Inflation via Rapid Tunneling in the Landscape (2006)
Freese, Katherine, Liu, James T., Spolyar, Douglas
Chain inflation takes place in the string theory landscape as the universe tunnels rapidly through a series of ever lower energy vacua such as may be characterized by quantized changes in four form...
Natural Inflation: status after WMAP 3-year data (2006)
Savage, Christopher, Freese, Katherine, Kinney, William H.
The model of Natural Inflation is examined in light of recent 3-year data from the Wilkinson Microwave Anisotropy Probe and shown to provide a good fit. The inflaton potential is naturally flat due...
Annual Modulation of Dark Matter in the Presence of Streams (2006)
Savage, Chris, Freese, Katherine, Gondolo, Paolo
In addition to a smooth component of WIMP dark matter in galaxies, there may be streams of material; the effects of WIMP streams on direct detection experiments is examined in this paper. The...
Savage, Chris, Newberg, H J, Freese, Katherine, Gondolo, Paolo
We obtain models for a triaxial Milky Way spheroid based on data by Newberg and Yanny. The best fits to the data occur for a spheroid centre that is shifted by 3 kpc from the Galactic Centre. We...
Savage, Christopher, Newberg, Heidi Jo, Freese, Katherine, Gondolo, Paolo
We obtain models for a triaxial Milky Way spheroid based on data by Newberg and Yanny. The best fits to the data occur for a spheroid center that is shifted by 3kpc from the Galactic Center. We...
Devaluation: a dynamical mechanism for a naturally small cosmological constant (2005)
Freese, Katherine, Liu, James T., Spolyar, Douglas
We propose a natural solution to the cosmological constant problem consistent with the standard cosmology and successful over a broad range of energies. This solution is based on the existence of a...
The age of the universe in Cardassian models (2005)
Savage, Chris, Sugiyama, Noriyuki, Freese, Katherine
The age of the universe is obtained in a subset of Cardassian models by using WMAP data. Cardassian expansion is a modification to the Friedmann equation that allows the universe to be flat, matter...
The Dark Side of the Universe (2005)
I will begin by reviewing the evidence for Dark Matter in the Universe, as well as the candidates for dark matter. At most 20% of the dark matter in galaxies can be in the form of MACHOs (Massive...
Chain inflation in the landscape: ‘bubble bubble toil and trouble’ (2005)
Freese, Katherine, Spolyar, Douglas
In the model of chain inflation, a sequential chain of coupled scalar fields drives inflation. We consider a multidimensional potential with a large number of bowls, or local minima, separated by...
Stojkovic, Dejan, Freese, Katherine, Starkman, Glenn D.
We propose a scenario in which the cosmological domain wall and monopole problems are solved without any fine tuning of the initial conditions or parameters in the Lagrangian of an underlying filed...
Adams, Fred C., Freese, Katherine
We present an inflationary universe model which utilizes two coupled real scalar fields. The inflation field $\phi$ experiences a first order phase transition and its potential dominates the energy...
Buchel, Alexander, Chishtie, F A, Elias, V, Freese, Katherine, Mann, R B, McKeon, D G C, ...
The Wilkinson microwave anisotropy probe microwave background data suggest that the primordial spectrum of scalar curvature fluctuations is suppressed at small wavenumbers. We propose a UV/IR mixing...
Inflating with the QCD Axion (2005)
Freese, Katherine, Liu, James T., Spolyar, Douglas
We show that the QCD axion can drive inflation via a series of tunneling events. For axion models with a softly broken $Z_N$ symmetry, the axion potential has a series of $N$ local minima and may be...
Cardassian Expansion: Dark Energy Density from Modified Friedmann Equations (2005)
The Cardassian universe is a proposed modification to the Friedmann equation in which the universe is flat, matter dominated, and accelerating. In the ordinary Friedmann equation, the right hand side...
Detectability of weakly interacting massive particles in the Sagittarius dwarf tidal stream (2005)
Gondolo, Paolo, Freese, Katherine; Newberg, Heidi Jo
Tidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be showering dark matter onto the solar system and contributing ~(0:3–23)% of the local density of our galactic halo. If the...
Chain Inflation in the Landscape: "Bubble Bubble Toil and Trouble" (2004)
Freese, Katherine, Spolyar, Douglas
In the model of Chain Inflation, a sequential chain of coupled scalar fields drives inflation. We consider a multidimensional potential with a large number of bowls, or local minima, separated by...
Probing the evolution of the dark energy density with future supernova surveys (2004)
Wang, Yun, Kostov, Veselin, Freese, Katherine, Frieman, Joshua A, Gondolo, Paolo
The time dependence of the dark energy density can be an important clue to the nature of dark energy in the universe. We show that future supernova data from dedicated telescopes (such as SNAP), when...
Buchel, A., Chishtie, F. A., Elias, V., Freese, Katherine, Mann, R. B., McKeon, D. G. C., ...
The Wilkinson Microwave Anisotropy Probe microwave background data suggest that the primordial spectrum of scalar curvature fluctuations is suppressed at small wavenumbers. We propose a UV/IR mixing...
Savage, Christopher, Gondolo, Paolo, Freese, Katherine
We examine whether the annual modulation found by the DAMA dark matter experiment can be explained by Weakly Interacting Massive Particles (WIMPs), in light of new null results from other...
The Phantom Bounce: A New Oscillating Cosmology (2004)
Brown, Matthew G., Freese, Katherine, Kinney, William H.
An oscillating universe cycles through a series of expansions and contractions. We propose a model in which ``phantom'' energy with $p < -\rho$ grows rapidly and dominates the late-time expanding...
Freese, Katherine, Kinney, William H.
We re-examine the original model of Natural inflation, in which the inflaton is a pseudo Nambu-Goldstone boson with potential of the form $ V(\phi) = \Lambda^4 [1 \pm \cos(\phi/f)]$, in light of...
A black hole solution to the cosmological monopole problem (2004)
Stojkovic, Dejan, Freese, Katherine
We propose a solution to the cosmological monopole problem: Primordial black holes, produced in the early universe, can accrete magnetic monopoles before the relics dominate the energy density of the...
Age of the Universe in the Cardassian Model (2004)
Savage, Christopher, Sugiyama, Noriyuki, Freese, Katherine
The age of the universe is obtained in a subset of Cardassian models by using WMAP data. Cardassian expansion is a modification to the Friedmann equation that allows the universe to be flat, matter...
Probing Dark Energy Using Its Density Instead of Its Equation of State (2004)
The variation of dark energy density with redshift, $\rho_X(z)$, provides a critical clue to the nature of dark energy. Since $\rho_X(z)$ depends on the dark energy equation of state $w_X(z)$ through...
Probing the Evolution of the Dark Energy Density with Future Supernova Surveys (2004)
Wang, Yun, Kostov, Veselin, Freese, Katherine, Frieman, Joshua A., Gondolo, Paolo
The time dependence of the dark energy density can be an important clue to the nature of dark energy in the universe. We show that future supernova data from dedicated telescopes (such as SNAP), when...
The Effects of the Sagittarius Dwarf Tidal Stream on Dark Matter Detectors (2003)
Freese, Katherine, Gondolo, Paolo, Newberg, Heidi Jo, Lewis, Matthew
The Sagittarius dwarf tidal stream may be showering dark matter onto the solar neighborhood, which can change the results and interpretation of WIMP direct detection experiments. Stars in the stream...
Detectability of Weakly Interacting Massive Particles in the Sagittarius Dwarf Tidal Stream (2003)
Freese, Katherine, Gondolo, Paolo, Newberg, Heidi Jo
Tidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be showering dark matter onto the solar system and contributing approx (0.3--23)% of the local density of our Galactic Halo. If the...
The Phase of the Annual Modulation as a Tool for Determining the WIMP Mass (2003)
Lewis, Matthew J., Freese, Katherine
The count rate of Weakly Interacting Massive Particle (WIMP) dark matter candidates in direct detection experiments experiences an annual modulation due to the Earth's motion around the Sun. In the...
Observational tests of open strings in braneworld scenarios (2003)
Freese, Katherine, Lewis, Matthew J.
We consider some consequences of describing the gauge and matter degrees of freedom in our universe by open strings, as suggested by the braneworld scenario. We focus on changes in causal structure...
Bastero-Gil, Mar, Freese, Katherine, Mersini-Houghton, Laura
The Wilkinson Microwave Anisotropy Probe microwave background data may be giving us clues about new physics at the transition from a ``stringy'' epoch of the universe to the standard Friedmann...
Hagedorn Inflation: Open Strings on Branes Can Drive Inflation (2003)
Abel, Steven, Freese, Katherine, Kogan, Ian
We demonstrate an inflationary solution to the cosmological horizon problem during the Hagedorn regime in the early universe. Here the observable universe is confined to three spatial dimensions (a...
Future Type Ia Supernova Data as Tests of Dark Energy from Modified Friedmann Equations (2003)
Wang, Yun, Freese, Katherine, Gondolo, Paolo, Lewis, Matthew
In the Cardassian model, dark energy density arises from modifications to the Friedmann equation, which becomes $H^2 = g(\rhom)$, where $g(\rhom)$ is a new function of the energy density. The...
Fluid interpretation of Cardassian expansion (2003)
Gondolo, Paolo, Freese, Katherine
A fluid interpretation of Cardassian expansion is developed. Here, the Friedmann equation takes the form H2=g(ρM) where ρM contains only matter and radiation ~no vacuum!. The function g(ρM)...
An Accelerating Universe from Dark Matter Interactions with Negative Pressure (2002)
Gondolo, Paolo, Freese, Katherine
As an explanation for the acceleration of the universe, we propose dark matter with self-interactions characterized by a negative pressure; there is no vacuum energy whatsoever in this Cardassian...
Observational Tests of Open Strings in Braneworld Scenarios (2002)
Freese, Katherine, Lewis, M, Van Der Schaar, J P
We consider some consequences of describing the gauge and matter degrees of freedom in our universe by open strings, as suggested by the braneworld scenario. We focus on the geometric effects...
Observational Tests of Open Strings in Braneworld Scenarios (2002)
Freese, Katherine, Lewis, Matthew, Van Der Schaar, Jan Pieter
We consider some consequences of describing the gauge and matter degrees of freedom in our universe by open strings, as suggested by the braneworld scenario. We focus on the geometric effects...
The positron excess and supersymmetric dark matter (2002)
Baltz, Edward A., Edsjo, Joakim, Freese, Katherine, Gondolo, Paolo
Using a new instrument, the HEAT collaboration has confirmed the excess of cosmic ray positrons that they first detected in 1994. We explore the possibility that this excess is due to the...
Fluid Interpretation of Cardassian Expansion (2002)
Gondolo, Paolo, Freese, Katherine
A fluid interpretation of Cardassian expansion is developed. Here, the Friedmann equation takes the form $H^2 = g(\rho_M)$ where $\rho_M$ contains only matter and radiation (no vacuum). The function...
The Cardassian universe is a proposed modification to the Friedmann Robertson Walker (FRW) equation in which the universe is flat, matter dominated, and accelerating. Here we generalize the original...
CP-Violating Effects in Neutralino Scattering and Annihilation (2002)
Gondolo, Paolo, Freese, Katherine
CP-violating effects that mix the CP-even and CP-odd Higgs bosons can have important consequences for annihilation and scattering of supersymmetric neutralino dark matter. Specifically, we study the...
Hagedorn Inflation: Open Strings on Branes Can Drive Inflation (2002)
Abel, Steven, Freese, Katherine, Kogan, Ian
We demonstrate an inflationary solution to the cosmological horizon problem during the Hagedorn regime in the early universe. Here the observable universe is confined to three spatial dimensions (a...
The Ultimate Fate of Life in an Accelerating Universe (2002)
Freese, Katherine, Kinney, William H.
The ultimate fate of life in a universe with accelerated expansion is considered. Previous work showed that life cannot go on indefinitely in a universe dominated by a cosmological constant. In this...
A Wavelet Analysis of Solar Climate Forcing: I) Solar Cycle Timescales (2002)
Lewis, Matthew J., Freese, Katherine
We use the technique of wavelet analysis to quantitatively investigate the role of solar variability in forcing terrestrial climate change on solar cycle timescales (roughly 11 years). We examine the...
Lensed Density Perturbations in Braneworlds: An Alternative to Perturbations from Inflation (2002)
Chung, D J H, Freese, Katherine
We consider a scenario in which our observable universe is a 3-dimensional surface (3-brane) living in extra dimensions with a warped geometry. We show that ``lensed'' density perturbations from...
Lensed Density Perturbations in Braneworlds: An Alternative to Perturbations from Inflation (2002)
Chung, Daniel J. H., Freese, Katherine
We consider a scenario in which our observable universe is a 3-dimensional surface (3-brane) living in extra dimensions with a warped geometry. We show that ``lensed'' density perturbations from...
Freese, Katherine, Lewis, Matthew
A modification to the Friedmann Robertson Walker equation is proposed in which the universe is flat, matter dominated, and accelerating. An additional term, which contains only matter or radiation...
The cosmic ray positron excess and neutralino dark matter (2001)
Baltz, Edward A., Edsjo, Joakim, Freese, Katherine, Gondolo, Paolo
Using a new instrument, the HEAT collaboration has confirmed the excess of cosmic ray positrons that they first detected in 1994. We explore the possibility that this excess is due to the...
On the direct detection of extragalactic WIMPs (2001)
Freese, Katherine, Gondolo, Paolo, Stodolsky, Leo
We consider the direct detection of WIMPs reaching the Earth from outside the Milky Way. If these WIMPs form a distinct population they will, although of much lower flux than typical galactic halo...
Hagedorn inflation of D-branes (2001)
Abel, Steven A., Freese, Katherine, Kogan, Ian I.
We examine the cosmological effects of the Hagedorn phase in models where the observable universe is pictured as a D-brane. It is shown that, even in the absence of a cosmological constant, winding...
On the direct detection of extragalactic weakly interacting massive particles (2001)
Gondolo, Paolo, Freese, Katherine; Stodolsky, Leo
We consider the direct detection of weakly interacting massive particles (WIMPs) reaching the Earth from outside the Milky Way. If these WIMPs form a distinct population they will, although of much...
Death of Stellar Baryonic Dark Matter Candidates (2000)
Freese, Katherine, Fields, Brian, Graff, David
The nature of the dark matter in the Universe is one of the outstanding questions in astrophysics. In this talk, I address possible stellar baryonic contributions to the 50-90% of our Galaxy that is...
Hagedorn inflation of D-branes (2000)
Abel, Steven, Freese, Katherine, Kogan, Ian I.
We examine the cosmological effects of the Hagedorn phase in models where the observable universe is pictured as a D-brane. It is shown that, even in the absence of a cosmological constant, winding...
Death of Stellar Baryonic Dark Matter (2000)
Freese, Katherine, Field, Brian D., Graff, David S.
The nature of the dark matter in the haloes of galaxies is one of the outstanding questions in astrophysics. All stellar candidates, until recently thought to be likely baryonic contributions to the...
Effects of CP-Violation in Neutralino Scattering and Annihilation (2000)
Gondolo, Paolo, Freese, Katherine
We summarize our paper hep-ph/9908390, where we find that in some regions of supersymmetric parameter space, CP violating effects that mix the CP-even and CP-odd Higgs bosons can enhance the...
Protogalactic Extension of the Parker Bound (1999)
Lewis, M. J., Freese, Katherine, Tarle, Gregory
We extend the Parker bound on the galactic flux $\cal F$ of magnetic monopoles. By requiring that a small initial seed field must survive the collapse of the protogalaxy, before any regenerative...
Can Geodesics in Extra Dimensions Solve the Cosmological Horizon Problem? (1999)
Chung, Daniel J. H., Freese, Katherine
We demonstrate a non-inflationary solution to the cosmological horizon problem in scenarios in which our observable universe is confined to three spatial dimensions (a three-brane) embedded in a...
CP-Violating Effects in Neutralino Scattering and Annihilation (1999)
Gondolo, Paolo, Freese, Katherine
We show that in some regions of supersymmetric parameter space, CP violating effects that mix the CP-even and CP-odd Higgs bosons can enhance the neutralino annihilation rate, and hence the indirect...
Cosmological Challenges in Theories with Extra Dimensions and Remarks on the Horizon Problem (1999)
Chung, Daniel J. H., Freese, Katherine
We consider the cosmology that results if our observable universe is a 3-brane in a higher dimensional universe. In particular, we focus on the case where our 3-brane is located at the $Z_2$ symmetry...
Freese, Katherine, Fields, Brian, Graff, David
The nature of the dark matter in the Halo of our Galaxy remains a mystery. Arguments are presented that the dark matter does not consist of ordinary stellar or substellar objects, i.e., the dark...
Chemical Abundance Constraints on White Dwarfs as Halo Dark Matter (1999)
Fields, Brian D., Freese, Katherine, Graff, David S.
We examine the chemical abundance constraints on a population of white dwarfs in the Halo of our Galaxy. We are motivated by microlensing evidence for massive compact halo objects (Machos) in the...
Constraining the cosmic abundance of stellar remnants with multi-TeV gamma-rays (1999)
Graff, David S., Freese, Katherine, Walker, Terry, Pinsonneault, Marc
If galactic halos contain stellar remnants, the infra-red flux from the remnant progenitors would contribute to the opacity of multi-TeV gamma-rays. The multi-TeV gamma-ray horizon is established to...
What are Machos? Limits on Stellar Objects as the Dark Matter of our Halo (1999)
Freese, Katherine, Fields, Brian, Graff, David
The nature of the Massive Compact Halo objects seen in microlensing experiments and interpreted as dark matter in the Halo of our Galaxy remains a mystery. Arguments are presented that these events...
Fields, Brian D., Freese, Katherine, Graff, David S.
[Abridged] We estimate the contribution of Massive Compact Halo Objects (Machos) and their stellar progenitors to the mass density of the Universe. If the Machos that have been detected reside in the...
A Bound on the Flux of Magnetic Monopoles from Catalysis of Nucleon Decay in White Dwarfs (1998)
Freese, Katherine, Krasteva, Eleonora
Catalysis of nucleon decay in white dwarfs is used to constrain the abundance of magnetic monopoles arising from Grand Unified Theories. Recent discoveries of the dimmest white dwarf ever observed,...
Constraints on the Intergalactic Transport of Cosmic Rays (1997)
Adams, Fred C., Freese, Katherine, Laughlin, Gregory, Tarl{é}, Gregory, Schwadron, Nathan
Motivated by recent experimental proposals to search for extragalactic cosmic rays (including anti-matter from distant galaxies), we study particle propagation through the intergalactic medium (IGM)....
MACHOs, White Dwarfs, and the Age of the Universe (1997)
Graff, David S., Laughlin, Gregory, Freese, Katherine
(Abridged Abstract) A favored interpretation of recent microlensing measurements towards the Large Magellanic Cloud implies that a large fraction (i.e. 10--50%) of the mass of the galactic halo is...
Indirect detection of a light Higgsino motivated by collider data (1997)
Freese, Katherine, Kamionkowski, Marc
Kane and Wells recently argued that collider data point to a Higgsino-like lightest supersymmetric partner which would explain the dark matter in our Galactic halo. They discuss direct detection of...
Baryogenesis During Reheating in Natural Inflation and Comments on Spontaneous Baryogenesis (1996)
Dolgov, Alexandre, Freese, Katherine, Rangarajan, Raghavan, Srednicki, Mark
We calculate the baryon asymmetry created by the decay of a pseudo Nambu-Goldstone boson whose interactions violate baryon number conservation. Our results are in disagreement with previous results...
Indirect Detection of a Light Higgsino Motivated by Collider Data (1996)
Freese, Katherine, Kamionkowski, Marc
Kane and Wells recently argued that collider data point to a Higgsino-like lightest supersymmetric partner which would explain the dark matter in our Galactic halo. They discuss direct detection of...
The Mass-Function of Low Mass Halo Stars: Limits on Baryonic Halo Dark Matter (1996)
Graff, David S., Freese, Katherine
We derive mass functions (MF) for halo red dwarfs (the faintest hydrogen burning stars) and then extrapolate to place limits on the total mass of halo brown dwarfs (stars not quite massive enough to...
Moduli Inflation with Large Scale Structure Produced by Topological Defects (1995)
Freese, Katherine, Gherghetta, Tony, Umeda, Hideyuki
It is tempting to inflate along one of the many flat directions that arise in supersymmetric theories. The required flatness of the potential to obtain sufficient inflation and to not overproduce...
Graff, David S., Freese, Katherine
We re-examine a deep {\it Hubble Space Telescope} pencil-beam search for red dwarfs, stars just massive enough to burn Hydrogen. The authors of this search (Bahcall, Flynn, Gould \& Kirhakos 1994)...
Dolgov, Alexandre, Freese, Katherine
A semiclassical calculation of particle production by a scalar field in a potential is performed. We focus on the particular case of production of fermions by a Nambu-Goldstone boson $\theta$. We...
Curvature and flatness in a Brans-Dicke universe (1994)
Levin, Janna J., Freese, Katherine
The evolution of a universe with Brans-Dicke gravity and nonzero curvature is investigated here. We find solutions to the equations of motion during the radiation dominated era. In a...
We find a coupling of Pseudo Nambu Goldstone bosons (PNGBs) to other (ordinary) scalars, and consider its importance in various contexts. Our original motivation was the model of Double Field...
The Scalar Field Potential in Inflationary Models: Reconstruction and Further Constraints (1994)
Adams, Fred C., Freese, Katherine
In this paper, we present quantitative constraints on the scalar field potential for a general class of inflationary models. (1) We first consider the reconstruction of the inflationary potential for...
Curvature and Flatness in a Brans-Dicke Universe (1993)
Levin, Janna, Freese, Katherine
The evolution of a universe with Brans-Dicke gravity and nonzero curvature is investigated here. We present the equations of motion and their solutions during the radiation dominated era. In a...
A pseudo-Nambu-Goldstone boson, with a potential of the form $ V(\phi) = \Lambda^4 [1 + \cos(\phi/f)]$, can naturally give rise to an epoch of inflation in the early universe (Freese, Frieman, and...
Levin, Janna J, Freese, Katherine
Extensions of Einstein gravity which allow the gravitational constant $G$ to change with time as the universe evolves may provide a resolution to the horizon problem without invoking a period of...
The Mad Era: A Possible New Resolution to the Horizon, Flatness, and Monopole Problems (1992)
Freese, Katherine, Levin, Janna J
A cosmology with a dynamical Planck mass $m_{pl}$ is shown to solve the horizon and monopole problems (and possibly flatness) if there is an early MAD (modified aging) era where the universe becomes...
Instability and subsequent evolution of electroweak bubbles (1992)
Kamionkowski, Marc, Freese, Katherine
Bubbles in a first-order electroweak phase transition are nucleated with radii R0 and expand with velocity v. If v is subsonic, a bubble becomes unstable to nonspherical perturbations when its radius...
Baryon Number Diffusion and Instabilities in the Quark/Hadron Phase Transition (1992)
Adams, Fred C., Freese, Katherine, Langer, J. S.
Hadron bubbles that nucleate with radius $R_{nuc}$ in a quark sea (if the phase transition is first order) are shown to be unstable to the growth of nonspherical structure when the bubble radii...
Instability and Subsequent Evolution of Electroweak Bubbles (1992)
Kamionkowski, Marc, Freese, Katherine
Bubbles in a first-order electroweak phase transition are nucleated with radii $R_0$ and expand with velocity $v$. If $v$ is subsonic, a bubble becomes unstable to non-spherical perturbations when...
Adams, Fred, Bond, J. R., Freese, Katherine, Frieman, Joshua, Olinto, Angela
A pseudo-Nambu-Goldstone boson, with a potential of the form $V(\phi) = \Lambda^4[1 \pm \cos(\phi/f)], naturally gives rise to inflation if $f \sim M_{Pl}$ and $\Lambda \sim M_{GUT}$. We show how...