The Physics of Cosmic Acceleration (2009)
Caldwell, Robert R., Kamionkowski, Marc
The discovery that the cosmic expansion is accelerating has been followed by an intense theoretical and experimental response in physics and astronomy. The discovery implies that our most basic...
A Multi-Parameter Investigation of Gravitational Slip (2009)
Daniel, Scott F., Caldwell, Robert R., Cooray, Asantha, Serra, Paolo, Melchiorri, Alessandro
A detailed analysis of gravitational slip, a new post-general relativity cosmological parameter characterizing the degree of departure of the laws of gravitation from general relativity on...
Large Scale Structure as a Probe of Gravitational Slip (2008)
Daniel, Scott F., Caldwell, Robert R., Cooray, Asantha, Melchiorri, Alessandro
A new time-dependent, scale-independent parameter, \varpi, is employed in a phenomenological model of the deviation from General Relativity in which the Newtonian and longitudinal gravitational...
Effects of Chern-Simons gravity on bodies orbiting the Earth (2008)
Smith, Tristan L., Erickcek, Adrienne L., Caldwell, Robert R., Kamionkowski, Marc
One of the possible low-energy consequences of string theory is the addition of a Chern-Simons term to the standard Einstein-Hilbert action of general relativity. It can be argued that the...
Consequences of a Cosmic Scalar with Kinetic Coupling to Curvature (2007)
Daniel, Scott F., Caldwell, Robert R.
The classical gravitational theory of a scalar field with a gradient coupling to the Ricci tensor is examined. This is a scalar-vector-tensor gravitational theory, but in the case that the coupling...
The effects of Chern-Simons gravity on bodies orbiting the Earth (2007)
Smith, Tristan L., Erickcek, Adrienne L., Caldwell, Robert R., Kamionkowski, Marc
One of the possible low-energy consequences of string theory is the addition of a Chern-Simons term to the standard Einstein-Hilbert action of general relativity. It can be argued that the...
Large-Scale Bulk Motions Complicate the Hubble Diagram (2006)
Cooray, Asantha, Caldwell, Robert R.
We investigate the extent to which correlated distortions of the luminosity distance-redshift relation due to large-scale bulk flows limit the precision with which cosmological parameters can be...
A Sudden Gravitational Transition (2005)
Caldwell, Robert R., Komp, William, Parker, Leonard, Vanzella, Daniel A. T.
We investigate the properties of a cosmological scenario which undergoes a gravitational phase transition at late times. In this scenario, the Universe evolves according to general relativity in the...
Cosmic shear of the microwave background: The curl diagnostic (2005)
Cooray, Asantha, Kamionkowski, Marc, Caldwell, Robert R.
Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is...
Cosmic Shear of the Microwave Background: The Curl Diagnostic (2005)
Cooray, Asantha, Kamionkowski, Marc, Caldwell, Robert R.
Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is...
Dark-Energy Evolution Across the Cosmological-Constant Boundary (2005)
Caldwell, Robert R., Doran, Michael
We explore the properties of dark energy models for which the equation-of-state, w, defined as the ratio of pressure to energy density, crosses the cosmological-constant boundary w = -1. We adopt an...
Dark-matter electric and magnetic dipole moments (2004)
Sigurdson, Kris, Doran, Michael, Kurylov, Andriy, Caldwell, Robert R., Kamionkowski, Marc
We consider the consequences of a neutral dark-matter particle with a nonzero electric and/or magnetic dipole moment. Theoretical constraints, as well as constraints from direct searches, precision...
Expansion, geometry, and gravity (2004)
Caldwell, Robert R., Kamionkowski, Marc
In general-relativistic cosmological models, the expansion history, matter content, and geometry are closely intertwined. In this brief paper, we clarify the distinction between the effects of...
Dark-Matter Electric and Magnetic Dipole Moments (2004)
Sigurdson, Kris, Doran, Michael, Kurylov, Andriy, Caldwell, Robert R., Kamionkowski, Marc
We consider the consequences of a neutral dark-matter particle with a nonzero electric and/or magnetic dipole moment. Theoretical constraints, as well as constraints from direct searches, precision...
Expansion, Geometry, and Gravity (2004)
Caldwell, Robert R., Kamionkowski, Marc
In general-relativistic cosmological models, the expansion history, matter content, and geometry are closely intertwined. In this brief paper, we clarify the distinction between the effects of...
Phantom Energy: Dark Energy with w (2003)
Caldwell, Robert R., Kamionkowski, Marc, Weinberg, Nevin N.
We explore the consequences that follow if the dark energy is phantom energy, in which the sum of the pressure and energy density is negative. The positive phantom-energy density becomes infinite in...
Caldwell, Robert R., Doran, Michael
We perform a detailed comparison of the Wilkinson Microwave Anisotropy Probe (WMAP) measurements of the cosmic microwave background (CMB) temperature and polarization anisotropy with the predictions...
Early Quintessence in Light of WMAP (2003)
Caldwell, Robert R., Doran, Michael, Mueller, Christian M., Schaefer, Gregor, Wetterich, Christof
We examine the cosmic microwave background (CMB) anisotropy for signatures of early quintessence dark energy -- a non-negligible quintessence energy density during the recombination and structure...
Phantom Energy and Cosmic Doomsday (2003)
Caldwell, Robert R., Kamionkowski, Marc, Weinberg, Nevin N.
Cosmologists have long wondered whether the Universe will eventually re-collapse and end with a Big Crunch, or expand forever, becoming increasingly cold and empty. Recent evidence for a flat...
Schuecker, Peter, Caldwell, Robert R., Böhringer, Hans, Collins, Chris A., Guzzo, Luigi, Weinberg, Nevin N.
New observational constraints on the cosmic matter density $\Omega_m$ and an effectively redshift-independent equation of state parameter $w_x$ of the dark energy are obtained while simultaneously...
Spintessence! New Models for Dark Matter and Dark Energy (2001)
Boyle, Latham A., Caldwell, Robert R., Kamionkowski, Marc
We investigate a class of models for dark matter and/or negative-pressure, dynamical dark energy consisting of ``spintessence,'' a complex scalar field $\phi$ spinning in a U(1)-symmetric potential...
Shortcuts in the fifth dimension (2001)
Caldwell, Robert R., Langlois, David
If our Universe is a three-brane embedded in a five-dimensional anti-deSitter spacetime, in which matter is confined to the brane and gravity inhabits an infinite bulk space, then the causal...