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More on Lensing by a Cosmological Constant
Mustapha Ishak, Wolfgang Rindler, Jason Dossett
The question of whether or not the cosmological constant affects the bending of light around a concentrated mass has been the subject of some recent papers. We present here a simpl…
A minimal set of invariants as a systematic approach to higher order gravity models
Mustapha Ishak, Jacob Moldenhauer
Higher-order gravity models have been recently the subject of much attention in the context of cosmic acceleration. These models are derived by adding various curvature invariants…
Light Deflection, Lensing, and Time Delays from Gravitational Potentials and Fermat's Principle in the Presence of a Cosmological Constant
Mustapha Ishak
The contribution of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's P…
A New Independent Limit on the Cosmological Constant/Dark Energy from the Relativistic Bending of Light by Galaxies and Clusters of Galaxies
Mustapha Ishak, Wolfgang Rindler, Jason Dossett +2
We derive new limits on the value of the cosmological constant, , based on the Einstein bending of light by systems where the lens is a distant galaxy or a cluster of galaxies.…
The Contribution of the Cosmological Constant to the Relativistic Bending of Light Revisited
Wolfgang Rindler, Mustapha Ishak
We study the effect of the cosmological constant on the bending of light by a concentrated spherically symmetric mass. Contrarily to previous claims, we show that when the Schw…
Dark Energy or Apparent Acceleration Due to a Relativistic Cosmological Model More Complex than FLRW?
Mustapha Ishak, James Richardson, David Garred +3
We use the Szekeres inhomogeneous relativistic models in order to fit supernova combined data sets. We show that with a choice of the spatial curvature function that is guided by c…
Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys
Christopher M. Hirata, Rachel Mandelbaum, Mustapha Ishak +5
Correlations between intrinsic shear and the density field on large scales, a potentially important contaminant for cosmic shear surveys, have been robustly detected at low redshif…
Detection of large scale intrinsic ellipticity-density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys
Rachel Mandelbaum, Christopher M. Hirata, Mustapha Ishak +2
The power spectrum of weak lensing shear caused by large-scale structure is an emerging tool for precision cosmology, in particular for measuring the effects of dark energy on the…
Probing Cosmic Acceleration Beyond the Equation of State: Distinguishing between Dark Energy and Modified Gravity Models
Mustapha Ishak, Amol Upadhye, David N. Spergel
If general relativity is the correct theory of physics on large scales, then there is a differential equation that relates the Hubble expansion function, inferred from measurements…
Remarks on the formulation of the cosmological constant/dark energy problems
Mustapha Ishak
Associated with the cosmic acceleration are the old and new cosmological constant problems, recently put into the more general context of the dark energy problem. In broad terms, t…
Probing decisive answers to dark energy questions from cosmic complementarity and lensing tomography
Mustapha Ishak
We study future constraints on dark energy parameters determined from several combinations of CMB experiments, supernova data, and weak lensing surveys with and without tomography.…
Dynamical dark energy: Current constraints and forecasts
Amol Upadhye, Mustapha Ishak, Paul J. Steinhardt
We consider how well the dark energy equation of state as a function of red shift will be measured using current and anticipated experiments. We use a procedure which takes…
Spectroscopic source redshifts and parameter constraints from weak lensing and CMB
Mustapha Ishak, Christopher M. Hirata
Weak lensing is a potentially robust and model-independent cosmological probe, but its accuracy is dependent on knowledge of the redshift distribution of the source galaxies used.…
Weak Lensing and CMB: Parameter forecasts including a running spectral index
Mustapha Ishak, Christopher M. Hirata, Patrick McDonald +1
We use statistical inference theory to explore the constraints from future galaxy weak lensing (cosmic shear) surveys combined with the current CMB constraints on cosmological para…