Weak lensing can be used to measure statistically the distribution of mass in structures that are not dense enough to be detected individually in mass reconstructions. This weak-lensing signal is conventionally known as "cosmic shear," and its measurement is one of the primary methods that has been proposed for accurately measuring cosmological parameters such as the matter and energy content of the universe, the curvature of the universe, and the scale of matter density fluctuations.
From 2000-2002, several competing groups produced the first measurements of cosmic shear from surveys each covering ~10 square degrees. A summary of these results can be found in this review article.
Weak lensing can be used to measure statistically the distribution of mass in structures that are not dense enough to be detected individually in mass reconstructions. This weak-lensing signal is conventionally known as "cosmic shear," and its measurement is one of the primary methods that has been proposed for accurately measuring cosmological parameters such as the matter and energy content of the universe, the curvature of the universe, and the scale of matter density fluctuations.
From 2000-2002, several competing groups produced the first measurements of cosmic shear from surveys each covering ~10 square degrees. A summary of these results can be found in this review article.
This paper describes a type of lensing that is between the strong and weak-lensing limits: only single images are formed, but lensing introduces a measurable curvature to the galaxy shape. There is some theoretical promise for this "flexion" improving the combination of strong and weak-lensing data, but current attempts to measure the effect have shown it to be difficult.
This paper describes a type of lensing that is between the strong and weak-lensing limits: only single images are formed, but lensing introduces a measurable curvature to the galaxy shape. There is some theoretical promise for this "flexion" improving the combination of strong and weak-lensing data, but current attempts to measure the effect have shown it to be difficult.
LoCuSS is a large sample of nearby galaxy clusters with good weak lensing and X-ray measurements; Zhang, et al., use these clusters to investigate the agreement between mass estimates based on X-ray and weak lensing, and provide a good discussion of potential sources of errors in both of these methods.
This paper compares mass measurements from weak lensing and X-ray observations for a large sample of clusters, also providing a good discussion of the differences among various methods of measuring the cluster mass just with weak-lensing data.
This paper describes further mass measurements of a particular merging cluster system, the "Bullet Cluster," showing how gravitational lensing can be used to measure the mass of a structure that is not in dynamical equilibrium, and without assuming that "mass follows light." Strong lensing information is combined in a joint analysis, improving the accuracy of the mass peak positions.
This paper describes mass measurements of a particular merging cluster system, the "Bullet Cluster," showing how gravitational lensing can be used to measure the mass of a structure that is not in dynamical equilibrium, and without assuming that "mass follows light." (In this case, it does not!) It also demonstrates how noise in the weak-lensing data can affect the centers of the inferred two-dimensional mass distributions.
This paper investigates an error that pervades mass measurements with weak lensing, namely the assumption of a spherical mass model when fitting a non-spherical system. It explores whether the departure from the expected
concentrations of certain clusters is a result of this effect. (A)
This paper investigates an error that pervades mass measurements with weak lensing, namely the assumption of a spherical mass model when fitting a non-spherical system. It gives theoretical expectations of the effect from N-body simulations and analytic tri-axial mass models. (A)
This paper investigates an error that pervades mass measurements with weak lensing, namely the assumption of a spherical mass model when fitting a non-spherical system. It gives theoretical expectations of the effect from N-body simulations and analytic tri-axial mass models. (A)
There is no publicly available package to fully perform a cosmic-shear analysis of a data set. However, some very useful tools can be found at Martin Kilbinger's webpage under his software section. (A)
Software for measuring galaxy shapes in images, including the PSF correction. Comes with some documentation, but also has a steep learning curves if is to be used effectively. We strongly encourage testing the software on the GREAT/STEP simulations before using them on actual data. (A).
Software for measuring galaxy shapes in images, including the PSF correction. Comes with some documentation, but also has a steep learning curves if is to be used effectively. We strongly encourage testing the software on the GREAT/STEP simulations before using them on actual data. (A)
Software for measuring galaxy shapes in images, including the PSF correction. Comes with some documentation, but also has a steep learning curves if is to be used effectively. We strongly encourage testing the software on the GREAT/STEP simulations before using them on actual data. (A)
Software for measuring galaxy shapes in images, including the PSF correction. Comes with some documentation, but also has a steep learning curves if is to be used effectively. We strongly encourage testing the software on the GREAT/STEP simulations before using them on actual data. (A)
