Publication

Euclid preparation: XI. Mean redshift determination from galaxy redshift probabilities for cosmic shear tomography

Gianluca Castignani, Yi Wang, Richard Massey, Fabio Finelli
2021
Journal Articles

Abstract

The analysis of weak gravitational lensing in wide-field imaging surveys is considered to be a major cosmological probe of dark energy. Our capacity to constrain the dark energy equation of state relies on an accurate knowledge of the galaxy mean redshift z. We investigate the possibility of measuring z with an accuracy better than 0.002 (1+z) in ten tomographic bins spanning the redshift interval 0.2

Official source

https://infoscience.epfl.ch/entities/publication/d8b031a7-7c00-419d-9b4d-5691f17622d4

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Gianluca Castignani, Yi Wang, Richard Massey, Fabio Finelli
2021
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/d8b031a7-7c00-419d-9b4d-5691f17622d4

About this result

Ontological neighbourhood

Astronomy

Astrophysics: Physical cosmology

Related concepts (32)

Dark energy

In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the universe does not expand at a constant rate; rather, the universe's expansion is accelerating. Understanding the universe's evolution requires knowledge of its starting conditions and composition. Before these observations, scientists thought that all forms of matter and energy in the universe would only cause the expansion to slow down over time.

Redshift

In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in frequency and energy, is known as a negative redshift, or blueshift. The terms derive from the colours red and blue which form the extremes of the visible light spectrum.

Weak gravitational lensing

While the presence of any mass bends the path of light passing near it, this effect rarely produces the giant arcs and multiple images associated with strong gravitational lensing. Most lines of sight in the universe are thoroughly in the weak lensing regime, in which the deflection is impossible to detect in a single background source. However, even in these cases, the presence of the foreground mass can be detected, by way of a systematic alignment of background sources around the lensing mass.

Related publications (32)

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Strong gravitational lensing's 'external shear' is not shear

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