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High precision astrometry now enables to measure the time drift of astrophysical observables in real time, hence providing new ways to probe different cosmological models. This article presents a general derivation of the redshift and…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-25 Oton H. Marcori , Cyril Pitrou , Jean-Philippe Uzan , Thiago S. Pereira

Cosmic spatial curvature is a fundamental geometric quantity of the Universe. We investigate a model independent, geometric approach to measure spatial curvature directly from observations, without any derivatives of data. This employs…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-01 Mikhail Denissenya , Eric V. Linder , Arman Shafieloo

We develop a cosmographic framework for analysing redshift drift signals of nearby sources model-independently, i.e., without making assumptions about the metric description of the Universe. We show that the…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-14 Asta Heinesen

Friedmann-Robertson-Walker universes with a presently large fraction of the energy density stored in an $X$-component with $w_X<-1/3$, are considered. We find all the critical points of the system for constant equations of state in that…

General Relativity and Quantum Cosmology · Physics 2011-05-05 M. Chevallier , D. Polarski

Distance-redshift data can impose strong constraints on dark energy models even when the equation of state is oscillatory. Despite the double integral dependence of the distance on the equation of state, precision measurement of the…

Astrophysics · Physics 2009-11-13 Eric V. Linder

Discoveries in the last few years have revolutionized our knowledge of the universe and our ideas of its ultimate fate. Measurements of the expansion of the universe show that it is not slowing down under normal gravity but accelerating due…

Astrophysics · Physics 2007-05-23 Eric V. Linder

When using distance measurements to probe spatial curvature, the geometric degeneracy between curvature and dark energy in the distance-redshift relation typically requires either making strong assumptions about the dark energy evolution or…

Cosmology and Nongalactic Astrophysics · Physics 2009-12-14 Michael J. Mortonson

The ability to map the cosmological expansion has developed enormously, spurred by the turning point one decade ago of the discovery of cosmic acceleration. The standard model of cosmology has shifted from a matter dominated, standard…

Astrophysics · Physics 2009-06-23 Eric V. Linder

Precision cosmology is crucial to understand the different energy components in the Universe and their evolution through cosmic time. Gravitational wave sources are standard sirens that can accurately map out distances in the Universe.…

General Relativity and Quantum Cosmology · Physics 2022-12-27 Arnab Dhani , Ssohrab Borhanian , Anuradha Gupta , Bangalore Sathyaprakash

In this outlook we describe what could be the next steps of the direct characterization of habitable exoplanets after first the medium and large mission projects and investigate the benefits of the spectroscopic and direct imaging…

Future space-based direct imaging missions are poised to search for biosignatures in the atmospheres of potentially habitable planets orbiting nearby AFGKM stars. Although these missions could conduct a survey of high-priority target stars…

Earth and Planetary Astrophysics · Physics 2019-03-26 Courtney D. Dressing , Christopher C. Stark , Peter Plavchan , Eric Lopez

A wide range of models describing modifications to General Relativity have been proposed, but no fundamental parameter set exists to describe them. Similarly, no fundamental theory exists for dark energy to parameterize its potential…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-27 Viviana Acquaviva , Eric Gawiser

For more that seventy years, the measurements of fluxes of galaxies at different wavelengths and derived colours have been used to estimate their corresponding cosmological distances. From the fields of galaxy and AGN evolution to precision…

Astrophysics of Galaxies · Physics 2018-06-06 Mara Salvato , Olivier Ilbert , Ben Hoyle

An accelerating flat universe with a variable cosmological term is obtained in the Robertson-Walker metric. The variable cosmological term is defined by the correction terms of the metric tensor field. Simple solutions of the scale factor…

Astrophysics · Physics 2015-06-24 Takao Fukui

Exotic dark matter together with the vacuum energy (associated with the cosmological constant) seem to dominate the Universe. Thus its direct detection is central to particle physics and cosmology. Supersymmetry provides a natural dark…

Astrophysics · Physics 2008-11-26 J. D. Vergados , D. Owen

Weak gravitational lensing of distant galaxies by foreground structures has proven to be a powerful tool to study the mass distribution in the universe. The advent of panoramic cameras on 4m class telescope has led to a first generation of…

Astrophysics · Physics 2019-10-23 Henk Hoekstra

Exoplanets mass measurements will be a critical next step to assess the habitability of Earth-like planets: a key aspect of the 2020 vision in the previous decadal survey and also central to NASA's strategic priorities. Precision astrometry…

Instrumentation and Methods for Astrophysics · Physics 2018-03-14 Eduardo Bendek , Mark Marley , Michael Shao , Olivier Guyon , Ruslan Belikov , Peter Tuthill

Although big bang cosmology effectively models even the most puzzling observational data, it offers no insight into why the cosmological expansion should occur at all. In this paper it is suggested that a finite Universe poses particular…

General Physics · Physics 2007-05-23 Alasdair Macleod