scholarly journals Multipole decomposition of redshift drift: Model-independent mapping of the expansion history of the Universe

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Asta Heinesen
Keyword(s):  
Drift Model ◽  
Redshift Drift ◽  
History Of ◽  
Model Independent ◽  
The Universe

scholarly journals COSMIC DYNAMICS IN CHAMELEON COSMOLOGY

2010 ◽  
Vol 19 (05) ◽  
pp. 621-633 ◽  
Author(s):  
H. FARAJOLLAHI ◽  
A. SALEHI
Keyword(s):  
Equation Of State ◽  
Eos Parameter ◽  
Cosmological Redshift ◽  
Cosmological Constraints ◽  
The Past ◽  
Redshift Drift ◽  
History Of ◽  
Model Independent ◽  
The Universe ◽  
Friedmann Robertson Walker

We study in this paper chameleon cosmology applied to Friedmann–Robertson–Walker space, which gives rise to the equation of state (EoS) parameter larger than -1 in the past and less than -1 today, satisfying current observations. We also study cosmological constraints on the model using the time evolution of the cosmological redshift of distant sources, which directly probes the expansion history of the universe. Due to the evolution of the universe's expansion rate, the model-independent cosmological redshift drift (CRD) test is expected to experience a small, systematic drift as a function of time. The model is supported by the observational data obtained from the test.

scholarly journals Forecasts of redshift drift constraints on cosmological parameters

2019 ◽  
Vol 488 (3) ◽  
pp. 3607-3624 ◽  
Author(s):  
C S Alves ◽  
A C O Leite ◽  
C J A P Martins ◽  
J G B Matos ◽  
T A Silva
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Intensity Mapping ◽  
Cosmological Observations ◽  
Universe Expand ◽  
Redshift Drift ◽  
Expansion Of The Universe ◽  
Model Independent ◽  
Weak Constraints ◽  
The Universe

ABSTRACT Cosmological observations usually map our present-day past light cone. However, it is also possible to compare different past light cones. This is the concept behind the redshift drift, a model-independent probe of fundamental cosmology. In simple physical terms, this effectively allows us to watch the Universe expand in real time. While current facilities only allow sensitivities several orders of magnitude worse than the expected signal, it should be possible to detect it with forthcoming ones. Here, we discuss the potential impact of measurements by three such facilities: the Extremely Large Telescope (the subject of most existing redshift drift forecasts), but also the Square Kilometre Array and intensity mapping experiments. For each of these we assume the measurement sensitivities estimated respectively in Liske et al. (2008), Klockner et al. (2015), and Yu, Zhang & Pen (2014). We focus on the role of these measurements in constraining dark energy scenarios, highlighting the fact that although on their own they yield comparatively weak constraints, they do probe regions of parameter space that are typically different from those probed by other experiments, as well as being redshift dependent. Specifically, we quantify how combinations of several redshift drift measurements at different redshifts, or combinations of redshift drift measurements with those from other canonical cosmological probes, can constrain some representative dark energy models. Our conclusion is that a model-independent mapping of the expansion of the universe from redshift z = 0 to z = 4 – a challenging but feasible goal for the next generation of astrophysical facilities – can have a significant impact on fundamental cosmology.

scholarly journals On the theory and applications of modern cosmography

2016 ◽  
Vol 13 (03) ◽  
pp. 1630002 ◽  
Author(s):  
Peter K. S. Dunsby ◽  
Orlando Luongo
Keyword(s):  
A Priori ◽  
Energy Models ◽  
Cosmological Expansion ◽  
History Of ◽  
Independent Technique ◽  
Cosmological Data ◽  
Model Independent ◽  
The Universe ◽  
Important Branch ◽  
Quantities Of Interest

Cosmography represents an important branch of cosmology which aims to describe the universe without the need of postulating a priori any particular cosmological model. All quantities of interest are expanded as a Taylor series around here and now, providing in principle, a way of directly matching with cosmological data. In this way, cosmography can be regarded a model-independent technique, able to fix cosmic bounds, although several issues limit its use in various model reconstructions. The main purpose of this review is to focus on the key features of cosmography, emphasizing both the strategy for obtaining the observable cosmographic series and pointing out any drawbacks which might plague the standard cosmographic treatment. In doing so, we relate cosmography to the most relevant cosmological quantities and to several dark energy models. We also investigate whether cosmography is able to provide information about the form of the cosmological expansion history, discussing how to reproduce the dark fluid from the cosmographic sound speed. Following this, we discuss limits on cosmographic priors and focus on how to experimentally treat cosmographic expansions. Finally, we present some of the latest developments of the cosmographic method, reviewing the use of rational approximations, based on cosmographic Padé polynomials. Future prospects leading to more accurate cosmographic results, able to better reproduce the expansion history of the universe, are also discussed in detail.

scholarly journals THE UNIVERSE DYNAMICS IN THE TACHYON COSMOLOGY WITH NON-MINIMAL COUPLING TO MATTER

2011 ◽  
Vol 26 (15) ◽  
pp. 1125-1135 ◽  
Author(s):  
H. FARAJOLLAHI ◽  
A. RAVANPAK ◽  
G. F. FADAKAR
Keyword(s):  
Distance Modulus ◽  
Tachyon Field ◽  
Cosmological Redshift ◽  
Redshift Drift ◽  
Phantom Crossing ◽  
Acceleration Of The Universe ◽  
Model Independent ◽  
The Difference ◽  
The Universe

Recently, the tachyon cosmology has been represented as dark energy model to support the current acceleration of the universe without phantom crossing. In this paper, we study the dynamics of the tachyon cosmology in which the field plays the role of tachyon field and also non-minimally coupled to the matter Lagrangian. The model shows current universe acceleration and also phantom crossing in the future. Two cosmological tests are also performed to validate the model; the difference in the distance modulus and the model independent Cosmological Redshift Drift (CRD) test.

scholarly journals Primordial nucleosynthesis constraints on high-z energy releases

2020 ◽  
Vol 499 (4) ◽  
pp. 5653-5655
Author(s):  
Gianfranco De Zotti ◽  
Matteo Bonato
Keyword(s):  
Energy Density ◽  
Cosmic Microwave Background ◽  
Thermal History ◽  
Microwave Background ◽  
Primordial Nucleosynthesis ◽  
Specific Entropy ◽  
History Of ◽  
Model Independent ◽  
Electron Photon ◽  
The Universe

ABSTRACT The cosmic microwave background (CMB) spectrum provides tight constraints on the thermal history of the universe up to z ∼ 2 × 106. At higher redshifts, thermalization processes become very efficient so that even large energy releases do not leave visible imprints in the CMB spectrum. In this paper, we show that the consistency between the accurate determinations of the specific entropy at primordial nucleosynthesis and at the electron–photon decoupling implies that no more than 7.8 per cent of the present-day CMB energy density could have been released in the post-nucleosynthesis era. As pointed out by previous studies, primordial nucleosynthesis complements model independent constraints provided by the CMB spectrum, extending them by two orders of magnitude in redshift.

scholarly journals Defying the laws of gravity I: model-independent reconstruction of the Universe expansion from growth data

2020 ◽  
Vol 494 (1) ◽  
pp. 819-826 ◽  
Author(s):  
Benjamin L’Huillier ◽  
Arman Shafieloo ◽  
David Polarski ◽  
Alexei A Starobinsky
Keyword(s):  
Type Ia Supernovae ◽  
Growth Data ◽  
Growth History ◽  
Type Ia ◽  
History Of ◽  
Space Distortion ◽  
Model Independent ◽  
Ia Supernovae ◽  
The Universe

ABSTRACT Using redshift space distortion data, we perform model-independent reconstructions of the growth history of matter inhomogeneity in the expanding Universe using two methods: crossing statistics and Gaussian processes. We then reconstruct the corresponding history of the Universe background expansion and fit it to Type Ia supernovae data, putting constraints on (Ωm, 0, σ8, 0). The results obtained are consistent with the concordance flat-ΛCDM model and General Relativity as the gravity theory given the current quality of the inhomogeneity growth data.

scholarly journals Model-independent reconstruction of the expansion history of the Universe from Type Ia supernovae

2011 ◽  
Vol 419 (1) ◽  
pp. 513-521 ◽  
Author(s):  
S. Benitez-Herrera ◽  
F. Röpke ◽  
W. Hillebrandt ◽  
C. Mignone ◽  
M. Bartelmann ◽  
...  
Keyword(s):  
Type Ia Supernovae ◽  
Type Ia ◽  
History Of ◽  
Model Independent ◽  
Ia Supernovae ◽  
The Universe
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