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Open AccessJournal ArticleDOI

Type Ia supernova discoveries at z > 1 from the Hubble Space Telescope: Evidence for past deceleration and constraints on dark energy evolution

TLDR
For a flat universe with a cosmological constant, the transition between the two epochs is constrained to be at z = 0.46 ± 0.13 as mentioned in this paper, and w = -1.02 ± (and w < -0.76 at the 95% confidence level) for an assumed static equation of state of dark energy.
Abstract
We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration. These objects, discovered during the course of the GOODS ACS Treasury program, include 6 of the 7 highest redshift SNe Ia known, all at z > 1.25, and populate the Hubble diagram in unexplored territory. The luminosity distances to these objects and to 170 previously reported SNe Ia have been determined using empirical relations between light-curve shape and luminosity. A purely kinematic interpretation of the SN Ia sample provides evidence at the greater than 99% confidence level for a transition from deceleration to acceleration or, similarly, strong evidence for a cosmic jerk. Using a simple model of the expansion history, the transition between the two epochs is constrained to be at z = 0.46 ± 0.13. The data are consistent with the cosmic concordance model of ΩM ≈ 0.3, ΩΛ ≈ 0.7 (χ = 1.06) and are inconsistent with a simple model of evolution or dust as an alternative to dark energy. For a flat universe with a cosmological constant, we measure ΩM = 0.29 ± (equivalently, ΩΛ = 0.71). When combined with external flat-universe constraints, including the cosmic microwave background and large-scale structure, we find w = -1.02 ± (and w < -0.76 at the 95% confidence level) for an assumed static equation of state of dark energy, P = wρc2. Joint constraints on both the recent equation of state of dark energy, w0, and its time evolution, dw/dz, are a factor of ~8 more precise than the first estimates and twice as precise as those without the SNe Ia discovered with HST. Our constraints are consistent with the static nature of and value of w expected for a cosmological constant (i.e., w0 = -1.0, dw/dz = 0) and are inconsistent with very rapid evolution of dark energy. We address consequences of evolving dark energy for the fate of the universe.

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How clustering dark energy affects matter perturbations

TL;DR: In this paper, two distinct equations of state for the dark energy component, $w_{\rm d}=const$ and $w͡m d} =w_0+w_1\left(\frac{z}{1+z}\right)$ with $c͡rm eff}$ as a free parameter, were derived under the assumption that dark matter and dark energy clustering were stable.
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One-loop f(R) Gravitational Modified Models

TL;DR: The one-loop quantization of a general class of modified gravity models around a classical de Sitter background is presented in this paper, where application to the stability of the models is addressed.
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Dynamics of f(R)-cosmologies containing Einstein static models

TL;DR: In this paper, the dynamics of homogeneous isotropic FRW cosmologies with positive spatial curvature in $f(R)$-gravity were studied, paying special attention to the existence of Einstein static models.
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Measuring cosmic proper distance from fast radio bursts

TL;DR: In this paper, the authors derived the proper distance-redshift relation from dispersion measures (DMs) of repeat fast radio burst (FRB) with measured redshifts from Monte Carlo simulations.
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Scalar field dark energy perturbations and their scale dependence

TL;DR: In this paper, the amplitude of perturbation in dark energy at different length scales for a quintessence model with an exponential potential was estimated, and it was shown that on length scales much smaller than the Hubble radius, perturbations in the dark energy are negligible in comparison to that in dark matter.
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Journal ArticleDOI

Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds

TL;DR: In this article, a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed, is presented.
Journal ArticleDOI

Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

TL;DR: In this paper, the authors presented a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed.
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