scholarly journals Improved Constraints on the Acceleration History of the Universe and the Properties of the Dark Energy

2008 ◽  
Vol 677 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Ruth A. Daly ◽  
S. G. Djorgovski ◽  
Kenneth A. Freeman ◽  
Matthew P. Mory ◽  
C. P. O’Dea ◽  
...  

2007 ◽  
Author(s):  
Ruth A. Daly ◽  
S. G. Djorgovski ◽  
Stefan Immler ◽  
Kurt Weiler


2007 ◽  
Author(s):  
Ruth A. Daly ◽  
S. G. Djorgovski ◽  
Stefan Immler ◽  
Kurt Weiler


2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Niels C. M. Martens

AbstractAccording to the standard model of cosmology, $$\Lambda $$ Λ CDM, the mass-energy budget of the current stage of the universe is not dominated by the luminous matter that we are familiar with, but instead by some form of dark matter (and dark energy). It is thus tempting to adopt scientific realism about dark matter. However, there are barely any constraints on the myriad of possible properties of this entity—it is not even certain that it is a form of matter. In light of this underdetermination I advocate caution: we should not (yet) be dark matter realists. The “not(-yet)-realism” that I have in mind is different from Hacking’s (Philos Sci 56 (4), 555–581, 1989) anti-realism, in that it is semantic rather than epistemological. It also differs from the semantic anti-realism of logical empiricism, in that it is naturalistic, such that it may only be temporary and does not automatically apply to all other unobservables (or even just to all other astronomical unobservables, as with Hacking’s anti-realism). The argument is illustrated with the analogy of the much longer history of the concept of a gene, as the current state of the concept of dark matter resembles in some relevant ways that of the early concept of genes.



2019 ◽  
Vol 35 (04) ◽  
pp. 2050002
Author(s):  
G. K. Goswami ◽  
Anirudh Pradhan ◽  
A. Beesham

In this paper, we have presented a model of the Friedmann–Lemaitre–Robertson–Walker (FLRW) universe filled with matter and dark energy (DE) fluids by assuming an ansatz that deceleration parameter (DP) is a linear function of the Hubble constant. This results in a time-dependent DP having decelerating–accelerating transition phase of the universe. This is a quintessence model [Formula: see text]. The quintessence phase remains for the period [Formula: see text]. The model is shown to satisfy current observational constraints. Various cosmological parameters relating to the history of the universe have been investigated.





2015 ◽  
Vol 24 (14) ◽  
pp. 1530029 ◽  
Author(s):  
Xiangcun Meng ◽  
Yan Gao ◽  
Zhanwen Han

Type Ia supernovae (SNe Ia) luminosities can be corrected in order to render them useful as standard candles that are able to probe the expansion history of the universe. This technique was successfully applied to discover the present acceleration of the universe. As the number of SNe Ia observed at high redshift increases and analysis techniques are perfected, people aim to use this technique to probe the equation-of-state of the dark energy (EOSDE). Nevertheless, the nature of SNe Ia progenitors remains controversial and concerns persist about possible evolution effects that may be larger and harder to characterize than the more obvious statistical uncertainties.



2016 ◽  
Vol 43 ◽  
pp. 1660189
Author(s):  
Christian L. Reichardt ◽  
Tijmen de Haan ◽  
Lindsey E. Bleem

The South Pole Telescope (SPT) is a 10-meter telescope designed to survey the millimeter-wave sky, taking advantage of the exceptional observing conditions at the Amundsen-Scott South Pole Station. The telescope and its ground-breaking 960-element bolometric camera finished surveying 2500 square degrees at 95. 150, and 220 GHz in November 2011. We have discovered hundreds of galaxy clusters in the SPT-SZ survey through the Sunyaev-Zel’dovich (SZ) effect. The formation of galaxy clusters the largest bound objects in the universe is highly sensitive to dark energy and the history of structure formation. I will discuss the cosmological constraints from the SPT-SZ galaxy cluster sample as well as future prospects with the soon to-be-installed SPT-3G camera.



2018 ◽  
Vol 2 (2) ◽  
pp. 93-110
Author(s):  
Nabil Nabil

Science in human life is very important to illuminate every walk of life, both physical (material) and metaphysical (immaterial). The universe was born millions and even billions of years ago, so many astronomical physicists calculate the origin of the universe, so the creation of the theory of bigbang, black holes, dark energy, dark matter, newton gravity, etc. Astronomy is important in teaching to know the phenomena of the universe (general), and to know times of worship (specifically). Before entering the science, it is better to know the history of astronomy, both the history of theory, and the figures then the hierarchy between geocentric and heliocentric in several views, both from the view of a character, as well as the view of the scriptures. Indeed, when humans think about the universe, in this case about the center of the universe there will be a hierarchy with the scriptures. This is a matter between different reason and revelation. Therefore, in this paper I touch on the issue of Heliocentric and Geocentric. And do not forget the astronomical figures from the West and East.



2006 ◽  
Vol 21 (01) ◽  
pp. 75-87 ◽  
Author(s):  
YUAN QIANG ◽  
TONG-JIE ZHANG

The dark energy cosmology with the equation of state w= const. is considered in this paper. The ΩDE-ΩM plane has been used to study the present state and expansion history of the universe. Through the mathematical analysis, we give the theoretical constraint of cosmological parameters. Together with some observations such as the transition redshift from deceleration to acceleration, more precise constraint on cosmological parameters can be acquired.



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