1,137 research outputs found
Impacts of different SNLS3 light-curve fitters on cosmological consequences of interacting dark energy models
We explore the cosmological consequences of interacting dark energy (IDE)
models using the SNLS3 supernova samples. In particular, we focus on the
impacts of different SNLS3 light-curve fitters (LCF) (corresponding to "SALT2",
"SiFTO", and "Combined" sample). Firstly, making use of the three SNLS3 data
sets, as well as the Planck distance priors data and the galaxy clustering
data, we constrain the parameter spaces of three IDE models. Then, we study the
cosmic evolutions of Hubble parameter , deceleration diagram ,
statefinder hierarchy and , and check whether or
not these dark energy diagnosis can distinguish the differences among the
results of different SNLS3 LCF. At last, we perform high redshift cosmic age
test using three old high redshift objects (OHRO), and explore the fate of the
Universe. We find that, the impacts of different SNLS3 LCF are rather small,
and can not be distinguished by using , , ,
, and the age data of OHRO. In addition, we infer, from the
current observations, how far we are from a cosmic doomsday in the worst case,
and find that the "Combined" sample always gives the largest 2 lower
limit of the time interval between "big rip" and today, while the results given
by the "SALT2" and the "SiFTO" sample are close to each other. These
conclusions are insensitive to a specific form of dark sector interaction. Our
method can be used to distinguish the differences among various cosmological
observations.Comment: 12 pages, 7 figures, 2 tables, accepted for publication in Astronomy
and Astrophysic
A Study of Renewable Portfolio Standards and Renewable Energy Certificate Prices in Five Northeastern States
A number of US states have passed renewable portfolio standard, a mandate that ensures a certain amount of energy to be generated by renewable sources, to offset carbon emission or create local jobs. While states\u27 renewable portfolio standards have similar features, their designs vary substantially. In this paper, I investigate the design features and renewable energy certificate prices in five northeastern states that are trading in two trading systems to see how renewable portfolio standards are working in those states. The regression on bidding and asking price differences reveals considerable differences among states in Class I renewable energy certificate prices and differences between bid and asking price. This leads us to question the effectiveness of these portfolio standards
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