In this work we present a nonparametric approach, which works on minimal assumptions, to reconstruct the cosmic expansion of the Universe. We propose to combine a locally weighted scatterplot smoothing method and a simulation-extrapolation method. The first one (Loess) is a nonparametric approach that allows to obtain smoothed curves with no prior knowledge of the functional relationship between variables nor of the cosmological quantities. The second one (Simex ) takes into account the effect of measurement errors on a variable via a simulation process. For the reconstructions we use as raw data the Union2.1 Type Ia Supernovae compilation, as well as recent Hubble parameter measurements. This work aims to illustrate the approach, which turns out to be a self-sufficient technique in the sense we do not have to choose anything by hand. We examine the details of the method, among them the amount of observational data needed to perform the locally weighted fit which will define the robustness of our reconstruction. In view of our results, we believe that our proposal offers a promising alternative for reconstructing global trends of cosmological data when there is little intuition on the relationship between the variables and we also think it even presents good prospects to generate reliable mock data points where the original sample is poor.
We present a sample of 74 Gamma-Ray Bursts (GRBs) from the Fermi-GBM catalogue for which we compute the distance moduli and use them to constrain effective dark energy models. To overcome the circularity problem affecting GRBs as distance indicators, we calibrate the Amati relation of our sample with a cosmology-independent technique. Specifically, we use the latest observational Hubble parameter data, including associated systematics, to approximate the cosmic expansion through a Bezier parametric curve. We subsequently obtain the distance moduli of the GRBs and include the data in a suite of recent cosmological observations of the expansion history (Planck Compressed 2018, 2012 BOSS release of BAO data and Pantheon SNIa), to compute Bayesian posterior constraints for the standard cosmological model ΛCDM, as well as ωCDM, and the CPL parametrization. Throughout the analysis we strive to keep under control the error propagation and limit our GRBs sample to avoid observational bias. As a result, we find no evidence in favour of the alternatives to ΛCDM model. The latter agrees very well with our calibrated sample of GRBs and presently available luminosity distance probes.
Reaction of the thiaplatinacyle [(Et3P)2Pt(C12H8S-C,S)] (3; derived from reaction of [Pt(Et3P)3] and dibenzothiophene (DBT)) with HCl gives largely 2-phenylthiophenol and a small amount of DBT. The thiaplatinacycle [(Et3P)2Pt(C8H6S-C,S)] (2; from benzothiophene (BT)) undergoes reaction with HCl to give 2,3-dihydrobenzothiophene (22%), a small amount of 2-vinylthiophenol, and BT, while the thiaplatinacycle [(Et3P)2Pt(C4H4S-C,S)] (1; from thiophene) regenerates thiophene with HCl; in each case the metal is found as [(Et3P)2PtCl2]. In contrast all the thiaplatinacycles react very similarly with HBF4 to give dinuclear [Pt2(Et3P)4(μ-SR)2](BF4)2 (7c, R = 2-phenylthiophenolate (from 3); 7b, R = 2-vinylthiophenolate (from 2); 7a, R = 1-thiolatobutadiene (from 1)). An X-ray structure determination of 7c confirmed the structure. Reaction of the dications 7a − c with HCl gave C4H6S (59%), 2-vinylthiophenol (83%), and 2-phenylthiophenol (91%), respectively.
In this work we set observational constraints of the Superfluid Chaplygin gas model, which gives a unified description of the dark sector of the Universe as a Bose-Einstein condensate (BEC) that behaves as dark energy (DE) while it is in the ground state and as dark matter (DM) when it is in the excited state. We first show and perform the various steps leading to a form of the equations suitable for the observational tests to be carried out. Then, by using a Markov Chain Monte Carlo (MCMC) code, we constrain the model with a sample of cosmology-independent long gamma-ray bursts (LGRBs) calibrated using their Type I Fundamental Plane, as well as the Union2.1 set and observational Hubble parameter data. In this analysis, using our cosmological constraints, we sketch the effective equation of state parameter and deceleration parameter, and we also obtain the redshift of the transition from deceleration to acceleration: zt.PACS numbers: 98.80.Jk, 95.36.+x, 95.35.+d
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