scholarly journals Boosting Monte Carlo sampling with a non-Gaussian fit

2020 ◽  
Vol 498 (1) ◽  
pp. 181-193
Author(s):  
Luca Amendola ◽  
Adrià Gómez-Valent
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Sampling ◽  
Microwave Background ◽  
Background Data ◽  
Gaussian Fit ◽  
Order Of Magnitude ◽  
Cosmic Microwave Background Data ◽  
Free Parameters ◽  
The Many ◽  
Non Gaussian

ABSTRACT We propose a new method, called Monte Carlo Posterior Fit, to boost the Monte Carlo sampling of likelihood (posterior) functions. The idea is to approximate the posterior function by an analytical multidimensional non-Gaussian fit. The many free parameters of this fit can be obtained by a smaller sampling than is needed to derive the full numerical posterior. In the examples that we consider, based on supernovae and cosmic microwave background data, we find that one needs an order of magnitude smaller sampling than in the standard algorithms to achieve comparable precision. This method can be applied to a variety of situations and is expected to significantly improve the performance of the Monte Carlo routines in all the cases in which sampling is very time consuming. Finally, it can also be applied to Fisher matrix forecasts and can help solve various limitations of the standard approach.

scholarly journals ΛCDM periodic cosmology

2020 ◽  
Vol 494 (2) ◽  
pp. 2183-2190
Author(s):  
Stéphane Fay
Keyword(s):  
Dark Energy ◽  
Cold Dark Matter ◽  
Accelerated Expansion ◽  
Density Parameter ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Hubble Expansion ◽  
Background Data ◽  
Periodic Models ◽  
Cosmic Microwave Background Data

ABSTRACT We examine the possibility that Universe expansion be made of some Λ-cold dark matter (ΛCDM) expansions repeating periodically, separated by some inflation- and radiation-dominated phases. This so-called ΛCDM periodic cosmology is motivated by the possibility that inflation and the present phase of accelerated expansion be due to the same dark energy. Then, in a phase space showing the variation of matter density parameter Ωm with respect to this of the radiation Ωr, the curve Ωm(Ωr) looks like a closed trajectory that Universe could run through forever. In this case, the end of the expansion acceleration of the ΛCDM phase is the beginning of a new inflation phase. We show that such a scenario implies the coupling of matter and/or radiation to dark energy. We consider the simplest of these ΛCDM periodic models i.e. a vacuum energy coupled to radiation. From matter domination phase to today, it behaves like a ΛCDM model, then followed by an inflation phase. But a sudden and fast decay of the dark energy into radiation periodically ends the expansion acceleration. This leads to a radiation-dominated Universe preceding a new ΛCDM type expansion. The model is constrained with Markov Chain Monte Carlo simulations using supernovae, Hubble expansion, Baryon Acoustic Oscillations (BAO), and cosmic microwave background data and fits the data as well as the ΛCDM one.

scholarly journals Spherical needlets for cosmic microwave background data analysis

2007 ◽  
Vol 383 (2) ◽  
pp. 539-545 ◽  
Author(s):  
D. Marinucci ◽  
D. Pietrobon ◽  
A. Balbi ◽  
P. Baldi ◽  
P. Cabella ◽  
...  
Keyword(s):  
Data Analysis ◽  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Background Data ◽  
Cosmic Microwave Background Data
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