Have acoustic oscillations been detected in the current cosmic microwave background data?

2002 ◽  
Vol 65 (8) ◽  
Author(s):  
M. Douspis ◽  
P. G. Ferreira
Keyword(s):  
Cosmic Microwave Background ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Background Data ◽  
Cosmic Microwave Background Data

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

Detecting Topology in a Nearly Flat Hyperbolic Universe

2003 ◽  
Vol 18 (30) ◽  
pp. 2099-2107 ◽  
Author(s):  
Jeffrey R. Weeks
Keyword(s):  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Observable Universe ◽  
Multiply Connected ◽  
Background Data ◽  
Cosmic Microwave Background Data

Cosmic microwave background data shows the observable universe to be nearly flat, but leaves open the question of whether it is simply or multiply connected. Several authors have investigated whether the topology of a multiconnected hyperbolic universe would be detectable when 0.9<Ω<1. However, the possibility of detecting a given topology varies depending on the location of the observer within the space. Recent studies have assumed the observer sits at a favorable location. The present paper extends that work to consider observers at all points in the space, and (for given values of Ωm and ΩΛ and a given topology) computes the probability that a randomly placed observer could detect the topology. The computations show that when Ω=0.98 a randomly placed observer has a reasonable chance (~50%) of detecting a hyperbolic topology, but when Ω=0.99 the chances are low (<10%) and decrease still further as Ω approaches one.

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