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Observing the temperature of the Big Bang through large scale structure

ArXiv 0708.0429 (2007)

Authors:

Pedro Ferreira, Joao Magueijo

Abstract:

It is widely accepted that the Universe underwent a period of thermal equilibrium at very early times. One expects a residue of this primordial state to be imprinted on the large scale structure of space time. In this paper we study the morphology of this thermal residue in a universe whose early dynamics is governed by a scalar field. We calculate the amplitude of fluctuations on large scales and compare it to the imprint of vacuum fluctuations. We then use the observed power spectrum of fluctuations on the cosmic microwave background to place a constraint on the temperature of the Universe before and during inflation. We also present an alternative scenario where the fluctuations are predominantly thermal and near scale-invariant.
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Generalized Einstein-Aether theories and the Solar System

(2007)

Authors:

Camille Bonvin, Ruth Durrer, Pedro G Ferreira, Glenn Starkman, Tom G Zlosnik
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Generalized Einstein-Aether theories and the Solar System

ArXiv 0707.3519 (2007)

Authors:

Camille Bonvin, Ruth Durrer, Pedro G Ferreira, Glenn Starkman, Tom G Zlosnik

Abstract:

It has been shown that generalized Einstein-Aether theories may lead to significant modifications to the non-relativistic limit of the Einstein equations. In this paper we study the effect of a general class of such theories on the Solar System. We consider corrections to the gravitational potential in negative and positive powers of distance from the source. Using measurements of the perihelion shift of Mercury and time delay of radar signals to Cassini, we place constraints on these corrections. We find that a subclass of generalized Einstein-Aether theories are compatible with these constraints.
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Searching for non Gaussian signals in the BOOMERanG 2003 CMB maps

ArXiv 0705.1615 (2007)

Authors:

G De Troia, PAR Ade, JJ Bock, JR Bond, J Borrill, A Boscaleri, P Cabella, CR Contaldi, BP Crill, P de Bernardis, G De Gasperis, A de Oliveira-Costa, G Di Stefano, PG Ferreira, E Hivon, AH Jaffe, TS Kisner, M Kunz, WC Jones, AE Lange, M Liguori, S Masi, S Matarrese, PD Mauskopf, CJ MacTavish, A Melchiorri, TE Montroy, P Natoli, CB Netterfield, E Pascale, F Piacentini, D Pogosyan, G Polenta, S Prunet, S Ricciardi, G Romeo, JE Ruhl, P Santini, M Tegmark, M Veneziani, N Vittorio

Abstract:

We analyze the BOOMERanG 2003 (B03) 145 GHz temperature map to constrain the amplitude of a non Gaussian, primordial contribution to CMB fluctuations. We perform a pixel space analysis restricted to a portion of the map chosen in view of high sensitivity, very low foreground contamination and tight control of systematic effects. We set up an estimator based on the three Minkowski functionals which relies on high quality simulated data, including non Gaussian CMB maps. We find good agreement with the Gaussian hypothesis and derive the first limits based on BOOMERanG data for the non linear coupling parameter f_NL as -300
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Implications of the cosmic background imager polarization data

Astrophysical Journal 660:2 I (2007) 976-987

Authors:

JL Sievers, C Achermann, JR Bond, L Bronfman, R Bustos, CR Contaldi, C Dickinson, PG Ferreira, ME Jones, AM Lewis, BS Mason, J May, ST Myers, N Oyarce, S Padin, TJ Pearson, M Pospieszalski, ACS Readhead, R Reeves, AC Taylor, SN Torres

Abstract:

We present new measurements of the power spectra of the E mode of cosmic microwave background (CMB) polarization, the temperature T, the cross-correlation of E and T, and upper limits on the B mode from 2.5 yr of dedicated Cosmic Background Imager (CBI) observations. Both raw maps and optimal signal images in the (u, v)-plane and the sky plane show strong detections of the E mode (11.7 σ for the EE power spectrum overall) and no detection of the B mode. The power spectra are used to constrain parameters of the flat tilted adiabatic ACDM models: those determined from EE and TE bandpowers agree with those from TT, which is a powerful consistency check. There is little tolerance for shifting polarization peaks from the TT-forecast locations, as measured by the angular sound crossing scale 0 = 100/ls= 1.03 ± 0.02 from EE and TE; compare with 1.044 ± 0.005 with the TT data included. The scope for extra out-of-phase peaks from subdominant isocurvature modes is also curtailed. The EE and TE measurements of CBI, DASI, and BOOMERANG are mutually consistent and, taken together rather than singly, give enced leverage for these tests. © 2007. The American Astronomical Society. All rights reserved.
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