Results 51 to 60 of about 973 (226)

Improved estimates of cosmological perturbations [PDF]

Physical Review D, 2004
We recently derived exact solutions for the scalar, vector and tensor mode functions of a single, minimally coupled scalar plus gravity in an arbitrary homogeneous and isotropic background. These solutions are applied to obtain improved estimates for the primordial scalar and tensor power spectra of anisotropies in the cosmic microwave background.
Tsamis, N. C., Woodard, R. P.
openaire   +2 more sources

Perturbations of cosmological redshift drift

Journal of Cosmology and Astroparticle Physics, 2023
Abstract In this paper we calculate the linear perturbations of the cosmological redshift drift. We show explicitly that our expressions are gauge-invariant and compute the power spectrum of the redshift drift perturbations and its correlations with galaxy number counts within linear perturbation theory.
Bessa, Pedro, Durrer, Ruth, Stock, Dennis   +2 more
openaire   +2 more sources

DENSITY PERTURBATIONS IN A REALISTIC UNIVERSE

Odessa Astronomical Publications, 2017
We analyze evolution of density perturbations in a flat or open universe filled in with matter, relativistic particles and possibly cosmological constant. Density perturbations grow very slowly in a universe filled in with low mass neutrinos.
M. Demianski, Z. Golda, A. Woszczyna
doaj   +1 more source

Generating cosmological perturbations in non-singular Horndeski cosmologies

Journal of High Energy Physics, 2023
We construct a concrete model of Horndeski bounce with strong gravity in the past. Within this model we show that the correct spectra of cosmological perturbations may be generated at early contracting epoch, with mild fine-tuning ensuring that the ...
Yulia Ageeva, Pavel Petrov, Valery Rubakov   +2 more
doaj   +1 more source

Proglacial lake records of Holocene glacier behaviour and catchment processes in Slettedalen, Northeast Greenland

Journal of Quaternary Science, EarlyView.
ABSTRACT Constraining Arctic catchment response to Holocene climate change is vital for understanding future environments. We present detailed sedimentological, geochemical and grain size end‐member analysis of two Holocene (~7.0 ka to present) lake sequences, S1 and S2, close to Zackenberg, Northeast Greenland.
Kathryn Adamson, Matt Carney, Stamatia Galata, Tom Bishop, Timothy Lane, Vikas Mackevicius, Rochelle Taylor   +6 more
wiley   +1 more source

Non-linear stability of α′-corrected Friedmann equations

Journal of High Energy Physics, 2023
We study the non-linear stability of fixed-point solutions to the α′-exact equations from O(d, d) invariant cosmology, with and without matter perturbations.
Heliudson Bernardo, Jan Chojnacki, Vincent Comeau   +2 more
doaj   +1 more source

The Age and Origin of Block Deposits in the Victorian Alps, Australia

Permafrost and Periglacial Processes, EarlyView.
ABSTRACT Large periglacial block deposits are found in the mountains of southeastern Australia. Despite their widespread distribution, their mode of formation and age are poorly understood. These landforms hold considerable potential to shed light on the nature of cooling during glacial periods. In this paper we present a new study of block deposits in
Timothy T. Barrows, Michelle S. Worland, Julian Murton, Stephanie C. Mills, L. Keith Fifield   +4 more
wiley   +1 more source

Discrete Newtonian cosmology: perturbations [PDF]

Classical and Quantum Gravity, 2015
In a previous paper [arXiv:1308.1852] we showed how a finite system of discrete particles interacting with each other via Newtonian gravitational attraction would lead to precisely the same dynamical equations for homothetic motion as in the case of the pressure-free Friedmann-Lemaître-Robertson-Walker cosmological models of General Relativity Theory ...
Ellis, George F. R., Gibbons, Gary W.
openaire   +2 more sources

Multiproxy Chronologies of the Hurd Rock Glacier (Livingston Island, South Shetland Islands, Maritime Antarctica): Between the Late‐Stage Stabilization and Flow Deceleration

Permafrost and Periglacial Processes, EarlyView.
ABSTRACT The Hurd Rock Glacier, located on Livingston Island (South Shetland Islands archipelago, Maritime Antarctica), is a tongue‐shaped feature composed of angular boulders, displaying transverse ridges and furrows, and featuring lobate structures, which are more prominently developed in its frontal sector.
Rosana Menéndez‐Duarte, Jesús Ruiz‐Fernández, Laura Rodríguez‐Rodríguez, José M. Fernández‐Fernández, Vincent Rinterknecht, ASTER Team   +5 more
wiley   +1 more source

Illegal Gold Mining in the Brazilian Amazon: Environmental Degradation in Yanomami Indigenous Lands, and Regulatory Failures

Sustainable Development, EarlyView.
ABSTRACT Illegal gold mining has emerged as a major sustainability threat in the Amazon, eroding Indigenous rights, forest integrity, and climate mitigation efforts. This study examines how international market incentives relate to the expansion of illegal mining and associated deforestation within the Yanomami Indigenous Territory (YIT) from 2008 to ...
Shirléia Lago Santos, Ana Claudia de Araujo Moxotó, Jurandir Moura Dutra   +2 more
wiley   +1 more source