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We present relativistic $N$-body simulations of a $\Lambda_{\rm s}$CDM - sign-switching cosmological constant (CC) - scenario under general relativity and compare its nonlinear matter power spectrum to $\Lambda$CDM at ${z =…

宇宙学与河外天体物理 · 物理学 2026-04-13 Özgür Akarsu , Eleonora Di Valentino , Jiří Vyskočil , Ezgi Yılmaz , A. Emrah Yükselci , Alexander Zhuk

Upcoming cosmic microwave background (CMB) lensing measurements and tomographic galaxy surveys are expected to provide us with high-precision data sets in the coming years, thus paving the way for fruitful cross-correlation analyses. In…

宇宙学与河外天体物理 · 物理学 2022-07-27 Priyesh Chakraborty , Shu-Fan Chen , Cora Dvorkin

In the standard Big Bang cosmology the canonical value for the ratio of relic neutrinos to CMB photons is 9/11. Within the framework of the Standard Model of particle physics there are small corrections, in sum about 1%, due to slight…

天体物理学 · 物理学 2009-10-30 Robert E. Lopez , Scott Dodelson , Andrew Heckler , Michael S. Turner

We investigate some properties of flat cosmological models with a $\Lambda$ term that decreases with time as $\Lambda \propto a^{-m}$ (a is the scale factor and m is a parameter $0\leq m < 3$). The models are equivalent to standard…

天体物理学 · 物理学 2009-10-30 V. Silveira , I. Waga

The standard cosmological model, LCDM, provides an excellent fit to Cosmic Microwave Background (CMB) data. However, the model has well known problems. For example, the cosmological constant, is fine-tuned to 1 part in 10^100 and the cold…

宇宙学与河外天体物理 · 物理学 2015-06-18 T. Shanks , R. W. F. Johnson , J. A. Schewtschenko , J. R. Whitbourn

We review the relevant 10+ parameters associated with inflation and matter content; the relation between LSS and primary and secondary CMB anisotropy probes; COBE constraints on energy injection; current anisotropy band-powers which…

天体物理学 · 物理学 2009-10-30 J. Richard Bond , Andrew H. Jaffe

Ever refined cosmological measurements have established the $\Lambda$CDM concordance model, with the key cosmological parameters being determined to percent-level precision today. This allows us to make explicit predictions for the spectral…

宇宙学与河外天体物理 · 物理学 2016-05-23 Jens Chluba

The current enthusiam to measure fluctuations in the CMB power spectrum at angular scales between 0.1 and 1 degree is largely motivated by the expectation that CMB determinations of cosmological parameters will be of unprecedented…

天体物理学 · 物理学 2007-05-23 C. H. Lineweaver

The Small-Correlated-Against-Large Estimator (SCALE) for small-scale lensing of the cosmic microwave background (CMB) provides a novel method for measuring the amplitude of CMB lensing power without the need for reconstruction of the…

宇宙学与河外天体物理 · 物理学 2026-01-23 Victor C. Chan , Renée Hložek , Joel Meyers , Alexander van Engelen

We exploit a suite of large \emph{N}-body simulations (up to N=$4096^3$) performed with \Abacus, of scale-free models with a range of spectral indices $n$, to better understand and quantify convergence of the matter power spectrum. Using…

宇宙学与河外天体物理 · 物理学 2022-03-30 Sara Maleubre , Daniel Eisenstein , Lehman H. Garrison , Michael Joyce

We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib$2^{\rm nd}$, a numerical Boltzmann code at second-order to compute CMB bispectra on the full sky.…

宇宙学与河外天体物理 · 物理学 2015-04-08 Zhiqi Huang , Filippo Vernizzi

Cross-correlating the lensing signals of galaxies and comic microwave background (CMB) fluctuations is expected to provide valuable cosmological information. In particular it may help tighten constraints on parameters describing the…

宇宙学与河外天体物理 · 物理学 2017-09-14 Philipp M. Merkel , Bjoern Malte Schaefer

Despite the ability of the cosmological concordance model ($\Lambda$CDM) to describe the cosmological observations exceedingly well, power law expansion of the Universe scale radius, $R(t)\propto t^n$, has been proposed as an alternative…

We study in detail how neutrino perturbations can be followed in linear theory by using only terms up to $l=2$ in the Boltzmann hierarchy. We provide a new approximation to the third moment and demonstrate that the neutrino power spectrum…

宇宙学与河外天体物理 · 物理学 2016-06-15 Maria Archidiacono , Steen Hannestad

We analyze the spectrum of cosmic microwave background (CMB) anisotropies in the timescape cosmology: a potentially viable alternative to homogeneous isotropic cosmologies without dark energy. We exploit the fact that the timescape…

宇宙学与河外天体物理 · 物理学 2015-03-18 M. Ahsan Nazer , David L. Wiltshire

We investigate the observational viability of a class of cosmological models in which the vacuum energy density decays linearly with the Hubble parameter, resulting in a production of cold dark matter particles at late times. Similarly to…

宇宙学与河外天体物理 · 物理学 2011-09-01 C. Pigozzo , M. A. Dantas , S. Carneiro , J. S. Alcaniz

The cross-correlation between the cosmic microwave background (CMB) fields and matter tracers carries important cosmological information. In this paper, we forecast by a signal-to-noise ratio analysis the information contained in the…

The majority of present efforts to constrain cosmological parameters with cosmic microwave background (CMB) anisotropy data employ approximate likelihood functions, the time consuming nature of a complete analysis being a major obstacle. We…

天体物理学 · 物理学 2007-05-23 M. Douspis , J. G. Bartlett , A. Blanchard , M. Le Dour

The lensing power spectrum from cosmic microwave background (CMB) temperature maps will be measured with unprecedented precision with upcoming experiments, including upgrades to ACT and SPT. Achieving significant improvements in…

宇宙学与河外天体物理 · 物理学 2015-06-17 A. van Engelen , S. Bhattacharya , N. Sehgal , G. P. Holder , O. Zahn , D. Nagai

We introduce an emulator approach to predict the non-linear matter power spectrum for broad classes of beyond-$\Lambda$CDM cosmologies, using only a suite of $\Lambda$CDM $N$-body simulations. By including a range of suitably modified…

宇宙学与河外天体物理 · 物理学 2019-10-02 Benjamin Giblin , Matteo Cataneo , Ben Moews , Catherine Heymans