Topic
Cosmology
About: Cosmology is a research topic. Over the lifetime, 18004 publications have been published within this topic receiving 631028 citations. The topic is also known as: physical cosmology & cosmologies.
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TL;DR: In this article, it was shown that the predicted number of low-energy cosmic-ray antiprotons is comparable to the observed flux of cosmic rays and gamma rays in the galactic halo and that the cosmological photino density and the masses of scalar quarks and leptons determined the present annihilation rate.
Abstract: Observational tests of the hypothesis that the universe is flat and dominated by dark matter in the form of massive photinos include the production of significant fluxes of cosmic rays and gamma rays in our galactic halo. Specification of the cosmological photino density and the masses of scalar quarks and leptons determines the present annihilation rate. The predicted number of low-energy cosmic-ray antiprotons is comparable to the observed flux.
294 citations
TL;DR: In this article, the soft limits of inflationary correlation functions are shown to be robust to detailed model-building assumptions, and a detailed case study of soft limits for quasi-single-field inflation is presented.
Abstract: Soft limits of inflationary correlation functions are both observationally relevant and theoretically robust. Various theorems can be proven about them that are insensitive to detailed model-building assumptions. In this paper, we re-derive several of these theorems in a universal way. Our method makes manifest why soft limits are such an interesting probe of the spectrum of additional light fields during inflation. We illustrate these abstract results with a detailed case study of the soft limits of quasi-single-field inflation.
294 citations
TL;DR: In this article, the effective energy-momentum tensor (EMT) for cosmological perturbations and the back-reaction problem were formulated in a gauge-invariant manner.
Abstract: We study the effective energy-momentum tensor (EMT) for cosmological perturbations and formulate the gravitational back-reaction problem in a gauge-invariant manner. We analyze the explicit expressions for the EMT in the cases of scalar metric fluctuations and of gravitational waves and derive the resulting equations of state. The formalism is applied to investigate the back-reaction effects in chaotic inflation. We find that for long wavelength scalar and tensor perturbations, the effective energy density is negative and thus counteracts any preexisting cosmological constant. For scalar perturbations during an epoch of inflation, the equation of state is de Sitter-like.
293 citations
01 Jan 2002
TL;DR: In this paper, the first bright objects and their role in the end of the Dark Ages were discussed, as well as the formation and growth of supermassive BH and the supermassive Black Holes.
Abstract: From the Contents: Clusters of Galaxies.- Brightest Galaxies.- Gamma-ray Bursts as the Lighthouses.- Gravitational Lensing and Gravitational Waves.- QSO, AGN, Blazars - Observational Data.- First Bright Objects and Their Role in the End of Dark Ages.- Formation and Growth of Supermassive BH.- Activity Connected with the Presence of Supermassive Black Holes.- Ultra-luminous X-ray Sources and Stellar Mass Black Holes.- QSO, AGN, Blazars as Probes of the Universe.- Lighthouses and the Cosmic Background Radiation.
291 citations
TL;DR: In this paper, a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg(2) of imaging data by the Kilo Degree Survey (KiDS-450) overlapping with two spectroscopic surveys: the 2dFLenS and the Baryon Oscillation Spectroscopic Survey (BOSS).
Abstract: We perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography, and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg(2) of imaging data by the Kilo Degree Survey (KiDS-450) overlapping with two spectroscopic surveys: the 2-degree Field Lensing Survey (2dFLenS) and the Baryon Oscillation Spectroscopic Survey (BOSS). We restrict the galaxy-galaxy lensing and multipole power spectrum measurements to the overlapping regions with KiDS, and self-consistently compute the full covariance between the different observables using a large suite of N-body simulations. We methodically analyse different combinations of the observables, finding that the galaxy-galaxy lensing measurements are particularly useful in improving the constraint on the intrinsic alignment amplitude, while the multipole power spectra are useful in tightening the constraints along the lensing degeneracy direction. The fully combined constraint on S-8 = sigma(8) root Omega(m)/0.3 = 0.742 +/- 0.035, which is an improvement by 20 per cent compared to KiDS alone, corresponds to a 2.6 sigma discordance with Planck, and is not significantly affected by fitting to a more conservative set of scales. Given the tightening of the parameter space, we are unable to resolve the discordance with an extended cosmology that is simultaneously favoured in a model selection sense, including the sum of neutrino masses, curvature, evolving dark energy and modified gravity. The complementarity of our observables allows for constraints on modified gravity degrees of freedom that are not simultaneously bounded with either probe alone, and up to a factor of three improvement in the S-8 constraint in the extended cosmology compared to KiDS alone.
291 citations