نتایج جستجو برای: cosmic microwave background cmb
تعداد نتایج: 905952 فیلتر نتایج به سال:
These lectures introduce some of the basic theory of cosmic microwave background (CMB) polarization with the primary aim of developing the theory of CMB polarization from inflationary gravitational waves, as well as some of the related theory of weak gravitational lensing (cosmic shear) of CMB polarization. We begin with production of polarization by Thomson scattering. We then discuss tensor-h...
The Atacama Cosmology Telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 GHz, from three seasons of data. At small scales the fluctuations in the primordial Cosmic Microwave Background (CMB) become increasingly obscured by extragalactic foregounds and secondary CMB signals. We present results from a nine-parameter model d...
In this paper, we present a power spectrum formalism that combines the full 3D information from the galaxy ellipticity field, with information from the cosmic microwave background (CMB). We include in this approach galaxy cosmic shear and galaxy intrinsic alignments, CMB deflection, CMB temperature, and CMB polarization data; including the interdatum power spectra between all quantities. We app...
The atomic recombination process leads to a softening of the matter equation of state as reflected by a reduced generalized adiabatic index, with accompanying heat release. We study the effects of this recombination softening and reheating of the cosmic plasma on the ionization history, visibility function, Cold Dark Matter (CDM) transfer function, and the Cosmic Microwave Background (CMB) spec...
Wewanttofindthecosmologicalconstantinfluenceoncosmicmicrowavebackground(CMB)temperatureduetomovinglinearcosmicstrings.Usingthespace-timemetricofalinearcosmicstringinanacceleratedexpandinguniverse,theGott-Kaiser Stebbins(GKS)effect,asanimportantmechanisminproducingtemperaturediscontinuityinthe(CMB),isconsidered;then,itsmodificationduetotheeffectofthecosmologicalconstantiscalculated.Theresultshowsthat...
In addition to its spectrum and temperature anisotropy, the 2.7 K cosmic microwave background (CMB) is also expected to exhibit a low level of polarization. The spatial power spectrum of the polarization can provide details about the formation of structure in the universe as well as its ionization history. Here we calculate the magnitude of the CMB polarization in various cosmological scenarios...
Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, which is valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We exten...
The characteristic mass of stars at early times may have been higher than today owing to the cosmic microwave background (CMB). This study proposes that (1) the testable predictions of this “CMB-IMF” hypothesis are an increase in the fraction of carbon-enhanced metal-poor (CEMP) stars with declining metallicity and an increase from younger to older populations at a single metallicity (e.g. disk...
— The measurement of the Compton edge of the scattered electrons in GRAAL facility in European Synchrotron Radiation Facility (ESRF) in Grenoble with respect to the Cosmic Microwave Background dipole reveals up to 10σ variations larger than the statistical errors. We now show that the variations are not due to the frequency variations of the accelerator. The nature of Compton edge variations re...
One of the most powerful tools to probe the existence of cosmic defects in the early universe is through the Cosmic Microwave Background (CMB) radiation. It is well known that computations with causal sources are more involved than the adiabatic counterparts based on inflation, and this fact has in part hampered the development of fine detailed predictions. Analytical modeling, while necessaril...
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