scholarly journals Analytic Model for CMB Temperature Fluctuations from Cosmic (Super-)Strings

2011 ◽  
Vol 190 ◽  
pp. 239-246
Author(s):  
Daisuke Yamauchi ◽  
Keitaro Takahashi ◽  
Yuuti Sendouda ◽  
Chul-Moon Yoo ◽  
Misao Sasaki
Keyword(s):  
Temperature Fluctuations ◽  
Analytic Model ◽  
Cmb Temperature

scholarly journals Distant foreground and the Planck-derived Hubble constant

2020 ◽  
Vol 492 (4) ◽  
pp. 5052-5056 ◽  
Author(s):  
V N Yershov ◽  
A A Raikov ◽  
N Yu Lovyagin ◽  
N P M Kuin ◽  
E A Popova
Keyword(s):  
Hubble Constant ◽  
Temperature Fluctuations ◽  
Coarse Grain ◽  
Model Parameters ◽  
Local Measurement ◽  
Microwave Background ◽  
Random Samples ◽  
Local Measurements ◽  
Grain Dust ◽  
Cmb Temperature

ABSTRACT It is possible to reduce the discrepancy between the local measurement of the cosmological parameter H0 and the value derived from the Planck measurements of the cosmic microwave background (CMB) by considering contamination of the CMB by emission from some medium around distant extragalactic sources, such as extremely cold coarse-grain dust. Though being distant, such a medium would still be in the foreground with respect to the CMB, and, as any other foreground, it would alter the CMB power spectrum. This could contribute to the dispersion of CMB temperature fluctuations. By generating a few random samples of CMB with different dispersions, we have checked that the increased dispersion leads to a smaller estimated value of H0, the rest of the cosmological model parameters remaining fixed. This might explain the reduced value of the Planck-derived parameter H0 with respect to the local measurements. The signature of the distant foreground in the CMB traced by supernovae (SNe) was previously reported by the authors of this paper – we found a correlation between the SN redshifts, zSN, and CMB temperature fluctuations at the SNe locations, TSN. Here we have used the slopes of the regression lines $T_{\rm SN}\, /\, z_{\rm SN}$ corresponding to different Planck wavebands in order to estimate the possible temperature of the distant extragalactic medium, which turns out to be very low, about 5 K. The most likely ingredient of this medium is coarse-grain (grey) dust, which is known to be almost undetectable, except for the effect of dimming remote extragalactic sources.

scholarly journals Skewness in CMB temperature fluctuations from curved cosmic (super-)strings

2010 ◽  
Vol 2010 (05) ◽  
pp. 033-033 ◽  
Author(s):  
Daisuke Yamauchi ◽  
Yuuiti Sendouda ◽  
Chul-Moon Yoo ◽  
Keitaro Takahashi ◽  
Atsushi Naruko ◽  
...  
Keyword(s):  
Temperature Fluctuations ◽  
Cmb Temperature

scholarly journals Extreme-Value Statistics for Testing Dark Energy

2014 ◽  
Vol 10 (S306) ◽  
pp. 54-56
Author(s):  
Simone Aiola ◽  
Arthur Kosowsky ◽  
Bingjie Wang
Keyword(s):  
Dark Energy ◽  
Null Hypothesis ◽  
Temperature Fluctuations ◽  
Extreme Value Statistics ◽  
Small Scale ◽  
Complementary Approach ◽  
Scale Temperature ◽  
Λcdm Model ◽  
The Universe ◽  
Cmb Temperature

AbstractThe integrated Sachs-Wolfe effect was recently detected at a level of 4.4σ by [Granett et al. (2008)], by stacking compensated CMB temperature patches corresponding to superstructures in the universe. We test the reported signal using realistic gaussian random realizations of the CMB sky, based on the temperature power spectrum predicted by the concordance ΛCDM model. Such simulations provide a complementary approach to the largely used N-body simulations and allow to include the contaminant effects due to small-scale temperature fluctuations. We also apply our pipeline to foreground-cleaned CMB sky maps using the [Granett et al. (2008)] voids/clusters catalog. We confirm the detection of a signal, which depart from the null hypothesis by 3.5σ, and we report a tension with our theoretical estimates at a significance of about 2.5σ.

scholarly journals ISW in ΛCDM or something else?

2019 ◽  
Vol 488 (2) ◽  
pp. 2732-2742
Author(s):  
A M Sołtan
Keyword(s):  
Dark Matter ◽  
Lower Limit ◽  
Cold Dark Matter ◽  
Temperature Fluctuations ◽  
Space Distribution ◽  
Bias Factor ◽  
Model Predictions ◽  
Λcdm Model ◽  
Theoretical Predictions ◽  
Cmb Temperature

ABSTRACT We investigate a correlation between the Planck’s CMB temperature map and statistics based on the space density of quasars in the SDSS catalogue. It is shown that the amplitude of the positive correlation imposes a lower limit on the amplitude of the Integrated Sachs–Wolfe effect independent of the quasar bias factor. Implications of this constraint for the ISW effect in the Λ cold dark matter (ΛCDM) model are examined. Strength of the correlation indicates that the rms of temperature fluctuations associated with the quasars distributed between 1500 and 3000 Mpc likely exceeds $11{\!-\!}12\, \mu$K. The signal seems to be related to an overall space distribution of quasars rather than to a few exceptionally dominant structures like supervoids. Although, the present estimates are subject to sizable uncertainties, the signal apparently exceeds the model predictions of the ISW effect for the standard ΛCDM cosmology. This conclusion is consistent with several other investigations that also claim some disparity between the observed ISW signal and the theoretical predictions.

scholarly journals Detectability of Torus Topology

2014 ◽  
Vol 10 (S306) ◽  
pp. 139-143
Author(s):  
Ophélia Fabre ◽  
Simon Prunet ◽  
Jean-Philippe Uzan
Keyword(s):  
Temperature Fluctuations ◽  
Connected Space ◽  
Microwave Background ◽  
Efficient Tool ◽  
Local Universe ◽  
Observable Universe ◽  
Leibler Divergence ◽  
Topology Of The Universe ◽  
The Universe ◽  
Cmb Temperature

AbstractThe global shape, or topology, of the universe is not constrained by the equations of General Relativity, which only describe the local universe. As a consequence, the boundaries of space are not fixed and topologies different from the trivial infinite Euclidean space are possible. The cosmic microwave background (CMB) is the most efficient tool to study topology and test alternative models. Multi-connected topologies, such as the 3-torus, are of great interest because they are anisotropic and allow us to test a possible violation of isotropy in CMB data. We show that the correlation function of the coefficients of the expansion of the temperature and polarization anisotropies in spherical harmonics encodes a topological signature. This signature can be used to distinguish an infinite space from a multi-connected space on sizes larger than the diameter of the last scattering surface (DLSS). With the help of the Kullback-Leibler divergence, we set the size of the edge of the biggest distinguishable torus with CMB temperature fluctuations and E-modes of polarization to 1.15 DLSS. CMB temperature fluctuations allow us to detect universes bigger than the observable universe, whereas E-modes are efficient to detect universes smaller than the observable universe.

scholarly journals Local burst model of CMB temperature fluctuations: luminescence in lines of primary para- and orthohelium

2018 ◽  
Vol 619 ◽  
pp. A29 ◽  
Author(s):  
V. Dubrovich ◽  
S. Grachev ◽  
T. Zalialiutdinov
Keyword(s):  
Quantum Yield ◽  
Background Radiation ◽  
Excited Atom ◽  
Temperature Fluctuations ◽  
Blackbody Radiation ◽  
Angular Distributions ◽  
Spherically Symmetric ◽  
Line Profiles ◽  
Radiation Sources ◽  
Cmb Temperature

We have considered the formation of the luminescent subordinate HeI lines by the absorption of continuum radiation from a source in the lines of the main HeI series in the expanding Universe. It is suggested that at some moment of time, corresponding to the redshift z0, a burst of superequilibrium blackbody radiation with a temperature T + ΔT occurs. This radiation is partially absorbed at different z <  z0 in the lines of the main HeI series and then converted into the radiation of subordinate lines. If νij is the laboratory frequency of the transition of some subordinate line originating at some z, then in the present time its frequency will be ν = νij/(1 + z). For different z (and, consequently, for different ν), the quantum yield for the subordinate lines of para- and orthohelium - the number of photons emitted in the subordinate line, per one initial excited atom and line profiles are calculated. Different pumping channels were considered. Spatial and angular distributions of radiation intensity of luminescent lines for the spherically symmetric radiation sources are presented. It is shown that for sufficiently large ΔT/T, the luminescent lines can be very noticeable in the spectrum of blackbody background radiation.

CMB temperature fluctuations

2010 ◽  
pp. 189-208
Author(s):  
Krzysztof Bolejko ◽  
Andrzej Krasinski ◽  
Charles Hellaby ◽  
Marie-Noelle Celerier
Keyword(s):  
Temperature Fluctuations ◽  
Cmb Temperature
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