544 research outputs found
Cosmic correction
No full textCopi C, Huterer D, Starkman G, Schwarz D. Cosmic correction. The New Scientist. 2005;185(2482):28-28
Is the Large Angle CMB Inconsistent with Concordance Cosmology?
No full textStarkman G, Copi CJ, Huterer D, Schwarz D. Is the Large Angle CMB Inconsistent with Concordance Cosmology? In: Proceedings of International Workshop on Cosmic Structure and Evolution — PoS(Cosmology2009). Trieste, Italy: Sissa Medialab; 2010: 011
Large angle anomalies in the CMB
No full textCopi CJ, Huterer D, Schwarz D, Starkman GD. Large angle anomalies in the CMB. Adv.Astron. 2010;2010:847541.We review the recently found large-scale anomalies in the maps of temperature anisotropies in the cosmic microwave background. These include alignments of the largest modes of CMB anisotropy with each other and with geometry and direction of motion of the Solar System, and the unusually low power at these largest scales. We discuss these findings in relation to expectation from standard inflationary cosmology, their statistical significance, the tools to study them, and the various attempts to explain them
Is the low-l microwave background cosmic?
No full textSchwarz D, Starkman GD, Huterer D, Copi CJ. Is the low-l microwave background cosmic? Physical Review Letters. 2004;93(22): 221301.The large-angle (low-l) correlations of the cosmic microwave background exhibit several statistically significant anomalies compared to the standard inflationary cosmology. We show that the quadrupole plane and the three octopole planes are far more aligned than previously thought (99.9% C.L.). Three of these planes are orthogonal to the ecliptic at 99.1% C.L., and the normals to these planes are aligned at 99.6% C.L. with the direction of the cosmological dipole and with the equinoxes. The remaining octopole plane is orthogonal to the supergalactic plane at 99.6% C.L
The Oddly Quiet Universe: How the CMB challenges cosmology's standard model
No full textStarkman GD, Copi CJ, Huterer D, Schwarz D. The Oddly Quiet Universe: How the CMB challenges cosmology's standard model. Romanian Journal of Physics. 2012;57(5-6, SI):599-991.We discuss selected large-scale anomalies in the maps of temperatureanisotropies in the cosmic microwave background. Specfically, these includealignments of the largest modes of CMB anisotropy with one another and with thegeometry and direction of motion of the Solar System, and the unexpectedabsence of two-point angular corellations especially outside the region of thesky most contaminated by the Galaxy. We discuss these findings in relation toexpectations from standard inflationary cosmology. This paper is adapted from atalk given by one of us (GDS) at the SEENET-2011 meeting in August 2011 on theSerbian bank of the Danube River
Limits on dark radiation, early dark energy, and relativistic degrees of freedom
No full textRecent cosmological data analyses hint at the presence of an extra relativistic energy component in the early universe. This component is often parametrized as an excess of the effective neutrino number N(eff) over the standard value of 3.046. The excess relativistic energy could be an indication for an extra (sterile) neutrino, but early dark energy and barotropic dark energy also contribute to the relativistic degrees of freedom. We examine the capabilities of current and future data to constrain and discriminate between these explanations, and to detect the early dark energy density associated with them. We find that while early dark energy does not alter the current constraints on N(eff), a dark radiation component, such as that provided by barotropic dark energy models, can substantially change current constraints on N(eff), bringing its value back to agreement with the theoretical prediction. Both dark energy models also have implications for the primordial mass fraction of Helium Y(p) and the scalar perturbation index n(s). The ongoing Planck satellite mission will be able to further discriminate between sterile neutrinos and early dark energy
Missing Power vs low-l Alignments in the Cosmic Microwave Background: No Correlation in the Standard Cosmological Model
No full textSarkar D, Huterer D, Copi CJ, Starkman GD, Schwarz D. Missing Power vs low-l Alignments in the Cosmic Microwave Background: No Correlation in the Standard Cosmological Model. Astropart.Phys. 2011;34(8):591-594.On large angular scales (greater than about 60 degrees), the two-point angular correlation function of the temperature of the cosmic microwave background (CMB), as measured (outside of the plane of the Galaxy) by the Wilkinson Microwave Anisotropy Probe, shows significantly lower large-angle correlations than expected from the standard inflationary cosmological model. Furthermore, when derived from the full CMB sky, the two lowest cosmologically interesting multipoles, the quadrupole (l=2) and the octopole (l=3), are unexpectedly aligned with each other. Using randomly generated full-sky and cut-sky maps, we investigate whether these anomalies are correlated at a statistically significant level. We conclusively demonstrate that, assuming Gaussian random and statistically isotropic CMB anisotropies, there is no statistically significant correlation between the missing power on large angular scales in the CMB and the alignment of the l=2 and l=3 multipoles. The chance to measure the sky with both such a lack of large-angle correlation and such an alignment of the low multipoles is thus quantified to be below 10^{-6}
Uncorrelated universe: Statistical anisotropy and the vanishing angular correlation function in WMAP years 1-3
No full textCopi CJ, Huterer D, Schwarz D, Starkman GD. Uncorrelated universe: Statistical anisotropy and the vanishing angular correlation function in WMAP years 1-3. PHYSICAL REVIEW D. 2007;75(2): 023507.The large-angle (low-l) correlations of the cosmic microwave background (CMB) as reported by the Wilkinson Microwave Anisotropy Probe (WMAP) after their first year of observations exhibited statistically significant anomalies compared to the predictions of the standard inflationary big-bang model. We suggested then that these implied the presence of a solar system foreground, a systematic correlated with solar system geometry, or both. We reexamine these anomalies for the data from the first three years of WMAP's operation. We show that, despite the identification by the WMAP team of a systematic correlated with the equinoxes and the ecliptic, the anomalies in the first-year internal linear combination (ILC) map persist in the three-year ILC map, in all-but-one case at similar statistical significance. The three-year ILC quadrupole and octopole therefore remain inconsistent with statistical isotropy - they are correlated with each other (99.6% C.L.), and there are statistically significant correlations with local geometry, especially that of the solar system. The angular two-point correlation function at scales > 60 deg in the regions outside the (kp0) galactic cut, where it is most reliably determined, is approximately zero in all wavebands and is even more discrepant with the best-fit Lambda CDM inflationary model than in the first-year data - 99.97% C.L. for the new ILC map. The full-sky ILC map, on the other hand, has a nonvanishing angular two-point correlation function, apparently driven by the region inside the cut, but which does not agree better with Lambda CDM. The role of the newly-identified low-l systematics is more puzzling than reassuring
CMB anomalies after Planck
No full textSchwarz D, Copi CJ, Huterer D, Starkman GD. CMB anomalies after Planck. Classical and Quantum Gravity. 2016;33(18): 184001.Several unexpected features have been observed in the microwave sky at large angular scales, both by WMAP and by Planck. Among those features is a lack of both variance and correlation on the largest angular scales, alignment of the lowest multipole moments with one another and with the motion and geometry of the solar system, a hemispherical power asymmetry or dipolar power modulation, a preference for odd parity modes and an unexpectedly large cold spot in the Southern hemisphere. The individual p-values of the significance of these features are in the per mille to per cent level, when compared to the expectations of the best-fit inflationary ACDM model. Some pairs of those features are demonstrably uncorrelated, increasing their combined statistical significance and indicating a significant detection of CMB features at angular scales larger than a few degrees on top of the standard model. Despite numerous detailed investigations, we still lack a clear understanding of these large-scale features, which seem to imply a violation of statistical isotropy and scale invariance of inflationary perturbations. In this contribution we present a critical analysis of our current understanding and discuss several ideas of how to make further progress
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