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Dipole anisotropy
About: Dipole anisotropy is a research topic. Over the lifetime, 272 publications have been published within this topic receiving 10532 citations.
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TL;DR: In this paper, the first year of data from the differential microwave radiometers on the Cosmic Background Explorer was presented, and the angular autocorrelation of the signal in each radiometer channel and cross-correlation between channels were consistent and gave a primordial fluctuation power-law spectrum with index of 1.1 +/- 0.5, and an rms-quadrupole-normalized amplitude of 16 +/- 4 micro-K.
Abstract: Results of the first year of data from the differential microwave radiometers on the Cosmic Background Explorer are presented. Statistically significant structure that is well described as scale-invariant fluctuations with a Gaussian distribution is shown. The rms sky variation, smoothed to a total 10-deg FWHM Gaussian, is 30 +/-5 micro-K for Galactic latitude greater than 20-deg data with the dipole anisotropy removed. The rms cosmic quadrupole amplitude is 13 +/-4 micro-K. The angular autocorrelation of the signal in each radiometer channel and cross-correlation between channels are consistent and give a primordial fluctuation power-law spectrum with index of 1.1 +/-0.5, and an rms-quadrupole-normalized amplitude of 16 +/-4 micro-K. These features are in accord with the Harrison-Zel'dovich spectrum predicted by models of inflationary cosmology.
2,195 citations
University of California, Berkeley1, University of Minnesota2, Queen Mary University of London3, Lawrence Berkeley National Laboratory4, California Institute of Technology5, Sapienza University of Rome6, Instituto Superior Técnico7, University of Oxford8, Cardiff University9, University of Toronto10
TL;DR: In this article, the authors presented a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA.
Abstract: We present a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA. MAXIMA is a balloon-borne experiment with an array of 16 bolometric photometers operated at 100 mK. MAXIMA observed a 124 deg region of the sky with 10' resolution at frequencies of 150, 240 and 410 GHz. The data were calibrated using in-flight measurements of the CMB dipole anisotropy. A map of the CMB anisotropy was produced from three 150 and one 240 GHz photometer without need for foreground subtractions. Analysis of this CMB map yields a power spectrum for the CMB anisotropy over the range 36 {le} {ell} {le} 785. The spectrum shows a peak with an amplitude of 78 {+-} 6 {mu}K at {ell} {approx_equal} 220 and an amplitude varying between {approx} 40 {mu}K and {approx} 50 {mu}K for 400 {approx}< {ell} {approx}< 785.
1,134 citations
TL;DR: In this article, the authors presented a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA.
Abstract: We present a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA. MAXIMA is a balloon-borne experiment with an array of 16 bolometric photometers operated at 100 mK. MAXIMA observed a 124 square degrees region of the sky with 10 arcminute resolution at frequencies of 150, 240 and 410 GHz. The data were calibrated using in-flight measurements of the CMB dipole anisotropy. A map of the CMB anisotropy was produced from three 150 and one 240 GHz photometer without need for foreground subtractions. Analysis of this CMB map yields a power spectrum for the CMB anisotropy over the range 36 < l < 785. The spectrum shows a peak with an amplitude of 78 +/- 6 micro-Kelvin at l ~ 220 and an amplitude varying between ~40 micro-Kelvin and ~50 micro-Kelvin for 400 < l < 785.
1,011 citations
TL;DR: The contribution of pulsars to the cosmic ray positron and electron spectra from PAMELA was investigated in this paper, where it was shown that a significant contribution is expected from the sum of all mature pulsars throughout the Milky Way, as well as from the most nearby mature pulsARS (such as Geminga and B0656+14) and that the signal from nearby pulsars is expected to generate a small but significant dipole anisotropy in the Cosmic Ray electron spectrum.
Abstract: Recent results from the PAMELA satellite indicate the presence of a large flux of positrons (relative to electrons) in the cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles in many models are predicted to contribute to the cosmic ray positron spectrum in this energy range, a great deal of interest has resulted from this observation. Here, we consider pulsars (rapidly spinning, magnetized neutron stars) as an alternative source of this signal. After calculating the contribution to the cosmic ray positron and electron spectra from pulsars, we find that the spectrum observed by PAMELA could plausibly originate from such sources. In particular, a significant contribution is expected from the sum of all mature pulsars throughout the Milky Way, as well as from the most nearby mature pulsars (such as Geminga and B0656+14). The signal from nearby pulsars is expected to generate a small but significant dipole anisotropy in the cosmic ray electron spectrum, potentially providing a method by which the Fermi gamma-ray space telescope would be capable of discriminating between the pulsar and dark matter origins of the observed high energy positrons.
612 citations
TL;DR: In this article, the authors presented a determination of the cosmic microwave background dipole amplitude and direction from the COBE Differential Microwave Radiometers (DMR) first year of data.
Abstract: We present a determination of the cosmic microwave background dipole amplitude and direction from the COBE Differential Microwave Radiometers (DMR) first year of data. Data from the six DMR channels are consistent with a Doppler-shifted Planck function of dipole amplitude ΔT=3.365±0.027 mK toward direction (l II , b II )=(264°.4±0°.3, 48°.4±0°.5). The implied velocity of the Local Group with respect to the CMB rest frame is v LG =627±22 km s −1 toward (l II , b II )=(276°±3°, 30°±3°). DMR has also mapped the dipole anisotropy resulting from the Earth's orbital motion about the Solar system barycenter, yielding a measurement of the monopole CMB temperature T 0 at 31.5, 53, and 90 GHz, T 0 =2.75±0.05 K
338 citations