Search Results

First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters [ Abstract, 3958 Cites, , Pre-print PDF ]

3958Spergel, D. N.; Verde, L.; Peiris, H. V. et al (2003-02-11) In The Astrophysical Journal 148 175 (2003)

WMAP precision data enables accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat Lambda-dominated universe seeded by nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. With parameters fixed only by WMAP data, we can fit finer scale CMB measurements and measurements of large scle structure (galaxy surveys and the Lyman alpha forest). This simple model is also consistent with a host of other astronomical measurements. We then fit the model parameters to a combination of WMAP data with other finer scale CMB experiments (ACBAR and CBI), 2dFGRS measurements and Lyman alpha forest data to find the model's best fit cosmological parameters: h=0.71+0.04-0.03, Omega_b h²=0.0224+-0.0009, Omega_m h²=0.135+0.008-0.009, tau=0.17+-0.06, n_s(0.05/Mpc)=0.93+-0.03, and sigma₈=0.84+-0.04. WMAP's best determination of tau=0.17+-0.04 arises directly from the TE data and not from this model fit, but they are consistent. These parameters imply that the age of the universe is 13.7+-0.2 Gyr. The data favors but does not require a slowly varying spectral index. By combining WMAP data with other astronomical data sets, we constrain the geometry of the universe, Omega_tot = 1.02 +- 0.02, the equation of state of the dark energy w < -0.78 (95% confidence limit assuming ... Comment: Replaced with version accepted by ApJ. One of thirteen companion papers on first-year WMAP results; 51 pages, 17 figures; a version with higher quality figures is available at http://lambda.gsfc.nasa.gov/

B0-B0bar mixing [ Abstract, 3752 Cites, , Pre-print PDF ]

3752Schneider, Olivier (2004-05-08) oai:arXiv.org:hep-ex/0405012

The subject of particle-antiparticle mixing in the neutral B meson systems is reviewed. The formalism of B0-B0bar mixing is recalled and basic Standard Model predictions are given, before experimental issues are discussed and the latest combinations of experimental results on mixing parameters are Comment: 12 pages, 2 figures, to appear in 2004 edition of the ``Review of Particle Physics'', S. Eidelman et al. (Particle Data Group), Phys. Lett. B (2004)

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant [ Abstract, 3126 Cites, , Pre-print PDF ]

3126Riess, Adam G.; Filippenko, Alexei V.; Challis, Peter et al (1998-05-14) In Astronomical Journal 116 1009 (1998)

We present observations of 10 type Ia supernovae (SNe Ia) between 0.16 < z < 0.62. With previous data from our High-Z Supernova Search Team, this expanded set of 16 high-redshift supernovae and 34 nearby supernovae are used to place constraints on the ... Comment: 36 pages, 13 figures, 3 table files Accepted to the Astronomical Journal

Measurements of Omega and Lambda from 42 High-Redshift Supernovae [ Abstract, 3098 Cites, , Pre-print PDF ]

3098Perlmutter, S.; Aldering, G.; Goldhaber, G. et al (1998-12-07) In The Astrophysical Journal 517 565 (1999)

, Omega_Lambda, of the universe based on the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these SNe, at redshifts between 0.18 and 0.83, are fit jointly with a set of SNe from the Calan/Tololo Supernova Survey, at redshifts below 0.1, to ... .5). For a flat (Omega_M + Omega_Lambda = 1) cosmology we find Omega_M = 0.28+0.09,-0.08 (1 sigma statistical) +0.05,-0.04 (identified systematics). The data are strongly inconsistent with a Lambda = 0 flat cosmology, the simplest inflationary universe model. An open, Lambda = 0 cosmology also does not fit the data well: the data indicate that the cosmological constant is non-zero and positive, with a confidence of P(Lambda > 0) = 99%, including the identified systematic ... Comment: 21 pages and 10 figures. Accepted for publication in the Astrophysical Journal. Individual color figures, supplementary tables, and preprint also available at http://www-supernova.lbl.gov/

Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds [ Abstract, 2716 Cites, , Pre-print PDF ]

2716Schlegel, David J.; Finkbeiner, Douglas P.; Davis, Marc (1997-10-28) In The Astrophysical Journal 500 525 (1998)

sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 micron and 240 micron data, we have constructed a map of the dust temperature, so that the 100 micron map can be converted to a map proportional to dust column density. The ... Comment: 65 pages, AAS LaTeX, 8 figures, 6 tables. ApJ, vol 499 (in press). Final revisions and updates to Tables 1, 2 and 5. The text, 14 figures, and the dust maps available at http://astro.berkeley.edu/davis/dust/index.html

Evidence for oscillation of atmospheric neutrinos [ Abstract, 2052 Cites, , Pre-print PDF ]

2052Collaboration, The Super-Kamiokande; al, Y. Fukuda et (1998-07-03) In Physical Review Letters 81 1562 (1998)

We present an analysis of atmospheric neutrino data from a 33.0 kiloton-year (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor nu_mu <-> nu_tau oscillations with sin²(2theta)>0.82 and 5x10^-4 < delta m² < 6x10^-3 eV² at 90% confidence level ... Comment: 9 pages (two-column) with 4 figures. Small corrections to Eqn.4 and Fig.3. Final version to appear in PRL

Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology [ Abstract, 1560 Cites, , Pre-print PDF ]

1560Spergel, D. N.; Bean, R.; Doré, O. et al (2006-03-19) In APJS 170 377 (2007)

, sigma₈, optical depth, tau, and a slope for the scalar perturbation spectrum, n_s) fits not only the three year WMAP temperature and polarization data, but also small scale CMB data, light element abundances, large-scale structure observations, and the supernova luminosity/distance relationship. Using WMAP data only, the best fit values for cosmological parameters for the power-law flat LCDM model are (Omega_m h², Omega_b h², h, n_s, tau, sigma₈) = 0.1277+0.0080-0.0079, 0.02229+-0.00073, 0.732+0.031-0.032, 0.958+-0.016, 0.089+-0.030, 0.761+0.049-0.048). The three year data dramatically shrink the allowed volume in this six dimensional parameter space. Assuming that the primordial fluctuations are adiabatic with a power law spectrum, the WMAP data_alone require dark matter, and favor a spectral index that is significantly less than the Harrison-Zel'dovich-Peebles scale-invariant spectrum (n_s=1, r=0 ... large-scale power through a running spectral index or a large-scale cut-off in the power spectrum are a better fit to the WMAP and small scale CMB data than the power-law LCDM model; however, the improvement in the fit to the WMAP data is only Delta chi² = 3 for 1 extra degree of freedom. The combination of WMAP and other astronomical data yields significant constraints on the geometry of the universe, the equation of state of the dark energy, the gravitational wave energy density, and ... Comment: 91 pgs, 28 figs. Accepted version of the 3-year paper as posted to http://lambda.gsfc.nasa.gov/product/map/dr2/map_bibliography.cfm in January 2007

Statistical mechanics of complex networks [ Abstract, 1274 Cites, , Pre-print PDF ]

1274Albert, Reka; Barabasi, Albert-Laszlo (2001-06-06) In Reviews of Modern Physics 74 47 (2002)

advances in the field of complex networks, focusing on the statistical mechanics of network topology and dynamics. After reviewing the empirical data that motivated the recent interest in networks, we discuss the main models and analytical tools, covering random graphs, small-world and scale-free ... Comment: 54 pages, submitted to Reviews of Modern Physics

Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution [ Abstract, 1079 Cites, , Pre-print PDF ]

1079Riess, Adam G.; Strolger, Louis-Gregory; Tonry, John et al (2004-02-23) In The Astrophysical Journal 607 665 (2004)

for a cosmic jerk. Using a simple model of the expansion history, the transition between the two epochs is constrained to be at z=0.46 +/- 0.13. The data are consistent with the cosmic concordance model of Omega_M ~ 0.3, Omega_Lambda~0.7 (chi²_dof=1.06), and are inconsistent with a simple model of ev ... Comment: Accepted Astrophysical Journal, to Appear June 2004 72 pages, 17 Figures

Big-Bang nucleosynthesis (Particle Data Group mini-review) [ Abstract, 1022 Cites, , Pre-print PDF ]

1022Fields, Brian; Sarkar, Subir (2006-01-23) In J.PHYS.G 33 1 (2006)

A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, η, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the indep Comment: 11 pages, 1 (new) figure; from Review of Particle Physics 2006 (http://pdg.lbl.gov/)