Interpreting CMB Anisotropy Observations: Trying to Tell the Truth with Statistics

A conflict has been reported between the baryon density inferred from deuterium observations and that found from recent CMB observations by BOOMERanG and MAXIMA. Despite the flurry of papers that attempt to resolve this conflict by adding new physics to the early universe, we will show that it can instead be resolved via a more careful usage of statistics. Indeed, the Bayesian analyses that produce this conflict are by their nature poorly suited for drawing this type of conclusion. A properly defined frequentist analysis can address this question directly and appears not to find a conflict. Finally, a conservative accounting of systematic uncertainties in measuring the deuterium abundance could reduce what is nominally a 3 sigma conflict to 1 sigma.Comment: 6 pages, to appear in proceedings of the 20th Texas Symposium on Relativistic Astrophysic

From the Cosmological Microwave Background to Large-Scale Structure

The shape of the primordial fluctuation spectrum is probed by cosmic microwave background fluctuations which measure density fluctuations at z~1000 on scales of hundreds of Mpc and from galaxy redshift surveys, which measure structure at low redshift out to several hundred Mpc. The currently acceptable library of cosmological models is inadequate to account for the current data, and more exotic models must be sought. New data sets such as SDSS and 2DF are urgently needed to verify whether the shape discrepancies in P(k) will persist.Comment: 11 pages including 4 color figures, to appear in Proc. of Nobel Symposium- Particle Physics and the Universe, Physica Script

Extracting Primordial Density Fluctuations

The combination of detections of anisotropy in the Cosmic Microwave Background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the Cold + Hot Dark Matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos.Comment: 20 pages including 4 color postscript figures. Full-size figures and data compilation available at http://cfpa.berkeley.edu/cmbserve/fluctuations/figures.htm

SED fitting with MCMC: methodology and application to large galaxy surveys

We present GalMC (Acquaviva et al 2011), our publicly available Markov Chain Monte Carlo algorithm for SED fitting, show the results obtained for a stacked sample of Lyman Alpha Emitting galaxies at z ~ 3, and discuss the dependence of the inferred SED parameters on the assumptions made in modeling the stellar populations. We also introduce SpeedyMC, a version of GalMC based on interpolation of pre-computed template libraries. While the flexibility and number of SED fitting parameters is reduced with respect to GalMC, the average running time decreases by a factor of 20,000, enabling SED fitting of each galaxy in about one second on a 2.2GHz MacBook Pro laptop, and making SpeedyMC the ideal instrument to analyze data from large photometric galaxy surveys.Comment: Proceedings of the IAU Symposium 284, "The Spectral Energy Distribution of galaxies"; typos fixed; refs adde