Stacking weak lensing signals of SZ clusters to constrain cluster physics

We show how to place constraints on cluster physics by stacking the weak lensing signals from multiple clusters found through the Sunyaev-Zeldovich (SZ) effect. For a survey that covers about 200 sq. deg. both in SZ and weak lensing observations, the slope and amplitude of the mass vs. SZ luminosity relation can be measured with few percent error for clusters at z~0.5. This can be used to constrain cluster physics, such as the nature of feedback. For example, we can distinguish a pre-heated model from a model with a decreased accretion rate at more than 5sigma. The power to discriminate among different non-gravitational processes in the ICM becomes even stronger if we use the central Compton parameter y_0, which could allow one to distinguish between models with pre-heating, SN feedback and AGN feedback, for example, at more than 5sigma. Measurement of these scaling relations as a function of redshift makes it possible to directly observe e.g., the evolution of the hot gas in clusters. With this approach the mass-L_SZ relation can be calibrated and its uncertainties can be quantified, leading to a more robust determination of cosmological parameters from clusters surveys. The mass-L_SZ relation calibrated in this way from a small area of the sky can be used to determine masses of SZ clusters from very large SZ-only surveys and is nicely complementary to other techniques proposed in the literature.Comment: Submitted to Ap

Limits on deviations from the inverse-square law on megaparsec scales

We present an attempt to constrain deviations from the gravitational inverse-square law on large-scale structure scales. A perturbed law modifies the Poisson equation, which implies a scale-dependent growth of overdensities in the linear regime and thus modifies the power spectrum shape. We use two large-scale structure surveys (the Sloan Digital Sky survey and the Anglo-Australian Two-degree field galaxy redshift survey) to constrain the parameters of two simple modifications of the inverse-square law. We find no evidence for deviations from normal gravity on the scales probed by these surveys (~ 10^(23) m.)Comment: 7 pages, 3 figures. Replaced with published versio

Smoothing spline primordial power spectrum reconstruction

We reconstruct the shape of the primordial power spectrum (PPS) using a smoothing spline. Our adapted smoothing spline technique provides a complementary method to existing efforts to search for smooth features in the PPS, such as a running spectral index. With this technique we find no significant indication with WMAP first-year data that the PPS deviates from Harrison-Zeldovich and no evidence for loss of power on large scales. We also examine the effect on the cosmological parameters of the additional PPS freedom. Smooth variations in the PPS are not significantly degenerate with other cosmological parameters, but the spline reconstruction greatly increases the errors on the optical depth and baryon fraction.Comment: 12 pages, 10 figures. Accepted to PR

Observing the Evolution of the Universe

How did the universe evolve? The fine angular scale (l>1000) temperature and polarization anisotropies in the CMB are a Rosetta stone for understanding the evolution of the universe. Through detailed measurements one may address everything from the physics of the birth of the universe to the history of star formation and the process by which galaxies formed. One may in addition track the evolution of the dark energy and discover the net neutrino mass. We are at the dawn of a new era in which hundreds of square degrees of sky can be mapped with arcminute resolution and sensitivities measured in microKelvin. Acquiring these data requires the use of special purpose telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and the South Pole Telescope (SPT). These new telescopes are outfitted with a new generation of custom mm-wave kilo-pixel arrays. Additional instruments are in the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey. Full list of 177 author available at http://cmbpol.uchicago.ed

A Cis-Regulatory Map of the Drosophila Genome

Systematic annotation of gene regulatory elements is a major challenge in genome science. Direct mapping of chromatin modification marks and transcriptional factor binding sites genome-wide1, 2 has successfully identified specific subtypes of regulatory elements3. In Drosophila several pioneering studies have provided genome-wide identification of Polycomb response elements4, chromatin states5, transcription factor binding sites6, 7, 8, 9, RNA polymerase II regulation8 and insulator elements10; however, comprehensive annotation of the regulatory genome remains a significant challenge. Here we describe results from the modENCODE cis-regulatory annotation project. We produced a map of the Drosophila melanogaster regulatory genome on the basis of more than 300 chromatin immunoprecipitation data sets for eight chromatin features, five histone deacetylases and thirty-eight site-specific transcription factors at different stages of development. Using these data we inferred more than 20,000 candidate regulatory elements and validated a subset of predictions for promoters, enhancers and insulators in vivo. We identified also nearly 2,000 genomic regions of dense transcription factor binding associated with chromatin activity and accessibility. We discovered hundreds of new transcription factor co-binding relationships and defined a transcription factor network with over 800 potential regulatory relationships

Testing assumptions underlying the standard analysis of cosmology

In the era of precision cosmology, cosmologists use extensive data sets to test theories about the structure and evolution of the universe. The standard cosmological model is consistent with all current data, including many independent measurements based on different physics, but mysteries such as dark energy and dark matter remain. I propose new methods for applying current and future data to probe the following important assumptions underlying standard analyses: the law of gravity at megaparsec scales, the shape of the primordial power spectrum (PPS), and the relationship between the Sunyaev-Zel\u27dovich (SZ) effect and the mass of galaxy clusters. In the current understanding of the universe, general relativity is extrapolated to length scales twelve orders of magnitude beyond the scales of previous experimental tests. To test this extrapolation, we place the first constraints on de viations from the inverse-square law on megaparsec scales. We examine the growth of large-scale structure (LSS) under a perturbed law of gravity, and compare the resulting deviation in the power spectrum to data from two LSS surveys. No evidence is found for any deviations from normal gravity. The standard cosmological model also assumes a nearly scale-invariant spectrum of initial density fluctuations, often parameterized by a power-law PPS. We apply a smoothing spline, a non-parametric statistical method, to reconstruct the shape of the PPS from cosmic microwave background (CMB) data. Our analysis finds no significant indication that the PPS deviates from a power law. Furthermore, smooth variations in the PPS are not significantly degenerate with other cosmological parameters. Future galaxy redshift surveys will observe thousands of galaxy clusters through the SZ effect. This data could constrain cosmology, including dark energy properties, if we assume a relation between cluster mass and SZ flux. We show how to directly probe this relation by combining measurements of the weak gravitational lensing of distant galaxies by multiple clusters. Such an analysis could be used to understand cluster physics, such as radiational cooling, heating from supernova, and feedback from active galactic nuclei

Testing assumptions underlying the standard analysis of cosmology

In the era of precision cosmology, cosmologists use extensive data sets to test theories about the structure and evolution of the universe. The standard cosmological model is consistent with all current data, including many independent measurements based on different physics, but mysteries such as dark energy and dark matter remain. I propose new methods for applying current and future data to probe the following important assumptions underlying standard analyses: the law of gravity at megaparsec scales, the shape of the primordial power spectrum (PPS), and the relationship between the Sunyaev-Zel\u27dovich (SZ) effect and the mass of galaxy clusters. In the current understanding of the universe, general relativity is extrapolated to length scales twelve orders of magnitude beyond the scales of previous experimental tests. To test this extrapolation, we place the first constraints on de viations from the inverse-square law on megaparsec scales. We examine the growth of large-scale structure (LSS) under a perturbed law of gravity, and compare the resulting deviation in the power spectrum to data from two LSS surveys. No evidence is found for any deviations from normal gravity. The standard cosmological model also assumes a nearly scale-invariant spectrum of initial density fluctuations, often parameterized by a power-law PPS. We apply a smoothing spline, a non-parametric statistical method, to reconstruct the shape of the PPS from cosmic microwave background (CMB) data. Our analysis finds no significant indication that the PPS deviates from a power law. Furthermore, smooth variations in the PPS are not significantly degenerate with other cosmological parameters. Future galaxy redshift surveys will observe thousands of galaxy clusters through the SZ effect. This data could constrain cosmology, including dark energy properties, if we assume a relation between cluster mass and SZ flux. We show how to directly probe this relation by combining measurements of the weak gravitational lensing of distant galaxies by multiple clusters. Such an analysis could be used to understand cluster physics, such as radiational cooling, heating from supernova, and feedback from active galactic nuclei