36960262
Weak Lensing from Space. III. Cosmological Parameters
Weak gravitational lensing provides a unique method to directly map the dark matter in the universe and measure cosmological parameters. Current weak-lensing surveys are limited by the atmospheric seeing from the ground and by the small fields of view of existing space telescopes. We study how a future wide-field space telescope can measure the lensing power spectrum and skewness and thus set constraints on cosmological parameters. The lensing sensitivity was calculated using detailed image simulations and instrumental specifications studied in earlier papers in this series. For instance, the planned SuperNova/Acceleration Probe (SNAP) mission will be able to measure the matter density parameter Ωm and the dark energy equation-of-state parameter w with precisions comparable and nearly orthogonal to those derived with SNAP from supernovae. The constraints degrade by a factor of about 2 if redshift tomography is not used but are little affected if only the skewness is dropped. We also study how the constraints on these parameters depend on the survey geometry and define an optimal observing strategy.
55970305
Satellite-Mounted Light Sources as Photometric Calibration Standards
A significant and growing portion of systematic error on a number of fundamental parameters in astrophysics and cosmology is due to uncertainties from absolute photometric and flux standards. A path toward achieving major reduction in such uncertainties may be provided by satellite-mounted light sources, resulting in improvement in the ability to precisely characterize atmospheric extinction, and thus helping to usher in the coming generation of precision results in astronomy. Toward this end, we have performed a campaign of observations of the 532 nm pulsed laser aboard the CALIPSO satellite, using a portable network of cameras and photodiodes, to precisely measure atmospheric extinction.
119507702
Measurement of gamma and 2 beta + gamma
We report on the initial measurements of the angle {gamma} and the sum of angles 2{beta} +{gamma} of the Unitarity Triangle. When compared with indirect information on the value of {gamma} from other measurements of CKM parameters, the measurement of these angles will provide a precise test of Standard Model predictions, as statistics increase. There are several methods for directly measuring {gamma} and 2{beta} +{gamma}. We report on the status of each of these techniques, and the resulting constraints on the values of these angles.
17561360
Search for Invisible Or Lepton-Flavor-Violating Upsilon Decays in BaBar
Both invisible and lepton-flavor-violating Upsilon decays are unobservably rare in the Standard Model, but are each predicted to occur in several beyond-Standard-Model scenarios. We search for invisible, as well as for lepton-flavor-violating, Upsilon decays in a sample of 117 × 10 6
18354661
Weak Lensing from Space. II. Dark Matter Mapping
We study the accuracy with which weak-lensing measurements could be made from a future space-based survey, predicting the subsequent precision of three-dimensional dark matter maps, projected two-dimensional dark matter maps, and mass-selected cluster catalogs. As a baseline, we use the instrumental specifications of the SuperNova/Acceleration Probe (SNAP) satellite. We first compute its sensitivity to weak lensing shear as a function of survey depth. Our predictions are based on detailed image simulations created using "shapelets," a complete and orthogonal parameterization of galaxy morphologies. We incorporate a realistic redshift distribution of source galaxies and calculate the average precision of photometric redshift recovery using the SNAP filter set to be Δz = 0.034. The high density of background galaxies resolved in a wide space-based survey allows projected dark matter maps with an rms sensitivity of 3% shear in 1 arcmin2 cells. This will be further improved using a proposed deep space-based survey, which will be able to detect isolated clusters using a three-dimensional lensing inversion technique with a 1 σ mass sensitivity of approximately 1013 M⊙ at z = 0.25. Weak-lensing measurements from space will thus be able to capture non-Gaussian features arising from gravitational instability and map out dark matter in the universe with unprecedented resolution.
53581559
Telescope Spectrophotometric and Absolute Flux Calibration, and National Security Applications, Using a Tunable Laser on a Satellite
We propose a tunable laser-based satellite-mounted spectrophotometric and absolute flux calibration system, to be utilized by ground- and space-based telescopes. As spectrophotometric calibration may play a significant role in the accuracy of photometric redshift measurement, and photometric redshift accuracy is important for measuring dark energy using SNIa, weak gravitational lensing, and baryon oscillations, a method for reducing such uncertainties is needed. We propose to improve spectrophotometric calibration, currently obtained using standard stars, by placing a tunable laser and a wide-angle light source on a satellite by early next decade (perhaps included in the upgrade to the GPS satellite network) to improve absolute flux calibration and relative spectrophotometric calibration across the visible and near-infrared spectrum. As well as fundamental astrophysical applications, the system proposed here potentially has broad utility for defense and national security applications such as ground target illumination and space communication.
126050065
Indication of Electron Neutrino Appearance in an Accelerator-Produced Muon Neutrino Beam
Indication of Electron Neutrino Appearance in an Accelerator-Produced Muon Neutrino Beam
119385567
FADC signal reconstruction for the MAGIC telescope
Until April 2007 the Major Atmospheric Gamma ray Imaging Cherenkov (MAGIC) telescope used a 300 MSamples/s flash analog-to-digital converter (FADC) system to sample the shaped photomultiplier tube (PMT) signals produced by the captured Cherenkov photons of air showers. Different algorithms to reconstruct the signal from the read-out samples (extractors) have been implemented and are described and compared. Criteria based on the obtained charge and time resolution/bias are defined and used to judge the different extractors, by applying them to calibration, cosmic and pedestal signals. The achievable charge and time resolution have been derived as functions of the number of incident photoelectrons. (C) 2008 Elsevier B.V. All rights reserved.