118360467
Antarctic Radio Frequency Albedo and Implications for Cosmic Ray Reconstruction
We describe herein a measurement of the Antarctic surface “roughness” performed by the balloon-borne ANITA (Antarctic Impulsive Transient Antenna) experiment. Originally purposed for cosmic ray astrophysics, the radio frequency (RF) receiver ANITA gondola, from its 38 km altitude vantage point, can scan a disk of snow surface 600 km in radius. The primary purpose of ANITA is to detect RF emissions from cosmic rays incident on Antarctica, such as neutrinos which penetrate through the atmosphere and interact within the ice, resulting in signal directed upward which then refracts at the ice-air interface and up and out to ANITA, or high-energy nuclei (most likely irons or protons), which interact in the upper atmosphere (at altitudes below ANITA) and produce a spray of down-coming RF which reflects off the snow surface and back up to the gondola. The energy of such high-energy nuclei can be inferred from the observed reflected signal only if the surface reflectivity is known. We describe herein an attempt to quantify the Antarctic surface reflectivity, using the Sun as a constant, unpolarized RF source. We find that the reflectivity of the surface generally follows the expectations from the Fresnel equations, lending support to the use of those equations to give an overall correction factor to calculate cosmic ray energies for all locations in Antarctica. The analysis described below is based on ANITA-II data. After launching from McMurdo Station in December 2008, ANITA-II was aloft for a period of 31 days with a typical instantaneous duty cycle exceeding 95%.
19032720
Search for MSSM Higgses at the Tevatron
We present an overview of searches for MSSM Higgs at the Tevatron, concentrating on searches probing the high tan {beta} region. We discuss the search for A/H {yields} {tau}{tau} which is soon to be completed in the Run I data and review the new tau triggers implemented by CDF and D0 in Run II, which will greatly impact this analysis. We also present the results of a Run I search for A/Hbb {yields} bbbb performed by CDF and highlight expected improvements in this channel by both experiments in Run II.
34851507
Constraints on Cosmic Neutrino Fluxes from the ANITA Experiment
P. F. Dowkontt, 4 M. A. DuVernois,5 P. A. Evenson, 6 D. Goldstein, 1 P. W. Gorham, 9 C. L. Hebert, 9 M. H. Israel,4 J. G. Learned, 9 K. M. Liewer,10 J. T. Link,9 S. Matsuno, 9 P. Miočinović,9 J. Nam, 1 C. J. Naudet, 10 R. Nichol,2 K. Palladino, 2 M. Rosen, 9 D. Saltzberg, 7 D. Seckel, 6 A. Silvestri,1 B. T. Stokes, 9 G. S. Varner, 9 and F. Wu1 1Department of Physics and Astronomy, University of California at Irvine, Irvine, California 2Department of Physics, Ohio State University, Columbus, Ohio 3Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 4Department of Physics, Washington University in St. Louis, St. Louis, Missouri 5School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 6Bartol Research Institute, University of Delaware, Newark, Delaware 7Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 8Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, Pennsylvania 9Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 10Jet Propulsion Laboratory, Pasadena, California
122312631
Design and initial performance of the Askaryan Radio Array prototype EeV neutrino detector at the South Pole
Abstract We report on studies of the viability and sensitivity of the Askaryan Radio Array (ARA), a new initiative to develop a Teraton-scale ultra-high energy neutrino detector in deep, radio-transparent ice near Amundsen-Scott station at the South Pole. An initial prototype ARA detector system was installed in January 2011, and has been operating continuously since then. We describe measurements of the background radio noise levels, the radio clarity of the ice, and the estimated sensitivity of the planned ARA array given these results, based on the first five months of operation. Anthropogenic radio interference in the vicinity of the South Pole currently leads to a few-percent loss of data, but no overall effect on the background noise levels, which are dominated by the thermal noise floor of the cold polar ice, and galactic noise at lower frequencies. We have also successfully detected signals originating from a 2.5 km deep impulse generator at a distance of over 3 km from our prototype detector, confirming prior estimates of kilometer-scale attenuation lengths for cold polar ice. These are also the first such measurements for propagation over such large slant distances in ice. Based on these data, ARA-37, the ∼200 km 2 array now in its initial construction phase, will achieve the highest sensitivity of any planned or existing neutrino detector in the 10 16 –10 19  eV energy range.
126012638
Studies of hadron-electron separators for the ZEUS barrel calorimeter
Abstract Two possible upgrades, a shower maximum detector and a presampler, designed to improve the low energy electron/hadron separation capabilities of the ZEUS barrel calorimeter are described and test-beam results are reported. The presampler can also be used to correct for energy loss of particles traversing the dead material in front of the calorimeter.
119205836
Status of SalSA
We report on the status of the Salt Sensor Array (SalSA), a proposed experiment for detecting ultra-high energy neutrinos through the radio \v{C}erenkov technique with an array of radio-microwave antennas embedded in a large, naturally occurring salt formation. We review the measurements to date aimed at assessing SalSA's feasibility, including a return visit of the Hockley Salt Mine in Hockley, Texas, and discuss the current status of the project.
118964721
Controlling the False-Discovery Rate in Astrophysical Data Analysis
The false-discovery rate (FDR) is a new statistical procedure to control the number of mistakes made when performing multiple hypothesis tests, i.e., when comparing many data against a given model hypothesis. The key advantage of FDR is that it allows one to a priori control the average fraction of false rejections made (when comparing with the null hypothesis) over the total number of rejections performed. We compare FDR with the standard procedure of rejecting all tests that do not match the null hypothesis above some arbitrarily chosen confidence limit, e.g., 2 σ, or at the 95% confidence level. We find a similar rate of correct detections, but with significantly fewer false detections. Moreover, the FDR procedure is quick and easy to compute and can be trivially adapted to work with correlated data. The purpose of this paper is to introduce the FDR procedure to the astrophysics community. We illustrate the power of FDR through several astronomical examples, including the detection of features against a smooth one-dimensional function, e.g., seeing the "baryon wiggles" in a power spectrum of matter fluctuations, and source pixel detection in imaging data. In this era of large data sets and high-precision measurements, FDR provides the means to adaptively control a scientifically meaningful quantity—the fraction of false discoveries over total discoveries.
1064450
Evolution in the Clustering of Galaxies for z < 1.0
Measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem. We have developed a new technique that uses photometric redshifts to measure the angular correlation function in redshift shells. This novel approach minimizes the galaxy projection effect inherent in standard angular-correlation measurements, and allows for a measurement of the evolution in the galaxy correlation strength with redshift. In this paper, we present new results that utilize more accurate photometric redshifts, derived from a multiband data set (U, B, R, and I) covering almost 200 arcmin2 to BAB ~ 26.5 mag, to quantify the evolution in the clustering of galaxies for z < 1. We also extend our technique to incorporate absolute magnitudes, which provides a simultaneous measurement of the evolution of clustering with both redshift and intrinsic luminosity. Specifically, we find a gradual decline in the strength of clustering with redshift out to z ~ 1, as predicted by semianalytic models of structure formation. Furthermore, we find that r0(z = 0) ≈ 4.0 h-1 Mpc for the predictions of linear theory in an Ω0 = 0.1 universe.
49262
Detection of Cosmic Magnification with the Sloan Digital Sky Survey
We present an 8 σ detection of cosmic magnification measured by the variation of quasar density due to gravitational lensing by foreground large-scale structure. To make this measurement we used 3800 deg2 of photometric observations from the Sloan Digital Sky Survey (SDSS) containing ~200,000 quasars and 13 million galaxies. Our measurement of the galaxy-quasar cross-correlation function exhibits the amplitude, angular dependence, and change in sign as a function of the slope of the observed quasar number counts that is expected from magnification bias due to weak gravitational lensing. We show that observational uncertainties (stellar contamination, Galactic dust extinction, seeing variations, and errors in the photometric redshifts) are well controlled and do not significantly affect the lensing signal. By weighting the quasars with the number count slope, we combine the cross-correlation of quasars for our full magnitude range and detect the lensing signal at >4 σ in all five SDSS filters. Our measurements of cosmic magnification probe scales ranging from 60 h-1 kpc to 10 h-1 Mpc and are in good agreement with theoretical predictions based on the WMAP concordance cosmology. As with galaxy-galaxy lensing, future measurements of cosmic magnification will provide useful constraints on the galaxy-mass power spectrum.
51858146
Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey
Supernova rates (SNRs) are directly coupled to high-mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper, we describe a probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 Type Ia supernovae ranging in age from –14 days to +40 days extracted from a parent sample of ~350,000 spectra from the SDSS DR5. We find an SNR of 0.472+0.048 –0.039(Systematic)+0.081 –0.071(Statistical)SNu at a redshift of z = 0.1. This value is higher than other values at low redshift at the 1σ level, but is consistent at the 3σ level. In this paper, we demonstrate the potential for the described approach to detect supernovae in future spectroscopic surveys.
18397566
A Robust Classification of Galaxy Spectra: Dealing with Noisy and Incomplete Data
Over the next few years new spectroscopic surveys (from the optical surveys of the Sloan Digital Sky Survey and the 2dF Galaxy Survey through to space-based ultraviolet satellites such as GALEX) will provide the opportunity and challenge of understanding how galaxies of different spectral type evolve with redshift. Techniques have been developed to classify galaxies based on their continuum and line spectra. Some of the most promising of these have used the Karhunen & Loeve transform (or principal component analysis) to separate galaxies into distinct classes. Their limitation has been that they assume that the spectral coverage and quality of the spectra are constant for all galaxies within a given sample. In this paper we develop a general formalism that accounts for the missing data within the observed spectra (such as the removal of sky lines or the effect of sampling different intrinsic rest-wavelength ranges due to the redshift of a galaxy). We demonstrate that by correcting for these gaps we can recover an almost redshift-independent classification scheme. From this classification we can derive an optimal interpolation that reconstructs the underlying galaxy spectral energy distributions in the regions of missing data. This provides a simple and effective mechanism for building galaxy spectral energy distributions directly from data that may be noisy, incomplete, or drawn from a number of different sources.