453973
The Galaxy Luminosity Function and Luminosity Density at Redshift z = 0.1
Using a catalog of 147,986 galaxy redshifts and fluxes from the Sloan Digital Sky Survey (SDSS), we measure the galaxy luminosity density at z = 0.1 in five optical bandpasses corresponding to the SDSS bandpasses shifted to match their rest-frame shape at z = 0.1. We denote the bands 0.1u, 0.1g, 0.1r, 0.1i, 0.1z with λeff = (3216, 4240, 5595, 6792, 8111 A), respectively. To estimate the luminosity function, we use a maximum likelihood method that allows for a general form for the shape of the luminosity function, fits for simple luminosity and number evolution, incorporates the flux uncertainties, and accounts for the flux limits of the survey. We find luminosity densities at z = 0.1 expressed in absolute AB magnitudes in a Mpc3 to be (-14.10 ± 0.15, -15.18 ± 0.03, -15.90 ± 0.03, -16.24 ± 0.03, -16.56 ± 0.02) in (0.1u, 0.1g, 0.1r, 0.1i, 0.1z), respectively, for a cosmological model with Ω0 = 0.3, ΩΛ = 0.7, and h = 1 and using SDSS Petrosian magnitudes. Similar results are obtained using Sersic model magnitudes, suggesting that flux from outside the Petrosian apertures is not a major correction. In the 0.1r band, the best-fit Schechter function to our results has * = (1.49 ± 0.04) × 10-2 h3 Mpc-3, M* - 5 log10 h = -20.44 ± 0.01, and α = -1.05 ± 0.01. In solar luminosities, the luminosity density in 0.1r is (1.84 ± 0.04) × 108 h L0.1r,☉ Mpc-3. Our results in the 0.1g band are consistent with other estimates of the luminosity density, from the Two-Degree Field Galaxy Redshift Survey and the Millennium Galaxy Catalog. They represent a substantial change (~0.5 mag) from earlier SDSS luminosity density results based on commissioning data, almost entirely because of the inclusion of evolution in the luminosity function model.
118985428
Three-Point Correlation Functions of SDSS Galaxies in Redshift Space: Morphology, Color, and Luminosity Dependence
We present measurements of the redshift-space three-point correlation function of galaxies in the Sloan Digital Sky Survey (SDSS). For the first time, we analyze the dependence of this statistic on galaxy morphology, color, and luminosity. In order to control systematics due to selection effects, we used r-band, volume-limited samples of galaxies, constructed from magnitude-limited SDSS data (14.5 <r< 17.5), and further divided the samples into two morphological types (early and late) or two color populations (red and blue). The three-point correlation function of SDSS galaxies follows the hierarchical relation well, and the reduced three-point amplitudes in redshift-space are almost scale-independent (Qz =0 .5 ∼ 1.0). In addition, their dependence on the morphology, color, and luminosity is not statistically significant. Given the robust morphological, color, and luminosity dependences of the two-point correlation function, this implies that galaxy biasing is complex on weakly non-linear to non-linear scales. We show that a simple deterministic linear relation with the underlying mass could not explain our measurements on these scales.
16921302
Toward a resolution of the discrepancy between different estimators of star formation rate
Different wavelength regimes and methods for estimating the space density of the star formation rate (SFR) result in discrepant values. While it is recognized that ultraviolet (UV) and Hα emission-line data must be corrected for the effects of extinction, the magnitude of the required correction is uncertain. Even when these corrections are made there remains a significant discrepancy between SFRs derived from UV and Hα measurements compared with those derived from far-infrared (FIR) and radio luminosities. Since the FIR-radio–derived SFRs are not affected by extinction and simple corrections to reconcile the UV and Hα measurement with these do not fully account for the discrepancies, a more sophisticated correction may be required. Recent results suggest that at least part of the solution may be a form of extinction that increases with increasing SFR (or luminosity, given the common assumption that SFR is proportional to luminosity). We present an analysis of the effects of a dust reddening dependent on star formation rate applied to estimators of SFR. We show (1) that the discrepancies between Hα and FIR-radio SFR estimates may be explained by such an effect and we present an iterative method for applying the correction and (2) that UV-based estimates of SFR are harder to reconcile with FIR-radio estimates using this method, although the extent of the remaining discrepancy is less than for a non-SFR–dependent correction. Particularly at high redshift, our understanding of extinction at UV wavelengths may require a still more complex explanation.
119191264
Classification of Stellar Spectra with LLE
We investigate the use of dimensionality reduction techniques for the classification of stellar spectra selected from the SDSS. Using local linear embedding (LLE), a technique that preserves the local (and possibly non-linear) structure within high dimensional data sets, we show that the majority of stellar spectra can be represented as a one dimensional sequence within a three dimensional space. The position along this sequence is highly correlated with spectral temperature. Deviations from this “stellar locus” are indicative of spectra with strong emission lines (including misclassified galaxies) or broad absorption lines (e.g. Carbon stars). Based on this analysis, we propose a hierarchical classification scheme using LLE that progressively identifies and classifies stellar spectra in a manner that requires no feature extraction and that can reproduce the classic MK classifications to an accuracy of one type.
8278022
First Results from the SPICES Survey
We present first results from SPICES, the Spectroscopic, Photometric, Infrared-Chosen Extragalactic Survey. SPICES is comprised of four ~30 square arcminute high Galactic latitude fields with deep BRIzJK imaging reaching depths of ~25th magnitude (AB) in the optical and ~23rd magnitude (AB) in the near-infrared. To date we have 626 spectroscopic redshifts for infrared-selected SPICES sources with K 1. One of the SPICES fields has been the target of a deep 190 ksec Chandra exposure; we discuss initial results from analysis of that data set. Finally, we briefly discuss a successful campaign to identify high-redshift sources in the SPICES fields.
119214510
INTERPOLATING MASKED WEAK-LENSING SIGNAL WITH KARHUNEN-LOÈVE ANALYSIS
We explore the utility of Karhunen-Lo?ve (KL) analysis in solving practical problems in the analysis of gravitational shear surveys. Shear catalogs from large-field weak-lensing surveys will be subject to many systematic limitations, notably incomplete coverage and pixel-level masking due to foreground sources. We develop a method to use two-dimensional KL eigenmodes of shear to interpolate noisy shear measurements across masked regions. We explore the results of this method with simulated shear catalogs, using statistics of high-convergence regions in the resulting map. We find that the KL procedure not only minimizes the bias due to masked regions in the field, it also reduces spurious peak counts from shape noise by a factor of ~3 in the cosmologically sensitive regime. This indicates that KL reconstructions of masked shear are not only useful for creating robust convergence maps from masked shear catalogs, but also offer promise of improved parameter constraints within studies of shear peak statistics.
119198061
Implications of ultra-high energy neutrino flux constraints for Lorentz-invariance violating cosmogenic neutrinos
We consider the implications of Lorentz-invariance violation (LIV) on cosmogenic neutrino observations, with particular focus on the constraints imposed on several well-developed models for ultra-high energy cosmogenic neutrino production by recent results from the Antarctic Impulsive Transient Antenna (ANITA) long-duration balloon payload, and Radio Ice Cherenkov Experiment (RICE) at the South Pole. Under a scenario proposed originally by Coleman and Glashow, each lepton family may attain maximum velocities that can exceed the speed of light, leading to energy-loss through several interaction channels during propagation. We show that future observations of cosmogenic neutrinos will provide by far the most stringent limit on LIV in the neutrino sector. We derive the implied level of LIV required to suppress observation of predicted fluxes from several mainstream cosmogenic neutrino models, and specifically those recently constrained by the ANITA and RICE experiments. We simulate via detailed Monte Carlo code the propagation of cosmogenic neutrino fluxes in the presence of LIV-induced energy losses. We show that this process produces several detectable effects in the resulting attenuated neutrino spectra, even at LIV-induced neutrino superluminality of (u_{\nu}-c)/c ~ 10^{-26}, about 13 orders of magnitude below current bounds.
119288671
The Effective Number Density of Galaxies for Weak Lensing Measurements in the LSST Project
Future weak lensing surveys potentially hold the highest statistical power for constraining cosmological parameters compared to other cosmological probes. The statistical power of a weak lensing survey is determined by the sky coverage, the inverse of the noise in shear measurements, and the galaxy number density. The combination of the latter two factors is often expressed in terms of $n_{\rm eff}$ -- the "effective number density of galaxies used for weak lensing measurements". In this work, we estimate $n_{\rm eff}$ for the Large Synoptic Survey Telescope (LSST) project, the most powerful ground-based lensing survey planned for the next two decades. We investigate how the following factors affect the resulting $n_{\rm eff}$ of the survey with detailed simulations: (1) survey time, (2) shear measurement algorithm, (3) algorithm for combining multiple exposures, (4) inclusion of data from multiple filter bands, (5) redshift distribution of the galaxies, and (6) masking and blending. For the first time, we quantify in a general weak lensing analysis pipeline the sensitivity of $n_{\rm eff}$ to the above factors. 
We find that with current weak lensing algorithms, expected distributions of observing parameters, and all lensing data ($r$- and $i$-band, covering 18,000 degree$^{2}$ of sky) for LSST, $n_{\rm eff} \approx37$ arcmin$^{-2}$ before considering blending and masking, $n_{\rm eff} \approx31$ arcmin$^{-2}$ when rejecting seriously blended galaxies and $n_{\rm eff} \approx26$ arcmin$^{-2}$ when considering an additional 15% loss of galaxies due to masking. With future improvements in weak lensing algorithms, these values could be expected to increase by up to 20%. Throughout the paper, we also stress the ways in which $n_{\rm eff}$ depends on our ability to understand and control systematic effects in the measurements.
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.
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.
35667083
Status of ANITA and ANITA-lite
We describe a new experiment to search for neutrinos with energies above 3 × 1018 eV based on the observation of short duration radio pulses that are emitted from neutrino-initiated cascades. The primary objective of the ANtarctic Impulse Transient Antenna (ANITA) mission is to measure the flux of Greisen-Zatsepin-Kuzmin (GZK) neutrinos and search for neutrinos from Active Galactic Nuclei (AGN). We present first results obtained from the successful launch of a 2-antenna prototype instrument (called ANITA-lite) that circled Antarctica for 18 days during the 03/04 Antarctic campaign and show preliminary results from attenuation length studies of electromagnetic waves at radio frequencies in Antarctic ice. The ANITA detector is funded by NASA, and the first flight is scheduled for December 2006.