271 research outputs found
Analysis of the impact of broad absorption lines on quasar redshift measurements with synthetic observations
Accurate quasar classifications and redshift measurements are increasingly important to precision cosmology experiments. Broad absorption line (BAL) features are present in 15-20 per cent of all quasars, and these features can introduce systematic redshift errors, and in extreme cases produce misclassifications. We quantitatively investigate the impact of BAL features on quasar classifications and redshift measurements with synthetic spectra that were designed to match observations by the Dark Energy Spectroscopic Instrument (DESI) survey. Over the course of 5 yr, DESI aims to measure spectra for 40 million galaxies and quasars, including nearly three million quasars. Our synthetic quasar spectra match the signal-to-noise ratio and redshift distributions of the first year of DESI observations, and include the same synthetic quasar spectra both with and without BAL features. We demonstrate that masking the locations of the BAL features decreases the redshift errors by about 1 per cent and reduces the number of catastrophic redshift errors by about 80 per cent. We conclude that identifying and masking BAL troughs should be a standard part of the redshift determination step for DESI and other large-scale spectroscopic surveys of quasars
Survey Operations for the Dark Energy Spectroscopic Instrument
The Dark Energy Spectroscopic Instrument (DESI) survey is a spectroscopic
survey of tens of millions of galaxies at covering 14,000 square
degrees of the sky. In its first 1.1 years of survey operations, it has
observed more than 14 million galaxies and 4 million stars. We describe the
processes that govern DESI's observations of the 15,000 fields composing the
survey. This includes the planning of each night's observations in the
afternoon; automatic selection of fields to observe during the night; real-time
assessment of field completeness on the basis of observing conditions during
each exposure; reduction, redshifting, and quality assurance of each field of
targets in the morning following observation; and updates to the list of future
targets to observe on the basis of these results. We also compare the
performance of the survey with historical expectations and find good agreement.
Simulations of the weather and of DESI observations using the real
field-selection algorithm show good agreement with the actual observations.
After accounting for major unplanned shutdowns, the dark time survey is
progressing about 7% faster than forecast, which is good agreement given
approximations made in the simulations.Comment: 30 pages, 12 figures; updated following referee repor
EpidemiologĂa del trauma por quemaduras en la poblaciĂłn atendida en un hospital infantil. manizales 2004-2005
Antecedentes. Las lesiones por quemaduras se han convertidoen un problema de salud pĂșblica, especialmente enpaĂses en desarrollo.Objetivo. Identificar la epidemiologĂa del trauma por quemadurasen la poblaciĂłn que consultĂł al servicio de urgenciasdel Hospital Infantil âRafael Henao Toroâ de la ciudadde Manizales en el perĂodo comprendido entre el año 2004y 2005.Material y mĂ©todos. Se realizĂł un estudio descriptivoretrospectivo con base en la revisiĂłn de 439 historias clĂnicas,evaluando las variables de edad, gĂ©nero, seguridad social,procedencia, ĂĄrea geogrĂĄfica, causa, profundidad, gravedad,extensiĂłn en porcentaje, ĂĄrea corporal comprometida,estancia hospitalaria y compañĂa.Resultados. Se encontrĂł que la mayorĂa de las quemadurasocurrieron en pacientes de un año de edad (21,6%),predominĂł el gĂ©nero masculino (59%). La mayorĂa notenĂa seguridad social (52,2%). El 44,9 por ciento de lospacientes residĂa en la ciudad de Manizales. La principaletiologĂa fueron los alimentos en 194 pacientes (44,2%)predominando el grado I de quemadura en un 78,1 porciento, con gravedad moderada en 314 pacientes (71,5%).La media de estancia hospitalaria fue 11,99 dĂas.Conclusiones. Se determinĂł una mayor frecuencia de quemadurasen niños, menores de cinco años, causadas poralimentos, en miembro superior y de gravedad moderada
Astrometric Calibration and Performance of the Dark Energy Spectroscopic Instrument Focal Plane
The Dark Energy Spectroscopic Instrument (DESI), consisting of 5020 robotic
fiber positioners and associated systems on the Mayall telescope at Kitt Peak,
Arizona, is carrying out a survey to measure the spectra of 40 million galaxies
and quasars and produce the largest 3D map of the universe to date. The primary
science goal is to use baryon acoustic oscillations to measure the expansion
history of the universe and the time evolution of dark energy. A key function
of the online control system is to position each fiber on a particular target
in the focal plane with an accuracy of 11m rms 2-D. This paper describes
the set of software programs used to perform this function along with the
methods used to validate their performance.Comment: 27 pages, 16 figures submitted to A
Constraining primordial non-Gaussianity from the large scale structure two-point and three-point correlation functions
Surveys of cosmological large-scale structure (LSS) are sensitive to the
presence of local primordial non-Gaussianity (PNG), and may be used to
constrain models of inflation. Local PNG, characterized by fNL, the amplitude
of the quadratic correction to the potential of a Gaussian random field, is
traditionally measured from LSS two-point and three-point clustering via the
power spectrum and bi-spectrum. We propose a framework to measure fNL using the
configuration space two-point correlation function (2pcf) monopole and
three-point correlation function (3pcf) monopole of survey tracers. Our model
estimates the effect of the scale-dependent bias induced by the presence of PNG
on the 2pcf and 3pcf from the clustering of simulated dark matter halos. We
describe how this effect may be scaled to an arbitrary tracer of the
cosmological matter density. The 2pcf and 3pcf of this tracer are measured to
constrain the value of fNL. Using simulations of luminous red galaxies observed
by the Dark Energy Spectroscopic Instrument (DESI), we demonstrate the accuracy
and constraining power of our model, and forecast the ability to constrainfNL
to a precision of sigma(fNL) = 22 with one year of DESI survey data
The Lyman- forest catalog from the Dark Energy Spectroscopic Instrument Early Data Release
We present and validate the catalog of Lyman- forest fluctuations for
3D analyses using the Early Data Release (EDR) from the Dark Energy
Spectroscopic Instrument (DESI) survey. We used 96,317 quasars collected from
DESI Survey Validation (SV) data and the first two months of the main survey
(M2). We present several improvements to the method used to extract the
Lyman- absorption fluctuations performed in previous analyses from the
Sloan Digital Sky Survey (SDSS). In particular, we modify the weighting scheme
and show that it can improve the precision of the correlation function
measurement by more than 20%. This catalog can be downloaded from
https://data.desi.lbl.gov/public/edr/vac/edr/lya/fuji/v0.3 and it will be used
in the near future for the first DESI measurements of the 3D correlations in
the Lyman- forest
Validation of the Scientific Program for the Dark Energy Spectroscopic Instrument
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a
survey covering 14,000 deg over five years to constrain the cosmic
expansion history through precise measurements of Baryon Acoustic Oscillations
(BAO). The scientific program for DESI was evaluated during a five month Survey
Validation (SV) campaign before beginning full operations. This program
produced deep spectra of tens of thousands of objects from each of the stellar
(MWS), bright galaxy (BGS), luminous red galaxy (LRG), emission line galaxy
(ELG), and quasar target classes. These SV spectra were used to optimize
redshift distributions, characterize exposure times, determine calibration
procedures, and assess observational overheads for the five-year program. In
this paper, we present the final target selection algorithms, redshift
distributions, and projected cosmology constraints resulting from those
studies. We also present a `One-Percent survey' conducted at the conclusion of
Survey Validation covering 140 deg using the final target selection
algorithms with exposures of a depth typical of the main survey. The Survey
Validation indicates that DESI will be able to complete the full 14,000 deg
program with spectroscopically-confirmed targets from the MWS, BGS, LRG, ELG,
and quasar programs with total sample sizes of 7.2, 13.8, 7.46, 15.7, and 2.87
million, respectively. These samples will allow exploration of the Milky Way
halo, clustering on all scales, and BAO measurements with a statistical
precision of 0.28% over the redshift interval , 0.39% over the redshift
interval , and 0.46% over the redshift interval .Comment: 42 pages, 18 figures, accepted by A
Low exposure long-baseline neutrino oscillation sensitivity of the DUNE experiment
The Deep Underground Neutrino Experiment (DUNE) will produce world-leading
neutrino oscillation measurements over the lifetime of the experiment. In this
work, we explore DUNE's sensitivity to observe charge-parity violation (CPV) in
the neutrino sector, and to resolve the mass ordering, for exposures of up to
100 kiloton-megawatt-years (kt-MW-yr). The analysis includes detailed
uncertainties on the flux prediction, the neutrino interaction model, and
detector effects. We demonstrate that DUNE will be able to unambiguously
resolve the neutrino mass ordering at a 3 (5) level, with a 66
(100) kt-MW-yr far detector exposure, and has the ability to make strong
statements at significantly shorter exposures depending on the true value of
other oscillation parameters. We also show that DUNE has the potential to make
a robust measurement of CPV at a 3 level with a 100 kt-MW-yr exposure
for the maximally CP-violating values \delta_{\rm CP}} = \pm\pi/2.
Additionally, the dependence of DUNE's sensitivity on the exposure taken in
neutrino-enhanced and antineutrino-enhanced running is discussed. An equal
fraction of exposure taken in each beam mode is found to be close to optimal
when considered over the entire space of interest
First results on ProtoDUNE-SP liquid argon time projection chamber performance from a beam test at the CERN Neutrino Platform
The ProtoDUNE-SP detector is a single-phase liquid argon time projection chamber with an active volume of 7.2Ă 6.1Ă 7.0 m3. It is installed at the CERN Neutrino Platform in a specially-constructed beam that delivers charged pions, kaons, protons, muons and electrons with momenta in the range 0.3 GeV/c to 7 GeV/c. Beam line instrumentation provides accurate momentum measurements and particle identification. The ProtoDUNE-SP detector is a prototype for the first far detector module of the Deep Underground Neutrino Experiment, and it incorporates full-size components as designed for that module. This paper describes the beam line, the time projection chamber, the photon detectors, the cosmic-ray tagger, the signal processing and particle reconstruction. It presents the first results on ProtoDUNE-SP\u27s performance, including noise and gain measurements, dE/dx calibration for muons, protons, pions and electrons, drift electron lifetime measurements, and photon detector noise, signal sensitivity and time resolution measurements. The measured values meet or exceed the specifications for the DUNE far detector, in several cases by large margins. ProtoDUNE-SP\u27s successful operation starting in 2018 and its production of large samples of high-quality data demonstrate the effectiveness of the single-phase far detector design
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