The one-dimensional power spectrum \(P_{\mathrm{1D}}\) of the Ly\(\alpha\) forest provides important information about cosmological and astrophysical parameters, including constraints on warm dark ...matter models, the sum of the masses of the three neutrino species, and the thermal state of the intergalactic medium. We present the first measurement of \(P_{\mathrm{1D}}\) with the quadratic maximum likelihood estimator (QMLE) from the Dark Energy Spectroscopic Instrument (DESI) survey early data sample. This early sample of \(54~600\) quasars is already comparable in size to the largest previous studies, and we conduct a thorough investigation of numerous instrumental and analysis systematic errors to evaluate their impact on DESI data with QMLE. We demonstrate the excellent performance of the spectroscopic pipeline noise estimation and the impressive accuracy of the spectrograph resolution matrix with two-dimensional image simulations of raw DESI images that we processed with the DESI spectroscopic pipeline. We also study metal line contamination and noise calibration systematics with quasar spectra on the red side of the Ly\(\alpha\) emission line. In a companion paper, we present a similar analysis based on the Fast Fourier Transform estimate of the power spectrum. We conclude with a comparison of these two approaches and implications for the upcoming DESI Year 1 analysis.
A novel Particle Identification Detector (PID) has been developed for the
BABAR
experiment which will operate at the PEP-II B factory at SLAC. The principles of this new concept of PID called the ...DIRC, based on ring imaging Cherenkov techniques, are briefly described. The results obtained with a large scale prototype and pion, kaon and proton beams at CERN are presented. The performances of this prototype are compared to the Monte-Carlo simulations and the
BABAR
requirements.
A detailed description is given of the analysis of neutral kaons decaying to \pipi , based on the complete data sample collected with the CPLEAR experiment.Using a novel approach involving initially ...strangeness-tagged \kn\ and \knb ,the time-dependent decay rate asymmetry has been measured. This asymmetry, resulting from the interference between the \ks\and \kl\ decay amplitudes, has enabled both the magnitudeand phase of the CP-violation parameter, \ita , to be measured, with aprecision comparable to that of the current world average values.
We present the Data Release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all ...SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities \(M_{\rm i} \left z=2 \right < -20.5\) (in a \(\Lambda\)CDM cosmology with \(H_0 = 70 \ {\rm km \ s^{-1} \ Mpc ^{-1}}\), \(\Omega_{\rm M} = 0.3\), and \(\Omega_{\rm \Lambda} = 0.7\)), and either display at least one emission line with a full width at half maximum (FWHM) larger than \(500 \ {\rm km \ s^{-1}}\) or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II and III. The catalog contains 526,356 quasars 144,046 are new discoveries since the beginning of SDSS-IV) detected over 9,376 deg\(^2\) (2,044 deg\(^2\) having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. The catalog identifies 21,877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents SDSS five-band CCD-based photometry with typical accuracy of 0.03 mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys.
The Lyman-\(\alpha\) (hereafter Ly-\(\alpha\)) forest is a probe of large-scale matter density fluctuations at high redshift, \(z > 2.1\). It consists of HI absorption spectra along individual ...lines-of-sight. If the line-of-sight density is large enough, 3D maps of HI absorption can be inferred by tomographic reconstruction. In this article, we investigate the Ly-\(\alpha\) forest available in the Stripe 82 field (\(220\,\mathrm{deg^{2}}\)), based on the quasar spectra from SDSS Data Release DR16. The density of observed quasar spectra is \(37\,\mathrm{deg^{-2}}\) with a mean pixel signal-to-noise ratio of two per angstrom. This study provides an intermediate case between the average SDSS density and that of the much denser but smaller CLAMATO survey. We derive a 3D map of large-scale matter fluctuations from these data, using a Wiener filter technique. The total volume of the map is \(0.94\,\mathrm{h^{-3} Gpc^{3}}\). Its resolution is \(13\,\mathrm{h^{-1} Mpc}\), which is related to the mean transverse distance between nearest lines-of-sight. From this map, we provide a catalog of voids and protocluster candidates in the cosmic web. The map-making and void catalog are compared to simulated eBOSS Stripe 82 observations. A stack over quasar positions provides a visualization of the Ly-\(\alpha\) quasar cross-correlation. This tomographic reconstruction constitutes the largest-volume high-redshift 3D map of matter fluctuations.
We present two wide-field catalogs of photometrically-selected emission line galaxies (ELGs) at z=0.8 covering about 2800 deg^2 over the south galactic cap. The catalogs were obtained using a Fisher ...discriminant technique described in a companion paper. The two catalogs differ by the imaging used to define the Fisher discriminant: the first catalog includes imaging from the Sloan Digital Sky Survey and the Wide-Field Infrared Survey Explorer, the second also includes information from the South Galactic Cap U-band Sky Survey (SCUSS). Containing respectively 560,045 and 615,601 objects, they represent the largest ELG catalogs available today and were designed for the ELG programme of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). We study potential sources of systematic variation in the angular distribution of the selected ELGs due to fluctuations of the observational parameters. We model the influence of the observational parameters using a multivariate regression and implement a weighting scheme that allows effective removal of all of the systematic errors induced by the observational parameters. We show that fluctuations in the imaging zero-points of the photometric bands have minor impact on the angular distribution of objects in our catalogs. We compute the angular clustering of both catalogs and show that our weighting procedure effectively removes spurious clustering on large scales. We fit a model to the small scale angular clustering, showing that the selections have similar biases of 1.35/D_a(z) and 1.28/D_a(z). Both catalogs are publicly available.
We present a new selection technique of producing spectroscopic target catalogues for massive spectroscopic surveys for cosmology. This work was conducted in the context of the extended Baryon ...Oscillation Spectroscopic Survey (eBOSS), which will use ~200 000 emission line galaxies (ELGs) at 0.6<zspec<1.0 to obtain a precise baryon acoustic oscillation measurement. Our proposed selection technique is based on optical and near-infrared broad-band filter photometry. We used a training sample to define a quantity, the Fisher discriminant (linear combination of colours), which correlates best with the desired properties of the target: redshift and OII flux. The proposed selections are simply done by applying a cut on magnitudes and this Fisher discriminant. We used public data and dedicated SDSS spectroscopy to quantify the redshift distribution and OII flux of our ELG target selections. We demonstrate that two of our selections fulfil the initial eBOSS/ELG redshift requirements: for a target density of 180 deg^2, ~70% of the selected objects have 0.6<zspec<1.0 and only ~1% of those galaxies in the range 0.6<zspec<1.0 are expected to have a catastrophic zspec estimate. Additionally, the stacked spectra and stacked deep images for those two selections show characteristic features of star-forming galaxies. The proposed approach using the Fisher discriminant could, however, be used to efficiently select other galaxy populations, based on multi-band photometry, providing that spectroscopic information is available. This technique could thus be useful for other future massive spectroscopic surveys such as PFS, DESI, and 4MOST.
Conference proceedings - Contribution aux Journ\'ees Scientifiques
"Les radiot\'elescopes du Futur. Technologies et avanc\'ees scientifiques" -
29-30 mars 2011, Paris 3D mapping of matter ...distribution in the universe through the 21 cm radio
emission of atomic hydrogen is a complementary approach to optical surveys for
the study of the Large Scale Structures, in particular for measuring the BAO
(Baryon Acoustic Oscillation) scale up to redshifts z <~ 3 and constrain dark
energy. We propose to carry such a survey through a novel method, called
intensity mapping, without detecting individual galaxies radio emission. This
method requires a wide band instrument, 100 MHz or larger, and multiple beams,
while a rather modest angular resolution of 10 arcmin would be sufficient. The
instrument would have a few thousand square meters of collecting area and few
hundreds of simultaneous beams. These constraints could be fulfilled with a
dense array of receivers in interferometric mode, or a phased array at the
focal plane of a large antenna.
We present an updated measurement of time-dependent \CP asymmetries and the \CP-odd fraction in the decay $B^0 \to D^{*+}D^{*-}$ using $232 \times 10^{6} \BB$ pairs collected by the \babar detector ...at the PEP-II $B$ factory. We determine the \CP-odd fraction to be $0.125 \pm 0.044\stat \pm 0.007\syst$. The time-dependent \CP asymmetry parameters $C_+$ and $S_+$ are determined to be $0.06\pm 0.17\stat \pm 0.03\syst$ and $-0.75 \pm 0.25\stat \pm 0.03\syst$, respectively. The Standard Model predicts these parameters to be 0 and $-\stwob$, respectively, in the absence of penguin amplitude contributions.
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