55 research outputs found
Present bounds on the relativistic energy density in the Universe from cosmological observables
We discuss the present bounds on the relativistic energy density in the
Universe parameterized in terms of the effective number of neutrinos N using
the most recent cosmological data on Cosmic Microwave Background (CMB)
temperature anisotropies and polarization, Large Scale galaxy clustering from
the Sloan Digital Sky Survey (SDSS) and 2dF, luminosity distances of type Ia
Supernovae, Lyman-alpha absorption clouds (Ly-alpha), the Baryonic Acoustic
Oscillations (BAO) detected in the Luminous Red Galaxies of the SDSS and
finally, Big Bang Nucleosynthesis (BBN) predictions for 4He and Deuterium
abundances. We find N= 5.2+2.7-2.2 from CMB and Large Scale Structure data,
while adding Ly-alpha and BAO we obtain N= 4.6+1.6-1.5 at 95 % c.l.. These
results show some tension with the standard value N=3.046 as well as with the
BBN range N= 3.1+1.4-1.2 at 95 % c.l., though the discrepancy is slightly below
the 2-sigma level. In general, considering a smaller set of data weakens the
constraints on N. We emphasize the impact of an improved upper limit (or
measurement) of the primordial value of 3He abundance in clarifying the issue
of whether the value of N at early (BBN) and more recent epochs coincide
Non-Gaussianity in the Very Small Array CMB maps with Smooth-Goodness-of-fit tests
(Abridged) We have used the Rayner & Best (1989) smooth tests of
goodness-of-fit to study the Gaussianity of the Very Small Array (VSA) data.
Out of the 41 published VSA individual pointings dedicated to cosmological
observations, 37 are found to be consistent with Gaussianity, whereas four
pointings show deviations from Gaussianity. In two of them, these deviations
can be explained as residual systematic effects of a few visibility points
which, when corrected, have a negligible impact on the angular power spectrum.
The non-Gaussianity found in the other two (adjacent) pointings seems to be
associated to a local deviation of the power spectrum of these fields with
respect to the common power spectrum of the complete data set, at angular
scales of the third acoustic peak (l = 700-900). No evidence of residual
systematics is found in this case, and unsubstracted point sources are not a
plausible explanation either. If those visibilities are removed, a cosmological
analysis based on this new VSA power spectrum alone shows no differences in the
parameter constraints with respect to our published results, except for the
physical baryon density, which decreases by 10 percent. Finally, the method has
been also used to analyse the VSA observations in the Corona Borealis
supercluster region (Genova-Santos et al. 2005), which show a strong decrement
which cannot be explained as primordial CMB. Our method finds a clear deviation
(99.82%) with respect to Gaussianity in the second-order moment of the
distribution, and which can not be explained as systematic effects. A detailed
study shows that the non-Gaussianity is produced in scales of l~500, and that
this deviation is intrinsic to the data (in the sense that can not be explained
in terms of a Gaussian field with a different power spectrum).Comment: 14 pages, 7 figures. Accepted for publication in MNRA
The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe
The 16th Data Release of the Sloan Digital Sky Surveys : First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).Peer reviewe
CMB-S4: Forecasting Constraints on Primordial Gravitational Waves
CMB-S4---the next-generation ground-based cosmic microwave background (CMB)
experiment---is set to significantly advance the sensitivity of CMB
measurements and enhance our understanding of the origin and evolution of the
Universe, from the highest energies at the dawn of time through the growth of
structure to the present day. Among the science cases pursued with CMB-S4, the
quest for detecting primordial gravitational waves is a central driver of the
experimental design. This work details the development of a forecasting
framework that includes a power-spectrum-based semi-analytic projection tool,
targeted explicitly towards optimizing constraints on the tensor-to-scalar
ratio, , in the presence of Galactic foregrounds and gravitational lensing
of the CMB. This framework is unique in its direct use of information from the
achieved performance of current Stage 2--3 CMB experiments to robustly forecast
the science reach of upcoming CMB-polarization endeavors. The methodology
allows for rapid iteration over experimental configurations and offers a
flexible way to optimize the design of future experiments given a desired
scientific goal. To form a closed-loop process, we couple this semi-analytic
tool with map-based validation studies, which allow for the injection of
additional complexity and verification of our forecasts with several
independent analysis methods. We document multiple rounds of forecasts for
CMB-S4 using this process and the resulting establishment of the current
reference design of the primordial gravitational-wave component of the Stage-4
experiment, optimized to achieve our science goals of detecting primordial
gravitational waves for at greater than , or, in the
absence of a detection, of reaching an upper limit of at CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note:
text overlap with arXiv:1907.0447
Large-scale clustering of Lyman α emission intensity from SDSS/BOSS
We present a tentative detection of the large-scale structure of Lyâα emission in the Universe at redshifts z = 2-3.5 by measuring the cross-correlation of Lyâα surface brightness with quasars in Sloan Digital Sky Survey/Baryon Oscillation Spectroscopic Survey. We use a million spectra targeting luminous red galaxies at z < 0.8, after subtracting a best-fitting model galaxy spectrum from each one, as an estimate of the high-redshift Lyâα surface brightness. The quasar-Lyâα emission cross-correlation is detected on scales 1 ⌠15âhâ1âMpc, with shape consistent with a ÎCDM model with Ωm=0.30+0.10â0.07 Ωm=0.30â0.07+0.10. The predicted amplitude of this cross-correlation is proportional to the product of the mean Lyâα surface brightness, ăΌαă, the amplitude of mass fluctuations and the quasar and Lyâα emission bias factors. We infer ăΌαăâ(bα/3) = (3.9 ± 0.9) Ă 10â21âergâsâ1 cmâ2 Ă
â1 arcsecâ2, where bα is the Lyâα emission bias. If star-forming galaxies dominate this emission, we find ÏSFR = (0.28 ± 0.07)(3/bα) yrâ1 Mpcâ3. For bα = 3, this value is âŒ30 times larger than previous estimates from individually detected Lyâα emitters, but consistent with the total ÏSFR derived from dust-corrected, continuum UV galaxy surveys, if most of the Lyâα photons from these galaxies avoid dust absorption and are reemitted after diffusing in large gas haloes. Heating of intergalactic gas by HeâII photoionization from quasar radiation or jets may alternatively explain the detected correlation, and cooling radiation from gas in galactic haloes may also contribute. We also detect redshift space anisotropy of the quasar-Lyâα emission cross-correlation, finding evidence at the 3.0Ï level that it is radially elongated, which may be explained by radiative-transfer effects. Our measurements represent the first application of the intensity mapping technique to optical observations
Cell-based data to predict the toxicity of chemicals to fish. Commentary on the manuscript by Rodrigues et al., 2019. Cell-based assays seem not to accurately predict fish short-term toxicity of pesticides. Environmental Pollution 252:476-482
Cell-based data to predict the toxicity of chemicals to fish. Commentary on the manuscript by Rodrigues et al., 2019. Cell-based assays seem not to accurately predict fish short-term toxicity of pesticides. Environmental Pollution 252:476â482
Preparation and catalytic performance of La0.8Sr0.2CoO3 supported on the mullite fiber ceramic
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