Planck 2015 results Ade, P A R; Aghanim, N; Arnaud, M ...
Astronomy and astrophysics (Berlin),
10/2016, Letnik:
594
Journal Article
Recenzirano
Odprti dostop
We present the implications for cosmic inflation of the Planck measurements of the cosmic microwave background (CMB) anisotropies in both temperature and polarization based on the full Planck survey, ...which includes more than twice the integration time of the nominal survey used for the 2013 release papers. The Planck full mission temperature data and a first release of polarization data on large angular scales measure the spectral index of curvature perturbations to be n sub(s)= 0.968 + or - 0.006 and tightly constrain its scale dependence to dn sub(s)/ dlnk= -0.003 + or - 0.007 when combined with the Planck lensing likelihood. When the Planck high-scriptl polarization data are included, the results are consistent and uncertainties are further reduced. The upper bound on the tensor-to-scalar ratio is r sub(0.002)< 0.11 (95% CL). This upper limit is consistent with the B-mode polarization constraint r< 0.12 (95% CL) obtained from a joint analysis of the BICEP2/Keck Array and Planck data. These results imply that V(phi) proportional = to phi super(2) and natural inflation are now disfavoured compared to models predicting a smaller tensor-to-scalar ratio, such as R super(2) inflation. We search for several physically motivated deviations from a simple power-law spectrum of curvature perturbations, including those motivated by a reconstruction of the inflaton potential not relying on the slow-roll approximation. We find that such models are not preferred, either according to a Bayesian model comparison or according to a frequentist simulation-based analysis. Three independent methods reconstructing the primordial power spectrum consistently recover a featureless and smooth scriptP sub()R super(()k)over the range of scales 0.008 Mpc super(-1)< or = k< or = 0.1 Mpc super(-1). At large scales, each method finds deviations from a power law, connected to a deficit at multipoles scriptlapproximate 20-40 in the temperature power spectrum, but at an uncompelling statistical significance owing to the large cosmic variance present at these multipoles. By combining power spectrum and non-Gaussianity bounds, we constrain models with generalized Lagrangians, including Galileon models and axion monodromy models. The Planck data are consistent with adiabatic primordial perturbations, and the estimated values for the parameters of the base Lambda cold dark matter (LambdaCDM) model are not significantly altered when more general initial conditions are admitted. In correlated mixed adiabatic and isocurvature models, the 95% CL upper bound for the non-adiabatic contribution to the observed CMB temperature variance is alpha sub(non - adi) < 1.9%, 4.0%, and 2.9% for CDM, neutrino density, and neutrino velocity isocurvature modes, respectively. We have tested inflationary models producing an anisotropic modulation of the primordial curvature power spectrum findingthat the dipolar modulation in the CMB temperature field induced by a CDM isocurvature perturbation is not preferred at a statistically significant level. We also establish tight constraints on a possible quadrupolar modulation of the curvature perturbation. These results are consistent with the Planck 2013 analysis based on the nominal mission data and further constrain slow-roll single-field inflationary models, as expected from the increased precision of Planck data using the full set of observations.
We present constraints on cosmological parameters using number counts as a function of redshift for a sub-sample of 189 galaxy clusters from the Planck SZ (PSZ) catalogue. The PSZ is selected through ...the signature of the Sunyaev-Zeldovich (SZ) effect, and the sub-sample used here has a signal-to-noise threshold of seven, with each object confirmed as a cluster and all but one with a redshift estimate. We discuss the completeness of the sample and our construction of a likelihood analysis. Using a relation between mass M and SZ signal Y calibrated to X-ray measurements, we derive constraints on the power spectrum amplitude σ8 and matter density parameter Ωm in a flat ΛCDM model. We test the robustness of our estimates and find that possible biases in the Y–M relation and the halo mass function are larger than the statistical uncertainties from the cluster sample. Assuming the X-ray determined mass to be biased low relative to the true mass by between zero and 30%, motivated by comparison of the observed mass scaling relations to those from a set of numerical simulations, we find that σ8 = 0.75 ± 0.03, Ωm = 0.29 ± 0.02, and σ8(Ωm/ 0.27)0.3 = 0.764 ± 0.025. The value of σ8 is degenerate with the mass bias; if the latter is fixed to a value of 20% (the central value from numerical simulations) we find σ8(Ωm/0.27)0.3 = 0.78 ± 0.01 and a tighter one-dimensional range σ8 = 0.77 ± 0.02. We find that the larger values of σ8 and Ωm preferred by Planck’s measurements of the primary CMB anisotropies can be accommodated by a mass bias of about 40%. Alternatively, consistency with the primary CMB constraints can be achieved by inclusion of processes that suppress power on small scales relative to the ΛCDM model, such as a component of massive neutrinos. We place our results in the context of other determinations of cosmologicalparameters, and discuss issues that need to be resolved in order to make further progress in this field.
Galileo observations of Europa's thermal emission show low-latitude diurnal brightness temperatures in the range of 86 to 132 kelvin. Nighttime temperatures form an unexpected pattern, with high ...temperatures on the bright ejecta blanket of the crater Pwyll and an equatorial minimum in temperatures after sunset, uncorrelated with surface albedo or geology. The nighttime anomalies may be due to regional thermal inertia variations of an unknown origin, which are equivalent to a two- to threefold variation in thermal conductivity, or to endogenic heat fluxes locally reaching 1 watt per square meter. Endogenic heat flow at this high level, although consistent with some geological evidence, is theoretically unlikely.
Planck 2015 results Aghanim, N; Arnaud, M; Ashdown, M ...
Astronomy and astrophysics (Berlin),
10/2016, Letnik:
594
Journal Article
Recenzirano
Odprti dostop
We have constructed all-sky Compton parameters maps, y-maps, of the thermal Sunyaev-Zeldovich (tSZ) effect by applying specifically tailored component separation algorithms to the 30 to 857GHz ...frequency channel maps from the Planck satellite. These reconstructed y-maps are delivered as part of the Planck 2015 release. The y-maps are characterized in terms of noise properties and residual foreground contamination, mainly thermal dust emission at large angular scales, and cosmic infrared background and extragalactic point sources at small angular scales. Specific masks are defined to minimize foreground residuals and systematics. Using these masks, we compute the y-map angular power spectrum and higher order statistics. From these we conclude that the y-map is dominated by tSZ signal in the multipole range, 20 <scriptl< 600. We compare the measured tSZ power spectrum and higher order statistics to various physically motivated models and discuss the implications of our results in terms of cluster physics and cosmology.
Planck 2015 results Adam, R; Ade, P A R; Aghanim, N ...
Astronomy and astrophysics (Berlin),
10/2016, Letnik:
594
Journal Article
Recenzirano
Odprti dostop
Planck has mapped the microwave sky in temperature over nine frequency bands between 30 and 857GHz and in polarization over seven frequency bands between 30 and 353GHz in polarization. In this paper ...we consider the problem of diffuse astrophysical component separation, and process these maps within a Bayesian framework to derive an internally consistent set of full-sky astrophysical component maps. Component separation dedicated to cosmic microwave background (CMB) reconstruction is described in a companion paper. For the temperature analysis, we combine the Planck observations with the 9-yr Wilkinson Microwave Anisotropy Probe (WMAP) sky maps and the Haslam et al. 408MHz map, to derive a joint model of CMB, synchrotron, free-free, spinning dust, CO, line emission in the 94 and 100GHz channels, and thermal dust emission. Full-sky maps are provided for each component, with an angular resolution varying between 7.5 and 1deg. Global parameters (monopoles, dipoles, relative calibration, and bandpass errors) are fitted jointly with the sky model, and best-fit values are tabulated. For polarization, the model includes CMB, synchrotron, and thermal dust emission. These models provide excellent fits to the observed data, with rms temperature residuals smaller than 4muK over 93% of the sky for all Planck frequencies up to 353GHz, and fractional errors smaller than 1% in the remaining 7% of the sky. The main limitations of the temperature model at the lower frequencies are internal degeneracies among the spinning dust, free-free, and synchrotron components; additional observations from external low-frequency experiments will be essential to break these degeneracies. The main limitations of the temperature model at the higher frequencies are uncertainties in the 545 and 857GHz calibration and zero-points. For polarization, the main outstanding issues are instrumental systematics in the 100-353GHz bands on large angular scales in the form of temperature-to-polarization leakage, uncertainties in the analogue-to-digital conversion, and corrections for the very long time constant of the bolometer detectors, all of which are expected to improve in the near future.
Planck 2018 results Akrami, Y.; Aumont, J.; Baccigalupi, C. ...
Astronomy and astrophysics (Berlin),
09/2020, Letnik:
641
Journal Article
Recenzirano
Odprti dostop
We analyse the
Planck
full-mission cosmic microwave background (CMB) temperature and
E
-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained ...from separable template-fitting, binned, and optimal modal bispectrum estimators, finding consistent values for the local, equilateral, and orthogonal bispectrum amplitudes. Our combined temperature and polarization analysis produces the following final results:
f
NL
local
= −0.9 ± 5.1;
f
NL
equil
= −26 ± 47; and
f
NL
ortho
= −38 ± 24 (68% CL, statistical). These results include low-multipole (4 ≤
ℓ
< 40) polarization data that are not included in our previous analysis. The results also pass an extensive battery of tests (with additional tests regarding foreground residuals compared to 2015), and they are stable with respect to our 2015 measurements (with small fluctuations, at the level of a fraction of a standard deviation, which is consistent with changes in data processing). Polarization-only bispectra display a significant improvement in robustness; they can now be used independently to set primordial NG constraints with a sensitivity comparable to WMAP temperature-based results and they give excellent agreement. In addition to the analysis of the standard local, equilateral, and orthogonal bispectrum shapes, we consider a large number of additional cases, such as scale-dependent feature and resonance bispectra, isocurvature primordial NG, and parity-breaking models, where we also place tight constraints but do not detect any signal. The non-primordial lensing bispectrum is, however, detected with an improved significance compared to 2015, excluding the null hypothesis at 3.5
σ
. Beyond estimates of individual shape amplitudes, we also present model-independent reconstructions and analyses of the
Planck
CMB bispectrum. Our final constraint on the local primordial trispectrum shape is
g
NL
local
= (−5.8 ± 6.5) × 10
4
(68% CL, statistical), while constraints for other trispectrum shapes are also determined. Exploiting the tight limits on various bispectrum and trispectrum shapes, we constrain the parameter space of different early-Universe scenarios that generate primordial NG, including general single-field models of inflation, multi-field models (e.g. curvaton models), models of inflation with axion fields producing parity-violation bispectra in the tensor sector, and inflationary models involving vector-like fields with directionally-dependent bispectra. Our results provide a high-precision test for structure-formation scenarios, showing complete agreement with the basic picture of the ΛCDM cosmology regarding the statistics of the initial conditions, with cosmic structures arising from adiabatic, passive, Gaussian, and primordial seed perturbations.
Planck 2015 results Adam, R; Ade, P A R; Aghanim, N ...
Astronomy and astrophysics (Berlin),
10/2016, Letnik:
594
Journal Article
Recenzirano
Odprti dostop
This paper describes the processing applied to the cleaned, time-ordered information obtained from the Planck High Frequency Instrument (HFI) with the aim of producing photometrically calibrated maps ...in temperature and (for the first time) in polarization. The data from the entire 2.5-year HFI mission include almost five full-sky surveys. HFI observes the sky over a broad range of frequencies, from 100 to 857GHz. To obtain the best accuracy on the calibration over such a large range, two different photometric calibration schemes have been used. The 545 and 857GHz data are calibrated using models of planetary atmospheric emission. The lower frequencies (from 100 to 353GHz) are calibrated using the time-variable cosmological microwave background dipole, which we call the orbital dipole. This source of calibration only depends on the satellite velocity with respect to the solar system. Using a CMB temperature of T sub(CMB)= 2.7255 + or - 0.0006 K, it permits an independent measurement of the amplitude of the CMB solar dipole (3364.3 + or - 1.5 muK), which is approximatively 1sigma higher than the WMAP measurement with a direction that is consistent between the two experiments. We describe the pipeline used to produce the maps ofintensity and linear polarization from the HFI timelines, and the scheme used to set the zero level of the maps a posteriori. We also summarize the noise characteristics of the HFI maps in the 2015 Planck data release and present some null tests to assess their quality. Finally, we discuss the major systematic effects and in particular the leakage induced by flux mismatch between the detectors that leads to spurious polarization signal.
A dominant human gut microbe, the well studied symbiont Bacteroides thetaiotaomicron (Bt), is a glyco‐specialist that harbors a large repertoire of genes devoted to carbohydrate processing. Despite ...strong similarities among them, many of the encoded enzymes have evolved distinct substrate specificities, and through the clustering of cognate genes within operons termed polysaccharide‐utilization loci (PULs) enable the fulfilment of complex biological roles. Structural analyses of two glycoside hydrolase family 92 α‐mannosidases, BT3130 and BT3965, together with mechanistically relevant complexes at 1.8–2.5 Å resolution reveal conservation of the global enzyme fold and core catalytic apparatus despite different linkage specificities. Structure comparison shows that Bt differentiates the activity of these enzymes through evolution of a highly variable substrate‐binding region immediately adjacent to the active site. These observations unveil a genetic/biochemical mechanism through which polysaccharide‐processing bacteria can evolve new and specific biochemical activities from otherwise highly similar gene products.
Analysing two sequence‐related bacterial glycoside hydrolase family 92 mannosidases with distinct functions, a structural basis for their varied specificities is revealed.
Abstract
As competition from alternative uses for grazing land increases, enhancing productivity per hectare is important to maintain and increase beef production. This multi-year study evaluates ...whether restricted grazing of small grains and summer annuals (INT) can reduce total land required for cow-calf production compared with an extensive production system using only native range (EXT). Cows in the EXT treatment had continuous access to native range stocked at 5.39 hectares/cow-calf pair/year. Cows in the INT treatment grazed annual forages during strategic periods to reduce total land usage to 3.56 hectares/cow-calf pair/year. During the restricted grazing period (Dec-Mar), INT had access to wheat pasture for an average of 9 hours per week, continuous access for graze out (Mar-May), then had continuous access to native range during early summer (May-Jul) and fall (Aug-Dec); and 4 hours restricted grazing per day on summer annuals during Late Summer (Jul-Aug). Cow BW and body condition score (BCS) were similar at the start of the trial and after the late summer grazing period (P > 0.11) but INT were greater at all other points (P < 0.02). INT calf weight was greater at all time points (P < 0.04) with the exception of initial weight (P = 0.90). Calf ADG was greater in INT calves during the wheat grazing periods (P < 0.02) but EXT was greater during the early summer (P = 0.01). Utilizing partial confinement during strategic periods of the year calf gains were increased and total land area for beef production was decreased.
Context. In photodissociation regions (PDRs), the physical conditions and the excitation evolve on short spatial scales as a function of depth within the cloud, providing a unique opportunity to ...study how the dust and gas populations evolve with the excitation and physical conditions. The mapping of the PDRs in NGC 7023 performed during the science demonstration phase of Herschel is part of the “Evolution of interstellar dust” key program. The goal of this project is to build a coherent database on interstellar dust emission from diffuse clouds to the sites of star formation. Aims. We study the far-infrared/submillimeter emission of the PDRs and their fainter surrounding regions. We combine the Herschel and Spitzer maps to derive at each position the full emission spectrum of all dust components, which we compare to dust and radiative transfer models in order to learn about the spatial variations in both the excitation conditions and the dust properties. Methods. We adjust the emission spectra derived from PACS and SPIRE maps using modified black bodies to derive the temperature and the emissivity index β of the dust in thermal equilibrium with the radiation field. We present a first modeling of the NGC 7023-E PDR with standard dust properties and abundances. Results. At the peak positions, a value of β equal to 2 is compatible with the data. The detected spectra and the spatial structures are strongly influenced by radiative transfer effects. We are able to reproduce the spectra at the peak positions deduced from Herschel maps and emitted by dust particles at thermal equilibrium, and also the evolution of the spatial structures observed from the near infrared to the submillimeter. On the other hand, the emission of the stochastically heated smaller particles is overestimated by a factor ~2.
PDF
