We present an estimation of the reionization optical depth
τ
from an improved analysis of data from the High Frequency Instrument (HFI) on board the
Planck
satellite. By using an improved version of ...the HFI map-making code, we greatly reduce the residual large-scale contamination affecting the data, characterised in, but not fully removed from, the
Planck
2018 legacy release. This brings the dipole distortion systematic effect, contaminating the very low multipoles, below the noise level. On large-scale polarization-only data, we measure
τ
= 0.0566
−0.0062
+0.0053
at 68% C.L., reducing the
Planck
2018 legacy release uncertainty by ∼40%. Within the ΛCDM model, in combination with the
Planck
large-scale temperature likelihood, and the high-ℓ temperature and polarization likelihood, we measure
τ
= 0.059 ± 0.006 at 68% C.L., which corresponds to a mid-point reionization redshift of
z
re
= 8.14 ± 0.61 at 68% C.L. This estimation of the reionization optical depth with 10% accuracy is the strongest constraint to date.
The cosmic microwave background (CMB) anisotropies are difficult to measure at large angular scales. In this paper, we present a new analysis of the
Planck
High Frequency Instrument data that brings ...the cosmological part and its major foreground signal close to the detector noise. The solar dipole signal induced by the motion of the Solar System with respect to the CMB is a very efficient tool for calibrating a detector or cross-calibrating sets of detectors with high accuracy. In this work, the solar dipole signal is used to extract corrections of the frequency map offsets, reducing uncertainties significantly. The solar dipole parameters are refined together with the improvement of the high-frequency foregrounds and the CMB large-scale cosmological anisotropies. The stability of the solar dipole parameters is a powerful way to control Galactic foreground removal in the component separation process. We use this stability to build a model of the spatial variations in spectral energy distribution of the interstellar dust emission. Knowledge of these variations will help future CMB analyses of intensity and polarization used to measure faint signals related to the optical reionization depth and the tensor-to-scalar ratio of the primordial anisotropies. The results of this work are: improved solar dipole parameters, a new interstellar dust model, and a large-scale intensity map of cosmological anisotropies.
There is a lack of large samples of spectroscopically confirmed clusters and protoclusters at high redshifts, z > 1.5. Discovering and characterizing distant (proto-)clusters is important for ...yielding insights into the formation of large-scale structure and on the physical processes responsible for regulating star-formation in galaxies in dense environments. The Spitzer Planck Herschel Infrared Cluster (SPHerIC) survey was initiated to identify these characteristically faint and dust-reddened sources during the epoch of their early assembly. We present Spitzer/IRAC observations of 82 galaxy (proto-)cluster candidates at 1.3 < zp < 3.0 that were vetted in a two step process: (1) using Planck to select by color those sources with the highest star-formation rates, and (2) using Herschel at higher resolution to separate out the individual red sources. The addition of the Spitzer data enables efficient detection of the central and massive brightest red cluster galaxies (BRCGs). We find that BRCGs are associated with highly significant, extended and crowded regions of IRAC sources which are more overdense than the field. This result corroborates our hypothesis that BRCGs within the Planck–Herschel sources trace some of the densest and actively star-forming proto-clusters in the early Universe. On the basis of a richness-mass proxy relation, we obtain an estimate of their mean masses which suggests our sample consists of some of the most massive clusters at z ≈ 2 and are the likely progenitors of the most massive clusters observed today.
This paper describes an improved map making approach with respect to the one used for the Planck High Frequency Instrument 2018 Legacy release. The algorithm SRoll2 better corrects the known ...instrumental effects that still affected mostly the polarized large-angular-scale data by distorting the signal, and/or leaving residuals observable in null tests. The main systematic effect is the nonlinear response of the onboard analog-to-digital convertors that was cleaned in the Planck HFI Legacy release as an empirical time-varying linear detector chain response which is the first-order effect. The SRoll2 method fits the model parameters for higher-order effects and corrects the full distortion of the signal. The model parameters are fitted using the redundancies in the data by iteratively comparing the data and a model. The polarization efficiency uncertainties and associated errors have also been corrected based on the redundancies in the data and their residual levels characterized with simulations. This paper demonstrates the effectiveness of the method using end-to-end simulations, and provides a measure of the systematic effect residuals that now fall well below the detector noise level. Finally, this paper describes and characterizes the resulting SRoll2 frequency maps using the associated simulations that are released to the community.
Aims. We quantify the contributions of 24 mu m galaxies to the Far-Infrared (FIR) Background at 70 and 160 mu m. We provide new estimates of the Cosmic Infrared Background (CIB), and compare it with ...the Cosmic Optical Background (COB). Methods. Using Spitzer data at 24, 70 and 160 mu m in three deep fields, we stacked more than 19000 MIPS 24 mu m sources with S sub(24) greater than or equal to 60 mu Jy at 70 and 160 mu m, and measured the resulting FIR flux densities. Results. This method allows a gain up to one order of magnitude in depth in the FIR. We find that the Mid-Infrared (MIR) 24 mu m selected sources contribute to more than 70% of the Cosmic Infrared Background (CIB) at 70 and 160 mu m. This is the first direct measurement of the contribution of MIR-selected galaxies to the FIR CIB. Galaxies contributing the most to the total CIB are thus z similar to 1 luminous infrared galaxies, which have intermediate stellar masses. We estimate that the CIB will be resolved at 0.9 mJy at 70 and 3 mJy at 160 mu m. By combining the extrapolation of the 24 mu m source counts below analysis, we obtain lower limits of 7.1 plus or minus 1.0 and 13.4 plus or minus 1.7 nW m super(-2) sr super(-1) for the CIB at 70 and 160 mu m, respectively. Conclusions. The MIPS surveys have resolved more than three quarters of the MIR and FIR CIB. By carefully integrating the Extragalactic Background Light (EBL) SED, we also find that the CIB has the same brightness as the COB, around 24 nW m super(-2) sr super(-1). The EBL is produced on average by 115 infrared photons for one visible photon. Finally, the galaxy formation and evolution processes emitted a brightness equivalent to 5% of the primordial electromagnetic background (CMB).
To characterize the cosmological evolution of the sources contributing to the infrared extragalactic background, we have developed a phenomenological model that constrains in a simple way the ...evolution of the galaxy luminosity function with redshift, and fits all the existing source counts and redshift distributions, cosmic infrared background intensity and fluctuation observations, from the mid-infrared to the submillimetre range. The model is based on template spectra of starburst and normal galaxies, and on the local infrared luminosity function. Although the cosmic infrared background can be modelled with very different luminosity functions as long as the radiation production with redshift is the right one, the number counts and the anisotropies of the unresolved background imply that the luminosity function must change dramatically with redshift, with a rapid evolution of the high-luminosity sources (L > 3 × 1011 L⊙) from z= 0 to z= 1, which then stay rather constant up to redshift z= 5. The derived evolution of the infrared luminosity function may be linked to a bimodal star formation process: one associated with the quiescent and passive phase of the galaxy evolution, and one associated with the starburst phase, triggered by merging and interactions. The latter dominates the infrared and submillimetre output energy of the Universe. The model is intended as a convenient tool to plan further observations, as illustrated through predictions for Herschel, Planck and ALMA observations. Our model predictions for given wavelengths, together with some useful routines, are available for general use.
Planck intermediate results Ade, P A R; Aghanim, N; Alves, M I R ...
Astronomy and astrophysics (Berlin),
02/2016, Letnik:
586
Journal Article
Recenzirano
Odprti dostop
We present all-sky modelling of the high resolution Planck, IRAS, and WISE infrared (IR) observations using the physical dust model presented by Draine & Li in 2007 (DL, ApJ, 657, 810). We study the ...performance and results of this model, and discuss implications for future dust modelling. The present work extends the DL dust modelling carried out on nearby galaxies using Herschel and Spitzer data to Galactic dust emission. We employ the DL dust model to generate maps of the dust mass surface density SMd, the dust optical extinction AV, and the starlight intensity heating the bulk of the dust, parametrized by Umin. The DL model reproduces the observed spectral energy distribution (SED) satisfactorily over most of the sky, with small deviations in the inner Galactic disk and in low ecliptic latitude areas, presumably due to zodiacal light contamination. The family of SEDs and the maps generated with the DL model are made public in the Planck Legacy Archive.
Context. The High Frequency Instrument (HFI) is one of the two focal instruments of the Planck mission. It will observe the whole sky in six bands in the 100 GHz–1 THz range. Aims. The HFI instrument ...is designed to measure the cosmic microwave background (CMB) with a sensitivity limited only by fundamental sources: the photon noise of the CMB itself and the residuals left after the removal of foregrounds. The two high frequency bands will provide full maps of the submillimetre sky, featuring mainly extended and point source foregrounds. Systematic effects must be kept at negligible levels or accurately monitored so that the signal can be corrected. This paper describes the HFI design and its characteristics deduced from ground tests and calibration. Methods. The HFI instrumental concept and architecture are feasible only by pushing new techniques to their extreme capabilities, mainly: (i) bolometers working at 100 mK and absorbing the radiation in grids; (ii) a dilution cooler providing 100 mK in microgravity conditions; (iii) a new type of AC biased readout electronics and (iv) optical channels using devices inspired from radio and infrared techniques. Results. The Planck-HFI instrument performance exceeds requirements for sensitivity and control of systematic effects. During ground-based calibration and tests, it was measured at instrument and system levels to be close to or better than the goal specification.
Polarized emission observed by Planck HFI at 353 GHz towards a sample of nearby fields is presented, focusing on the statistics of polarization fractions p and angles ψ. The polarization fractions ...and column densities in these nearby fields are representative of the range of values obtained over the whole sky. We find that: (i) the largest polarization fractions are reached in the most diffuse fields; (ii) the maximum polarization fraction pmax decreases with column density NH in the more opaque fields with NH> 1021 cm-2; and (iii) the polarization fraction along a given line of sight is correlated with the local spatial coherence of the polarization angle. These observations are compared to polarized emission maps computed in simulations of anisotropic magnetohydrodynamical turbulence in which we assume a uniform intrinsic polarization fraction of the dust grains. We find that an estimate of this parameter may be recovered from the maximum polarization fraction pmax in diffuse regions where the magnetic field is ordered on large scales and perpendicular to the line of sight. This emphasizes the impact of anisotropies of the magnetic field on the emerging polarization signal. The decrease of the maximum polarization fraction with column density in nearby molecular clouds is well reproduced in the simulations, indicating that it is essentially due to the turbulent structure of the magnetic field: an accumulation of variously polarized structures along the line of sight leads to such an anti-correlation. In the simulations, polarization fractions are also found to anti-correlate with the angle dispersion function 𝒮. However, the dispersion of the polarization angle for a given polarization fraction is found to be larger in the simulations than in the observations, suggesting a shortcoming in the physical content of these numerical models. In summary, we find that the turbulent structure of the magnetic field is able to reproduce the main statistical properties of the dust polarization as observed in a variety of nearby clouds, dense cores excluded, and that the large-scale field orientation with respect to the line of sight plays a major role in the quantitative analysis of these statistical properties.
Planck 2018 results Aghanim, N.; Akrami, Y.; Aumont, J. ...
Astronomy and astrophysics (Berlin),
09/2020, Letnik:
641
Journal Article
Recenzirano
Odprti dostop
We present cosmological parameter results from the final full-mission
Planck
measurements of the cosmic microwave background (CMB) anisotropies, combining information from the temperature and ...polarization maps and the lensing reconstruction. Compared to the 2015 results, improved measurements of large-scale polarization allow the reionization optical depth to be measured with higher precision, leading to significant gains in the precision of other correlated parameters. Improved modelling of the small-scale polarization leads to more robust constraints on many parameters, with residual modelling uncertainties estimated to affect them only at the 0.5
σ
level. We find good consistency with the standard spatially-flat 6-parameter ΛCDM cosmology having a power-law spectrum of adiabatic scalar perturbations (denoted “base ΛCDM” in this paper), from polarization, temperature, and lensing, separately and in combination. A combined analysis gives dark matter density Ω
c
h
2
= 0.120 ± 0.001, baryon density Ω
b
h
2
= 0.0224 ± 0.0001, scalar spectral index
n
s
= 0.965 ± 0.004, and optical depth
τ
= 0.054 ± 0.007 (in this abstract we quote 68% confidence regions on measured parameters and 95% on upper limits). The angular acoustic scale is measured to 0.03% precision, with 100
θ
*
= 1.0411 ± 0.0003. These results are only weakly dependent on the cosmological model and remain stable, with somewhat increased errors, in many commonly considered extensions. Assuming the base-ΛCDM cosmology, the inferred (model-dependent) late-Universe parameters are: Hubble constant
H
0
= (67.4 ± 0.5) km s
−1
Mpc
−1
; matter density parameter Ω
m
= 0.315 ± 0.007; and matter fluctuation amplitude
σ
8
= 0.811 ± 0.006. We find no compelling evidence for extensions to the base-ΛCDM model. Combining with baryon acoustic oscillation (BAO) measurements (and considering single-parameter extensions) we constrain the effective extra relativistic degrees of freedom to be
N
eff
= 2.99 ± 0.17, in agreement with the Standard Model prediction
N
eff
= 3.046, and find that the neutrino mass is tightly constrained to ∑
m
ν
< 0.12 eV. The CMB spectra continue to prefer higher lensing amplitudes than predicted in base ΛCDM at over 2
σ
, which pulls some parameters that affect the lensing amplitude away from the ΛCDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAO data. The joint constraint with BAO measurements on spatial curvature is consistent with a flat universe, Ω
K
= 0.001 ± 0.002. Also combining with Type Ia supernovae (SNe), the dark-energy equation of state parameter is measured to be
w
0
= −1.03 ± 0.03, consistent with a cosmological constant. We find no evidence for deviations from a purely power-law primordial spectrum, and combining with data from BAO, BICEP2, and Keck Array data, we place a limit on the tensor-to-scalar ratio
r
0.002
< 0.06. Standard big-bang nucleosynthesis predictions for the helium and deuterium abundances for the base-ΛCDM cosmology are in excellent agreement with observations. The
Planck
base-ΛCDM results are in good agreement with BAO, SNe, and some galaxy lensing observations, but in slight tension with the Dark Energy Survey’s combined-probe results including galaxy clustering (which prefers lower fluctuation amplitudes or matter density parameters), and in significant, 3.6
σ
, tension with local measurements of the Hubble constant (which prefer a higher value). Simple model extensions that can partially resolve these tensions are not favoured by the
Planck
data.
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