Publications
368 results found
Collaboration TSO, Abitbol MH, Adachi S, et al., 2019, The Simons observatory: Astro2020 decadal project whitepaper, Publisher: arXiv
The Simons Observatory (SO) is a ground-based cosmic microwave background(CMB) experiment sited on Cerro Toco in the Atacama Desert in Chile thatpromises to provide breakthrough discoveries in fundamental physics, cosmology,and astrophysics. Supported by the Simons Foundation, the Heising-SimonsFoundation, and with contributions from collaborating institutions, SO will seefirst light in 2021 and start a five year survey in 2022. SO has 287collaborators from 12 countries and 53 institutions, including 85 students and90 postdocs. The SO experiment in its currently funded form ('SO-Nominal') consists ofthree 0.4 m Small Aperture Telescopes (SATs) and one 6 m Large ApertureTelescope (LAT). Optimized for minimizing systematic errors in polarizationmeasurements at large angular scales, the SATs will perform a deep,degree-scale survey of 10% of the sky to search for the signature of primordialgravitational waves. The LAT will survey 40% of the sky with arc-minuteresolution. These observations will measure (or limit) the sum of neutrinomasses, search for light relics, measure the early behavior of Dark Energy, andrefine our understanding of the intergalactic medium, clusters and the role offeedback in galaxy formation. With up to ten times the sensitivity and five times the angular resolution ofthe Planck satellite, and roughly an order of magnitude increase in mappingspeed over currently operating ("Stage 3") experiments, SO will measure the CMBtemperature and polarization fluctuations to exquisite precision in sixfrequency bands from 27 to 280 GHz. SO will rapidly advance CMB science whileinforming the design of future observatories such as CMB-S4.
Conneely C, Jaffe AH, Mingarelli CMF, 2019, On the amplitude and Stokes parameters of a stochastic gravitational-wave background, Monthly Notices of the Royal Astronomical Society, Vol: 487, Pages: 562-579, ISSN: 0035-8711
The direct detection of gravitational waves has provided new opportunities for studying the Universe, but also new challenges, such as the detection and characterization of stochastic gravitational-wave backgrounds at different gravitational-wave frequencies. In this paper, we examine two different methods for their description, one based on the amplitude of a gravitational-wave signal and one on its Stokes parameters. We find that the Stokes parameters are able to describe anisotropic and correlated backgrounds, whereas the usual power spectra of the amplitudes cannot – i.e. the Stokes spectra are sensitive to properties such as the spatial distribution of the gravitational-wave sources in a realistic backgrounds.
Collaboration P, Akrami Y, Arroja F, et al., 2019, Planck 2018 results. IX. Constraints on primordial non-Gaussianity, Publisher: arXiv
We analyse the Planck full-mission cosmic microwave background (CMB)temperature and E-mode polarization maps to obtain constraints on primordialnon-Gaussianity (NG). We compare estimates obtained from separabletemplate-fitting, binned, and modal bispectrum estimators, finding consistentvalues for the local, equilateral, and orthogonal bispectrum amplitudes. Ourcombined temperature and polarization analysis produces the following 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 the low-multipole (4 <= l < 40)polarization data, not included in our previous analysis, pass an extensivebattery of tests, and are stable with respect to our 2015 measurements.Polarization bispectra display a significant improvement in robustness; theycan now be used independently to set NG constraints. We consider a large numberof additional cases, e.g. scale-dependent feature and resonance bispectra,isocurvature primordial NG, and parity-breaking models, where we also placetight constraints but do not detect any signal. The non-primordial lensingbispectrum is detected with an improved significance compared to 2015,excluding the null hypothesis at 3.5 sigma. We present model-independentreconstructions and analyses of the CMB bispectrum. Our final constraint on thelocal trispectrum shape is g_NLl^local = (-5.8 +\-6.5) x 10^4 (68%CL,statistical), while constraints for other trispectra are also determined. Weconstrain the parameter space of different early-Universe scenarios, includinggeneral single-field models of inflation, multi-field and axion fieldparity-breaking models. Our results provide a high-precision test forstructure-formation scenarios, in complete agreement with the basic picture ofthe LambdaCDM cosmology regarding the statistics of the initial conditions(abridged).
Didier J, Miller AD, Araujo D, et al., 2019, Intensity-Coupled-Polarization in Instruments with a Continuously Rotating Half-Wave Plate, Astrophysical Journal, ISSN: 0004-637X
We discuss a systematic effect associated with measuring polarization with acontinuously rotating half-wave plate. The effect was identified with the datafrom the E and B Experiment (EBEX), which was a balloon-borne instrumentdesigned to measure the polarization of the CMB as well as that from Galacticdust. The data show polarization fraction larger than 10\% while less than 3\%were expected from instrumental polarization. We give evidence that the excesspolarization is due to detector non-linearity in the presence of a continuouslyrotating HWP. The non-linearity couples intensity signals into polarization. Wedevelop a map-based method to remove the excess polarization. Applying thismethod for the 150 (250) GHz bands data we find that 81\% (92\%) of the excesspolarization was removed. Characterization and mitigation of this effect isimportant for future experiments aiming to measure the CMB B-modes with acontinuously rotating HWP.
Ade P, Aguirre J, Ahmed Z, et al., 2019, The Simons Observatory: science goals and forecasts, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516
Westbrook B, Ade PAR, Aguilar M, et al., 2018, The POLARBEAR-2 and Simons Array Focal Plane Fabrication Status, JOURNAL OF LOW TEMPERATURE PHYSICS, Vol: 193, Pages: 758-770, ISSN: 0022-2291
Aboobaker A, Ade P, Araujo D, et al., 2018, The EBEX Balloon-borne Experiment-Gondola, Attitude Control, and Control Software, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 239, ISSN: 0067-0049
Abitbol M, Aboobaker AM, Ade P, et al., 2018, The EBEX Balloon-borne Experiment-Detectors and Readout, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 239, ISSN: 0067-0049
Aboobaker AM, Ade P, Araujo D, et al., 2018, The EBEX Balloon-borne Experiment-Optics, Receiver, and Polarimetry, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 239, ISSN: 0067-0049
Akrami Y, Argueso F, Ashdown M, et al., 2018, Planck intermediate results LIV. The Planck multi-frequency catalogue of non-thermal sources, ASTRONOMY & ASTROPHYSICS, Vol: 619, ISSN: 1432-0746
Aghanim N, Akrami Y, Ashdown M, et al., 2018, Planck intermediate results LIII. Detection of velocity dispersion from the kinetic Sunyaev-Zeldovich effect, ASTRONOMY & ASTROPHYSICS, Vol: 617, ISSN: 1432-0746
Jaffe A, Jackson F, Yale E, et al., 2018, Summer reads: Darwin’s dilemma on sexual selection, ecology versus empire, and the dark side of the greater good, Nature, Vol: 559, Pages: 328-330, ISSN: 0028-0836
Jaffe A, 2018, The illusion of time, Nature, Vol: 556, Pages: 304-305, ISSN: 0028-0836
Ade PAR, Aghanim N, Alves MIR, et al., 2018, Planck intermediate results XV. A study of anomalous microwave emission in Galactic clouds (vol 565, A103, 2014), Astronomy and Astrophysics: a European journal, Vol: 610, ISSN: 0004-6361
This article is an erratum for: https://doi.org/10.1051/0004-6361/201322612
Ade PAR, Aghanim N, Alves MIR, et al., 2018, <i>Planck</i> intermediate results, Astronomy & Astrophysics, Vol: 610, Pages: C1-C1, ISSN: 0004-6361
Hotinli SC, Frazer J, Jaffe AH, et al., 2018, Effect of reheating on predictions following multiple-field inflation, PHYSICAL REVIEW D, Vol: 97, ISSN: 2470-0010
Aubin F, Aboobaker AM, Bao C, et al., 2018, Temperature calibration of the E and B experiment, Fourteenth Marcel Grossmann Meeting - MG14, Pages: 2084-2089
Copyright © 2018 by the Editors.All rights reserved. The E and B Experiment (EBEX) is a balloon-borne polarimeter designed to measure the polarization of the cosmic microwave background radiation and to characterize the polarization of galactic dust. EBEX was launched December 29, 2012 and circumnavigated Antarctica observing ∼6,000 square degrees of sky during 11 days at three frequency bands centered around 150, 250 and 410 GHz. EBEX was the first experiment to operate a kilo-pixel array of transition-edge sensor bolometers and a continuously rotating achromatic half-wave plate aboard a balloon platform. It also pioneered the use of detector readout based on digital frequency domain multiplexing. We describe the temperature calibration of the experiment. The gain response of the experiment is calibrated using a two-step iterative process. We use signals measured on passes across the Galactic plane to convert from readout-system counts to power. The effective smoothing scale of the EBEX optics and the star camera-to-detector offset angles are determined through χ2 minimization using the compact HII region RCW 38. This two-step process is initially performed with parameters measured before the EBEX 2013 flight and then repeated until the calibration factor and parameters converge.
Heavens A, Alsing J, Jaffe A, et al., 2017, Bayesian hierarchical modelling of weak lensing - the golden goal, MG14 Meeting on General Relativity, Publisher: World Scientific, Pages: 3005-3010
To accomplish correct Bayesian inference from weak lensing shear datarequires a complete statistical description of the data. The natural frameworkto do this is a Bayesian Hierarchical Model, which divides the chain ofreasoning into component steps. Starting with a catalogue of shear estimates intomographic bins, we build a model that allows us to sample simultaneously fromthe the underlying tomographic shear fields and the relevant power spectra(E-mode, B-mode, and E-B, for auto- and cross-power spectra). The proceduredeals easily with masked data and intrinsic alignments. Using Gibbs samplingand messenger fields, we show with simulated data that the large (over67000-)dimensional parameter space can be efficiently sampled and the fulljoint posterior probability density function for the parameters can feasibly beobtained. The method correctly recovers the underlying shear fields and all ofthe power spectra, including at levels well below the shot noise.
Akrami Y, Ashdown M, Aumont J, et al., 2017, Planck intermediate results LII. Planet flux densities, Astronomy and Astrophysics, Vol: 607, ISSN: 0004-6361
Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100–857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn’s rings to the planet’s total flux density suggests a best fit value for the spectral index of Saturn’s ring system of βring = 2.30 ± 0.03 over the 30–1000 GHz frequency range. Estimates of the polarization amplitude of the planets have also been made in the four bands that have polarization-sensitive detectors (100–353 GHz); this analysis provides a 95% confidence level upper limit on Mars’s polarization of 1.8, 1.7, 1.2, and 1.7% at 100, 143, 217, and 353 GHz, respectively. The average ratio between the Planck-HFI measurements and the adopted model predictions for all five planets (excluding Jupiter observations for 353 GHz) is 1.004, 1.002, 1.021, and 1.033 for 100, 143, 217, and 353 GHz, respectively. Model predictions for planet thermodynamic temperatures are therefore consistent with the absolute calibration of Planck-HFI detectors at about the three-percent level. We compare our measurements with published results from recent cosmic microwave background experiments. In particular, we observe that the flux densities measured
Aghanim N, Akrami Y, Ashdown M, et al., 2017, Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters, Astronomy and Astrophysics, Vol: 607, ISSN: 0004-6361
The six parameters of the standard ΛCDM model have best-fit values derived from the Planck temperature power spectrum that are shiftedsomewhat from the best-fit values derived from WMAP data. These shifts are driven by features in the Planck temperature power spectrum atangular scales that had never before been measured to cosmic-variance level precision. We have investigated these shifts to determine whetherthey are within the range of expectation and to understand their origin in the data. Taking our parameter set to be the optical depth of the reionizedintergalactic medium τ, the baryon density ωb, the matter density ωm, the angular size of the sound horizon θ∗, the spectral index of the primordialpower spectrum, ns, and Ase−2τ(where Asis the amplitude of the primordial power spectrum), we have examined the change in best-fit valuesbetween a WMAP-like large angular-scale data set (with multipole moment ` < 800 in the Planck temperature power spectrum) and an all angularscaledata set (` < 2500 Planck temperature power spectrum), each with a prior on τ of 0.07 ± 0.02. We find that the shifts, in units of the 1σexpected dispersion for each parameter, are {∆τ, ∆Ase−2τ, ∆ns, ∆ωm, ∆ωb, ∆θ∗} = {−1.7, −2.2, 1.2, −2.0, 1.1, 0.9}, with a χ2 value of 8.0. We findthat this χ2 value is exceeded in 15% of our simulated data sets, and that a parameter deviates by more than 2.2σ in 9% of simulated data sets,meaning that the shifts are not unusually large. Comparing ` < 800 instead to ` > 800, or splitting at a different multipole, yields similar results.We examined the ` < 800 model residuals in the ` > 800 power spectrum data and find that the features there that drive these shifts are a set ofoscillations across a broad range of angular scales. Although they partly appear similar to the effects of enhanced gravitational lensing
Ade PAR, Aguilar M, Akiba Y, et al., 2017, A measurement of the cosmic microwave background B-mode polarization power spectrum at subdegree scales from two years of POLARBEAR data, Astrophysical Journal, Vol: 848, ISSN: 0004-637X
We report an improved measurement of the cosmic microwave background B-mode polarization power spectrum with the Polarbear experiment at 150 GHz. By adding new data collected during the second season of observations (2013–2014) to re-analyzed data from the first season (2012–2013), we have reduced twofold the band-power uncertainties. The band powers are reported over angular multipoles $500\leqslant {\ell }\leqslant 2100$, where the dominant B-mode signal is expected to be due to the gravitational lensing of E-modes. We reject the null hypothesis of no B-mode polarization at a confidence of 3.1σ including both statistical and systematic uncertainties. We test the consistency of the measured B-modes with the Λ Cold Dark Matter (ΛCDM) framework by fitting for a single lensing amplitude parameter A L relative to the Planck 2015 best-fit model prediction. We obtain ${A}_{L}={0.60}_{-0.24}^{+0.26}(\mathrm{stat}{)}_{-0.04}^{+0.00}(\mathrm{inst})$ ± 0.14(foreground) ± 0.04(multi), where ${A}_{L}=1$ is the fiducial ΛCDM value.
Ade PAR, Akiba Y, Anthony AE, et al., 2017, Erratum: "A measurement of the cosmic microwave background B-Mode polarization power spectrum at sub-degree scales with POLARBEAR (2014, ApJ, 794, 171), Astrophysical Journal, Vol: 848, ISSN: 0004-637X
Takakura S, Aguilar M, Akiba Y, et al., 2017, Performance of a continuously rotating half-wave plate on the POLARBEAR telescope, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516
Poletti D, Fabbian G, Le Jeune M, et al., 2017, Making maps of cosmic microwave background polarization for B-mode studies: the POLARBEAR example, Astronomy and Astrophysics, Vol: 600, ISSN: 0004-6361
Analysis of cosmic microwave background (CMB) datasets typically requires some filtering of the raw time-ordered data. For instance, in thecontext of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/orscan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguouslyremove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We showthat such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimatedsimultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can renderan unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice ofmap-making and power spectrum estimation approaches in the context of B-mode polarization studies. Specifically, we have studied the effects oftime-domain filtering on the noise correlation structure in the map domain, as well as impact it may have on the performance of the popular pseudospectrumestimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation ofthe sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal andspecial care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domainfiltering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused onpolarization-sensitive measurements targeting the B-mode component of the CMB signal and apply the proposed methods to realistic simulationsbased on
Aghanim N, Ashdown M, Aumont J, et al., 2017, Planck intermediate results L. Evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB B-mode analysis, Astronomy and Astrophysics, Vol: 599, ISSN: 0004-6361
The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the CBBℓ angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce decorrelations between 217 and 353 GHz data similar to the values we observe in the data.
Aghanim N, Alves MIR, Arzoumanian D, et al., 2016, Planck intermediate results XLIV. Structure of the Galactic magnetic field from dust polarization maps of the southern Galactic cap, Astronomy & Astrophysics, Vol: 596, ISSN: 1432-0746
Using data from the Planck satellite, we study the statistical properties of interstellar dust polarization at high Galactic latitudes around the south pole (b < −60°). Our aim is to advance the understanding of the magnetized interstellar medium (ISM), and to provide a modelling framework of the polarized dust foreground for use in cosmic microwave background (CMB) component-separation procedures. We examine the Stokes I, Q, and U maps at 353 GHz, and particularly the statistical distribution of the polarization fraction (p) and angle (ψ), in order to characterize the ordered and turbulent components of the Galactic magnetic field (GMF) in the solar neighbourhood. The Q and U maps show patterns at large angular scales, which we relate to the mean orientation of the GMF towards Galactic coordinates (l0,b0) = (70° ± 5°,24° ± 5°). The histogram of the observed p values shows a wide dispersion up to 25%. The histogram of ψ has a standard deviation of 12° about the regular pattern expected from the ordered GMF. We build a phenomenological model that connects the distributions of p and ψ to a statistical description of the turbulent component of the GMF, assuming a uniform effective polarization fraction (p0) of dust emission. To compute the Stokes parameters, we approximate the integration along the line of sight (LOS) as a sum over a set of N independent polarization layers, in each of which the turbulent component of the GMF is obtained from Gaussian realizations of a power-law power spectrum. We are able to reproduce the observed p and ψ distributions using a p0 value of 26%, a ratio of 0.9 between the strengths of the turbulent and mean components of the GMF, and a small value of N. The mean value of p (inferred from the fit of the large-scale patterns in the Stokes maps) is 12 ± 1%. We relate the polarization layers to the density structure and to the correlation length of the GMF along th
Adam R, Ade PAR, Aghanim N, et al., 2016, Planck intermediate results XLIII. Spectral energy distribution of dust in clusters of galaxies, ASTRONOMY & ASTROPHYSICS, Vol: 596, ISSN: 1432-0746
Ade PAR, Aghanim N, Aller HD, et al., 2016, Planck intermediate results XLV. Radio spectra of northern extragalactic radio sources, Astronomy and Astrophysics, Vol: 596, ISSN: 0004-6361
Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37 GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.
Aghanim N, Ashdown M, Aumont J, et al., 2016, Planck intermediate results XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies, ASTRONOMY & ASTROPHYSICS, Vol: 596, ISSN: 1432-0746
Ade PAR, Aghanim N, Arnaud M, et al., 2016, Planck intermediate results XL. The Sunyaev-Zeldovich signal from the Virgo cluster, Astronomy and Astrophysics, Vol: 596, ISSN: 0004-6361
The Virgo cluster is the largest Sunyaev-Zeldovich (SZ) source in the sky, both in terms of angular size and total integrated flux. Planck’s wide angular scale and frequency coverage, together with its high sensitivity, enable a detailed study of this big object through the SZ effect. Virgo is well resolved by Planck, showing an elongated structure that correlates well with the morphology observed from X-rays, but extends beyond the observed X-ray signal. We find good agreement between the SZ signal (or Compton parameter, yc) observed by Planck and the expected signal inferred from X-ray observations and simple analytical models. Owing to its proximity to us, the gas beyond the virial radius in Virgo can be studied with unprecedented sensitivity by integrating the SZ signal over tens of square degrees. We study the signal in the outskirts of Virgo and compare it with analytical models and a constrained simulation of the environment of Virgo. Planck data suggest that significant amounts of low-density plasma surround Virgo, out to twice the virial radius. We find the SZ signal in the outskirts of Virgo to be consistent with a simple model that extrapolates the inferred pressure at lower radii, while assuming that the temperature stays in the keV range beyond the virial radius. The observed signal is also consistent with simulations and points to a shallow pressure profile in the outskirts of the cluster. This reservoir of gas at large radii can be linked with the hottest phase of the elusivewarm/hot intergalactic medium. Taking the lack of symmetry of Virgo into account, we find that a prolate model is favoured by the combination of SZ and X-ray data, in agreement with predictions. Finally, based on the combination of the same SZ and X-ray data, we constrain the total amount of gas in Virgo. Under the hypothesis that the abundance of baryons in Virgo is representative of the cosmic average, we also infer a distance for Virgo of approximately 18 Mpc, in g
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