Publications
371 results found
Loureiro A, Whiteaway L, Sellentin E, et al., 2023, Almanac: Weak Lensing power spectra and map inference on the masked sphere, The Open Journal of Astrophysics, Vol: 6, Pages: 1-18, ISSN: 2565-6120
We present a field-based signal extraction of weak lensing from noisy observations on the curved and masked sky. We test the analysis on a simulated Euclid-like survey, using a Euclid-like mask and noise level. To make optimal use of the information available in such a galaxy survey, we present a Bayesian method for inferring the angular power spectra of the weak lensing fields, together with an inference of the noise-cleaned tomographic weak lensing shear and convergence (projected mass) maps. The latter can be used for field-level inference with the aim of extracting cosmological parameter information including non-gaussianity of cosmic fields. We jointly infer all-sky E-mode and B-mode tomographic auto- and cross-power spectra from the masked sky, and potentially parity-violating EB-mode power spectra, up to a maximum multipole of ℓmax=2048. We use Hamiltonian Monte Carlo sampling, inferring simultaneously the power spectra and denoised maps with a total of ∼16.8 million free parameters. The main output and natural outcome is the set of samples of the posterior, which does not suffer from leakage of power from E to B unless reduced to point estimates. However, such point estimates of the power spectra, the mean and most likely maps, and their variances and covariances, can be computed if desired.
Petersen P, Akrami Y, Copi C, et al., 2023, Cosmic topology. Part I. Limits on orientable Euclidean manifolds from circle searches, Journal of Cosmology and Astroparticle Physics, Vol: 2023
The Einstein field equations of general relativity constrain the local curvature at every point in spacetime, but say nothing about the global topology of the Universe. Cosmic microwave background anisotropies have proven to be the most powerful probe of non-trivial topology since, within ΛCDM, these anisotropies have well-characterized statistical properties, the signal is principally from a thin spherical shell centered on the observer (the last scattering surface), and space-based observations nearly cover the full sky. The most generic signature of cosmic topology in the microwave background is pairs of circles with matching temperature and polarization patterns. No such circle pairs have been seen above noise in the WMAP or Planck temperature data, implying that the shortest non-contractible loop around the Universe through our location is longer than 98.5% of the comoving diameter of the last scattering surface. We translate this generic constraint into limits on the parameters that characterize manifolds with each of the nine possible non-trivial orientable Euclidean topologies, and provide a code which computes these constraints. In all but the simplest cases, the shortest non-contractible loop in the space can avoid us, and be shorter than the diameter of the last scattering surface by a factor ranging from 2 to at least 6. This result implies that a broader range of manifolds is observationally allowed than widely appreciated. Probing these manifolds will require more subtle statistical signatures than matched circles, such as off-diagonal correlations of harmonic coefficients.
Akrami Y, Anselmi S, Copi CJ, et al., 2022, The Search for the Topology of the Universe Has Just Begun
Microwave background anomalies motivate further searches for cosmic topology.For manifolds other than the simple 3-torus, existing searches allow theshortest distance around the Universe to be much less than the distance to thehorizon. Yet, to explain anomalies, the shortest distance through us is likelyto just exceed the horizon size. While galaxy and 21cm surveys are potentiallymore powerful, a more thorough microwave background search is merited asprevious ones considered only a subset of topologies and of their parameterspaces. Current limits on topology are much weaker than generally understood.
Abdalla E, Abellán GF, Aboubrahim A, et al., 2022, Cosmology intertwined: A review of the particle physics, astrophysics, and cosmology associated with the cosmological tensions and anomalies, Journal of High Energy Astrophysics, Vol: 34, Pages: 49-211, ISSN: 2214-4048
The standard Cold Dark Matter (CDM) cosmological model provides a good description of a widerange of astrophysical and cosmological data. However, there are a few big open questions that make thestandard model look like an approximation to a more realistic scenario yet to be found. In this paper,we list a few important goals that need to be addressed in the next decade, taking into account thecurrent discordances between the different cosmological probes, such as the disagreement in the valueof the Hubble constant H0, the σ8–S8 tension, and other less statistically significant anomalies. Whilethese discordances can still be in part the result of systematic errors, their persistence after several yearsof accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity fornew physics or generalisations beyond the standard model. In this paper, we focus on the 5.0 σ tensionbetween the Planck CMB estimate of the Hubble constant H0 and the SH0ES collaboration measurements.After showing the H0 evaluations made from different teams using different methods and geometriccalibrations, we list a few interesting new physics models that could alleviate this tension and discusshow the next decade’s experiments will be crucial. Moreover, we focus on the tension of the PlanckCMB data with weak lensing measurements and redshift surveys, about the value of the matter energydensity m, and the amplitude or rate of the growth of structure (σ8, f σ8). We list a few interestingmodels proposed for alleviating this tension, and we discuss the importance of trying to fit a full arrayof data with a single model and not just one parameter at a time. Additionally, we present a wide rangeof other less discussed anomalies at a statistical significance level lower than the H0–S8 tensions whichmay also constitute hints towards new physics, and we discuss possible generic theoretical approachesthat can collectively explain
Farren GS, Grin D, Jaffe AH, et al., 2022, Ultralight axions and the kinetic Sunyaev-Zel'dovich effect, PHYSICAL REVIEW D, Vol: 105, ISSN: 2470-0010
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- Citations: 6
Mootoovaloo A, Jaffe AH, Heavens AF, et al., 2022, Kernel-based emulator for the 3D matter power spectrum from CLASS, Astronomy and Computing, Vol: 38, Pages: 100508-100508, ISSN: 2213-1337
The 3D matter power spectrum, is a fundamental quantity in the analysis of cosmological data such as large-scale structure, 21 cm observations, and weak lensing. Existing computer models (Boltzmann codes) such as CLASS can provide it at the expense of immoderate computational cost. In this paper, we propose a fast Bayesian method to generate the 3D matter power spectrum, for a given set of wavenumbers, and redshifts, . Our code allows one to calculate the following quantities: the linear matter power spectrum at a given redshift (the default is set to 0); the non-linear 3D matter power spectrum with/without baryon feedback; the weak lensing power spectrum. The gradient of the 3D matter power spectrum with respect to the input cosmological parameters is also returned and this is useful for Hamiltonian Monte Carlo samplers. The derivatives are also useful for Fisher matrix calculations. In our application, the emulator is accurate when evaluated at a set of cosmological parameters, drawn from the prior, with the fractional uncertainty, centred on 0. It is also times faster compared to CLASS, hence making the emulator amenable to sampling cosmological and nuisance parameters in a Monte Carlo routine. In addition, once the 3D matter power spectrum is calculated, it can be used with a specific redshift distribution, to calculate the weak lensing and intrinsic alignment power spectra, which can then be used to derive constraints on cosmological parameters in a weak lensing data analysis problem. The software (emuPK) can be trained with any set of points and is distributed on Github, and comes with a pre-trained set of Gaussian Process (GP) models, based on 1000 Latin Hypercube (LH) samples, which follow roughly the current priors for current weak lensing analyses.
Li Z, Louis T, Calabrese E, et al., 2021, The Simons Observatory: a new open-source power spectrum pipeline applied to the Planck legacy data
We present a reproduction of the Planck 2018 angular power spectra at $\ell >30$, and associated covariance matrices, for intensity and polarization maps at100, 143 and 217 GHz. This uses a new, publicly available, pipeline that ispart of the PSpipe package. As a test case we use the same input maps,ancillary products, and analysis choices as in the Planck 2018 analysis, andfind that we can reproduce the spectra to 0.1$\sigma$ precision, and thecovariance matrices to 10%. We show that cosmological parameters estimated fromour re-derived products agree with the public Planck products to 0.1$\sigma$,providing an independent cross-check of the Planck team's analysis. Goingforward, the publicly-available code can be easily adapted to use alternativeinput maps, data selections and analysis choices, for future optimal analysisof Planck data with new ground-based Cosmic Microwave Background data.
Aghanim N, Akrami Y, Ashdown M, et al., 2021, Planck 2018 results: VI. Cosmological parameters (vol 641, A6, 2020), ASTRONOMY & ASTROPHYSICS, Vol: 652, ISSN: 0004-6361
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- Citations: 58
Heavens A, Sellentin E, Jaffe A, 2020, Extreme data compression while searching for new physics, Monthly Notices of the Royal Astronomical Society, Vol: 498, Pages: 3440-3451, ISSN: 0035-8711
Bringing a high-dimensional dataset into science-ready shape is a formidablechallenge that often necessitates data compression. Compression has accordinglybecome a key consideration for contemporary cosmology, affecting public datareleases, and reanalyses searching for new physics. However, data compressionoptimized for a particular model can suppress signs of new physics, or evenremove them altogether. We therefore provide a solution for exploring newphysics \emph{during} data compression. In particular, we store additionalagnostic compressed data points, selected to enable precise constraints ofnon-standard physics at a later date. Our procedure is based on the maximalcompression of the MOPED algorithm, which optimally filters the data withrespect to a baseline model. We select additional filters, based on ageneralised principal component analysis, which are carefully constructed toscout for new physics at high precision and speed. We refer to the augmentedset of filters as MOPED-PC. They enable an analytic computation of Bayesianevidences that may indicate the presence of new physics, and fast analyticestimates of best-fitting parameters when adopting a specific non-standardtheory, without further expensive MCMC analysis. As there may be large numbersof non-standard theories, the speed of the method becomes essential. Should nonew physics be found, then our approach preserves the precision of the standardparameters. As a result, we achieve very rapid and maximally preciseconstraints of standard and non-standard physics, with a technique that scaleswell to large dimensional datasets.
Akrami Y, Ashdown M, Aumont J, et al., 2020, Planck 2018 results: IV. Diffuse component separation, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 87
Aghanim N, Akrami Y, Alves MIR, et al., 2020, Planck 2018 results: XII. Galactic astrophysics using polarized dust emission, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 32
Collaboration P, Akrami Y, Ashdown M, et al., 2020, Planck 2018 results. VII. Isotropy and statistics of the CMB, Astronomy and Astrophysics: a European journal, Vol: 641, Pages: 1-61, ISSN: 0004-6361
Analysis of the Planck 2018 data set indicates that the statisticalproperties of the cosmic microwave background (CMB) temperature anisotropiesare in excellent agreement with previous studies using the 2013 and 2015 datareleases. In particular, they are consistent with the Gaussian predictions ofthe $\Lambda$CDM cosmological model, yet also confirm the presence of severalso-called "anomalies" on large angular scales. The novelty of the currentstudy, however, lies in being a first attempt at a comprehensive analysis ofthe statistics of the polarization signal over all angular scales, using eithermaps of the Stokes parameters, $Q$ and $U$, or the $E$-mode signal derived fromthese using a new methodology (which we describe in an appendix). Althoughremarkable progress has been made in reducing the systematic effects thatcontaminated the 2015 polarization maps on large angular scales, it is stillthe case that residual systematics (and our ability to simulate them) can limitsome tests of non-Gaussianity and isotropy. However, a detailed set of nulltests applied to the maps indicates that these issues do not dominate theanalysis on intermediate and large angular scales (i.e., $\ell \lesssim 400$).In this regime, no unambiguous detections of cosmological non-Gaussianity, orof anomalies corresponding to those seen in temperature, are claimed. Notably,the stacking of CMB polarization signals centred on the positions oftemperature hot and cold spots exhibits excellent agreement with the$\Lambda$CDM cosmological model, and also gives a clear indication of howPlanck provides state-of-the-art measurements of CMB temperature andpolarization on degree scales.
Aghanim N, Akrami Y, Ashdown M, et al., 2020, Planck 2018 results: VIII. Gravitational lensing, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 850
Collaboration P, Aghanim N, Akrami Y, et al., 2020, Planck 2018 results. V. CMB power spectra and likelihoods, Astronomy and Astrophysics: a European journal, Vol: 641, ISSN: 0004-6361
This paper describes the 2018 Planck CMB likelihoods, following a hybridapproach similar to the 2015 one, with different approximations at low and highmultipoles, and implementing several methodological and analysis refinements.With more realistic simulations, and better correction and modelling ofsystematics, we can now make full use of the High Frequency Instrumentpolarization data. The low-multipole 100x143 GHz EE cross-spectrum constrainsthe reionization optical-depth parameter $\tau$ to better than 15% (incombination with with the other low- and high-$\ell$ likelihoods). We alsoupdate the 2015 baseline low-$\ell$ joint TEB likelihood based on the LowFrequency Instrument data, which provides a weaker $\tau$ constraint. At highmultipoles, a better model of the temperature-to-polarization leakage andcorrections for the effective calibrations of the polarization channels(polarization efficiency or PE) allow us to fully use the polarization spectra,improving the constraints on the $\Lambda$CDM parameters by 20 to 30% comparedto TT-only constraints. Tests on the modelling of the polarization demonstrategood consistency, with some residual modelling uncertainties, the accuracy ofthe PE modelling being the main limitation. Using our various tests,simulations, and comparison between different high-$\ell$ implementations, weestimate the consistency of the results to be better than the 0.5$\sigma$level. Minor curiosities already present before (differences between $\ell$<800and $\ell$>800 parameters or the preference for more smoothing of the $C_\ell$peaks) are shown to be driven by the TT power spectrum and are notsignificantly modified by the inclusion of polarization. Overall, the legacyPlanck CMB likelihoods provide a robust tool for constraining the cosmologicalmodel and represent a reference for future CMB observations. (Abridged)
Aghanim N, Akrami Y, Ashdown M, et al., 2020, Planck 2018 results: III. High Frequency Instrument data processing and frequency maps, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 68
Aghanim N, Akrami Y, Arroja F, et al., 2020, Planck 2018 results: I. Overview and the cosmological legacy of Planck, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 240
Akrami Y, Arroja F, Ashdown M, et al., 2020, Planck 2018 results: X. Constraints on inflation, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 624
Akrami Y, Argueso F, Ashdown M, et al., 2020, Planck 2018 results: II. Low Frequency Instrument data processing, ASTRONOMY & ASTROPHYSICS, Vol: 641, ISSN: 0004-6361
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- Citations: 26
Collaboration P, Akrami Y, Ashdown M, et al., 2020, Planck intermediate results. LVI. Detection of the CMB dipole through modulation of the thermal Sunyaev-Zeldovich effect: Eppur si muove II, Publisher: arXiv
The largest temperature anisotropy in the cosmic microwave background (CMB)is the dipole, which has been measured with increasing accuracy for more thanthree decades, particularly with the Planck satellite. The simplestinterpretation of the dipole is that it is due to our motion with respect tothe rest frame of the CMB. Since current CMB experiments infer temperatureanisotropies from angular intensity variations, the dipole modulates thetemperature anisotropies with the same frequency dependence as the thermalSunyaev-Zeldovich (tSZ) effect. We present the first, and significant,detection of this signal in the tSZ maps and find that it is consistent withdirect measurements of the CMB dipole, as expected. The signal contributespower in the tSZ maps, which is modulated in a quadrupolar pattern, and weestimate its contribution to the tSZ bispectrum, noting that it contributesnegligible noise to the bispectrum at relevant scales.
Mootoovaloo A, Heavens AF, Jaffe AH, et al., 2020, Parameter Inference for Weak Lensing using Gaussian Processes and MOPED, Monthly Notices of the Royal Astronomical Society, Vol: 497, Pages: 2213-2226, ISSN: 0035-8711
In this paper, we propose a Gaussian Process (GP) emulator for the calculation both of tomographic weak lensing band powers, and of coefficients of summary data massively compressed with the MOPED algorithm. In the former case cosmological parameter inference is accelerated by a factor of ∼10–30 compared with Boltzmann solver class applied to KiDS-450 weak lensing data. Much larger gains of order 103 will come with future data, and MOPED with GPs will be fast enough to permit the Limber approximation to be dropped, with acceleration in this case of ∼105. A potential advantage of GPs is that an error on the emulated function can be computed and this uncertainty incorporated into the likelihood. However, it is known that the GP error can be unreliable when applied to deterministic functions, and we find, using the Kullback–Leibler divergence between the emulator and class likelihoods, and from the uncertainties on the parameters, that agreement is better when the GP uncertainty is not used. In future, weak lensing surveys such as Euclid, and the Legacy Survey of Space and Time, will have up to ∼104 summary statistics, and inference will be correspondingly more challenging. However, since the speed of MOPED is determined not the number of summary data, but by the number of parameters, MOPED analysis scales almost perfectly, provided that a fast way to compute the theoretical MOPED coefficients is available. The GP provides such a fast mechanism.
Aghanim N, Akrami Y, Ashdown M, et al., 2020, Planck 2018 results: cosmological parameters, Astronomy & Astrophysics, Vol: 641, Pages: A6-A6, ISSN: 0004-6361
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 0.5σ 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 Ωch2 = 0.120 ± 0.001, baryon density Ωbh2 = 0.0224 ± 0.0001, scalar spectral index ns = 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 100θ* = 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 H0 = (67.4 ± 0.5) km s−1 Mpc−1; matter density parameter Ωm = 0.315 ± 0.007; and matter fluctuation amplitude σ8 = 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 singl
Akrami Y, Ashdown M, Aumont J, et al., 2020, Planck 2018 results. XI. Polarized dust foregrounds, Astronomy & Astrophysics, Vol: 641, Pages: A11-A11, ISSN: 0004-6361
<jats:p>The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization in the quest for the curl-like <jats:italic>B</jats:italic>-mode polarization from primordial gravitational waves and the low-multipole <jats:italic>E</jats:italic>-mode polarization associated with the reionization of the Universe. We used the new <jats:italic>Planck</jats:italic> PR3 maps to characterize Galactic dust emission at high latitudes as a foreground to the CMB polarization and use end-to-end simulations to compute uncertainties and assess the statistical significance of our measurements. We present <jats:italic>Planck</jats:italic> <jats:italic>EE</jats:italic>, <jats:italic>BB</jats:italic>, and <jats:italic>TE</jats:italic> power spectra of dust polarization at 353 GHz for a set of six nested high-Galactic-latitude sky regions covering from 24 to 71% of the sky. We present power-law fits to the angular power spectra, yielding evidence for statistically significant variations of the exponents over sky regions and a difference between the values for the <jats:italic>EE</jats:italic> and <jats:italic>BB</jats:italic> spectra, which for the largest sky region are <jats:italic>α</jats:italic><jats:sub><jats:italic>E</jats:italic><jats:italic>E</jats:italic></jats:sub> = −2.42 ± 0.02 and <jats:italic>α</jats:italic><jats:sub><jats:italic>B</jats:italic><jats:italic>B</jats:italic></jats:sub> = −2.54 ± 0.02, respectively. The spectra show that the <jats:italic>TE</jats:italic> correlation and <jats:italic>E/B</jats:italic> power asymmetry discovered by <jats:italic>Planck</jats:italic> extend to low multipoles that were not included in earlier &
Collaboration P, Akrami Y, Andersen KJ, et al., 2020, Planck intermediate results. LVII. Joint Planck LFI and HFI data processing, Publisher: arXiv
We present the NPIPE processing pipeline, which produces calibrated frequencymaps in temperature and polarization from data from the Planck Low FrequencyInstrument (LFI) and High Frequency Instrument (HFI) using high-performancecomputers. NPIPE represents a natural evolution of previous Planck analysisefforts, and combines some of the most powerful features of the separate LFIand HFI analysis pipelines. The net effect of the improvements is lower levelsof noise and systematics in both frequency and component maps at essentiallyall angular scales, as well as notably improved internal consistency betweenthe various frequency channels. Based on the NPIPE maps, we present the firstestimate of the Solar dipole determined through component separation across allnine Planck frequencies. The amplitude is ($3366.6 \pm 2.7$)$\mu$K, consistentwith, albeit slightly higher than, earlier estimates. From the large-scalepolarization data, we derive an updated estimate of the optical depth ofreionization of $\tau = 0.051 \pm 0.006$, which appears robust with respect todata and sky cuts. There are 600 complete signal, noise and systematicssimulations of the full-frequency and detector-set maps. As a Planck first,these simulations include full time-domain processing of the beam-convolved CMBanisotropies. The release of NPIPE maps and simulations is accompanied with acomplete suite of raw and processed time-ordered data and the software,scripts, auxiliary data, and parameter files needed to improve further on theanalysis and to run matching simulations.
Leclercq F, Faure B, Lavaux G, et al., 2020, Perfectly parallel cosmological simulations using spatial comoving Lagrangian acceleration, Astronomy and Astrophysics: a European journal, Vol: 639, ISSN: 0004-6361
Context. Existing cosmological simulation methods lack a high degree of parallelism due to the long-range nature of the gravitational force, which limits the size of simulations that can be run at high resolution.Aims. To solve this problem, we propose a new, perfectly parallel approach to simulate cosmic structure formation, which is based on the spatial COmoving Lagrangian Acceleration (sCOLA) framework.Methods. Building upon a hybrid analytical and numerical description of particles’ trajectories, our algorithm allows for an efficient tiling of a cosmological volume, where the dynamics within each tile is computed independently. As a consequence, the degree of parallelism is equal to the number of tiles. We optimised the accuracy of sCOLA through the use of a buffer region around tiles and of appropriate Dirichlet boundary conditions around sCOLA boxes.Results. As a result, we show that cosmological simulations at the degree of accuracy required for the analysis of the next generation of surveys can be run in drastically reduced wall-clock times and with very low memory requirements.Conclusions. The perfect scalability of our algorithm unlocks profoundly new possibilities for computing larger cosmological simulations at high resolution, taking advantage of a variety of hardware architectures.
Hotinli SC, Kamionkowski M, Jaffe AH, 2020, The search for anisotropy in the gravitational-wave background with pulsar-timing arrays, Publisher: arXiv
Pulsar-timing arrays (PTAs) are seeking gravitational waves fromsupermassive-black-hole binaries, and there are prospects to complement thesesearches with stellar-astrometry measurements. Theorists still disagree,however, as to whether the local gravitational-wave background will bestatistically isotropic, as arises if it is the summed contributions from manySMBH binaries, or whether it exhibits the type of statistical anisotropy thatarises if the local background is dominated by a handful (or even one) brightsource. Here we derive, using bipolar spherical harmonics, the optimal PTAestimators for statistical anisotropy in the GW background and simple estimatesof the detectability of this anisotropy. We provide results on the smallestdetectable amplitude of a dipole anisotropy (and several other low-ordermultipole moments) and also the smallest detectable amplitude of a "beam" ofgravitational waves. Results are presented as a function of the signal-to-noisewith which the GW signal is detected and as a function of the number of pulsars(assuming uniform distribution on the sky and equal sensitivity per pulsar). Weprovide results first for measurements with a single time-domain windowfunction and then show how the results are augmented with the inclusion oftime-domain information. The approach here is intended to be conceptuallystraightforward and to complement the results of more detailed (butcorrespondingly less intuitive) modeling of the actual measurements.
Adachi S, Faúndez MAOA, Arnold K, et al., 2020, A measurement of the CMB E-mode angular power spectrum at subdegree scales from 670 square degrees of POLARBEAR data, Publisher: arXiv
We report a measurement of the E-mode polarization power spectrum of thecosmic microwave background (CMB) using 150 GHz data taken from July 2014 toDecember 2016 with the POLARBEAR experiment. We reach an effective polarizationmap noise level of $32\,\mu\mathrm{K}$-$\mathrm{arcmin}$ across an observationarea of 670 square degrees. We measure the EE power spectrum over the angularmultipole range $500 \leq \ell <3000$, tracing the third to seventh acousticpeaks with high sensitivity. The statistical uncertainty on E-mode bandpowersis $\sim 2.3 \mu {\rm K}^2$ at $\ell \sim 1000$ with a systematic uncertaintyof 0.5$\mu {\rm K}^2$. The data are consistent with the standard $\Lambda$CDMcosmological model with a probability-to-exceed of 0.38. We combine recent CMBE-mode measurements and make inferences about cosmological parameters in$\Lambda$CDM as well as in extensions to $\Lambda$CDM. Adding the ground-basedCMB polarization measurements to the Planck dataset reduces the uncertainty onthe Hubble constant by a factor of 1.2 to $H_0 = 67.20 \pm 0.57 {\rm km\,s^{-1}\,Mpc^{-1}}$. When allowing the number of relativistic species ($N_{eff}$) tovary, we find $N_{eff} = 2.94 \pm 0.16$, which is in good agreement with thestandard value of 3.046. Instead allowing the primordial helium abundance($Y_{He}$) to vary, the data favor $Y_{He} = 0.248 \pm 0.012$. This is veryclose to the expectation of 0.2467 from Big Bang Nucleosynthesis. When varyingboth $Y_{He}$ and $N_{eff}$, we find $N_{eff} = 2.70 \pm 0.26$ and $Y_{He} =0.262 \pm 0.015$.
Chinone Y, Adachi S, Ade PAR, et al., 2020, Results of gravitational lensing and primordial gravitational waves from the POLARBEAR experiment, 16TH INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS (TAUP 2019), Vol: 1468, ISSN: 1742-6588
Beck D, Ade PAR, Aguilar M, et al., 2020, Latest results, current data-analysis and upcoming upgrades of the polarbear/simons array experiments, Pages: 125-132
Since May 2012 the Polarbear experiment is observing the cosmic microwave background (CMB) polarization in the 150 GHz band from the Huan Tran Telescope at the Atacama Desert in Chile. It houses 1,274 transition edge sensor (TES) bolometers producing high quality data constraining the lensing-induced, small-scale B-mode polarization and permitting testing novel technologies. In this talk I will present the latest results and the current status of the data-analysis for Polarbear-1 and give an update on the development of Polarbear-2/Simons Array.
Hotinli SC, Kamionkowski M, Jaffe AH, 2019, The search for statistical anisotropy in the gravitational-wave background with pulsar timing arrays, The Open Journal of Astrophysics, Vol: 2, Pages: 1-11
Pulsar-timing arrays (PTAs) are seeking gravitational waves from supermassive-black-hole binaries, and there are prospects to complement these searches with stellar-astrometry measurements. Theorists still disagree, however, as to whether the local gravitational-wave background will be statistically isotropic, as arises if it is the summed contributions from many SMBH binaries, or whether it exhibits the type of statistical anisotropy that arises if the local background is dominated by a handful (or even one) bright source. Here we derive, using bipolar spherical harmonics, the optimal PTA estimators for statistical anisotropy in the GW background and simple estimates of the detectability of this anisotropy. We provide results on the smallest detectable amplitude of a dipole anisotropy (and several other low-order multipole moments) and also the smallest detectable amplitude of a "beam’’ of gravitational waves. Results are presented as a function of the signal-to-noise with which the GW signal is detected and as a function of the number of pulsars (assuming uniform distribution on the sky and equal sensitivity per pulsar). We provide results first for measurements with a single time-domain window function and then show how the results are augmented with the inclusion of time-domain information. The approach here is intended to be conceptually straightforward and to complement the results of more detailed (but correspondingly less intuitive) modeling of the actual measurements.
Hotinli SC, Meyers J, Dalal N, et al., 2019, Transverse velocities with the moving lens effect, Physical Review Letters, Vol: 123, ISSN: 0031-9007
Gravitational potentials that change in time induce fluctuations in the observed cosmic microwave background (CMB) temperature. Cosmological structure moving transverse to our line of sight provides a specific example known as the moving lens effect. Here, we explore how the observed CMB temperature fluctuations, combined with the observed matter overdensity, can be used to infer the transverse velocity of cosmological structures on large scales. We show that near-future CMB surveys and galaxy surveys will have the statistical power to make a first detection of the moving lens effect, and we discuss applications for the reconstructed transverse velocity.
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