Dissipation and nonlocality in a general expanding braneworld universe

We study the evolution of both scalar and tensor cosmological perturbations in a Randall-Sundrum braneworld having an arbitrary expansion history. We adopt a four dimensional point of view where the degrees of freedom on the brane constitute an open quantum system coupled to an environment composed of the bulk gravitons. Due to the expansion of the universe, the brane degrees of freedom and the bulk degrees of freedom interact as they propagate forward in time. Brane excitations may decay through the emission of bulk gravitons which may escape to future infinity, leading to a sort of dissipation from the four dimensional point of view of an observer on the brane. Bulk gravitons may also be reflected off of the curved bulk and reabsorbed by the brane, thereby transformed into quanta on the brane, leading to a sort of nonlocality from the four dimensional point of view. The dissipation and the nonlocality are encoded into the retarded bulk propagator. We estimate the dissipation rates of the bound state as well as of the matter degrees of freedom at different cosmological epochs and for different sources of matter on the brane. We use a near-brane limit of the bulk geometry for the study when purely nonlocal bulk effects are encountered.Comment: v2, 34 pages, 7 figures, minor changes, comments and references added, version to appear in Phys. Rev.

Can we neglect relativistic temperature corrections in the Planck thermal SZ analysis?

Measurements of the thermal Sunyaev-Zel'dovich (tSZ) effect have long been recognized as a powerful cosmological probe. Here we assess the importance of relativistic temperature corrections to the tSZ signal on the power spectrum analysis of the Planck Compton-$y$ map, developing a novel formalism to account for the associated effects. The amplitude of the tSZ power spectrum is found to be sensitive to the effective electron temperature, $\bar{T}_e$, of the cluster sample. Omitting the corresponding modifications leads to an underestimation of the $yy$-power spectrum amplitude. Relativistic corrections thus add to the error budget of tSZ power spectrum observables such as $\sigma_8$. This could help alleviate the tension between various cosmological probes, with the correction scaling as $\Delta \sigma_8/\sigma_8 \simeq 0.019\,[k\bar{T}_e\,/\,5\,{\rm keV}]$ for Planck. At the current level of precision, this implies a systematic shift by $\simeq 1\sigma$, which can also be interpreted as an overestimation of the hydrostatic mass bias by $\Delta b \simeq 0.046\,(1-b)\,[k\bar{T}_e\,/\,5\,{\rm keV}]$, bringing it into better agreement with hydrodynamical simulations. It is thus time to consider relativistic temperature corrections in the processing of current and future tSZ data.Comment: 6 pages, 4 figures, minor changes, updated to match version accepted by MNRA

Mapping the relativistic electron gas temperature across the sky

With increasing sensitivity, angular resolution, and frequency coverage, future cosmic microwave background (CMB) experiments like PICO will allow us to access new information about galaxy clusters through the relativistic thermal Sunyaev-Zeldovich (SZ) effect. We will be able to map the temperature of relativistic electrons across the entire sky, going well beyond a simple detection of the relativistic SZ effect by cluster stacking methods that currently define the state-of-the-art. Here, we propose a new map-based approach utilizing SZ-temperature moment expansion and constrained-ILC methods to extract electron gas temperature maps from foreground-obscured CMB data. This delivers a new independent map-based observable, the electron temperature power spectrum $T_{\rm e}^{yy}(\ell)$, which can be used to constrain cosmology in addition to the Compton-$y$ power spectrum $C_\ell^{yy}(\ell)$ . We find that PICO has the required sensitivity, resolution, and frequency coverage to accurately map the electron gas temperature of galaxy clusters across the full sky, covering a broad range of angular scales. Frequency-coverage at $\nu\gtrsim 300\,{\rm GHz}$ plays an important role for extracting the relativistic SZ effect in the presence of foregrounds. For Coma, PICO will allow us to directly reconstruct the electron temperature profile using the relativistic SZ effect. Coma's average electron temperature will be measured to $10\sigma$ significance after foreground removal using PICO. Low-angular resolution CMB experiment like LiteBIRD could achieve $2\sigma$ to $3\sigma$ measurement of the electron temperature of this largest cluster. Our analysis highlights a new spectroscopic window into the thermodynamic properties of galaxy clusters and the diffuse electron gas at large angular scales.Comment: 17 pages, 18 figures, updated to match version accepted by MNRA

Measurement of the pairwise kinematic Sunyaev-Zeldovich effect with Planck and BOSS data

We present a new measurement of the kinetic Sunyaev-Zeldovich effect (kSZ) using Planck cosmic microwave background (CMB) and Baryon Oscillation Spectroscopic Survey (BOSS) data. Using the `LowZ North/South' galaxy catalogue from BOSS DR12, and the group catalogue from BOSS DR13, we evaluate the mean pairwise kSZ temperature associated with BOSS galaxies. We construct a `Central Galaxies Catalogue' (CGC) which consists of isolated galaxies from the original BOSS data set, and apply the aperture photometry (AP) filter to suppress the primary CMB contribution. By constructing a halo model to fit the pairwise kSZ function, we constrain the mean optical depth to be $\bar{\tau}=(0.53\pm0.32)\times10^{-4}(1.65\,\sigma)$ for `LowZ North CGC', $\bar{\tau}=(0.30\pm0.57)\times10^{-4}(0.53\,\sigma)$ for `LowZ South CGC', and $\bar{\tau}=(0.43\pm0.28)\times10^{-4}(1.53\,\sigma)$ for `DR13 Group'. In addition, we vary the radius of the AP filter and find that the AP size of $7\,{\rm arcmin}$ gives the maximum detection for $\bar{\tau}$. We also investigate the dependence of the signal with halo mass and find $\bar{\tau}=(0.32\pm0.36)\times10^{-4}(0.8\,\sigma)$ and $\bar{\tau}=(0.67\pm0.46)\times10^{-4}(1.4\,\sigma)$ for `DR13 Group' with halo mass restricted to, respectively, less and greater than its median halo mass, $10^{12}\, h^{-1}{\rm M}_{\odot}$. For the `LowZ North CGC' sample restricted to $M_{\rm h} \gtrsim 10^{14}\, h^{-1}{\rm M}_\odot$ there is no detection of the kSZ signal because these high mass halos are associated with the high-redshift galaxies of the LowZ North catalogue, which have limited contribution to the pairwise kSZ signals.Comment: 11 pages, 11 figures, 2 table

Impact of SZ cluster residuals in CMB maps and CMB-LSS cross-correlations

Residual foreground contamination in cosmic microwave background (CMB) maps, such as the residual contamination from thermal Sunyaev-Zeldovich (SZ) effect in the direction of galaxy clusters, can bias the cross-correlation measurements between CMB and large-scale structure optical surveys. It is thus essential to quantify those residuals and, if possible, to null out SZ cluster residuals in CMB maps. We quantify for the first time the amount of SZ cluster contamination in the released Planck 2015 CMB maps through (i) the stacking of CMB maps in the direction of the clusters, and (ii) the computation of cross-correlation power spectra between CMB maps and the SDSS-IV large-scale structure data. Our cross-power spectrum analysis yields a $30\sigma$ detection at the cluster scale ($\ell=1500-2500$) and a $39\sigma$ detection on larger scales ($\ell=500-1500$) due to clustering of SZ clusters, giving an overall $54\sigma$ detection of SZ cluster residuals in the Planck CMB maps. The Planck 2015 NILC CMB map is shown to have $44\pm4\%$ of thermal SZ foreground emission left in it. Using the 'Constrained ILC' component separation technique, we construct an alternative Planck CMB map, the 2D-ILC map, which is shown to have negligible SZ contamination, at the cost of being slightly more contaminated by Galactic foregrounds and noise. We also discuss the impact of the SZ residuals in CMB maps on the measurement of the ISW effect, which is shown to be negligible based on our analysis.Comment: 14 pages, 11 figures, 1 table, accepted by MNRAS, close to the published versio

An improved Compton parameter map of thermal Sunyaev-Zeldovich effect from Planck PR4 data

Taking advantage of the reduced levels of noise and systematics in the data of the latest Planck release (PR4, also known as NPIPE), we construct a new all-sky Compton-$y$ parameter map (hereafter, $y$-map) of the thermal Sunyaev-Zeldovich (SZ) effect from the Planck PR4 data. A tailored Needlet Internal Linear Combination (NILC) pipeline, first validated on detailed sky simulations, is applied to the nine single-frequency Planck PR4 sky maps, ranging from $30$ to $857$ GHz, to produce the PR4 $y$-map over 98% of the sky. Using map comparisons, angular power spectra and one-point statistics we show that the PR4 NILC $y$-map is of improved quality compared to that of the previous PR2 release. The new $y$-map shows reduced levels of large-scale striations associated with $1/f$ noise in the scan direction. Regions near the Galactic plane also show lower residual contamination by Galactic thermal dust emission. At small angular scales, the residual contamination by thermal noise and cosmic infrared background (CIB) emission is found to be reduced by around 7% and 34%, respectively, in the PR4 $y$-map. The PR4 NILC $y$-map is made publicly available for astrophysical and cosmological analyses of the thermal SZ effect.Comment: 17 pages, 17 figures. Public data products available at https://doi.org/10.5281/zenodo.7940376 . Updated to match the version accepted by MNRA

CMB Lensing Reconstruction in Real Space

We explore the reconstruction of the gravitational lensing field of the cosmic microwave background in real space showing that very little statistical information is lost when estimators of short range on the celestial sphere are used in place of the customary estimators in harmonic space, which are nonlocal and in principle require a simultaneous analysis of the entire sky without any cuts or excisions. Because virtually all the information relevant to lensing reconstruction lies on angular scales close to the resolution scale of the sky map, the gravitational lensing dilatation and shear fields (which unlike the deflection field or lensing potential are directly related to the observations in a local manner) may be reconstructed by means of quadratic combinations involving only very closely separated pixels. Even though harmonic space provides a more natural context for understanding lensing reconstruction theoretically, the real space methods developed here have the virtue of being faster to implement and are likely to prove useful for analyzing realistic maps containing a galactic cut and possibly numerous small excisions to exclude point sources that cannot be reliably subtracted.Comment: 21 pages, 8 figure

Foreground component separation with generalised ILC

The 'Internal Linear Combination' (ILC) component separation method has been extensively used to extract a single component, the CMB, from the WMAP multifrequency data. We generalise the ILC approach for separating other millimetre astrophysical emissions. We construct in particular a multidimensional ILC filter, which can be used, for instance, to estimate the diffuse emission of a complex component originating from multiple correlated emissions, such as the total emission of the Galactic interstellar medium. The performance of such generalised ILC methods, implemented on a needlet frame, is tested on simulations of Planck mission observations, for which we successfully reconstruct a low noise estimate of emission from astrophysical foregrounds with vanishing CMB and SZ contamination.Comment: 11 pages, 6 figures (2 figures added), 1 reference added, introduction expanded, V2: version accepted by MNRA

Impact of calibration errors on CMB component separation using FastICA and ILC

The separation of emissions from different astrophysical processes is an important step towards the understanding of observational data. This topic of component separation is of particular importance in the observation of the relic Cosmic Microwave Background Radiation, as performed by the WMAP satellite and the more recent Planck mission, launched May 14th, 2009 from Kourou and currently taking data. When performing any sort of component separation, some assumptions about the components must be used. One assumption that many techniques typically use is knowledge of the frequency scaling of one or more components. This assumption may be broken in the presence of calibration errors. Here we compare, in the context of imperfect calibration, the recovery of a clean map of emission of the Cosmic Microwave Background from observational data with two methods: FastICA (which makes no assumption of the frequency scaling of the components), and an `Internal Linear Combination' (ILC), which explicitly extracts a component with a given frequency scaling. We find that even in the presence of small calibration errors with a Planck-style mission, the ILC method can lead to inaccurate CMB reconstruction in the high signal-to-noise regime, because of partial cancellation of the CMB emission in the recovered map. While there is no indication that the failure of the ILC will translate to other foreground cleaning or component separation techniques, we propose that all methods which assume knowledge of the frequency scaling of one or more components be careful to estimate the effects of calibration errors.Comment: 13 pages, 5 figure