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Register a new userConstraining the ionized gas evolution with CMB-spectroscopic survey cross-correlation
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Yin-Zhe Ma
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We forecast the prospective constraints on the ionized gas model $f_{rm gas}(z)$ at different evolutionary epochs via the tomographic cross-correlation between kinetic Sunyaev-Zeldovich (kSZ) effect and the reconstructed momentum field at different redshifts. The experiments we consider are the Planck and CMB Stage-4 survey for CMB and the SDSS-III for the galaxy spectroscopic survey. We calculate the tomographic cross-correlation power spectrum, and use the Fisher matrix to forecast the detectability of different $f_{rm gas}(z)$ models. We find that for constant $f_{rm gas}$ model, Planck can constrain the error of $f_{rm gas}$ ($sigma_{f_{rm gas}}$) at each redshift bin to $sim 0.2$, whereas four cases of CMB-S4 can achieve $sigma_{f_{rm gas}} sim 10^{-3}$. For $f_{rm gas}(z)=f_{rm gas,0}/(1+z)$ model the error budget will be slightly broadened. We also investigate the model $f_{rm gas}(z)=f_{rm gas,0}/(1+z)^{alpha}$. Planck is unable to constrain the index of redshift evolution, but the CMB-S4 experiments can constrain the index $alpha$ to the level of $sigma_{alpha} sim 0.01$--$0.1$. The tomographic cross-correlation method will provide an accurate measurement of the ionized gas evolution at different epochs of the Universe.
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We propose a new reionization probe that uses cosmic microwave background (CMB) observations; the cross-correlation between fluctuations in the CMB optical depth which probes the integrated electron density, $deltatau$, and the Compton $y$-map which probes the integrated electron pressure. This cross-correlation is much less contaminated than the $y$-map power spectrum by late-time cluster contributions. In addition, this cross-correlation can constrain the temperature of ionized bubbles while the optical-depth fluctuations and kinetic SZ effect can not. We measure this new observable using a Planck $y$-map as well as a map of optical-depth fluctuations that we reconstruct from Planck CMB temperature data. We use our measurements to derive a first CMB-only upper limit on the temperature inside ionized bubbles, $T_{rm b}lesssim 7.0times10^5,$K ($2,sigma$). We also present future forecasts, assuming a fiducial model with characteristic reionization bubble size $R_{rm b}=5,$Mpc and $T_{rm b}=5times10^4,$K. The signal-to-noise ratio of the fiducial cross-correlation using a signal dominated PICO-like $y$-map becomes $simeq7$ with CMB-S4 $deltatau$ and $simeq13$ with CMB-HD $deltatau$. For the fiducial model, we predict that the CMB-HD $-$ PICO cross-correlation should achieve an accurate measurement of the reionization parameters; $T_{rm b}simeq 49800^{+4500}_{-5100},$K and $R_{rm b}simeq 5.09^{+0.66}_{-0.79},$Mpc. Since the power spectrum of the electron density fluctuations is constrained by the $deltatau$ auto spectrum, the temperature constraints should be only weakly model-dependent on the details of the electron distributions and should be statistically representative of the temperature in ionized bubbles during reionization. This cross-correlation could, therefore, become an important observable for future CMB experiments.
We measure the cross-correlation between galaxy groups constructed from DESI Legacy Imaging Survey DR8 and Planck CMB lensing, over overlapping sky area of 16876 $rm deg^2$. The detections are significant and consistent with the expected signal of the large scale structure of the universe, over group samples of various redshift, mass and richness $N_{rm g}$ and over various scale cuts. The overall S/N is 39 for a conservative sample with $N_{rm g}geq 5$, and increases to $48$ for the sample with $N_{rm g}geq 2$. Adopting the Planck 2018 cosmology, we constrain the density bias of groups with $N_{rm g}geq 5$ as $b_{rm g}=1.31pm 0.10$, $2.22pm 0.10$, $3.52pm 0.20$ at $0.1<zleq 0.33$, $0.33<zleq 0.67$, $0.67<zleq1$ respectively. The value-added group catalog allows us to detect the dependence of bias on group mass with high significance. It also allows us to compare the measured bias with the theoretically predicted one using the estimated group mass. We find excellent agreement for the two high redshift bins. However, it is lower than the theory by $sim 3sigma$ for the lowest redshift bin. Another interesting finding is the significant impact of the thermal Sunyaev Zeldovich (tSZ). It contaminates the galaxy group-CMB lensing cross-correlation at $sim 30%$ level, and must be deprojected first in CMB lensing reconstruction.
Cross-correlations between the lensing of the cosmic microwave background (CMB) and other tracers of large-scale structure provide a unique way to reconstruct the growth of dark matter, break degeneracies between cosmology and galaxy physics, and test theories of modified gravity. We detect a cross-correlation between DESI-like luminous red galaxies (LRGs) selected from DECaLS imaging and CMB lensing maps reconstructed with the Planck satellite at a significance of $S/N = 27.2$ over scales $ell_{rm min} = 30$, $ell_{rm max} = 1000$. To correct for magnification bias, we determine the slope of the LRG cumulative magnitude function at the faint limit as $s = 0.999 pm 0.015$, and find corresponding corrections on the order of a few percent for $C^{kappa g}_{ell}, C^{gg}_{ell}$ across the scales of interest. We fit the large-scale galaxy bias at the effective redshift of the cross-correlation $z_{rm eff} approx 0.68$ using two different bias evolution agnostic models: a HaloFit times linear bias model where the bias evolution is folded into the clustering-based estimation of the redshift kernel, and a Lagrangian perturbation theory model of the clustering evaluated at $z_{rm eff}$. We also determine the error on the bias from uncertainty in the redshift distribution; within this error, the two methods show excellent agreement with each other and with DESI survey expectations.
The CMB temperature-redshift relation, T_CMB(z)=T_0(1+z), is a key prediction of the standard cosmology, but is violated in many non standard models. Constraining possible deviations to this law is an effective way to test the LambdaCDM paradigm and to search for hints of new physics. We have determined T_CMB(z), with a precision up to 3%, for a subsample (104 clusters) of the Planck SZ cluster catalog, at redshift in the range 0.01-- 0.94, using measurements of the spectrum of the Sunyaev Zeldovich effect obtained from Planck temperature maps at frequencies from 70 to 353 GHz. The method adopted to provide individual determinations of T_CMB(z) at cluster redshift relies on the use of SZ intensity change, Delta I_SZ(nu), at different frequencies, and on a Monte-Carlo Markov Chain approach. By applying this method to the sample of 104 clusters, we limit possible deviations of the form T_CMB(z)=T_0(1+z)^(1-beta) to be beta= 0.022 +/- 0.018, at 1 sigma uncertainty, consistent with the prediction of the standard model. Combining these measurements with previously published results we get beta=0.016+/-0.012.
The lensing convergence measurable with future CMB surveys like CMB-S4 will be highly correlated with the clustering observed by deep photometric large scale structure (LSS) surveys such as the LSST, with cross-correlation coefficient as high as 95%. This will enable use of sample variance cancellation techniques to determine cosmological parameters, and use of cross-correlation measurements to break parameter degeneracies. Assuming large sky overlap between CMB-S4 and LSST, we show that a joint analysis of CMB-S4 lensing and LSST clustering can yield very tight constraints on the matter amplitude $sigma_8(z)$, halo bias, and $f_mathrm{NL}$, competitive with the best stage IV experiment predictions, but using complementary methods, which may carry different and possibly lower systematics. Having no sky overlap between experiments degrades the precision of $sigma_8(z)$ by a factor of 20, and that of $f_mathrm{NL}$ by a factor of 1.5 to 2. Without CMB lensing, the precision always degrades by an order of magnitude or more, showing that a joint analysis is critical. Our results also suggest that CMB lensing in combination with LSS photometric surveys is a competitive probe of the evolution of structure in the redshift range $zsimeq 1-7$, probing a regime that is not well tested observationally. We explore predictions against other surveys and experiment configurations, finding that wide patches with maximal sky overlap between CMB and LSS surveys are most powerful for $sigma_8(z)$ and $f_mathrm{NL}$.
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