Renan A. Oliveira, Thiago S. Pereira, Miguel Quartin

We present the first null and model-independent CMB test of statistical isotropy using Multipole Vectors (MVs) at all scales. Because MVs are insensitive to the angular power spectrum $C_\ell$, our results are independent from the assumed cosmological model. We test all Planck temperature maps in the range $\ell \in [2,1500]$, where the (anisotropic) instrumental noise can safely be neglected. All four masked Planck maps, both from the 2015 and 2018 releases, are shown to be in agreement with statistical isotropy. Even some of the full sky (i.e., unmasked) maps are consistent with isotropy, to wit: NILC 2015 and 2018, SMICA 2015 and 2018, and Commander 2015. On the other hand, both unmasked SEVEM 2015 and 2018 are ruled out as statistically isotropic at >~ 80 sigma; in the unmasked Commander 2018 the anisotropy is blatant (~6000 sigma), probably due to the simplified foreground model employed in this release. This shows that MVs can be a useful tool in the detection of residual foreground contamination in CMB maps and thus in determining which regions to mask.

Mario Ballardini, Roy Maartens

The late-time integrated Sachs-Wolfe (ISW) signal in the CMB temperature anisotropies is an important probe of dark energy when it can be detected by cross-correlation with large-scale structure surveys. Because of their huge volume, surveys in the radio are well-suited to ISW detection. We show that 21cm intensity mapping and radio continuum surveys with the SKA in Phase~1 promise a $\sim5\sigma$ detection, with a similar forecast for the precursor EMU survey. In SKA2, the 21cm galaxy redshift survey could deliver a $\sim6\sigma$ detection, which is probably the maximum achievable level. Our analysis includes the observational effects on the radio surveys of lensing magnification, Doppler and other relativistic corrections. These effects alter the shape of the measured ISW signal, especially at high redshift. The cross-correlation between lensing magnification and CMB temperature at high redshift is not a direct probe of dark energy and could bias the ISW reconstruction. We find that cross-correlation between different redshift bins compensates the shift due to adding the relativistic corrections in the ISW detection and improves the quality of the ISW reconstruction.

Xue Zhang, Qing-Guo Huang

We report the constraints of $H_0$ obtained from Wilkinson Microwave Anisotropy Probe (WMAP) combined with the latest baryonic acoustic oscillations (BAO) measurements. We use the BAO measurements from the 6dF Galaxy Survey (6dFGS), the SDSS DR7 main galaxies sample (MGS), the BOSS DR12 galaxies and the eBOSS DR14 quasars. Adding the recent BAO measurements to the cosmic microwave background (CMB) data from WMAP, we constrain cosmological parameters $\Omega_m=0.298\pm0.005$, $H_0=68.36^{+0.53}_{-0.52}$ km s$^{-1}$ Mpc$^{-1}$, $\sigma_8=0.8170^{+0.0159}_{-0.0175}$ in a spatially flat $\Lambda$ cold dark matter ($\Lambda$CDM) model, and $\Omega_m=0.302\pm0.008$, $H_0=67.63\pm1.30$ km s$^{-1}$ Mpc$^{-1}$, $\sigma_8=0.7988^{+0.0345}_{-0.0338}$ in a spatially flat $w$CDM model, respectively. The combined constraint on $w$ from CMB and BAO in a spatially flat $w$CDM model is $w=-0.96\pm0.07$. Our measured $H_0$ results prefer a value lower than 70 km s$^{-1}$ Mpc$^{-1}$, consistent with the recent data on CMB constraints from Planck (2018), but in $3.1\sim 3.5\sigma$ tension with local measurements of Riess et al. (2018) in $\Lambda$CDM and $w$CDM framework, respectively. Compared with the WMAP alone analysis, the WMPA+BAO analysis reduces the error bar by 75.4% in $\Lambda$CDM model and 95.3% in $w$CDM model.