Primordial gravitational waves arising during inflation are expected to imprint a B-mode polarization pattern on the cosmic microwave background (CMB). The BICEP/Keck experiments target this primordial signature by observing the polarized microwave sky at degree-scale resolution from the South Pole. Attempting to observe the very faint primordial B-mode signal requires an instrument with...
One of the promising cosmological probes in the next decades is the CMB polarization. While CMB temperature anisotropies have been already measured very precisely, CMB polarization, in particular a twisting pattern in the polarization map (B mode) is still dominated by the statistical noise at most of the scales. The precise measurements of B mode will enable us to explore not only the...
Exploiting the weak gravitational lensing signal of the CMB has become one of the primary targets of current and upcoming CMB observatories, since it allows to tighten constraints on the physics of structure formation in a more direct way than by CMB power spectrum measurements. In this context, future CMB experiments target a sub-percent measurement of the CMB lensing power spectrum, aiming...
Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. $\Omega_M$, $\sigma_8$ and the sum of neutrino masses. In this talk, I will present a measurement of the CMB lensing potential and its power spectrum using data...
With the next generation of CMB surveys promising to map linear perturbation modes (in both temperature and E-mode polarization) down to the cosmic variance limit for $\ell$ below $\sim 3000$, cosmologists are turning to different avenues to further constrain the $\Lambda CDM$ model. Primordial gravitational waves, in the form of linear B-modes polarization, could be detected in the near...
Primordial Magnetic Fields (PMFs), being present before the epoch of cosmic recombination, induce small-scale baryonic density fluctuations. These inhomogeneities lead to an inhomogeneous recombination process which alters the peaks and heights of the large-scale anisotropies of the Cosmic Microwave Backround (CMB) radiation. Utilizing numerical compressible MHD calculations, and a Monte Carlo...
In this talk, I will detail two ways to search for low-mass axion dark matter using cosmic microwave background (CMB) polarization measurements. These appear, in particular, to be some of the most promising ways to directly detect fuzzy dark matter. Axion dark matter causes rotation of the polarization of light passing through it. This gives rise to two novel phenomena in the CMB. First, the...
Most of the modern Boltzmann solvers are based on seminal work by Ma and Bertschinger (Astrophys.J. 455 (1995) 7-25). We found that in the work as well as in the code, the baryon equations of motions breaks general covariance. There are terms missing at the order of $c_s^2$. Considering a covariant action for baryon perfect fluid with tiny temperature which has non vanishing $c_s^2$, we show...
Local measurements of the Hubble parameter are increasingly in tension with the value inferred from a LCDM fit to the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data. A general class of solutions to this tension involves temporarily increasing the energy density of the Universe close to the epoch of matter-radiation equality to reduce the size of the baryon-photon...
According to cosmological low and intermediate-redshift data, what is the statistical evidence in favor of the current speed-up of the Universe? Although this question seems to be kind of outdated, a review to the many papers that address this pivotal question in the literature tells us that the answer is not obvious at all. Determining the value of the deceleration parameter, i.e. q0=q(z=0),...
Measurements of the CMB temperature anisotropies on large angular scales have uncovered a number of anomalous features of marginal statistical significance: a hemispherical power asymmetry, lack of power on large angular scales, and features in the power spectrum. Because the primary CMB temperature has been measured at the cosmic variance limit, determining if these anomalies are hints of new...
New physics in the neutrino sector might be necessary to address anomalies between different neutrino oscillation experiments. Intriguingly, it also offers a possible solution to the discrepant cosmological measurements of $H_0$. We show that delaying the onset of neutrino free-streaming until close to the epoch of matter-radiation equality can naturally accommodate a larger value for the...
The by far strongest bound on the sum of the neutrino masses today comes from cosmological observations. Future surveys promise to even tighten this bound significantly and will be realized within the next decade. It is therefore crucial to be aware of parameter degeneracies and the main assumptions hiding behind the cosmological mass bound. We study the impact of non-standard momentum...
Going beyond the primary CMB, there is overwhelming evidence that measuring the late time effects on the CMB photons (secondaries) will provide new and valuable information for cosmological inference, in particular upon cross-correlating with large-scale structure surveys. It has been shown recently (arXiv:1812.03167) that the near-future CMB surveys and galaxy surveys will have the...
Next generation cosmic microwave background (CMB) experiments will allow us to put the most stringent constraints on primordial non-Gaussianity (PNG). However as these experiments push to increasingly small scales we become increasingly sensitive to biases and noise from other sky signals, such as extragalactic sources and gravitational lensing. In this work we explore how lensing acts as a...
Understanding the thermal properties of the cosmic gas is vital in order to mitigate important astrophysical systematics for cosmology. The relation between mass and gas pressure is a particularly relevant one, which affects both Sunyaev-Zel'dovich (SZ) cluster studies and weak lensing analyses. In this work, we use the SZ effect, quantified through the Planck Compton-y maps, and galaxy number...
We study small field inflationary models that can generate a significant Gravitational Wave (GW) signal while producing CMB observables that conform to current experimental values. To this end, we have created a stand-alone numerical simulator that, given an inflationary potential, yields the associated Primordial Power Spectrum (PPS). We found a discrepancy between the results of analytical...
We show that the cosmic birefringence and miscalibrated polarisation angles can be determined simultaneously by cosmic microwave background (CMB) experiments using the cross-correlation between E- and B-mode polarisation data. This is possible because polarisation angles of the CMB are rotated by both the cosmic birefringence and miscalibration effects,whereas those of the Galactic foreground...
