Moderadores
Cosmology
- Ali Rida Khalife (IAP-CNRS and Sorbonne University)
Cosmology
- Hidde Jense ()
We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, and the most recent constraints on cosmology from these, as measured from the Data Release 6 (DR6) of the Atacama Cosmology Telescope (ACT) data. ACT DR6 measures the CMB power spectra over a quarter of the sky in multiple bands in both temperature and polarization with arcminute...
The 21-cm signal is emerging as a promising probe of dark matter. However, heating-based constraints are strongly affected by astrophysical uncertainties entering in the choice of fiducial model. I will illustrate this effect for accreting primordial black holes with masses in the range $1-10^3 \, M_{\odot}$. To address this issue, I will then introduce a novel mechanism in which dark matter...
Axion-like particles (ALPs), radiated from a network of cosmic strings, may be a large part of Dark Matter (DM). In the era of precision cosmology, it is possible to characterize the effect of such particles - which almost scale invariant distribution function spans many orders of magnitudes in momentum - on the observables. In this work, we employ the CLASS code and cosmological data to place...
Magnetic monopoles are a long-sought prediction of Grand Unified Theories (GUTs), yet their efficient production in the early universe would lead to a monopole abundance that far exceeds observational limits—a challenge known as the cosmological monopole problem. The standard resolution invokes inflation occurring after monopole production, diluting their density to undetectable levels and...
In this work, we employ a model-independent approach to jointly reconstruct the dark energy equation of state $w_\mathrm{DE}$ and the sum of neutrino masses $\sum m_\nu$.
We adopt the Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) method with five fixed nodes in which we allow $w_\mathrm{DE}$ and $\sum m_\nu$ to vary. We employ CMB, BAO and SN data to constrain the values of...
Light scalar fields acquire isocurvature fluctuations during inflation. While these fluctuations could lead to interesting observable signatures at small scales, they are strongly constrained on large scales by cosmic microwave background (CMB) observations. When the mass of the scalar is much lighter than the inflationary Hubble scale, $m\ll H_I$, the spectrum of these fluctuations is flat....
Recently, the South Pole Telescope (SPT) released its measurements of temperature (T) and E-mode polarization power spectra of the cosmic microwave background (CMB). These measurements, made by two years of observation of 4% of the sky, are the most precise in EE and TE spectra for the multipole ranges 1800-4000 and 2200-4000, respectively. When combined with ACT-DR6 and Planck data, these...
Tensions between independent cosmological probes continue to challenge the $\Lambda$CDM framework. The persistent ~5$\sigma$ discrepancy between early- and late-time determinations of the Hubble parameter remains unresolved, while recent DESI BAO measurements, when interpreted within $\Lambda$CDM, yield constraints on the sum of neutrino masses that increasingly conflict with lower bounds from...
We present a comprehensive analysis of the effects of models with very low reheating scenarios ($T_\text{RH} \sim \mathcal{O}(\text{MeV})$) on the cosmological observables and derive corresponding bounds on the reheating temperature. With respect to previous work, our study includes a more precise computation of neutrino distribution functions, leveraging the latest datasets from cosmological...
Axiogenesis links the baryon asymmetry and dark matter abundance through the dynamics of the QCD axion, but its minimal form overproduces dark matter and can exacerbate the QCD axion quality problem. In this talk, I’ll show how these issues are naturally resolved in an axiverse framework, where the QCD axion arises from multiple interacting axions. This setup generates large axion velocities...
Recently, the James Webb Space Telescope (JWST) has found early galaxies producing photons from more efficient ionization than previously assumed. This may suggest a reionization process with a larger reionization optical depth, $\tau_{reio}$, in some mild disagreement with that inferred from measurements of cosmic microwave background (CMB). Intriguingly, the CMB would prefer larger values of...
We use the Mochima suite of cosmological zoom-in simulations (arXiv:2004.06008) to examine how different star formation and feedback models shape the dark matter distribution in a Milky Way–mass galaxy and its satellites (arXiv:2301.06189). All runs share identical initial conditions, allowing controlled comparisons across subgrid prescriptions. In every hydrodynamical case, the host halo...
Based on arXiv: 2409.13022 and arXiv: 2504.15340 (both published in ApJ Letters) We update constraints on cosmological parameters in a 12-parameter model, which extends the standard 6-parameter ΛCDM to include dynamical dark energy and massive neutrinos, along with other new parameters. We use the latest Planck PR4 (2020) likelihoods, DESI DR1 & DR2 BAO, and the latest uncalibrated type Ia...
