Conveners
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Monday block 1
- Joan Solà Peracaula (Universitat de Barcelona)
- Adrià Gómez-Valent (Institut de Ciències del Cosmos, Universitat de Barcelona)
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Monday block 2
- Joan Solà Peracaula (Universitat de Barcelona)
- Adrià Gómez-Valent (Institut de Ciències del Cosmos, Universitat de Barcelona)
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Tuesday block 1
- Adrià Gómez-Valent (INFN, Sezione di Roma 2, Università di Roma Tor Vergata)
- Joan Solà Peracaula (Universitat de Barcelona)
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Tuesday block 2
- Adrià Gómez-Valent (INFN, Sezione di Roma 2, Università di Roma Tor Vergata)
- Joan Solà Peracaula (Universitat de Barcelona)
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Friday block 1
- Adrià Gómez-Valent (INFN, Sezione di Roma 2, Università di Roma Tor Vergata)
- Joan Solà Peracaula (Universitat de Barcelona)
Current status of the H_0 and growth tensions: theoretical models and model-independent constraints: Friday block 2
- Adrià Gómez-Valent (INFN, Sezione di Roma 2, Università di Roma Tor Vergata)
- Joan Solà Peracaula (Universitat de Barcelona)
Description
The era of high-precision cosmology has brought to the very forefront of our field a number of persistent discrepancies between observational data sets and the predictions of the standard model of cosmology, also known as the LCDM model. This situation has generated a lot of debate about whether the standard model is entering a crisis, maybe requiring some modifications or even a new theoretical paradigm, or whether the cosmological measurements are affected by unsuspected systematic errors. This session at MG17 will focus on the current status of these tensions both from the observational as well as from the theoretical point of view. Specifically, there will be talks addressing the following salient topics, among others:
(i) The direct and inverse cosmic distance ladders, their significance in determining the Hubble tension, methods for constructing them robustly, and potential sources of systematic errors.
(ii) Measurements of large-scale structure through galaxy clustering and weak lensing, and the implications for the growth tension.
(iii) Theoretical models beyond LCDM aimed at resolving these tensions.
(iv) Techniques for extracting model-independent information from cosmological data.
In this talk I will present a method devised to test the consistency between the background expansion and the evolution of cosmological perturbations. Such a test can be performed in a model independent way thanks to machine learning techniques and it will allow the detection of possible failures of the standard cosmological model, providing a direction to explore with alternative theoretical...
The persistence in some of the tensions and anomalies that affect the standard model of cosmology, like the $H_0$-tension, the $\sigma_8$-tension and the lensing anomaly, has motivated the study of alternative models capable of dealing with them. We re-analyze some of the most common extensions of the $\Lambda$CDM model in addition to other more theoretically motivated models in light of...
The Transitional Planck Mass (TPM) model is a useful application of the Effective Field Theory of Dark Energy and Modified Gravity, characterized by a step-like transition in the Planck Mass at cosmological scales. This transition, occurring during the radiation era, has shown efficacy in mitigating the Hubble tension. It achieves this by decreasing the sound horizon as detected by Cosmic...
Reconstructing the expansion history of the universe and properties of dark energy have been among the main goals of physical cosmology. I will discuss about reconstructing dark energy in light of most recent cosmological observations including DESI-2024 BAO observations, Union3 supernova compilation and Planck CMB data.
In this talk I will first review the late-time phenomenology required to solve the Hubble tension, making especial emphasis on the pivotal role played by the data on baryon acoustic oscillations (BAO) in the building of the inverse distance ladder. I will show, in particular, how the angular (2D) and anisotropic (3D) BAO data, despite being obtained from the same parent catalogues of tracers,...
The possibility that the vacuum energy density (VED) could be time dependent in the expanding Universe is intuitively more reasonable than just a rigid cosmological constant for the entire cosmic history. The framework of the running vacuum model (RVM) is a remarcable example, in which the VED appears as a power series of the Hubble rate, H(t), and its derivatives. The RVM contributes to...
Using a new sample consisting of 264 GRBs with measured redshifts and spectra, we applied different techniques to calibrate the Ep,I-Eiso correlation against the type Ia SN data to build a calibrated GRB Hubble diagram. We tested the possible redshift dependence of the correlation and its effect on the Hubble diagram to investigate the tension with the flat ΛCDM model and the dark energy...
I will review what the perspectives of quasars in the context of observational cosmology are and I will present recent measurements of the expansion rate of the Universe based on a Hubble diagram of quasars detected up to the highest redshift ever observed (z~7.5). A deviation from the ΛCDM model emerges at higher redshift, with a statistical significance of ~4σ. If an evolution of the dark...
It is a fact that the universe lives on a gravitational wave background (GWB), which is extra space–time energy that is not contained in Einstein’s field equations. In a previous work, this energy is treated as a property of space–time and not as a source. With this in mind, a new model was developed that incorporates this energy to explain the current accelerated expansion of the universe...
We use the state-of-the-art data on cosmic chronometers (CCH) and the Pantheon+ compilation of supernovae of Type Ia (SNIa) to test the constancy of the SNIa absolute magnitude, $M$, and the robustness of the cosmological principle (CP) at $z<2$ with a model-agnostic approach. We do so by reconstructing $M(z)$ and the curvature parameter $\Omega_{k}(z)$ using Gaussian Processes. Moreover, we...
Since the very first observations, the Cosmic Microwave Background (CMB) has revealed on large scales unexpected features known as anomalies, which challenge the standard $\Lambda$ cold dark matter ($\Lambda$CDM) cosmological model. One of these is the hemispherical power asymmetry, i.e. a difference in the average power on the two hemispheres centered around (l, b) = (221, −20), which shows a...
Quantum gravity has yet remained elusive from an observational standpoint. In this talk, I will discuss Swerves, a proposal within quantum gravity phenomenology that predicts testable effects in cosmological data. Motivated by considerations in Causal Set Theory, a discrete approach to quantum gravity, we have formulated the covariant Brownian motion of free particles around their geodesics....
In this talk I am presenting Bayesian Model Averaging, a well established statistical technique that offers a principled approach to model uncertainty marginalization in a Bayesian context.Specifically, this talk goes through the two recent papers I published in which I describe an implementation of such methodology for Cosmological analyses with 1) an application to the early dark energy as a...
Gravitational waves (GWs) from the coalescence of compact binaries are among the most promising cosmological probes. Their signal can be used to study the late-time cosmic expansion of the Universe independently from other known cosmological probes and without the need for an intermediate calibrator. However, this is only possible if the binary redshift is known.
Different methods have been...
Constraining the expansion history of the Universe with new and complementary approaches is crucial now that we are in the age of precision cosmology, where managing systematic effects and increasing the accuracy of the measurements is essential.
In this talk, I will present how the ages of the oldest objects in our Universe can shed light on its expansion history, both in the local...
The $\Lambda$-ColdDarkMatter model, despite being in well agreement with many observational datasets at the background level, exhibits a growth of perturbations troubled by some inconsistencies: the $H_0$ and $\sigma_8$ tensions. Adopting a theoretical perspective, this opens the question about the possibility of having a cosmological model, based on other than a cosmological constant and...
Dark Gravity is a natural extension of general relativity
in presence of a flat non dynamical background. Matter and radiation
fields from its dark sector, as soon as their gravity dominates over our side fields gravity, produce a constant acceleration law of the scale factor. After a brief reminder of the Dark Gravity theory foundations the confrontation with the main cosmological probes is...
The aim of this analysis of a historical compilation of Hubble-Lemaître constant (H0) values in the standard cosmological model is to determine whether or not the stated error bars truly represent the dispersion of values given. For this analysis, a chi-squared test was executed on a compiled list of past measurements. It was found through statistical analyses of the data (163 data points...
We investigate whether there are evidences for the existence of a new tension on the matter density parameter, independent or in relation with the Hubble or the matter fluctuation parameter tension, and that using a combination of multiple probes in a model independent approach where we relax most of the calibration parameters related to the aforementioned discrepancies.
Type Ia Supernovae (SNe Ia) are considered the most reliable standard candles and they have played an invaluable role in cosmology since the discovery of the Universe's accelerated expansion. During the last decades, the SNe Ia samples have been improved in number, redshift coverage, calibration methodology, and systematics treatment. These efforts led to the most recent "Pantheon" (2018) and...
