Cosmology intertwined: A review of the particle physics, astrophysics, and cosmology associated with the cosmological tensions and anomalies
Élcio Abdalla, Guillermo Franco Abellán, Amin Aboubrahim, Adriano Agnello, Özgür Akarsu, Y. Akrami, George Alestas, Daniel Aloni, Luca Amendola, Luis A. Anchordoqui, Richard I. Anderson, Nikki Arendse, Marika Asgari, M. Ballardini, V. Barger, Spyros Basilakos, Ronaldo C. Batista, E. S. Battistelli, Richard A. Battye, Micol Benetti, David Benisty, Asher Berlin, P. de Bernardis, Emanuele Berti, Bohdan Bidenko, Simon Birrer, John P. Blakeslee, Kimberly K. Boddy, Clécio R. Bom, Alexander Bonilla, Nicola Borghi, F. R. Bouchet, Matteo Braglia, Thomas Buchert, E. Buckley‐Geer, Erminia Calabrese, Robert R. Caldwell, David Camarena, Salvatore Capozzıello, Stefano Casertano, Geoff C.-F. Chen, Jens Chluba, Angela Chen, Hsin-Yu Chen, Anton Chudaykin, Michele Cicoli, Craig J. Copi, F. Courbin, Francis-Yan Cyr-Racine, B. Czerny, Maria Giovanna Dainotti, Guido D’Amico, Anne-Christine Davis, Javier de Cruz Pérez, Jaume de Haro, Jacques Delabrouille, Peter B. Denton, Suhail Dhawan, Keith R. Dienes, Eleonora Di Valentino, Pu Du, D. Eckert, Celia Escamilla‐Rivera, A. Ferté, F. Finelli⋆, P. Fosalba, Wendy L. Freedman, Noemi Frusciante, E. Gaztañaga, William Giarè, Elena Giusarma, Adrià Gómez-Valent, Will Handley, I. Harrison, Luke Hart, Dhiraj Kumar Hazra, Alan Heavens, Asta Heinesen, H. Hildebrandt, J. Colin Hill, Natalie B Hogg, D. E. Holz, Deanna C. Hooper, Nikoo Hosseininejad, Dragan Huterer, Mustapha Ishak, Mikhail M. Ivanov, A. H. Jaffe, In Sung Jang, Karsten Jedamzik, Raúl Jiménez, Melissa Joseph, Shahab Joudaki, Marc Kamionkowski, Tanvi Karwal, Lavrentios Kazantzidis, Ryan E. Keeley, Michael Klasen, Eiichiro Komatsu, L. V. E. Koopmans
Abstract
The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good description of a wide range of astrophysical and cosmological data. However, there are a few big open questions that make the standard model look like an approximation to a more realistic scenario yet to be found. In this paper, we list a few important goals that need to be addressed in the next decade, taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant H0, the σ8–S8 tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the 5.0σ tension between the Planck CMB estimate of the Hubble constant H0 and the SH0ES collaboration measurements. After showing the H0 evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the Planck CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density Ωm, and the amplitude or rate of the growth of structure (σ8,fσ8). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the H0–S8 tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals. Finally, we give an overview of upgraded experiments and next-generation space missions and facilities on Earth that will be of crucial importance to address all these open questions.