Article
Astronomy & Astrophysics
Fulvio Ferlito, Sunny Vagnozzi, David F. Mota, Marco Baldi
Summary: In this study, we investigate the non-linear effects of scattering between dark energy and baryons on the formation of cosmic structures. Using large N-body simulations, we find that the signatures of this scattering in the non-linear regime are significantly larger than in the linear regime, and could potentially be constrained through a combination of observables.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Mihir Kulkarni, Jeremiah P. Ostriker
Summary: Fuzzy dark matter, composed of ultra-light axions, is an alternative theory designed to address the small-scale problems faced by the standard cold dark matter proposal. It alleviates some of the apparent discrepancies faced by the standard ACDM paradigm.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Sara Konrad, Yonadav Barry Ginat, Matthias Bartelmann
Summary: We study the small-scale asymptotic behaviour of the cold dark matter density fluctuation power spectrum in the Zel'dovich approximation and derive an asymptotic series dominated by a k(-3) tail. Our results are important for understanding perturbative terms in kinetic field theory and the non-linear power spectrum, as well as the sensitivity of small-scale behaviour to the spectral index.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. Sten Delos, Joseph Silk
Summary: Primordial black holes (PBHs) form from initial large-amplitude density fluctuations and may make up some or all of the dark matter. PBHs with a broad mass spectrum or in mixed PBH-particle dark matter scenarios also give rise to the formation of a larger abundance of ultra-dense dark matter minihaloes. These minihaloes can have internal densities around 10^12 M(circle dot)pc(-3) and can consist of either particle dark matter or smaller PBHs. This discovery has important implications for PBH scenarios and allows for the possibility of new observational tests.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Biswajit Das, Biswajit Pandey
Summary: In this study, we theoretical investigate the one parameter Li holographic dark energy and the two parameter Barrow holographic dark energy models by analyzing the configuration entropy of matter distribution in the universe. We find that there is a distinct minimum of configuration entropy rate at a specific scale factor, which corresponds to the epoch when dark energy dominates the accelerated expansion of the universe. The location of the minimum and the magnitude of the entropy rate at the minimum are sensitive to the parameters of the models, and we propose using these relations to constrain the parameters of holographic dark energy models from future observations. Our study suggests that the large quantum gravitational effect on the future event horizon can be detected from measurements of the configuration entropy of matter distribution at multiple redshifts.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Rafael Garcia, Edgar Salazar, Eduardo Rozo, Susmita Adhikari, Han Aung, Benedikt Diemer, Daisuke Nagai, Brandon Wolfe
Summary: Dark matter haloes are recognized as fundamental building blocks of large-scale structure formation models. We propose a physically motivated and parameter-free definition for haloes. We demonstrate that the mass function of physical haloes follows Press-Schechter and the clustering amplitude prediction is statistically consistent with simulation data, with an accuracy of approximately 5%.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Tibor Dome, Anastasia Fialkov, Nina Sartorio, Philip Mocz
Summary: N-body simulations using the fuzzy dark matter (FDM) model reveal that cosmic sheets, walls, and voids are more pronounced structures in FDM cosmologies compared to cold dark matter (CDM). The conditioned overdensity PDFs show a strong mid-range peak in FDM cosmologies, and the skewness estimates of the total overdensity PDF are consistently higher in FDM cosmologies, especially at high redshifts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Payaswinee Dhoke, Aseem Paranjape
Summary: The study investigates the relationship between mass accretion by dark haloes and environmental changes in simulations of CDM and WDM cosmologies. It reveals that WDM haloes have higher specific accretion rates and exhibit environment-dependent characteristics compared to CDM haloes. The results also show significant assembly bias due to diffuse mass accretion for low-mass CDM and WDM haloes, which could impact predictions of galaxy evolution models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Mehdi Rezaei, Joan Sola Peracaula, Mohammad Malekjani
Summary: This study focuses on different types of dark energy models within the cosmographic approach, finding that the running vacuum models are preferred in cosmological analysis and are successful in alleviating cosmographic tensions in observational data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Hung-Jin Huang, Tim Eifler, Rachel Mandelbaum, Gary M. Bernstein, Anqi Chen, Ami Choi, Juan Garcia-Bellido, Dragan Huterer, Elisabeth Krause, Eduardo Rozo, Sukhdeep Singh, Sarah Bridle, Joseph DeRose, Jack Elvin-Poole, Xiao Fang, Oliver Friedrich, Marco Gatti, Enrique Gaztanaga, Daniel Gruen, Will Hartley, Ben Hoyle, Mike Jarvis, Niall MacCrann, Vivian Miranda, Markus Rau, Judit Prat, Carles Sanchez, Simon Samuroff, Michael Troxel, Joe Zuntz, Tim Abbott, Michel Aguena, James Annis, Santiago Avila, Matthew Becker, Emmanuel Bertin, David Brooks, David Burke, Aurelio Carnero Rosell, Matias Carrasco Kind, Jorge Carretero, Francisco Javier Castander, Luiz da Costa, Juan De Vicente, Joerg Dietrich, Peter Doel, Spencer Everett, Brenna Flaugher, Pablo Fosalba, Josh Frieman, Robert Gruendl, Gaston Gutierrez, Samuel Hinton, Klaus Honscheid, David James, Kyler Kuehn, Ofer Lahav, Marcos Lima, Marcio Maia, Jennifer Marshall, Felipe Menanteau, Ramon Miquel, Francisco Paz-Chinchon, Andres Plazas Malagon, Kathy Romer, Aaron Roodman, Eusebio Sanchez, Vic Scarpine, Santiago Serrano, Ignacio Sevilla, Mathew Smith, Marcelle Soares-Santos, Eric Suchyta, Molly Swanson, Gregory Tarle, Diehl H. Thomas, Jochen Weller
Summary: This study demonstrates the importance of incorporating baryonic physics in interpreting large-scale structure measurements, leading to a 20% improvement in constraining cosmological parameters. By combining DES Y1 data with external information, constraints on baryon feedback strength and cosmology have been significantly refined, with implications for understanding the evolution of the universe.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
S. Capozziello, S. Zare, D. F. Mota, H. Hassanabadi
Summary: In this study, the effects of a dark matter spike near the supermassive black hole in M87 (Virgo A galaxy) were investigated using the Bumblebee Gravity theory. The aim was to determine the impact of spontaneous Lorentz symmetry breaking on the horizon, ergo-region, and shadow of the Kerr Bumblebee black hole in the spike region. Dark matter distribution was incorporated into a Lorentz-violating spherically symmetric space-time, and the resulting solution was generalized to a Kerr Bumblebee black hole. The shapes of the shadow were examined based on observational data for the dark matter spike density and radius.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Tom Rudelius
Summary: A popular proposal for resolving the Hubble tension involves early dark energy models driven by an axion field. However, these models are tightly constrained by the axion weak gravity conjecture, making it challenging to realize them in a UV complete theory of quantum gravity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Zahra Davari, Sohrab Rahvar
Summary: By comparing the MOG theory and the ΛCDM cosmology, the study explored their differences in background cosmological properties and structure formation, showing that the MOG model is consistent with the ΛCDM model in statistical analysis.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Hernandez-Almada, Genly Leon, Juan Magana, Miguel A. Garcia-Aspeitia, V Motta, Emmanuel N. Saridakis, Kuralay Yesmakhanova
Summary: In this study, we investigate Kaniadakis-holographic dark energy by comparing it with observational data. By conducting a Markov Chain Monte Carlo analysis using cosmic chronometers, supernovae type Ia, and Baryon Acoustic Oscillations data, we find that the Kaniadakis parameter is constrained around zero, which is consistent with the standard Bekenstein-Hawking entropy. Additionally, the present matter density parameter Omega((0))(m) is slightly smaller in the Kaniadakis scenario compared to the Lambda CDM model. Furthermore, we reconstruct the evolution of the Hubble, deceleration, and jerk parameters and extract the redshift of the deceleration-acceleration transition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Matteo Cataneo, Cora Uhlemann, Christian Arnold, Alex Gough, Baojiu Li, Catherine Heymans
Summary: In this study, an analytical description of the probability distribution function (PDF) of the smoothed 3D matter density field for modified gravity and dark energy is presented. The approach is based on Large Deviations Theory and is applicable to various extensions of the standard cosmology. The results show high accuracy in the mildly non-linear regime and demonstrate the power of combining measurements of the 3D matter PDF with the 3D matter power spectrum.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Mehdi Rezaei, Joan Sola Peracaula, Mohammad Malekjani
Summary: This study focuses on different types of dark energy models within the cosmographic approach, finding that the running vacuum models are preferred in cosmological analysis and are successful in alleviating cosmographic tensions in observational data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Review
Physics, Nuclear
A. Addazi, J. Alvarez-Muniz, R. Alves Batista, G. Amelino-Camelia, V Antonelli, M. Arzano, M. Asorey, J-L Atteia, S. Bahamonde, F. Bajardi, A. Ballesteros, B. Baret, D. M. Barreiros, S. Basilakos, D. Benisty, O. Birnholtz, J. J. Blanco-Pillado, D. Blas, J. Bolmont, D. Boncioli, P. Bosso, G. Calcagni, S. Capozziello, J. M. Carmona, S. Cerci, M. Chernyakova, S. Clesse, J. A. B. Coelho, S. M. Colak, J. L. Cortes, S. Das, V D'Esposito, M. Demirci, M. G. Di Luca, A. di Matteo, D. Dimitrijevic, G. Djordjevic, D. Dominis Prester, A. Eichhorn, J. Ellis, C. Escamilla-Rivera, G. Fabiano, S. A. Franchino-Vinas, A. M. Frassino, D. Frattulillo, S. Funk, A. Fuster, J. Gamboa, A. Gent, L. A. Gergely, M. Giammarchi, K. Giesel, J-F Glicenstein, J. Gracia-Bondia, R. Gracia-Ruiz, G. Gubitosi, E. Guendelman, I Gutierrez-Sagredo, L. Haegel, S. Heefer, A. Held, F. J. Herranz, T. Hinderer, J. I. Illana, A. Ioannisian, P. Jetzer, F. R. Joaquim, K-H Kampert, A. Karasu Uysal, T. Katori, N. Kazarian, D. Kerszberg, J. Kowalski-Glikman, S. Kuroyanagi, C. Lammerzahl, J. Levi Said, S. Liberati, E. Lim, I. P. Lobo, M. Lopez-Moya, G. G. Luciano, M. Manganaro, A. Marciano, P. Martin-Moruno, Manel Martinez, Mario Martinez, H. Martinez-Huerta, P. Martinez-Mirave, M. Masip, D. Mattingly, N. Mavromatos, A. Mazumdar, F. Mendez, F. Mercati, S. Micanovic, J. Mielczarek, A. L. Miller, M. Milosevic, D. Minic, L. Miramonti, V. A. Mitsou, P. Moniz, S. Mukherjee, G. Nardini, S. Navas, M. Niechciol, A. B. Nielsen, N. A. Obers, F. Oikonomou, D. Oriti, C. F. Paganini, S. Palomares-Ruiz, R. Pasechnik, V Pasic, C. Perez de los Heros, C. Pfeifer, M. Pieroni, T. Piran, A. Platania, S. Rastgoo, J. J. Relancio, M. A. Reyes, A. Ricciardone, M. Risse, M. D. Rodriguez Frias, G. Rosati, D. Rubiera-Garcia, H. Sahlmann, M. Sakellariadou, F. Salamida, E. N. Saridakis, P. Satunin, M. Schiffer, F. Schussler, G. Sigl, J. Sitarek, J. Sola Peracaula, C. F. Sopuerta, T. P. Sotiriou, M. Spurio, D. Staicova, N. Stergioulas, S. Stoica, J. Striskovic, T. Stuttard, D. Sunar Cerci, Y. Tavakoli, C. A. Ternes, T. Terzic, T. Thiemann, P. Tinyakov, M. D. C. Torri, M. Tortola, C. Trimarelli, T. Trzesniewski, A. Tureanu, F. R. Urban, E. C. Vagenas, D. Vernieri, V. Vitagliano, J-C Wallet, J. D. Zornoza
Summary: The exploration of the universe has entered a new era with the multi-messenger paradigm, providing us with more information about the universe and opening up the possibility of searching for quantum gravity phenomena.
PROGRESS IN PARTICLE AND NUCLEAR PHYSICS
(2022)
Article
Physics, Particles & Fields
Emmanuel N. Saridakis, Weiqiang Yang, Supriya Pan, Fotios K. Anagnostopoulos, Spyros Basilakos
Summary: Soft cosmology extends the standard cosmology by allowing for different equation-of-state parameters for dark matter and dark energy at different scales. Data analysis suggests that soft cosmology is favored by observational constraints.
Article
Astronomy & Astrophysics
Joan Sola Peracaula, Adria Gomez-Valent, Javier de Cruz Perez, Cristian Moreno-Pulido
Summary: Recent phenomenological and theoretical work suggests that the vacuum energy density of the universe is dynamical, adopting the 'running vacuum model' form. This dynamic scenario is based on studies of quantum field theory in curved spacetime and string theory. The cosmological constant is no longer a rigid parameter but a nearly constant value at any given epoch, and its possible running could resolve tensions in the current cosmological model. Using modern cosmological data, the running vacuum model is found to provide a better fit than the concordance LCDM model and alleviate tensions between s8 and H0.
Article
Physics, Particles & Fields
Cristian Moreno-Pulido, Joan Sola Peracaula, Samira Cheraghchi
Summary: Phenomenological work supports the idea of running vacuum energy density with cosmological evolution, helping alleviate cosmological tensions. This study computes fermionic contributions to the energy density and combines them with previous scalar field computations. A new renormalization procedure is used, and the quantum scaling of the energy density is related to cosmic evolution. The equation of state of the vacuum receives quantum corrections, resulting in the appearance of quintessence.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Petros Asimakis, Spyros Basilakos, Andreas Lymperis, Maria Petronikolou, Emmanuel N. Saridakis
Summary: This study constructs new classes of modified theories that couple the matter sector with the Einstein tensor, specifically considering direct couplings to the energy-momentum tensor and its trace derivatives. The general field equations, without higher-order derivatives, are derived and applied in a cosmological framework, resulting in Friedmann equations with additional terms that give rise to an effective dark energy sector. The study shows successful description of the thermal history of the universe at the background level, with matter and dark energy epochs, and the dark energy equation-of-state parameter can approach -1 as time progresses. Comparison with cosmic chronometer data demonstrates a very good agreement. Detailed investigations of scalar and tensor perturbations validate the predicted behavior of the matter overdensity.
Article
Physics, Particles & Fields
Fotios K. Anagnostopoulos, Viktor Gakis, Emmanuel N. Saridakis, Spyros Basilakos
Summary: The f(Q) theories of modified gravity, based on non-metricity as the fundamental geometric quantity, have shown great effectiveness in describing the late-time Universe. By using Big Bang Nucleosynthesis (BBN) formalism and observations, constraints on various classes of f(Q) models are obtained. The deviations on the freeze-out temperature caused by f(Q) terms are calculated and constraints on the model parameters are imposed by applying the observational bound on |delta Tf/Tf|. It is found that f(Q) gravity can pass the BBN constraints, distinguishing itself from many other gravitational modifications that fail to do so.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Theodoros Papanikolaou, Charalampos Tzerefos, Spyros Basilakos, Emmanuel N. Saridakis
Summary: Research shows that the fluctuations of primordial black holes can be used as a novel tool to test general relativity and constrain possible modified gravity deviations in the framework of f(T) gravity. By investigating three viable mono-parametric models, we find that the deviations from general relativity in terms of the gravitational-wave source and propagation are negligible within the observationally allowed range of f(T) model parameters. Therefore, we conclude that realistic and viable f(T) theories can safely pass the primordial black hole constraints, providing additional support for them.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Proceedings Paper
Engineering, Aerospace
Zoran Sodnik, Donatas Miklusis, Hans Smit, Harald Hauschildt, Emmanuel M. Xilouris, Panayotis Hantzios, John Alikakos, Alexis Gourzelas, Athanasios Maroussis, Spyros Basilakos, Manolis Plionis
Summary: This paper describes the experiments conducted by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing in Greece, using their telescope for optical/quantum and deep-space communication. It also provides an overview of the installation of optical communication equipment to convert the observatory into an optical ground station. This is part of ESA's strategic program and involves the participation of two other Greek observatories.
2022 IEEE INTERNATIONAL CONFERENCE ON SPACE OPTICAL SYSTEMS AND APPLICATIONS (ICSOS)
(2022)
Article
Astronomy & Astrophysics
Maria Petronikolou, Spyros Basilakos, Emmanuel N. Saridakis
Summary: In this study, we demonstrate that the H0 tension can be alleviated in the framework of Horndeski/generalized Galileon gravity. We construct specific subclasses where the friction in the Friedmann equation depends only on the field's kinetic energy, resulting in a controlled increase of the Hubble function at low redshifts. The models are found to exhibit stable scalar metric perturbations and are consistent with Supernovae type Ia and cosmic chronometer data.
Article
Astronomy & Astrophysics
G. Papagiannopoulos, Spyros Basilakos, Emmanuel N. Saridakis
Summary: In this study, we analyze the dynamical system of Myrzakulov or F(R, T) gravity, focusing on its subclasses and their critical points. We examine the stability and physical features of these models. Our findings show that in class 1 models, the Universe will result in a dark-energy-dominated critical point, while in class 2 models, the behavior of dark energy can be more varied.
Article
Astronomy & Astrophysics
Genly Leon, Andronikos Paliathanasis, Emmanuel N. Saridakis, Spyros Basilakos
Summary: This study presents a unified description of the matter and dark energy epochs using a class of scalar-torsion theories. Two specific classes of scalar-field potentials are obtained by applying Noether's theorem and requiring linear-in-momentum conservation laws. The analysis reveals critical points that correspond to different stages in the evolution of the universe, including the dust-matter domination period, the accelerated period, and the de Sitter phase.
Article
Physics, Particles & Fields
Mehdi Rezaei, Joan Sola Peracaula
Summary: In this study, different types of dynamical dark energy models were compared using the cosmographic method. The Running Vacuum models showed comparable ability to fit the overall cosmological data to the standard cosmological model and alleviate the tension between sigma(8) and H-0. The Holographic dark energy models were also examined under the assumptions of fixed and evolving holographic length scale, with the latter showing better performance.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Cristian Moreno-Pulido, Joan Sola Peracaula
Summary: The renormalization of vacuum energy in quantum field theory can be problematic due to theoretical conundrums that arise during the process. However, by employing different perspectives and techniques, one can overcome these issues and obtain satisfactory results, such as smooth functions, running vacuum models, and the equation of state of quantum vacuum.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Petros Asimakis, Spyros Basilakos, Nick E. Mavromatos, Emmanuel N. Saridakis
Summary: This study imposes constraints on higher-order modified gravity models by using big bang nucleosynthesis data. The study finds that all models satisfy the constraints of big bang nucleosynthesis and can explain the phenomena of dark energy and late-time acceleration.
