Космологија и гравитација

Cosmology and Gravitation

Копредседници научног комитета секције:

Section Scientific Committee Co-Chairpersons:

Др Предраг Јовановић (Астрономска опсерваторија у Београду, Србија), Др Еди Бон (Астрономска опсерваторија у Београду, Србија) Dr Predrag Jovanović (Astronomical Observatory, Belgrade, Serbia), Dr Edi Bon (Astronomical Observatory, Belgrade, Serbia)

Чланови научног комитета секције:

Section Scientific Committee Members:

Др Предраг Јовановић (Астрономска опсерваторија у Београду, Србија)
Др Еди Бон (Астрономска опсерваторија у Београду, Србија)
Др Весна Борка Јовановић (Институт за нуклеарне науке "Винча", Србија)
Др Драган Хутерер (Универзитет у Мичигену, САД)
Др Дејан Стојковић (Универзитет у Бафалу, САД)
Др Салваторе Капоцијело (Јужна виша школа; Универзитет у Напуљу "Фредерик II", Напуљ, Италија)
Др Александр Ф. Захаров (Национални истраживачки центар "Институт Курчатов", Москва; Обједињени институт за нуклеарна истраживања, Дубна, Русија)

Опис секције:

Section Description:

Секција "Космологија и гравитација" посвећена је презентовању научних резултата који доприносе добијању нових фундаменталних сазнања о гравитационој интеракцији и њеним ефектима на астрофизичким и космолошким скалама. Предавања у оквиру ове секције посвећена су међународно препознатим и најсавременијим истраживањима галактичких, вангалактичких и космолошких појава и објеката којима управља гравитација и обухватају следеће области:

  1. Општа теорија релативности и алтернативне/модификоване теорије гравитације
  2. Стандардни ΛCDM и алтернативни космолошки модели, посматрачка космологија и космолошке тензије
  3. Физика раног космоса, космичка инфлација и примордијални гравитациони таласи
  4. Структура и еволуција космоса на великим скалама
  5. Тамна материја, тамна енергија и њихове алтернативе
  6. Гравитациони таласи, мулти-месинџер астрономија и физика компактних објеката
  7. Примена гравитационих сочива у космологији

The "Cosmology and Gravitation" section is dedicated to presenting scientific results that contribute to obtaining new fundamental insights into gravitational interaction and its effects on astrophysical and cosmological scales. Lectures within this section address internationally recognized, state-of-the-art research on galactic, extragalactic, and cosmological phenomena and objects governed by gravity, covering the following areas:

  1. General Relativity and alternative/modified theories of gravity
  2. Standard ΛCDM and alternative cosmological models, observational cosmology, and cosmological tensions
  3. Early Universe physics, cosmic inflation, and primordial gravitational waves
  4. Large-scale structure and evolution of the Universe
  5. Dark matter, dark energy, and their alternatives
  6. Gravitational waves, multi-messenger astronomy, and compact object physics
  7. Cosmological applications of gravitational lensing

Позвани предавачи:

Prof. Dragan Huterer, PhD (University of Michigan, USA)
Наслов: Cosmological Tensions and the Quest for the Physics of Dark Energy
Апстракт: A quarter-century after the discovery of the accelerated expansion of the universe, the constraints on dark energy that powers this acceleration have become very good, but the physical nature of dark energy, as well as the particle nature of dark matter, both remain elusive. I will discuss two major recent developments in cosmology. The first is the so-called "Hubble tension", a highly statistically significant disagreement in the measurements of the expansion rate of the universe measured by two principal methods. The second anomaly that I will discuss is provided with the measurements of baryon acoustic oscillations (BAO) by the Dark Energy Spectroscopic Instrument (DESI) and other data, and appears to indicate a time-evolving dark energy density. These two anomalies are a possible indicator of new physics in the late-time universe, and have caused both excitement and consternation in the field of cosmology. I will discuss these findings and their implication for our understanding of the physics of the universe.

Prof. Salvatore Capozziello, PhD (Scuola Superiore Meridionale, Universita' di Napoli "Federico II", Napoli, Italy)
Наслов: Is Dark Energy Dynamical in the DESI Era?
Апстракт: We investigate whether the recent DESI DR2 measurements provide or not evidences for dynamical dark energy by exploring the ΛCDM model and its extensions. Using a comprehensive MCMC analysis with a wide range of cosmological datasets including DESI DR2 BAO, Lyman alpha data, CMBR, BBN, cosmic chronometers, and multiple Type Ia supernova compilations, we assess the statistical preference for departures from ΛCDM. We find that neither ΛCDM nor ω0-ωaCDM models reduces the sound horizon by the 7 % required to alleviate the Hubble tension. DESI DR2 consistently favors the quadrant ω0 > -1 and ωa < 0, indicating a preference for dynamical dark energy of the Quintom-B type at less 3 sigma level for most dataset combinations, rising to 3.8 sigma only when the DES-SN5Y supernova sample is included. Furthermore, we get neutrino mass constraints. The systematics diagnosis shows that the preference for dynamical dark energy is biased at redshift z<0.1. When these low-z SNe Ia are excluded, our analysis no longer requires a dynamical dark energy and fully restores the ΛCDM model. The reconstructed evolution of ω(z) shows a transition from the phantom to the quintessence regime by crossing the phantom divide. Overall, DESI DR2 provides valuable new insights into dark energy but does not yet challenge completely the ΛCDM paradigm. Forthcoming surveys, including DESI DR3, Rubin Observatory, Euclid, Roman Space Telescope, and the Simons Observatory will be crucial for determining whether these hints of dynamical dark energy persist or are due to statistical fluctuations or residual systematics in low-redshift supernova samples. The talk is based on the review paper: Phys.Dark Univ. 51 (2026) 102196.

Prof. Alexander F. Zakharov, PhD (National Research Center – Kurchatov Institute, Moscow, Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Russia)
Наслов: Astrophysical black holes as laboratories for gravity theories
Апстракт: Recent observations of supermassive black holes (such as Sgr A* in the Galactic Center and M87*) made by the Event Horizon Telescope (EHT) collaboration, as well as gravitational wave detections of binary black hole mergers by LIGO/Virgo/KAGRA, open a new era in testing general relativity and alternative theories of gravity in strong-field regimes. We discuss how shadows of black holes and accretion disk emission profiles can serve as robust probes to constrain alternative/modified theories of gravity, wormholes, and naked singularities. Particular emphasis is placed on future space-based and ground-based interferometric projects that will significantly improve angular resolution and allow us to distinguish between general relativity and competing theoretical models.

Invited Speakers:

Prof. Dragan Huterer, PhD (University of Michigan, USA)
Title: Cosmological Tensions and the Quest for the Physics of Dark Energy
Abstract: A quarter-century after the discovery of the accelerated expansion of the universe, the constraints on dark energy that powers this acceleration have become very good, but the physical nature of dark energy, as well as the particle nature of dark matter, both remain elusive. I will discuss two major recent developments in cosmology. The first is the so-called "Hubble tension", a highly statistically significant disagreement in the measurements of the expansion rate of the universe measured by two principal methods. The second anomaly that I will discuss is provided with the measurements of baryon acoustic oscillations (BAO) by the Dark Energy Spectroscopic Instrument (DESI) and other data, and appears to indicate a time-evolving dark energy density. These two anomalies are a possible indicator of new physics in the late-time universe, and have caused both excitement and consternation in the field of cosmology. I will discuss these findings and their implication for our understanding of the physics of the universe.

Prof. Salvatore Capozziello, PhD (Scuola Superiore Meridionale, Universita' di Napoli "Federico II", Napoli, Italy)
Title: Is Dark Energy Dynamical in the DESI Era?
Abstract: We investigate whether the recent DESI DR2 measurements provide or not evidences for dynamical dark energy by exploring the ΛCDM model and its extensions. Using a comprehensive MCMC analysis with a wide range of cosmological datasets including DESI DR2 BAO, Lyman alpha data, CMBR, BBN, cosmic chronometers, and multiple Type Ia supernova compilations, we assess the statistical preference for departures from ΛCDM. We find that neither ΛCDM nor ω0-ωaCDM models reduces the sound horizon by the 7 % required to alleviate the Hubble tension. DESI DR2 consistently favors the quadrant ω0 > -1 and ωa < 0, indicating a preference for dynamical dark energy of the Quintom-B type at less 3 sigma level for most dataset combinations, rising to 3.8 sigma only when the DES-SN5Y supernova sample is included. Furthermore, we get neutrino mass constraints. The systematics diagnosis shows that the preference for dynamical dark energy is biased at redshift z<0.1. When these low-z SNe Ia are excluded, our analysis no longer requires a dynamical dark energy and fully restores the ΛCDM model. The reconstructed evolution of ω(z) shows a transition from the phantom to the quintessence regime by crossing the phantom divide. Overall, DESI DR2 provides valuable new insights into dark energy but does not yet challenge completely the ΛCDM paradigm. Forthcoming surveys, including DESI DR3, Rubin Observatory, Euclid, Roman Space Telescope, and the Simons Observatory will be crucial for determining whether these hints of dynamical dark energy persist or are due to statistical fluctuations or residual systematics in low-redshift supernova samples. The talk is based on the review paper: Phys.Dark Univ. 51 (2026) 102196.

Prof. Alexander F. Zakharov, PhD (National Research Center – Kurchatov Institute, Moscow, Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Russia)
Title: Astrophysical black holes as laboratories for gravity theories
Abstract: Recent observations of supermassive black holes (such as Sgr A* in the Galactic Center and M87*) made by the Event Horizon Telescope (EHT) collaboration, as well as gravitational wave detections of binary black hole mergers by LIGO/Virgo/KAGRA, open a new era in testing general relativity and alternative theories of gravity in strong-field regimes. We discuss how shadows of black holes and accretion disk emission profiles can serve as robust probes to constrain alternative/modified theories of gravity, wormholes, and naked singularities. Particular emphasis is placed on future space-based and ground-based interferometric projects that will significantly improve angular resolution and allow us to distinguish between general relativity and competing theoretical models.