Conveners
Astrophysics and Cosmology
- Anton Rudakovskyi (Bogolyubov Institute for Theoretical Physics)
The 21 cm line of neutral hydrogen provides a powerful observational window into the early Universe, particularly during the Dark Ages (redshifts ( z \sim 30\text{--}200 )), before the emergence of the first luminous objects. In this work, presented a theoretical study of the angular power spectrum ( C_\ell ) of 21 cm brightness temperature fluctuations and its dependence on key...
We study the impact of primordial magnetic fields on the global 21 cm signal during the Dark Ages. By modeling magnetic heating effects, we show that the signal is sensitive to PMFs amplitude and spectral index, offering a potential probe of early-universe magnetogenesis with upcoming 21 cm observations.
In the recent sixth data release (DR6) of the Atacama Cosmology Telescope (ACT) collaboration, the value of $n_{\rm s}=0.9743 \pm 0.0034$ for the scalar spectral index is reported, which excludes the Starobinsky and Higgs inflationary models at $2\sigma$ level. In this paper, we perform a Bayesian inference of the parameters of the Starobinsky or Higgs inflationary model with non-instantaneous...
Electromagnetic fields of pulsars can generate coherent axion signals at their rotational frequencies, which may be detected by laboratory experiments—pulsarscopes. As a promising case study, we model axion emission from the well-studied Crab pulsar, predicting a signal at $f \approx 29.6$ Hz that would be present regardless of whether axions contribute to the dark matter abundance. We...
Among popular candidates for dark matter (DM) particles are weakly interacting massive particles (WIMPs) with masses of the order of 100 GeV, sterile right-handed neutrinos with masses of several keV, and axion-like particles with masses of $\mu$eV. We consider a model of ultralight dark matter (ULDM) because of its interesting phenomenology. ULDM is composed of bosonic particles with masses...
We present the first steps of a new approach aimed at improving photoionization analysis in dwarf galaxies by replacing unresolved features in chemodynamical simulations (Recchi and Hensler 2013) with physically consistent structures from hydrodynamical modeling. In previous works (Melekh et al. 2015, 2024), artificial thin dense shells (TDS) were introduced to emulate shock fronts that could...
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The epoch of cosmic reionization marks a pivotal stage in the history of the Universe, during which the first sources of ionizing radiation transformed the intergalactic medium from a neutral to an ionized state. While it was traditionally believed that massive galaxies and quasars played the dominant role in this process, recent observations and theoretical models increasingly suggest that...
Photoionization modelling allows us to monitor the radiation transfer taking into account all important processes in nebular plasmas.
The spatial distributions of densities , chemical abundances and temperatures are needed for such modelling were obtained from chemodynamical simulations of dwarf galaxies. In present work we check the reliability of older version of CLOUDY C08.00 [1] in...
