Conveners
Extragalactic astrophysics and cosmology
- Iryna Chemerynska (Institut d'Astrophysique de Paris, Paris, France)
- Olena Shubina (Astronomical Institute of Slovak Academy of Sciences, Stará Lesná, Slovakia)
Large-scale structures (LSS) form via relentless action of gravitational forces on density perturbations over cosmic length and time scales. Thus, the non-linear regime of LSS formation is sensitive to the underlying theory of gravity, and hence provides estimates for observables that can help distinguish modified gravity effects from the expected standard GR results. In this work, I focus on...
We studied scalar field φCDM models: ten quintessence models and seven phantom models. We reconstructed these models, using the phenomenological method developed by us. Resulting in, for each potential the following ranges were found: (i) model parameters; (ii) EoS parameters; (iii) initial conditions for differential equations, which describe the dynamics of the universe. Using the MCMC...
We present the results of photometrical observations of hyperbolic comet C/2013 X1 (Pan-STARRS) in broadband Johnson-Cousins filters. Data were obtained during the pre-perihelion passage of the comet in the period December 2015 - January 2016 using the 61-cm telescope at the Scalnat\'{e} Pleco observatory. Analyzing the dust productivity via $Af\rho$ proxy, we revealed a sharp increase in...
Toroidal (or ring) structures are quite common objects in the Universe. For example, these are obscuring dust tori in active galactic nuclei (ANGs), protoplanetary and accretion disks, ring galaxies, etc. In some objects, where the torus can be massive enough, it affects the motion and dynamics of matter. N-body simulations of the torus in the field of the central mass show that the...
Zone of Avoidance (ZoA) is the sky area that is blocked from extragalactic observations by the plane of our own Galaxy. It covers approximately 20% of the sky in the optical and poses significant problems for these cosmological tests that require full-sky coverage, necessitating compensation, usually by artificial filling. There are many possibilities of filling the ZoA with artificial...
The standard hierarchical model of galaxy formation predicts that small objects form first before growing and merging into more massive objects. In this context, the shape of the luminosity and mass distribution of galaxies provides a direct constraint on galaxy formation models. The interplay between gas accretion and feedback is likely reflected in the shape of the luminosity function (LF)...
We present the detailed analysis of 11 local luminous infrared galaxies (LIRGs) from ultraviolet, through far-infrared to radio ($\sim$70\, MHz to $\sim$15\,GHz) bands. We derive the physical properties through spectral energy distribution (SED) modeling using the Code Investigating GALaxy Emission (CIGALE) and UltraNest codes. The radio SEDs include our new observations at 325 and 610\,MHz...
Cosmic voids gravitationally lens the cosmic microwave background(CMB). This weak lensing shows itself as negative convergence(kappa) imprint on the CMB lensing map. We use one of the largest available sky surveys(Dark Energy Survey Y3) and Planck 2018 CMB lensing map along with a simulated CMB lensing convergence map from the MICE N-body simulation to calibrate our detection. We stack void...
Within the standard paradigm of cosmology, the hierarchical growth of dark matter perturbations is an essential assumption to explain galaxy formation. As a consequence, the relevance of dark matter halos for probing large-scale structure has motivated the search for a quantitative understanding of their abundance. Although computational cosmology has so far been the main arena for determining...
Galaxies live in dark matter haloes and hence the galaxy properties are majorly defined by the properties of the haloes. Thus the environmental dependence of dark matter halo properties prompts a correlation between galaxy properties and the environment. In this talk, I will discuss the results from our recent works (arXiv:2102.04177 and arXiv:2201.10480) that explored how luminosities in...
The intergalactic medium is revealed by the numerous absorption lines of neutral Hydrogen H~{\sc i} (the so-called Ly$\alpha$ forest) seen in the spectra of distant quasars ($z > 2$), which traces the thermal and radiative history of the Universe, as well as the evolution of underlying matter distribution over a wide range of scales and redshifts. It is possible due to the relation of the...
The global redshifted 21cm signal emitted by neutral hydrogen at radio frequencies offers novel insights into the birth of the first stars, known as the Cosmic Dawn, which is currently a largely unexplored chapter in our universe's history. The Mapper of the IGM Spin Temperature (MIST) is a multi-institutional collaboration that aims to observe the global 21cm signal from some of the most...
Ionosphere impact may be critical for radio observations below 100 MHz. The three dominating effects in the ionosphere - attenuation, emission and refraction - not only depend on the observational frequency but also change with time due to day-to-day variations in electron density. To account for these temporal variations, we created a global, dynamic model of the ionosphere. Our model uses a...
The ALBATROS experiment is composed of an array of radio telescopes operating in the 1.2 – 125Mhz range with the aim of laying the groundwork for probing the cosmic dark ages (<30Mhz) through measurement of the 21cm redshifted emission of neutral hydrogen. To better understand the behaviour of the antennas used in this array, we propose to fly a transmission source mounted to a custom-built...
Mapping Dark Matter Using Gravitational Lensing Techniques/SuperBIT
Mila Arasu (Sunanda Thirunavukkarasu)
Galaxy clusters are one of the primary tools for constraining dark matter when combined with the distortion of light from distant galaxies as it travels through a cluster’s gravitational potential. Constraining cosmology by measuring cluster abundance proves to be extremely challenging...
AGNs are very powerful galaxies characterized by extremely bright emissions coming out from their central massive black holes. Knowing the redshifts of AGNs provides us an opportunity to determine their distance to investigate important astrophysical problems such as the evolution of the early stars, their formation along with the structure of early galaxies. The redshift determination is...
