First author: Nhat-Minh Nguyen
We present evidence for a suppressed growth rate of large-scale structure during the dark-energy dominated era. Modeling the growth rate of perturbations with the ``growth index’’ $\gamma$, we find that current cosmological data strongly prefer a higher growth index than the value $\gamma=0.55$ predicted by general relativity in a flat $\Lambda$CDM cosmology. Both the cosmic microwave background data from Planck and the large-scale structure data from weak lensing, galaxy clustering, and cosmic velocities separately favor growth suppression.
First author: Roman Krivonos
We present the results of our study of the X-ray emission from the Ophiuchus galaxy cluster based on INTEGRAL/IBIS data in the energy range 20-120 keV. Our goal is the search for a nonthermal emission component from the cluster. Using the INTEGRAL data over the period of observations 2003-2009, we have constructed the images of the Ophiuchus galaxy cluster in different energy bands from 20 to 120~keV with the extraction of spectral information.
First author: Jun-Sung Moon
We develop a new model within which the radius-dependent transition of the galaxy inner spins with respect to the cosmic web and the variation of the transition threshold radius ($r_{\rm th}$) with galaxy mass ($M_{\rm vir}$), smoothing scale ($r_{f}$), and redshift ($z$) can be coherently explained. The key tenet of this model is that the competition between the pressure effect of the inner mass and the compression effect of the local tidal field determines which principal direction of the tidal field the inner spins are aligned with.
First author: I. E. López
Studies indicate strong evidence of a scaling relation in the local Universe between the supermassive black hole mass ($M_\rm{BH}$) and the stellar mass of their host galaxies ($M_\star$). They even show similar histories across cosmic times of their differential terms: star formation rate (SFR) and black hole accretion rate (BHAR). However, a clear picture of this coevolution is far from being understood. We select an X-ray sample of active galactic nuclei (AGN) up to $z=2.
First author: Carrie Filion
Many disc galaxies host galactic bars, which exert time-dependent, non-axisymmetric forces that can alter the orbits of stars. There should be both angle and radius-dependence in the resulting radial re-arrangement of stars (‘radial mixing’) due to a bar; we present here novel results and trends through analysis of the joint impact of these factors. We use an N-body simulation to investigate the changes in the radial locations of star particles in a disc after a bar forms by quantifying the change in orbital radii in a series of annuli at different times post bar-formation.
First author: Aaron Ouellette
We use topological summaries based on Betti curves to characterize the large-scale spatial distribution of simulated dark matter haloes and galaxies. Using the IllustrisTNG and CAMELS-SAM simulations, we show that the topology of the galaxy distribution is significantly different from the topology of the dark matter halo distribution. Further, there are significant differences between the distributions of star-forming and quiescent galaxies. These topological differences are broadly consistent across all simulations, while at the same time there are noticeable differences when comparing between different models.
First author: Radosław Wojtak
The currently used standardisation of type Ia supernovae results in Hubble residuals whose physical origin is unaccounted for. This poses a limitation to the accuracy and precision of distances that can be derived from supernova observations. Here, we present a complete physical interpretation of the Hubble residuals based on a novel Bayesian hierarchical model of type Ia supernovae in which latent variables describing intrinsic and extrinsic (dust related) supernova properties originate from two populations.
First author: I. Georgantopoulos
We explore the properties of the host galaxies of X-ray selected AGN in the COSMOS field using the Chandra Legacy sample and the LEGA-C survey VLT optical spectra. Our main goal is to compare the relative ages of the host galaxies of the obscured and unobscured AGN by means of the calcium break Dn(4000) and the Hdelta Balmer line. The host galaxy ages are examined in conjunction with other properties such as the galaxy stellar mass, and star-formation rate as well as the AGN Eddington ratio.
First author: Alvaro Pozo
Low mass galaxies in the Local Group are dominated by dark matter and comprise the well studied dwarf Spheroidal" (dSph) class, with typical masses of $10^{9-10}M_\odot$ and also the equally numerous ultra faint dwarfs" (UFD), discovered recently, that are distinctly smaller and denser with masses of only $10^{7-8}M_\odot$. This bimodality amongst low mass galaxies contrasts with the scale free continuity expected for galaxies formed under gravity, as in the standard Cold Dark Matter (CDM) model for heavy particles.
First author: Euclid Collaboration
The photometric catalogue of galaxy clusters extracted from ESA Euclid data is expected to be very competitive for cosmological studies. Using state-of-the-art hydrodynamical simulations, we present systematic analyses simulating the expected weak lensing profiles from clusters in a variety of dynamic states and at wide range of redshifts. In order to derive cluster masses, we use a model consistent with the implementation within the Euclid Consortium of the dedicated processing function and find that, when jointly modelling mass and the concentration parameter of the Navarro-Frenk-White halo profile, the weak lensing masses tend to be, on average, biased low with respect to the true mass.
