Fantastic Fits with fantasy of Active Galactic Nuclei Spectra -- Exploring the Fe II emission near the Hα\alpha line

In this study, a refined approach for multicomponent fitting of active galactic nuclei (AGN) spectra is presented utilizing the newly developed Python code $fantasy$ (fully automated python tool for AGN spectra analysis). AGN spectra are modeled by simultaneously considering the underlying broken power-law continuum, predefined emission line lists, and an Fe II model, which is here extended to cover the wavelength range 3700 - 11000 A. The Fe II model, founded solely on atomic data, effectively describes the extensive emission of the complex iron ion in the vicinity of the H$\gamma$ and H$\beta$ lines, as well as near the H$\alpha$ line, which was previously rarely studied. The proposed spectral fitting approach is tested on a sample of high-quality AGN spectra from the Sloan Digital Sky Survey (SDSS) Data Release 17. The results indicate that when Fe II emission is present near H$\beta$, it is also detected redward from H$\alpha$, potentially contaminating the broad H$\alpha$ line wings and thus affecting the measurements of its flux and width. The production of Fe II emission is found to be strongly correlated with Eddington luminosity and appears to be controlled by the similar mechanism as the hydrogen Balmer lines. The study highlights the benefits of fitting AGN type 1 spectra with the $fantasy$ code, pointing that it may be used as a robust tool for analyzing a large number of AGN spectra in the coming spectral surveys.Comment: Accepted in ApJ

The intrinsic Baldwin effect in broad Balmer lines of six long-term monitored AGNs

We investigate the intrinsic Baldwin effect (Beff) of the broad H$\alpha$ and H$\beta$ emission lines for six Type 1 active galactic nuclei (AGNs) with different broad line characteristics: two Seyfert 1 (NGC 4151 and NGC 5548), two AGNs with double-peaked broad line profiles (3C 390.3 and Arp 102B), one narrow line Seyfert 1 (Ark 564), and one high-luminosity quasar with highly red asymmetric broad line profiles (E1821+643). We found that a significant intrinsic Beff was present in all Type 1 AGNs in our sample. Moreover, we do not see strong difference in intrinsic Beff slopes in different types of AGNs which probably have different physical properties, such as inclination, broad line region geometry, or accretion rate. Additionally, we found that the intrinsic Beff was not connected with the global one, which, instead, could not be detected in the broad H$\alpha$ or H$\beta$ emission lines. In the case of NGC 4151, the detected variation of the Beff slope could be due to the change in the site of line formation in the BLR. Finally, the intrinsic Beff might be caused by the additional optical continuum component that is not part of the ionization continuum.Comment: 12 pages, 8 figures, Accepted for publication in A&

Black holes, gravitational waves and fundamental physics: a roadmap

The grand challenges of contemporary fundamental physics—dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem—all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'

Student Performance on an E-Learning Platform: Mixed Method Approach

E-learning is considered a leading application of digital technologies in educational systems. The aim of the paper is to explore the utilization and impact of digital technologies on an e-learning platform. For this purpose, research was conducted at the Moodle learning management system. Data from the e-learning platform were empirically evaluated in order to find key indicators of student performance in different courses. Student success with the e-learning system was evaluated using a mixed-method: Social Network Analysis, K-Means Clustering, and Multiple Linear Regression. The research was conducted at the University of Novi Sad, Faculty of Technical Sciences, Serbia. The results indicate a significant relationship between the performance of students and the use of digital educational resources from the e-learning platform

Supramolecular Perspective of Coordination Effects on Fluorine Interactions

Coordination effects have been considered through the most common interactions in the crystal structures of fluoro compounds (C-H/F and F/F interactions). The supramolecular profile of these effects is based on quantum-chemical calculations for the assessment of the interaction strength and electrostatic potential maps, which provide a qualitative insight into the examined effect. Coordination of aliphatic fluorides leads to an increase of the negative potential of the F atoms, and, hence, an increase in the hydrogen-bonding acceptor ability (strengthening of C-H/F interactions) and a weakening of the F/F interactions, due to an increase in repulsive interactions between the F atoms. There is no significant change in the potential of the F atoms due to coordination of C-6-aromatic fluorides, as in the case of aliphatic ones. This results in slight changes in the strengths of the C-H/F and F/F interactions (coupled with parallel interaction at large offsets, PILO), in a noticeable enhancement of stacking interactions, as well as in a significant enhancement of interactions involving the pi-system (F/pi - and C-H/pi interactions). It has also been shown that a decrease in the charge of the metal ions leads to a decrease in the negative potential of the F atom and also that the nature of the metal ion has a significant influence on the value of the potential of the F atoms