First author: Marta Galbiati
We use 28 quasar fields with high-resolution (HIRES and UVES) spectroscopy from the MUSE Analysis of Gas Around Galaxies survey to study the connection between Ly${\alpha}$ emitters (LAEs) and metal-enriched ionized gas traced by CIV in absorption at redshift $z\approx3-4$. In a sample of 220 CIV absorbers, we identify 143 LAEs connected to CIV gas within a line-of-sight separation ${\rm \pm 500,km,s^{-1}}$, equal to a detection rate of $36\pm 5$ per cent once we account for multiple LAEs connected to the same CIV absorber.
First author: Esraa Ali Elkhateeb
In this work, we reconstruct the cosmological unified dark fluid model proposed previously by Elkhateeb \cite{Elkhateeb:2017oqy} in the framework of $f(R)$ gravity. Utilizing the equivalence between the scalar-tensor theory and the $f(R)$ gravity theory, the scalar field for the dark fluid is obtained, whence the $f(R)$ function is extracted and its viability is discussed. The linear growth of matter perturbations on the low redshifts is studied in our constructed $f(R)$ function, and the results are in good agreement with those from the $\Lambda$CDM model for the dark universe.
First author: Léo Vacher
One of the few firm predictions of string theory is the existence of a massless scalar field coupled to gravity, the dilaton. In its presence, the value of the fundamental constants of the universe, such as the fine-structure constant, will vary with the time-dependent vacuum expectation value of this field, in direct violation of the Einstein Equivalence Principle. The \emph{runaway dilaton} proposed by Damour, Piazza, and Veneziano provides a physically motivated cosmological scenario which reconciles the existence of a massless dilaton with observations, while still providing non-standard and testable predictions.
First author: Agnibha De Sarkar
We present a simple phenomenological model of hadronic interaction between protons accelerated in an old supernova remnant (SNR) and cold protons situated within the associated molecular clouds (MCs). The accelerated protons from the old SNR escaped the SNR shock front, and got injected into the MCs at an earlier time, producing ultra high energy gamma-rays and neutrinos through inelastic proton-proton interaction. We also take into account the acceleration and subsequent escape of electrons from the SNR shock front.
First author: Frank M. Rieger
The last decade has seen tremendous developments in gamma-ray astronomy with the extragalactic sky becoming highly populated by Active Galactic Nuclei (AGNs). This brief review highlights some of the progress in AGN research achieved over the years, and discusses exemplary advances in the theory and physics of gamma-ray loud AGNs, including black-hole magnetospheric processes, the physics of pc-scales jets, as well as particle acceleration and high-energy emission in the large-scale jets of AGNs.
First author: Huynh Anh N. Le
We present a study of the relation between the $[OIII]$ 5007A emission line width (sigma_{$[OIII]$}) and stellar velocity dispersion (sigma_{}), utilizing a sample of 740 type 1 active galactic nuclei (AGNs) with high-quality spectra at redshift z < 1.0. We find the broad correlation between the core component of $[OIII]$ emission line width (sigma_{$[OIII,core]$}) and sigma_{} with a scatter of 0.11~dex for the low redshift (z < 0.
First author: James Negus
Despite the importance of AGN in galaxy evolution, accurate AGN identification is often challenging, as common AGN diagnostics can be confused by contributions from star formation and other effects (e.g., Baldwin-Phillips-Terlevich diagrams). However, one promising avenue for identifying AGNs are coronal emission lines" (CLs"), which are highly ionized species of gas with ionization potentials $\ge$ 100 eV. These CLs may serve as excellent signatures for the strong ionizing continuum of AGN.
First author: Louis Gabarra
The next generation of wide spectroscopic surveys such as Euclid will scan the sky in the near-infrared to obtain both photometry and spectroscopy. For this purpose, the Euclid telescope will rely on a Near-Infrared Spectrometer and Photometer (NISP) instrument whose spectroscopic channel has been designed to operate in slitless configuration. This powerful and easy to operate configuration makes it possible to avoid any prior selection on the targeted galaxies while covering the entire field of view.
Rajendra P. Gupta
Equations governing the evolution of a star involve multiple coupling constants. Thus, the time it spends as a main-sequence star can be expected to depend on whether or not such constants vary over the time scale of stellar evolution. When the star belongs to a globular cluster, the star's age cannot exceed that of the globular cluster, and the latter cannot exceed the age of the Universe.
First author: Louis Gabarra
Spectral energy distribution (SED) models of galaxies at 0.3 <= z <= 2.5 were constructed to be processed by the Euclid spectroscopic channel simulator in order to investigate the Euclid Near- Infrared Spectrometer and Photometer (NISP) capabilities. We developed a solid methodology to build a realistic and representative synthetic SED library of star-forming galaxies, including reliable emission line fluxes and widths. The construction of the SEDs consists in computing the continuum using the Bruzual & Charlot (2003) models, calling out SED fitting parameters available in publicly released multi-wavelength catalogues.
