First author: Wilmar Cardona
Interesting discrepancies in cosmological parameters are challenging the success of the $\Lambda$CDM model. Direct measurements of the Hubble constant $H_0$ using Cepheid variables and supernovae turn out to be higher than inferred from the Cosmic Microwave Background (CMB). Weak galaxy lensing surveys consistently report values of the strength of matter clustering $\sigma_8$ lower than values derived from the CMB in the context of $\Lambda$CDM. In this paper we address these discrepancies in cosmological parameters by considering Dark Energy (DE) as a fluid with evolving equation of state $w_{\mathrm{de}}(z)$, constant sound speed squared $\hat{c}{\mathrm{s}}^{2}$, and vanishing anisotropic stress $\sigma$.
First author: David Garofalo
Jet re-orientation associated with the time evolution of radio quasars explains the formation of X-shaped radio galaxies and their preference for isolated environments. But since X-shaped radio galaxies are generally not found in dense environments (e.g. groups/clusters), the jet re-orientation phenomenon for radio galaxies in groups and clusters has been ignored. We take a closer look at the re-orientation of FRI jets with respect to FRII jets, and find that it may constitute the as-yet unidentified trigger for star formation suppression in radio galaxies.
First author: Zi-Qing Xia
The fast evolving TeV-PeV transients and their delayed GeV-TeV cascade emission in principle server as an ideal probe of the inter-galactic magnetic fields which are hard to be measured by other methods. Very recently, LHASSO has detected the very high energy emission of the extraordinary powerful GRB 221009A up to $\sim 18$ TeV within $\sim 2000$ s after the burst trigger. Here we report the detection of a $\sim 400$ GeV photon, without accompanying prominent $\gamma$ rays down to $\sim 2$ GeV, by Fermi-LAT in the direction of GRB 221009A at about 0.
First author: Andrei M. Beloborodov
Magnetospheres of neutron stars can be perturbed by star quakes or interaction in a binary system. The perturbations are typically in the kHz band and excite magnetohydrodynamic (MHD) waves. We show that compressive magnetospheric waves steepen into monster shocks mediated by radiation reaction, different from normal collisionless shocks. The shocks admit a simple analytical description. They expand through the magnetosphere with radiative losses, and then a blast wave is launched into the neutron-star wind.
First author: Amira A. Tawfeek
We present a study of barred galaxies in the cluster environment, exploiting a sample of galaxies drawn from the extended WIde-field Nearby Galaxy-cluster Survey (OmegaWINGS) that covers up to the outer regions of 32 local X-ray selected clusters. Barred galaxies are identified through a semi-automatic analysis of ellipticity and position angle profiles. We find, in agreement with previous studies, a strong co-dependence of the bar fraction with the galaxy stellar mass and morphological type, being maximum for massive late-type galaxies.
First author: Saeed Fakhry
Cosmic voids are known as underdense substructures of the cosmic web that cover a large volume of the Universe. It is known that cosmic voids contain a small number of dark matter halos, so the existence of primordial black holes (PBHs) in these secluded regions of the Universe is not unlikely. In this work, we calculate the merger rate of PBHs in dark matter halos structured in cosmic voids and determine their contribution to gravitational wave events resulting from black hole mergers recorded by the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO)-Advanced Virgo (aVirgo) detectors.
First author: M. A. Cordiner
The presence of phosphine (PH$_3$) in the atmosphere of Venus was reported by Greaves et al. (2021a), based on observations of the J=1-0 transition at 267 GHz using ground-based, millimeter-wave spectroscopy. This unexpected discovery presents a challenge for our understanding of Venus’s atmosphere, and has led to a reappraisal of the possible sources and sinks of atmospheric phosphorous-bearing gases. Here we present results from a search for PH$_3$ on Venus using the GREAT instrument aboard the SOFIA aircraft, over three flights conducted in November 2021.
Pascale Berner
The analysis of cosmological galaxy surveys requires realistic simulations for their interpretation. Forward modelling is a powerful method to simulate galaxy clustering without the need for an underlying complex model. This approach requires fast cosmological simulations with a high resolution and large volume, to resolve small dark matter halos associated to single galaxies. In this work, we present fast halo and subhalo clustering simulations based on the Lagrangian perturbation theory code PINOCCHIO, which generates halos and merger trees.
First author: C. L. Carilli
We present simulations of the capabilities of the ngVLA to image at $\sim 0.75$ kpc resolution ($0.085"$), molecular line emission from star forming disk galaxies at high redshift. The results are compared to the current capabilities of ALMA. ALMA can detect the integrated emission, and determine the velocity gradient and size across the brighter emission regions of the galaxy. The ngVLA is a factor $\sim 6$ more sensitive at the adopted spatial and velocity resolution.
First author: Meris Sipp
AI super-resolution, combining deep learning and N-body simulations has been shown to successfully reproduce the large scale structure and halo abundances in the Lambda Cold Dark Matter cosmological model. Here, we extend its use to models with a different dark matter content, in this case Fuzzy Dark Matter (FDM), in the approximation that the difference is encoded in the initial power spectrum. We focus on redshift z = 2, with simulations that model smaller scales and lower masses, the latter by two orders of magnitude, than has been done in previous AI super-resolution work.
