The hypothesis that the late Universe is isotropic and homogeneous is a cornerstone of the standard cosmological model. The cosmic expansion rate H0 is assumed to be spatially constant, while bulk flow motions are believed to be negligible for scales larger than 200 Mpc. Any deviation from this consensus can strongly bias the results of cosmological studies and can put the validity of the Cosmological Principle and ΛCDM under question. Scaling relations of galaxy clusters can be effectively used for testing the assumption of isotropy. By measuring many different cluster properties, several scaling relations with different cosmological sensitivities can be built. Nearly independent tests of cosmic isotropy and large bulk flows are then feasible. We use up to 570 clusters with measured properties at X-ray, microwave, and infrared wavelengths to construct ten different cluster scaling relations and test the isotropy of the local Universe. Through rigorous and robust tests, we ensure that our analysis is not prone to systematic biases and X-ray absorption issues. By combining all available information, we detect an apparent 9% spatial variation in the local Hubble constant, H0. The observed anisotropy has a nearly dipole form. Using isotropic Monte Carlo simulations, we assess the statistical significance of the anisotropy to be >5 sigma. This result could also be attributed to a 900 km/s cluster bulk flow, which seems to extend out to at least 500 Mpc. These two effects will be indistinguishable until more distant clusters are observed and new low-scattered cluster scaling relations are utilized.

Predicting the solar wind characteristics at Earth is of utmost importance not only for forecasting medium- to large-scale geomagnetic storms caused by fast solar wind streams, but also for predicting large-scale geomagnetic storms caused by coronal mass ejections (CMEs). Such storms mainly occur during periods of high solar activity and can lead to power grid outages and damages to oil and gas pipelines. CMEs propagate within the solar wind, therefore, realistic modeling of the latter is imperative to predict extreme space weather phenomena. The European Heliospheric Forecasting Information Asset (EUHFORIA, Pomoell & Poedts, 2018) is a 3D magnetohydrodynamics space weather forecasting tool for modeling solar wind and CMEs within the inner heliosphere. It consists of two parts: the coronal part which extends from the solar photosphere until 0.1 AU, and the heliospheric part which extends from 0.1 AU onwards. In this talk, we will explain how this state-of-the-art model works for predicting space weather conditions at Earth. We will discuss recent efforts for improving solar wind predictions with EUHFORIA, as well as current limitations. We will also address the important role of metrics and show applications for assessing the quality of our model’s performance.

AGN-launched jets are a crucial element in the study of super-massive black holes (SMBH) and their closest surroundings. The formation of such jets, whether they are launched by magnetic field lines anchored to the accretion disk or directly connected to the black hole’s (BH) ergosphere, is the subject of ongoing, extensive research. 3C 84, the compact radio source in the central galaxy NGC 1275 of the Perseus super-cluster, is a prime laboratory for testing such jet launching scenarios, as well as studying the innermost AGN structure and jet origin. Very long baseline interferometry (VLBI) offers a unique view into the physical processes in action, in the immediate vicinity of BHs, unparalleled by other obser- vational techniques. With VLBI at short (millimeter) wavelengths particular high angular resolutions are obtained. Utilising such mm-VLBI observations of 3C84, we determine the true position of its BH, the magnetic field strength and its con- figuration. We furthermore study the jet kinematics of the VLBI core of 3C84 by employing the largest historical, highly sensitive mm-VLBI data set of this source. In this talk I will present our most recent results and offer a comprehensive summary of jet launching in 3C 84.

White dwarfs (WDs) are the end stage of low mass stars and they can often be found in binaries. When a WD accretes mass from a binary companion it may end up in a thermonuclear explosion known as Type Ia Supernova, leaving no compact remnant. However, there is an alternative scenario in which massive WDs undergo electron capture because of their high central densities leading to a core collapse. This event is known as Accretion Induced Collapse. The aim of our project is to explore the dynamics and explosion outcome from different progenitors and set limits in the nucleosynthesis that occurs in these events.

The magnetospheres of giant planets in our Solar System (Jupiter and Saturn), are a unique type of space laboratories for magnetized plasma. Their rapid rotation, composition and size result in major differences compared to the terrestrial magnetosphere, the most prominent being the presence of a disc-type magnetic structure. A global model of these magnetospheres, including the “magnetodisc”, can be constructed via an iterative scheme first presented by Caudal (1986). We improve Caudal's model for the Jovian magnetosphere, implementing now a numerical algorithm (Pontius,1997) to calculate more accurately the plasma angular velocity. An interesting application of the model is the study of the compressibility of the Jovian magnetosphere and the effect on particle trajectories.