相关论文: Simulations of cluster ultra-diffuse galaxies in M…

We present preliminary results of an extensive study of the fundamental properties of dwarf elliptical galaxies (dEs) in the Coma cluster. Our study will combine HST surface photometry with ground-based UBRIJK photometry and optical…

The hot gas permeating galaxy clusters-the intracluster medium (ICM)-is a key tracer of their assembly history and internal dynamics. Understanding the motion of this gas provides critical insight into processes such as mergers, turbulence,…

We reconsider the hypothesis of a vast cometary reservoir surrounding the Solar System - the Oort cloud of comets - within the framework of Milgromian Dynamics (MD or MOND). For this purpose we built a numerical model of the cloud assuming…

A numerical simulation model of the injection and cooling of nonthermal particles energized by shocks formed in merging clusters of galaxies is used to fit radio and X-ray data observed from the Coma cluster of galaxies. The results are…

Galactic discs are known to have exponential radial profiles in luminosity and stellar surface density in their bright inner regions. Nonetheless, their faint outer regions often display a break, with either a down-bending or an up-bending…

We have investigated the peculiar motions of clusters of galaxies in the Ursa Major (UMa) supercluster and its neighborhood. Based on SDSS (Sloan Digital Sky Survey) data, we have compiled a sample of early-type galaxies and used their…

Spectroscopic studies of low-luminosity early-type galaxies are essential to understand their origin and evolution but remain challenging because of low surface brightness levels. We describe an observational campaign with the new…

We show, using global 3D grid-based hydrodynamical simulations, that Ultra Fast Outflows (UFOs) from Active Galactic Nuclei (AGN) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy.…

The Fornax dwarf spheroidal galaxy has five massive globular clusters (GCs). They are often used for testing different dark matter and modified gravity theories, because it is difficult to reconcile their old stellar ages with the short…

In addition to their low stellar densities, ultra-diffuse galaxies (UDGs) have a broad variety of dynamical mass-to-light ratios, ranging from dark matter (DM) dominated systems to objects nearly devoid of DM. To investigate the origin of…

A main topic at this meeting is how galaxies are affected when they enter for the first time the cluster environment from the outskirts. Most of the times we are forced to infer the environmental effects indirectly, relying on systematic…

We present a new Particle-Mesh cosmological N-body code for accurately solving the modified Poisson equation of the Quasi Linear formulation of MOND. We generate initial conditions for the Angus (2009) cosmological model, which is identical…

The survival of unbound density substructure against orbital mixing imposes strong constraints on the slope of the underlying gravitational potential and provides a new test on modified gravities. Here we investigate whether the…

Ultra-diffuse galaxies (UDGs) are attractive candidates to probe cosmological models and test theories of galaxy formation at low masses; however, they are difficult to detect because of their low surface brightness. In the Local Group a…

We present Hubble Space Telescope imaging of 14 gas-rich, low surface brightness galaxies in the field at distances of 25-36 Mpc, with mean effective radii and $g$-band central surface brightnesses of 1.9 kpc and 24.2 mag arcsec$^{-2}$.…

Modified Newtonian Dynamics (MOND) has been shown to be able to fit spiral galaxy rotation curves as well as giving a theoretical foundation for empirically determined scaling relations, such as the Tully - Fisher law, without the need for…

We have discovered a new type of galaxy in the Fornax Cluster: ``ultra-compact'' dwarfs (UCDs). The UCDs are unresolved in ground-based imaging and have spectra typical of old stellar systems. Although the UCDs resemble overgrown globular…

The distributions of peculiar velocities of rich clusters and of groups of galaxies are investigated for different cosmological models and are compared with observations. Four cosmological models are studied: standard ($\Omega=1$) CDM,…

We have carried out a study of the velocity dispersion of the stars in the outskirts of the globular cluster Omega Centauri, finding that the velocity dispersion remains constant at large radii rather than decrease monotonically. The…

The Modified Newtonian Dynamics (MOND) generically predicts a violation of the strong version of the equivalence principle. As a result the gravitational dynamics of a system depends on the external gravitational field in which the system…