Related papers: Galactic Traversability: A New Concept for Extraga…
Theoretical considerations and observational data support the idea that mergers were more frequent in the past. At redshifts z = 2 to 5, violent interactions and mergers may be implicated by observations of Lyman-break galaxies, sub-mm…
Recent observations show that spiral galaxies are surrounded by extended gaseous halos as predicted by the hierarchical structure formation scenario. The origin and nature of extraplanar gas is often unclear since the halo is continuously…
I set the stage for discussion of the stellar populations in interacting galaxies by looking back over the slow development of our understanding of these systems. From early anecdotal collections, to systematic cataloging, and finally to…
The Interstellar Medium (ISM) is a complex, multi-phase system, where the history of the stars occurs. The processes of birth and death of stars are strongly coupled to the dynamics of the ISM. The observed chaotic and diffusive motions of…
Theoretical models have suggested peculiar velocity dispersion profiles of star clusters facing dissolution. They predicted that, besides bound stars that still belong to the star cluster, and unbound ones already stripped off, there is an…
Determining the spatial distribution of Galactic cosmic rays (CRs) is fundamental to understand how these particles propagate in interstellar space and to infer their source spectra. The most sensitive method of studying this problem is…
There is a strong connection between the formation of a disk galaxy and the properties of the interstellar medium (ISM). Theoretical work has typically either focused on the cosmological buildup of a galaxy with a relatively crude model for…
We predict that there is a population of low-luminosity dwarf galaxies orbiting within the halo of the Milky Way that have surface brightnesses low enough to have escaped detection in star-count surveys. The overall count of stealth…
The search for planets orbiting other stars has recently expanded to include stars from galaxies outside the Milky Way. With the TESS and Gaia surveys, photometric and kinematic information can be combined to identify transiting planet…
We use data from the Evolution and Assembly of GaLaxies in their Environment (EAGLE) cosmological simulation to study properties of galaxies in the cosmic web. Galaxies become more redder and form stars at a lower rate relative to their…
The distribution of nearby (cz < 7500 km/s) galaxies has been explored by minimal spanning trees; allowance has been made for the drastic decrease of data with distance. The investigation finds that all galaxies are members of irregular…
Due to the foreground extinction of the Milky Way, galaxies appear increasingly fainter the closer they lie to the Galactic Equator, creating a "zone of avoidance" of about 25% in the distribution of optically visible galaxies. A…
Globular clusters will be present at high redshifts, near the very beginning of the galaxy formation process. Stellar evolution ensures that they will be much more luminous than today. We show that the redshift distribution at nano-Jansky…
The enrichment of the intergalactic medium (IGM) with heavy elements provides us with a record of past star formation and with an opportunity to study the interactions between galaxies and their environments. We summarize current data…
I propose the Cosmic Hitchhikers hypothesis as follows. Advanced extraterrestrial civilizations may use free-floating planets as interstellar transportation for space exploration and interstellar colonization. Large groups or populations of…
The circumgalactic medium (CGM) of galaxies serves as a record of the influences of outflows and accretion that drive the evolution of galaxies. Feedback from star formation drives outflows that carry mass and metals away from galaxies to…
In this article I review recent observations of the gaseous halos of galaxies and the intergalactic medium at low redshift. In the first part I discuss distribution, metal content, and physical properties of the Galactic intermediate- and…
Galaxies are surrounded by extended atmospheres, which are often called the circumgalactic medium (CGM) and are the least understood part of galactic ecosystems. The CGM serves as a reservoir of both diffuse, metal-poor gas accreted from…
The design and comparison of satellite-terrestrial routing (STR) and inter-satellite routing (ISR) in low Earth orbit satellite constellations is a widely discussed topic. The signal propagation distance under STR is generally longer than…
Extraterrestrial intelligences are speculated to surround stars with structures to collect their energy or to signal distant observers. If they exist, these most likely are megaswarms, vast constellations of satellites (elements) in orbit…