3 research outputs found
Astrophysical structures from primordial quantum black holes
The characteristic sizes of astrophysical structures, up to the whole
observed Universe, can be recovered, in principle, assuming that gravity is the
overall interaction assembling systems starting from microscopic scales, whose
order of magnitude is ruled by the Planck length and the related Compton
wavelength. This result agrees with the absence of screening mechanisms for the
gravitational interaction and could be connected to the presence of Yukawa
corrections in the Newtonian potential which introduce typical interaction
lengths. This result directly comes out from quantization of primordial black
holes and then characteristic interaction lengths directly emerge from quantum
field theory.Comment: 11 page
Tides in colliding galaxies
Long tails and streams of stars are the most noticeable upshots of galaxy
collisions. Their origin as gravitational, tidal, disturbances has however been
recognized only less than fifty years ago and more than ten years after their
first observations. This Review describes how the idea of galactic tides
emerged, in particular thanks to the advances in numerical simulations, from
the first ones that included tens of particles to the most sophisticated ones
with tens of millions of them and state-of-the-art hydrodynamical
prescriptions. Theoretical aspects pertaining to the formation of tidal tails
are then presented. The third part of the review turns to observations and
underlines the need for collecting deep multi-wavelength data to tackle the
variety of physical processes exhibited by collisional debris. Tidal tails are
not just stellar structures, but turn out to contain all the components usually
found in galactic disks, in particular atomic / molecular gas and dust. They
host star-forming complexes and are able to form star-clusters or even
second-generation dwarf galaxies. The final part of the review discusses what
tidal tails can tell us (or not) about the structure and content of present-day
galaxies, including their dark components, and explains how tidal tails may be
used to probe the past evolution of galaxies and their mass assembly history.
On-going deep wide-field surveys disclose many new low-surface brightness
structures in the nearby Universe, offering great opportunities for attempting
galactic archeology with tidal tails.Comment: 46 pages, 13 figures, Review to be published in "Tidal effects in
Astronomy and Astrophysics", Lecture Notes in Physics. Comments are most
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