5 research outputs found
Universality in the distribution of caustics in the expanding Universe
We numerically investigate the long--time evolution of density perturbations
after the first appearance of caustics in an expanding cosmological model with
one--dimensional `single--wave' initial conditions. Focussing on the
time--intervals of caustic appearances and the spatial distribution of caustics
at subsequent times, we find that the time--intervals of caustic appearances
approach a constant, i.e., their time--subsequent ratio converges to 1; it is
also found that the spatial distribution of caustics at a given time features
some universality rules, e.g., the ratio between the position of the nearest
caustic from the center and that of the second nearest caustic from the center
approaches a constant. Furthermore we find some rules for the mass distribution
for each caustic. Using these universality constants we are in the position to
predict the spatial distribution of caustics at an arbitrary time in order to
give an estimate for the power spectral index in the fully--developed
non--dissipative turbulent (`virialized') regime.Comment: 23 pages, 19 figure
The JWST Galactic Center Survey -- A White Paper
The inner hundred parsecs of the Milky Way hosts the nearest supermassive
black hole, largest reservoir of dense gas, greatest stellar density, hundreds
of massive main and post main sequence stars, and the highest volume density of
supernovae in the Galaxy. As the nearest environment in which it is possible to
simultaneously observe many of the extreme processes shaping the Universe, it
is one of the most well-studied regions in astrophysics. Due to its proximity,
we can study the center of our Galaxy on scales down to a few hundred AU, a
hundred times better than in similar Local Group galaxies and thousands of
times better than in the nearest active galaxies. The Galactic Center (GC) is
therefore of outstanding astrophysical interest. However, in spite of intense
observational work over the past decades, there are still fundamental things
unknown about the GC. JWST has the unique capability to provide us with the
necessary, game-changing data. In this White Paper, we advocate for a JWST
NIRCam survey that aims at solving central questions, that we have identified
as a community: i) the 3D structure and kinematics of gas and stars; ii)
ancient star formation and its relation with the overall history of the Milky
Way, as well as recent star formation and its implications for the overall
energetics of our galaxy's nucleus; and iii) the (non-)universality of star
formation and the stellar initial mass function. We advocate for a large-area,
multi-epoch, multi-wavelength NIRCam survey of the inner 100\,pc of the Galaxy
in the form of a Treasury GO JWST Large Program that is open to the community.
We describe how this survey will derive the physical and kinematic properties
of ~10,000,000 stars, how this will solve the key unknowns and provide a
valuable resource for the community with long-lasting legacy value.Comment: This White Paper will be updated when required (e.g. new authors
joining, editing of content). Most recent update: 24 Oct 202