511 research outputs found
Abstracts of theses and related literature indicating current trends in arithmetic for the academically talented elementary school child written between 1957 and 1961
Thesis (Ed.M.)--Boston Universit
On the relation between the mass of Compact Massive Objects and their host galaxies
Supermassive black holes and/or very dense stellar clusters are found in the
central regions of galaxies. Nuclear star clusters are present mainly in faint
galaxies while upermassive black holes are common in galaxies with masses M. In the intermediate galactic mass range both types of
central massive objects (CMOs) are found. Here we present our collection of a
huge set of nuclear star cluster and massive black hole data that enlarges
significantly already existing data bases useful to investigate for
correlations of their absolute magnitudes, velocity dispersions and masses with
structural parameters of their host galaxies. In particular, we directed our
attention to some differences between the correlations of nuclear star clusters
and massive black holes as subsets of CMOs with hosting galaxies. In this
context, the mass-velocity dispersion relation plays a relevant role because it
seems the one that shows a clearer difference between the supermassive black
holes and nuclear star clusters. The has a slope of while has the much smaller slope of .
The slopes of the CMO mass- host galaxy B magnitude of the two types of CMOs
are indistinguishable within the errors while that of the NSC mass-host galaxy
mass relation is significantly smaller than for supermassive black holes.
Another important result is the clear depauperation of the NSC population in
bright galaxy hosts, which reflects also in a clear flattening of the NSC mass
vs host galaxy mass at high host masses.Comment: 12 pages, 22 figures, 2 tables, accepted for publication in MNRA
Turismo sui campi di battaglia in Italia e in Spagna. Due esperienze a confronto (1919-1939)
The article focuses on the practices of war tourism in Italy and Spain into the 1930s. The
journeys on the battlefields become for the dictatorial regimes of Mussolini and Franco an instrument of
political propaganda for domestic and international tourism. The article highlights the similarities and
differences between the travels organized in Italy and those organized in Spain
Scaling Correlations Among Central Massive Objects and Their Host Galaxies
The central regions of galaxies show the presence of super massive black
holes and/or very dense stellar clusters. Both such objects seem to follow
similar host-galaxy correlations, suggesting that they are members of the same
family of Compact Massive Objects. Here we investigate a huge data collection
of Compact Massive Objects properties to correlate them with absolute
magnitude, velocity dispersion and mass of their host galaxies. We draw also
some preliminary astrophysical conclusions
Formation and evolution of clumpy tidal tails around globular clusters
We present some results of numerical simulations of a globular cluster
orbiting in the central region of a triaxial galaxy on a set of 'loop' orbits.
Tails start forming after about a quarter of the globular cluster orbital
period and develop, in most cases, along the cluster orbit, showing clumpy
substructures as observed, for example, in Palomar 5. If completely detectable,
clumps can contain about 7,000 solar masses each, i.e. about 10% of the cluster
mass at that epoch. The morphology of tails and clumps and the kinematical
properties of stars in the tails are studied and compared with available
observational data. Our finding is that the stellar velocity dispersion tends
to level off at large radii, in agreement to that found for M15 and Omega
Centauri.Comment: LaTeX 2e, uses AASTeX v5.x, 40 pages with 18 figures. Submitted to
The Astronomical Journa
Merging of globular clusters within inner galactic regions. II. The Nuclear Star Cluster formation
In this paper we present the results of two detailed N-body simulations of
the interaction of a sample of four massive globular clusters in the inner
region of a triaxial galaxy. A full merging of the clusters takes place,
leading to a slowly evolving cluster which is quite similar to observed Nuclear
Clusters. Actually, both the density and the velocity dispersion profiles match
qualitatively, and quantitatively after scaling, with observed features of many
nucleated galaxies. In the case of dense initial clusters, the merger remnant
shows a density profile more concentrated than that of the progenitors, with a
central density higher than the sum of the central progenitors central
densities. These findings support the idea that a massive Nuclear Cluster may
have formed in early phases of the mother galaxy evolution and lead to the
formation of a nucleus, which, in many galaxies, has indeed a luminosity
profile similar to that of an extended King model. A correlation with galactic
nuclear activity is suggested.Comment: 18 pages, 10 figures, 3 tables. Submitted to ApJ, main journa
Elliptical galaxy nuclei activity powered by infalling globular clusters
Globular cluster systems evolve, in galaxies, due to internal and external
dynamics and tidal phenomena. One of the causes of evolution, dynamical
friction, is responsible for the orbital decay of massive clusters into the
innermost galactic regions. It is found that these clusters are effective
source of matter to feed a central galactic black hole such to make it grow and
shine as an AGN.Comment: 8 pages, 2 eps figures, in press in the Proc. of the Meeting Baryons
in Cosmic Structures, Monte Porzio (Italy), oct. 20-21 2003, ASP Conf. Ser.,
eds. E. Giallongo, G. De Zotti, N. Menc
Direct -body code on low-power embedded ARM GPUs
This work arises on the environment of the ExaNeSt project aiming at design
and development of an exascale ready supercomputer with low energy consumption
profile but able to support the most demanding scientific and technical
applications. The ExaNeSt compute unit consists of densely-packed low-power
64-bit ARM processors, embedded within Xilinx FPGA SoCs. SoC boards are
heterogeneous architecture where computing power is supplied both by CPUs and
GPUs, and are emerging as a possible low-power and low-cost alternative to
clusters based on traditional CPUs. A state-of-the-art direct -body code
suitable for astrophysical simulations has been re-engineered in order to
exploit SoC heterogeneous platforms based on ARM CPUs and embedded GPUs.
Performance tests show that embedded GPUs can be effectively used to accelerate
real-life scientific calculations, and that are promising also because of their
energy efficiency, which is a crucial design in future exascale platforms.Comment: 16 pages, 7 figures, 1 table, accepted for publication in the
Computing Conference 2019 proceeding
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