326 research outputs found
Astrocomp: web technologies for high performance computing on a network of supercomputers
No full textAstrocomp is a project developed by the INAF-Astrophysical Observatory of Catania, University of Roma La Sapienza and Enea in collaboration with Oneiros s.r.l. The project has the goal of building a web-based user-friendly interface which allows the international community to run some parallel codes on a set of high-performance computing (HPC) resources, with no need for specific knowledge about Unix and Operating Systems commands. Astrocomp provides CPU times, on parallel systems, available to the authorized user. The portal makes codes for astronomy available: FLY code, a cosmological code for studying three-dimensional collisionless self-gravitating systems with periodic boundary conditions [Becciani, Antonuccio, Comput. Phys. Comm. 136 (2001) 54]. ATD treecode, a parallel tree-code for the simulation of the dynamics of self-gravitating systems [Miocchi, Capazzo Dolcetta, A&A 382 (2002) 758]. MARA a code for stellar light curves analysis [Rodono et al., A&A 371 (2001) 174]. Other codes will be added to the portal in the future. (C) 2004 Elsevier B.V. All rights reserved
Archive systems for the TNG telescope: lessons learned in the VO perspective
No full texted. A. Szala
Archive systems for the TNG telescope: lessons learned in the VO perspective
No full texted. A. Szala
Astrocomp: web technologies for high performance computing on a grid of supercomputers
No full textAstrocomp is a project developed by the Astrophysical Observatory of Catania, University of Roma La Sapienza and ENEA. The project goal is to build a web-based user-friendly interface which allows the international community to run some parellel codes on a set of high performance computing (HPC) resources. There' s no need for specific knowledge about Unix commands and Operating Systems. Astrocomp makes some CPU times, on large parallel platform, available to the referenced use
AstroComp: using the portal to perform astrophysical N-body simulations
No full textA practical utilization of the Astrocomp web portal is illustrated in the framework of the numerical simulations of Astrophysical systems.
It is shown how to handle the various aspects related to the performing and managing of a typical N-body simulation. For this purpose, the features and usage of one of the parallel codes available in AstroComp, namely the ``treeATD'' code, are briefly described
Astrocomp: a web portal for high performance computing on a grid of supercomputers
No full textAstrocomp is a project based on a collaboration among the University of Roma La Sapienza, the Astrophysical Observatory of Catania and ENEA. The main motivation of the AstroComp project is to construct a portal, which allows to set up a repository of computational codes and common databases, making them available and enjoyable, with a user-friendly graphical web interface, to the international community. AstroComp will allow the scientific community to benefit by the use of many different numerical tools implemented on high performance computing (HPC) resources, both for theoretical astrophysics and cosmology and for the storage and analysis of astronomical data, without the need of specific training, know-how and experience either in computational techniques or in database construction and management methods. An essential feature of Astrocomp is that it makes available to subscribers some CPU time on large parallel platforms, via specific grants. Astrocomp is partly financed by a grant of the Italian national research Council (CNR)
Dissecting the spin distribution of dark matter haloes
No full textThe spin probability distribution of dark matter haloes has often been modelled as being very near to a lognormal. Most of the theoretical attempts to explain its origin and evolution invoke some hypotheses concerning the influence of tidal interactions or merging on haloes. Here we apply a very general statistical theorem introduced by Cramér (1936) to study the origin of the deviations from the reference lognormal shape: we find that these deviations originate from correlations between two quantities entering the definition of spin, namely the ratio J/M5/2 (which depends only on mass) and the modulus E of the total (gravitational + kinetic) energy. To reach this conclusion, we have made usage of the results deduced from two high spatial- and mass-resolution simulations. Our simulations cover a relatively small volume and produce a sample of more than 16000 gravitationally bound haloes, each traced by at least 300 particles. We verify that our results are stable to different systematics, by comparing our results with those derived by the GIF2 and by a more recent simulation performed by Macciò et al. We find that the spin probability distribution function shows systematic deviations from a lognormal, at all redshifts z <~ 1. These deviations depend on mass and redshift: at small masses they change little with redshift, and also the best lognormal fits are more stable. The J -M relationship is well described by a power law of exponent ñ very near to the linear theory prediction (ñ = 5/3), but systematically lower than this at z <~ 0.3. We argue that the fact that deviations from a lognormal PDF are present only for high-spin haloes could point to a role of large-scale tidal fields in the evolution of the spin PDF
Feeding an astrophysical database via distributed computing resources: The case of BaSTI
No full textStellar evolution model databases, spanning a wide ranges of masses and initial chemical compositions, are nowadays a major tool to study Galactic and extragalactic stellar populations. The Bag of Stellar Tracks and Isochrones (BaSTI) database is a VO-compliant theoretical astrophysical catalogue that collects fundamental datasets involving stars formation and evolution. The creation of this database implies a large number of stellar evolutionary computations that are extremely demanding in term of computing power. Here we discuss the efforts devoted to create and update the database using Distributed Computing Infrastructures and a Science Gateway and its future developments within the framework of the Italian Virtual Observatory project
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