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Palestra 8

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The gravitational N-body simulations have become a powerful tool for testing the theories of structure formation in astrophysical and cosmological systems [1]. In particular, it has been shown that the statistical characterization of dark matter distribution is an important ingredient in the investigation of large-scale structure formation in the Hubble volume simulated from the GADGET-VC algorithm [2]. Recently, an established statistical method was used to demonstrate the importance of considering chaotic advection (or Lagrange Turbulence) [3] in combination with gravitational instabilities in the Λ – CDM simulations performed from the Virgo Consortium (VC) [4]. However, the GADGET-VC algorithm does not allow the computation of the kinematics of a single particle, information that is necessary for the investigation of the chaotic advection. This limitation appears because the interaction forces are computed by the TreePM scheme [5]. Hence, the LAC -INPE and the IC-UFF develop the Cosmic LAgrangian TUrbulence Simulator (COLATUS) to perform gravitational N-body simulations allowing the computation of the velocity of a single particle at every time-step and then the evaluation of its energy power spectrum. To achieve its objective COLATUS compute the gravitational forces by using a direct summation scheme. COLATUS is implemented in a Compute Unified Device Architecture (CUDA) by using the Nvidia graphics processing units (GPUs) to reduce the simulation runtime. We use the simulator for testing a hypothesis of an alternative cosmological scenario where the dark matter is interpreted as spatio-temporal deformations due to an alternative coupled expanding universe [6]. These deformations are included as the action of relativistic potentials. In the present work we show the preliminary simulations including up to 106 particles using 1536 cores of NVIDIA GTX680. The respective energy power spectra are shown for several deformation potentials which are dicussed in the alternative cosmological context. For astrophysical purposes we also discuss the application of this new algorithm in the study of galactic dynamics, highlighting a possible alternative investigation of the bullet cluster.


[1] Bertschinger,E. Simulation of Structure formation in the universe. Annu. Rev Astron.Astrophys 36 (1996) 5999-654.
[2] Caretta, C.A., R. R. Rosa, H. F. C. Velho, F. M. Ramos, M. M. Evidence of turbulence-like universality in the formation of galaxy-sized dark matter haloes. Astron. Astrophys 487 (2008) 445-451.
[3] Aref, H., The development of chaotic advection. Physics of Fluids, 14 (2002) 1315-1325.
[4] Rosa, R. R. ; Ramos, F. M. ; Caretta, C. A. ; Velho, H. F. C. Extreme event dynamics in the formation of galaxy-sized dark matter structures. Computer Physics Communications 180 (4) (2009) 621-624.
[5] Springel, V. The cosmological simulation code GADGET-2. Computer Physics Communications, Mon. Not. R. Astron. Soc. 364 (2005) 1105-1134.
[6] Rosa, R. An alternative coupled expanding universe without cosmological singularity. In: 38th COSPAR Scientific Assembly. [S.l.: s.n.], 2010. v. 38,p. 3663.



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