Smoothed Particle Hydrodynamics (SPH) a meshfree particle method for astrophysics *

Transcription

1 Smoothed Particle Hydrodynamics (SPH) a meshfree particle method for astrophysics * Supplement 3: Example simulations using SPH and advanced graphics David Hobbs Lund Observatory ASTM17

2 Galaxy collision Authors: Volker Springel Simula3on Tool: Gadget (SPH) Visualiza3on Tool: (?) Download video This movie shows two colliding and merging spiral galaxies. The simulabon follows dark mader, gas, and a stellar component, but only the baryonic component is visualized. Note: Baryonic mader is mader composed mostly of baryons (by mass), which includes atoms of any sort (and thus includes nearly all mader that we may encounter or experience in everyday life, including our bodies). Non baryonic mader, as implied by the name, is any sort of mader that is not primarily composed of baryons. This might include such ordinary mader as neutrinos or free electrons; however, it may also include exobc species of non baryonic dark mader, such as supersymmetric parbcles, axions or black holes. The disbncbon between baryonic and non baryonic mader is important in cosmology, because Big Bang nucleosynthesis models set Bght constraints on the amount of baryonic mader present in the early universe.

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4 Authors: Klaus Dolag Simula3on Tool: Gadget 2 (SPH) Visualiza3on Tool: Splotch Download video Galaxy cluster Flight through a high resolution simulation of a galaxy cluster. After zooming into the cluster, the flight follows an orbit around the center. Visible are prominent structure within the hot plasma, building the atmosphere of the cluster. Some of the structures inside the cluster are able to maintain an self-bound atmosphere for a while (shown in light blue). The population of free floating stars, which originate from destroyed galaxies show prominent stripes as imprint of the orbits of the former galaxies they belong to. Despite such destruction, more than thousand of individual galaxies can still be identified within the cluster, even forming new stars in their centers (shown in dark blue). Only a small number of them are still maintaining an own, hot, self-bound atmosphere (shown in light blue). For the zoom out all stars formed within the simulation are shown.

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6 Simula3ng the joint evolu3on of quasars, galaxies and their large scale distribu3on Authors: Volker Springel, Simon D. M. White, Adrian Jenkins, Carlos S. Frenk, Naoki Yoshida, Liang Gao, Julio Navarro, Robert Thacker, Darren Croton, John Helly, John A. Peacock, Shaun Cole, Peter Thomas, Hugh Couchman, August Evrard, Joerg Colberg, Frazer Pearce Simula3on Tool: Gadget 2 (SPH) Visualiza3on Tool: Splotch (?) Download video This movie shows the dark mader distribubon in the universe at the present Bme, based on the Millennium SimulaBon, the largest N body simulabon carried out thus far (more than parbcles). By zooming in on a massive cluster of galaxies, the movie highlights the morphology of the structure on different scales, and the large dynamic range of the simulabon (10 5 per dimension in 3D). The zoom extends from scales of several Gpc down to resolved substructures as small as ~10 kpc.

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8 Authors: Klaus Dolag Simulation Tool: Gadget 2 (SPH) Visualization Tool: Splotch Download video Evolu3on of galaxy cluster The evolution of a galaxy cluster from very early times on. The visualization starts when the universe has just 5% of its actual age, and the first galaxies are forming (about z=6). The light would need about 30 millions of years to pass the region of space shown. Shown is the temperature of the plasma, which fills the space between stars and galaxies. At z about 3.5 the universe has 15% of its actual age and the forming large-scale structure (filaments) can be clearly recognized. The inlay down in the right shows a zoom into the interior of one of the two prominent protoclusters. In such structures (clusters of galaxies) several thousands of galaxies can be bound by gravity. At z about 0.8 the universe is half as old as now and the two prominent protoclusters begin to merge into one galaxy cluster. Such events are the most energetic phenomena since universe was born in the Big Bang. In the final phase of this merging event a gigantic shockwave is initiated, releasing enormous amount of energy.

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10 Authors: Klaus Dolag Simulation Tool: Gadget 2 (SPH) Visualization Tool: Splotch Download video Flying through galaxy clusters Flying through the hot plasma atmosphere of a galaxy clusters visualizing temperature, reveling the richness of substructure and their dynamics during the formation of the largest gravitational bound objects in the universe. When falling into the cluster, the galaxies are losing their gaseous atmosphere (appearing in white), forming comet-like features of gas trails. Due to tidal forces these trails sometimes get deformed into arc-like structures.

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12 Flying through the Local Universe Authors: Klaus Dolag Simulation Tool: Gadget 2 (SPH) Visualization Tool: Splotch Download video Same simulation as done in the constrained realization project but including diffuse baryons. Visualized is the gas temperature. Structures which can be identified directly with observed galaxy clusters are labeled

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14 Flying through a filament Authors: Klaus Dolag Simulation Tool: Gadget 2 (SPH) Visualization Tool: Splotch Download video Flight through a evolving cosmic structure (filament) which connects several galaxy clusters. The gas between the galaxy clusters is visualized in colors ranging from brown to light blue, the stars formed within the simulation are colored from purple to white. The movie captures a fly through the final structure with a wide field of view.

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16 Proper3es of clusters of galaxies Authors: Volker Springel Simula3on Tool: Gadget 2 (SPH) Visualiza3on Tool: Splotch Download video This high-resolution animation shows the formation of a rich cluster of galaxies from cosmological initial conditions. The simulation follows dark matter and baryonic gas.

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18 Fly through 4D Universe Authors: Klaus Dolag, Claudio Gheller and Silvani Imboden SimulaBon Tool: Gadget 2 (SPH) VisualizaBon Tool: Splotch Download video Flying through a evolving cosmic structure, starting at early times (the so called dark ages), where the material in the universe is in a cold and neutral state. First objects collapse and form the first proto galaxies embedded in a heated atmosphere, hosting the first stars and QSOs. The energetic light from those stars/qsos heat and ionize the material in the universes (note that this simulation takes this not self consistently into account, but uses a uniform, time dependent background radiation field), revealing the fine, filamentary structures formed so far. Now, lager and larger structures form within a long and violent process of merging of smaller structures leading to the largest objects observed in the present universe, the so called galaxy clusters, still connected to each other by filamentary structures. At the end, the movie zooms down to a spiral galaxy, similar to what we expect the Milky Way looks like, for a final fly-by. In this case the galaxy is artificial constructed from an astronomical image, as it is still impossible to obtain such detailed and realistic galaxies directly within cosmological simulations. This movie is also shown in the Virtual Reality facility of the new Turin Planetarium.

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