Séminaire Doctoral / Seminar PhD |
| « The epic fight between gravity and baryonic forces -- Gaining insight into galactic battles » |
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Nicolas Cornuault |
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The physics of galaxy formation and evolution may be seen as the perpetual attempt from gravity to condense matter. Gravity has a powerful ally in dark matter (DM). It lets itself fall in gravitational wells and reinforces them -- even if eventually angular momentum prevents DM from concentrating into a single point. But baryonic matter (BM, that could stand for "bright matter") fights back with the help of electro-magnetics, weak interaction and light. And each time gravity seems winning over BM, the defeated matter sends back its weapons and ammunition to the surroundings, delaying the end of the battle.
Electro-magnetics provide BM with the ability to collide. This leads to all gas (and plasma) physics, from thermodynamics, to chemistry, to turbulence. Depending on spatial and time scales, taking into account the possible interactions between spatial scales, different phenomena will more or less delay BM's ultimate doom. The specific strategy of (supersonic) turbulence against gravity has been studied in molecular clouds but not much in hot halo gas. It has been seen in simulations but numerical limitations may prevent us from capturing the correct amplitudes and scales of turbulence. We will set the battlefield in an ideal galactic halo of any realistic mass, at any redshift z<6 and study the battles in terms of local and global energy balances. We will particularly focus on one battle, that of gas accretion. |
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mercredi 3 juin 2015 - 17:00 Salle Entresol Daniel Chalonge, Institut d'Astrophysique |
| Page web du séminaire / Seminar's webpage |