BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Nonlinear Relativistic effects in Structure Formation in ΛCDM DTSTART:20250320T143000Z DTEND:20250320T160000Z DTSTAMP:20260722T064023Z UID:0c66daff-f5f6-4722-aa04-427875c0c531 SEQUENCE:1 CREATED:20250317T152530Z DESCRIPTION: In this talk I will give an overview of work on nonlinear str ucture formation in ΛCDM in the context of General Relativity (GR). Start ing from briefly presenting a post-Friedmann approximation (similar to pos t-Minkowski\, but on a cosmological background and assuming small peculiar velocities)\, I will show how at leading order the gravito-magnetic effec t (AKA frame-dragging) can be extracted from standard Newtonian N-body sim ulations\, as well as from N-body simulations with GRAMSES\, an approximat e GR code. In this context\, one can conjecture about going beyond-leading order with the aim of computing  the  gravitational wave background. I will then present full-GR simulations of a toy-model “cosmic web” of o ver-densities\,  voids and filaments with the Einstein Toolkit fluid code \, showing how the first shell-crossing at peaks of over-densities is very well predicted by the simple "\;top hat"\; model\, while in the f ormation of the cosmic web a role is played by gravito-magnetism\, especia lly around filaments. In the last part of the talk I will illustrate some work in progress\, some aimed at extending the work on frame-dragging on s maller galactic scales\, some aimed at understanding to what extent relati vistic effects can play a role during collapse and past the first shall cr ossing and virialization. I will conclude with an outline of possible futu re work. LAST-MODIFIED:20250317T152530Z LOCATION:DF Seminar Room (2-8.3)\, 2nd floor of Physics Building URL:http://df.vps.tecnico.ulisboa.pt/en/events/nonlinear-relativistic-effe cts-in-structure-formation-in-%CE%BBcdm/ X-ALT-DESC;FMTTYPE=text/html:

In this talk I wil l give an overview of work on nonlinear structure formation in ΛCDM in th e context of General Relativity (GR). Starting from briefly presenting a p ost-Friedmann approximation (similar to post-Minkowski\, but on a cosmolog ical background and assuming small peculiar velocities)\, I will show how at leading order the gravito-magnetic effect (AKA frame-dragging) can be e xtracted from standard Newtonian N-body simulations\, as well as from N-bo dy simulations with GRAMSES\, an approximate GR code. In this context\, on e can conjecture about going beyond-leading order with the aim of computin g  the  gravitational wave background.

I will then present ful l-GR simulations of a toy-model “cosmic web” of over-densities\,  voi ds and filaments with the Einstein Toolkit fluid code\, showing how the fi rst shell-crossing at peaks of over-densities is very well predicted by th e simple "\;top hat"\; model\, while in the formation of the cosmi c web a role is played by gravito-magnetism\, especially around filaments. In the last part of the talk I will illustrate some work in progress\, so me aimed at extending the work on frame-dragging on smaller galactic scale s\, some aimed at understanding to what extent relativistic effects can pl ay a role during collapse and past the first shall crossing and virializat ion. I will conclude with an outline of possible future work.

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