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SUMMARY:Formulation Improvements for Critical Collapse - Daniela Cors Agul
 lo\, DAMTP\, University of Cambridge
DTSTART:20240119T130000Z
DTEND:20240119T140000Z
UID:TALK211000@talks.cam.ac.uk
CONTACT:Xi Tong
DESCRIPTION:Reliable numerical simulations require a thorough control of a
 ll non-physical dynamics that can appear\, such as constraint violations a
 nd coordinate singularities. These become more challenging in the strong-f
 ield regime and particularly near the threshold of collapse\, where\, in t
 he absence of a horizon\, arbitrarily large curvatures cannot be excised. 
 At this threshold\, a regular and universal structure emerges in spherical
  symmetry\, referred to as critical phenomena. Beyond sphericity\, the pic
 ture of critical collapse is unclear. Clarification demands simulations th
 at are closer to the threshold. To that end\, we propose two formulation i
 mprovements for critical collapse simulations. To control constraint viola
 tions\, we modify the constraint damping parameters of the generalised har
 monic gauge formulation\, adapting them to collapsing spacetimes. This all
 ows us to simulate at the closest to the threshold with this formulation t
 o date. Secondly\, we propose a necessary condition for a gauge choice to 
 respect discrete self-similarity. After evaluating common gauge choices ag
 ainst this condition\, we suggest a compatible gauge source function.
LOCATION:Potter room/Zoom
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