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SUMMARY:Can we really ignore galaxy astrophysics in cosmology?
DTSTART:20260331T090000Z
DTEND:20260331T100000Z
DTSTAMP:20260515T050200Z
UID:indico-event-134@indico.iap.fr
DESCRIPTION:Speakers: Romain Paviot (CEA DAP)\n\n As cosmological surveys
  reach unprecedented statistical precision\, the question of whether galax
 y astrophysics can be treated as a nuisance — or must be modeled careful
 ly — becomes increasingly important. In this talk\, I will speak about t
 wo key ingredients that are more physically complex than standard assumpti
 ons suggest\, with potentially significant consequences for cosmological p
 arameter inference.\nThe first concerns intrinsic alignments (IA) of galax
 ies. Rather than a simple tidal response\, IA appears to depend strongly o
 n galaxy type\, colour\, and stellar mass\, with distinct alignment signal
 s between early and late-type galaxies. The amplitude and even the sign of
  these alignments likely reflect the formation history of galaxies — whe
 n and how they assembled — making IA a multi-dimensional astrophysical p
 rocess. I will discuss how current models may be insufficient to capture t
 his complexity\, and what need to be done to further constraints IA for st
 age IV surveys analyses.\nThe second concerns the Halo Occupation Distribu
 tion (HOD) framework\, widely used to populate dark matter halos with gala
 xies for clustering and lensing analyses. Standard HOD assumptions — inc
 luding assembly-bias-free prescriptions and simple satellite profiles — 
 are a convenient but potentially inadequate description of reality. I will
  discuss how extensions motivated by galaxy formation physics can alter pr
 edicted two-point statistics at a level relevant to current and forthcomin
 g surveys.\nTogether\, these two threads point to a broader message: galax
 y astrophysics is not simply a foreground to be marginalized over\, but ca
 rries physical information that\, if ignored\, may bias our cosmological c
 onclusions.\n\nhttps://indico.iap.fr/event/134/
LOCATION:Salle des séminaires (IAP)
URL:https://indico.iap.fr/event/134/
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