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SUMMARY:Constraining Modified Gravity with the Marked Power Spectrum
DTSTART;VALUE=DATE-TIME:20261028T182500Z
DTEND;VALUE=DATE-TIME:20261028T182600Z
DTSTAMP;VALUE=DATE-TIME:20261024T222147Z
UID:indico-contribution-3712@nyx.physics.mcgill.ca
DESCRIPTION:Speakers: Amani Hussien (University of Toronto)\nThe nature of
  cosmic acceleration remains an open question\, with Modified Gravity (MG)
  providing an alternative to dark energy models within General Relativity.
  Cosmic voids are particularly sensitive tracers of MG and their two-point
  clustering captures higher order density field statistics. Since conventi
 onal two-point statistics are primarily dominated by overdensities\, we us
 e the marked power spectrum\, which reweights the matter overdensity field
  to enhance information from voids. We first verify that the MG boost from
  COLA (COmoving Lagrangian Acceleration) simulations is comparable to that
  from corresponding full N-body simulations for the marked power spectrum 
 and cross-spectrum within ~1%. We further show that this agreement holds a
 cross a range of mark definitions. Since the marked field contains non-Gau
 ssian information\, we develop a simulation-based inference (SBI) pipeline
  using a Neural Posterior Estimator (NPE) to constrain phenomenological MG
  (μ\, η) and cosmological parameters (Ωm\, As). We test this pipeline b
 y performing parameter inference on 500 Lognormal Mock and 150 MGCOLA simu
 lations. Our results demonstrate the feasibility of using the marked power
  spectrum within the SBI framework to constrain MG and cosmological parame
 ters. This framework has the potential to extract additional information f
 rom underdense regions and improve MG constraints by combining CMB lensing
  maps with marked void statistics.\n\nhttps://nyx.physics.mcgill.ca/event/
 587/contributions/3712/
LOCATION:Online 
URL:https://nyx.physics.mcgill.ca/event/587/contributions/3712/
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