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SUMMARY:New Isocurvature Constraints and its Axionic Interpretations
DTSTART;VALUE=DATE-TIME:20260811T025000Z
DTEND;VALUE=DATE-TIME:20260811T031500Z
DTSTAMP;VALUE=DATE-TIME:20260824T165438Z
UID:indico-contribution-2689@indico.itp.ac.cn
DESCRIPTION:Speakers: Lingfeng Li ()\nAlthough measurements of the Cosmic 
 Microwave Background (CMB) have shown a nearly scale-invariant primordial 
 spectrum of adiabatic perturbations\, in which the energy densities of dif
 ferent components (radiation\, baryons\, and dark matter) fluctuate propor
 tionally\, there could also exist isocurvature perturbations\, in which de
 nsity fluctuations of the individual components differ from the adiabatic 
 mode. Cold dark matter isocurvature (CDI) perturbations with a variety of 
 spectral tilts generated in pre-inflationary axion models provide one such
  example. In this article\, we present the most updated constraints on the
 se axion CDI perturbations using the latest CMB anisotropy measurements fr
 om Planck\, the Atacama Cosmology Telescope (ACT)\, and the South Pole Tel
 escope (SPT). \n   We study both fixed spectral indices with values rangin
 g from red- to blue-tilted spectra as well as the case with a free index. 
 We find that the constraint on the spectral index gets moderately improved
  with the combined datasets compared to Planck alone\, while the bounds on
  the isocurvature amplitudes for fixed spectral indices we consider do not
  get tighter.\n\nhttps://indico.itp.ac.cn/event/416/contributions/2689/
LOCATION:Conference Center (2F) Back Area
URL:https://indico.itp.ac.cn/event/416/contributions/2689/
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