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SUMMARY:Hidden Degrees of Freedom: Isocurvature in Cosmological Inference
DTSTART:20260407T090000Z
DTEND:20260407T100000Z
DTSTAMP:20260504T033800Z
UID:indico-event-9319@scitalks.tifr.res.in
DESCRIPTION:Speakers: Sai Chaitanya (Indiana University\, USA)\n\nThe stan
 dard cosmological model explains the growth of cosmic structure through ti
 ny primordial fluctuations that grow under gravity. These are typically as
 sumed to be adiabatic\, where all components (matter\, radiation etc.) of 
 the universe fluctuate together. However\, an alternative possibility\, is
 ocurvature fluctuations\, allows different components to vary relative to 
 one another. Although strongly constrained on large cosmological scales (v
 ia CMB) and often treated as a nuisance parameter\, isocurvature can act a
 s an additional degree of freedom that affects cosmological inference. In 
 this talk I will present an isocurvature-forward program: we study generat
 ion of dark matter isocurvature with scale-dependent (often blue-tilted) s
 pectra\, construct data-ready templates\, and quantify their impact within
  standard analyses. As an example\, we shall discuss a new generation mech
 anism motivated by hyperbolic internal geometry. I will then discuss how e
 ven a small isocurvature component can modify the interpretation of cosmol
 ogical data\, for example existing bounds on thermal warm dark matter mass
  can be relaxed by a factor of 10. I will briefly comment on similar impli
 cations for ultra-light axion dark matter\, early-time JWST observations a
 nd measurements of neutrino mass. Overall\, this highlights how allowing a
 n additional isocurvature degree of freedom in the early universe can resh
 ape our interpretation of cosmological data.\n\nhttps://scitalks.tifr.res.
 in/event/9319/
LOCATION:AG 66 and on Zoom
URL:https://scitalks.tifr.res.in/event/9319/
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