BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Testing DDE and Constraining high-z reionization with Cosmological
  Data
DTSTART:20251023T150000Z
DTEND:20251023T160000Z
DTSTAMP:20260710T193900Z
UID:indico-event-48667@agenda.infn.it
DESCRIPTION:Speakers: Cheng Hanyu (University of Sheffield)\n\nI  will di
 scuss two research projects about testing DDE and Constraining high-z reio
 nization with cosmological data. First\, we explore an extension of the LC
 DM model that introduces a time-dependent evolution of the pressure parame
 ter p in the dark energy fluid\, where the corresponding energy density \\
 rho is derived by a continuity equation and the equation of state w evolve
 s during the late-time expansion of the Universe. We model the pressure pa
 rameter using a Taylor expansion within the dynamical dark energy (DDE) fr
 amework\, initially truncating at first order with a single additional par
 ameter allowing deviation from the cosmological constant value\, then exte
 nding to second order to demonstrate that observational data can constrain
  both parameters. Since no significant deviation from CDM was detected for
  the relevant cosmological parameters\, we did not include higher-order te
 rms. We modified the publicly available CAMB code and performed Markov Cha
 in Monte Carlo analysis\, extending the LCDM parameter space to incorporat
 e the pressure parameterizations. Second\, we use Gaussian processes to gi
 ve a model-independent reconstruction of the reionization history of the U
 niverse constrained by the Planck CMB measurements\, providing consistent 
 reconstruction of standard reionization at z<10 and strongly constraining 
 any additional high-z reionization. We construct a new derived parameter e
 xpressing the high-z contribution to the CMB optical depth\, whose posteri
 or distribution can be used to set accurate constraints on models for exot
 ic energy injection\, which we demonstrate for the case of decaying dark m
 atter with particle mass in the range about 1 MeV. Our results can be reca
 st to different models using the provided data and code available at: http
 s://github.com/Cheng-Hanyu/CLASS_reio_gpr.\n\nhttps://agenda.infn.it/event
 /48667/
LOCATION:Aula Conversi (Dip. di Fisica - Edificio G. Marconi)
URL:https://agenda.infn.it/event/48667/
END:VEVENT
END:VCALENDAR