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SUMMARY:Contributory: Quintom dark energy: Future attractor and phantom cr
 ossing in light of DESI DR2 observations
DTSTART;VALUE=DATE-TIME:20261120T053000Z
DTEND;VALUE=DATE-TIME:20261120T054500Z
DTSTAMP;VALUE=DATE-TIME:20261026T160511Z
UID:indico-contribution-1077@indico.narit.or.th
DESCRIPTION:Speakers: Phusuda Thanankullaphong (Centre for Theoretical Phy
 sics and Natural Philosophy\, Mahidol University)\nWe study the late-time 
 cosmological dynamics of a two-field dark-energy model consisting of a can
 onical quintessence scalar field and a phantom scalar field in a spatially
  flat Friedmann-Lemaître-Robertson-Walker universe. The fields are minima
 lly coupled to gravity and uncoupled at the level of the potential\, with 
 the quintessence sector governed by an exponential potential and the phant
 om sector by an inverse power-law potential. By reformulating the backgrou
 nd equations as a five-dimensional autonomous dynamical system\, we identi
 fy and analyze the fixed points and their stability properties\, revealing
  stable late-time attractors corresponding to phantom-dominated accelerate
 d expansion. We confront the model with observations through a Bayesian pa
 rameter estimation performed using the cobaya framework\, employing severa
 l combinations of recent cosmological datasets\, including Pantheon+ super
 novae\, compressed cosmic microwave background distance priors\, DESI DR2 
 baryon acoustic oscillation measurements\, and DES year-5 supernova data. 
 The observational constraints favor a dynamical dark-energy sector moderat
 ely and are consistent with deviations from a cosmological constant at the
  present epoch. The regions of parameter space preferred by the data are c
 ompatible with the stable accelerating solutions identified in the dynamic
 al analysis\, establishing a direct connection between phase-space stabili
 ty and observational viability. A notable feature of the model is that the
  effective dark-energy equation of state undergoes phantom divide crossing
  in a gradual and asymptotic manner\, rather than as a sharp transition.\n
 \nhttps://indico.narit.or.th/event/234/contributions/1077/
LOCATION:Pattaya\, Thailand D Varee Jomtien Beach Pattaya Hotel
URL:https://indico.narit.or.th/event/234/contributions/1077/
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