Constraining quintessence field dynamics with recent cosmological observations

Abstract We present an investigation of a scalar field dark energy model in the context of the FLRW universe, focusing on the parameterization of the deceleration parameter q ( z ) to study the evolution of cosmic acceleration. By employing extensive observational datasets—including 30 independent cosmic chronometer measurements, 17 additional baryon acoustic oscillation data points, and standard candle datasets from Pantheon Type Ia supernovae, Quasars, and Gamma-Ray Bursts—we provide constraints on cosmological parameters using advanced Markov chain Monte Carlo methods. Our analysis identifies a transition redshift of $$z_t = 0.62$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>z</mml:mi> <mml:mi>t</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.62</mml:mn> </mml:mrow> </mml:math> , marking the shift from decelerated to accelerated expansion, with a current deceleration parameter of $$q_0 = -0.59$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>q</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>-</mml:mo> <mml:mn>0.59</mml:mn> </mml:mrow> </mml:math> . The equation of state parameter confirms the dynamical behavior of quintessence, deviating slightly from a cosmological constant. Furthermore, the model demonstrates strong consistency with $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM at lower redshifts while revealing distinct deviations at higher redshifts, which provides valuable insights into the late-time dynamics of the universe. By examining the evolution of cosmography parameters, energy density, pressure, and the scalar field equation of state, this study contributes the relevance of scalar field models as promising candidates for dark energy.