05 خرداد 1403
راضيه زارع گنبدي

راضیه زارع گنبدی

مرتبه علمی: استادیار
نشانی:
تحصیلات: دکترای تخصصی / فیزیک-گرانش و کیهان شناسی
تلفن:
دانشکده: دانشکده علوم پایه

مشخصات پژوهش

عنوان
Cosmological Solutions of Chameleon Scalar Field Model
نوع پژوهش مقاله چاپ شده
کلیدواژه‌ها
Chameleon Scalar Field, Cosmology, Late-time acceleration
سال
2023
مجله EUROPEAN PHYSICAL JOURNAL C
پژوهشگران راضیه زارع گنبدی

چکیده

‎We investigate cosmological solutions of the chameleon model‎ ‎with a non-minimal coupling between the matter and the scalar‎ ‎field through a conformal factor with gravitational strength‎. ‎By‎ ‎considering the spatially flat FLRW metric and the matter density‎ ‎as a non-relativistic perfect fluid‎, ‎we focus on the‎ ‎matter-dominated phase and the late-time accelerated-phase of the‎ ‎universe‎. ‎In this regard‎, ‎we manipulate and scrutinize the related‎ ‎field equations for the density parameters of the matter and the‎ ‎scalar fields with respect to the e-folding‎. ‎Since the scalar‎ ‎field fluctuations depend on the background and the field‎ ‎equations become highly non-linear‎, ‎we probe and derive the‎ ‎governing equations in the context of various cases of the‎ ‎relation between the kinetic and potential energies of the‎ ‎chameleon scalar field‎, ‎or indeed‎, ‎for some specific cases of the‎ ‎scalar field equation of state parameter‎. ‎Thereupon‎, ‎we‎ ‎schematically plot those density parameters for two different‎ ‎values of the chameleon non-minimal coupling parameter‎, ‎and‎ ‎discuss the results‎. ‎In the both considered phases‎, ‎we specify‎ ‎that‎, ‎when the kinetic energy of the chameleon scalar field is‎ ‎much less than its potential energy (i.e.‎, ‎when the scalar field‎ ‎equation of state parameter is $\simeq‎ - ‎1 $)‎, ‎the behavior of the‎ ‎chameleon model is similar to the $\Lambda CDM$ model‎. ‎Such‎ ‎compatibility suggests that the chameleon model is‎ ‎phenomenologically viable and can be tested with the observational‎ ‎data‎.