Variable Chaplygin Gas: Constraints from CMBR and SNe Ia

Abstract

We constrain the parameters of the variable Chaplygin gas model, using the location of peaks of the CMBR spectrum and SNe Ia ``gold '' data set. Equation of state of the model is $P=-A(a)/ρ$, where $A(a)=A_0 a^{-n}$ is a positive function of the cosmological scale factor $a$, $A_0$ and $n$ being constants. The variable Chaplygin gas interpolates from dust-dominated era to quintessence dominated era. The model is found to be compatible with current type Ia Supernovae data and location of first peak if the values of $Ω_m$ and $n$ lie in the interval $[0.017,~0.117]$ and $[-1.3,~2.6]$ respectively.