A new class of accelerating cosmological models driven by a one-parameter version of the general Chaplygin-type equation of state is proposed .
The simplified version is naturally obtained from causality considerations with basis on the adiabatic sound speed v _ { S } plus the observed accelerating stage of the universe .
We show that very stringent constraints on the unique free parameter \alpha describing the simplified Chaplygin model can be obtained from a joint analysis involving the latest SNe type Ia data and the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations ( BAO ) .
In our analysis we have considered separately the SNe type Ia gold sample measured by Riess et al .
( 2004 ) and the Supernova Legacy Survey ( SNLS ) from Astier et al .
( 2006 ) .
At 95.4 % ( c.l .
) , we find for BAO + gold sample , 0.91 \leq \alpha \leq 1.0 and \Omega _ { M } = 0.28 ^ { +0.043 } _ { -0.048 } while BAO + SNLS analysis provides 0.94 \leq \alpha \leq 1.0 and \Omega _ { M } = 0.27 ^ { +0.048 } _ { -0.045 } .