University, Dalian 116029, People’s Republic of China
author:
- 'Xin Zhang$^{1,2}$, Feng-Quan Wu$^{1,2}$, and Jingfei Zhang$^{3}$\'
title: New generalized Chaplygin gas as a scheme for unification of dark energy and dark matter
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epsf

Introduction
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Recent observations of Type Ia supernovae (SNe Ia) [@sn] indicate that the expansion of the Universe is accelerating at the present time. These results, when combined with the observations of cosmic microwave background (CMB) [@wmap] and large scale structure (LSS) [@sdss], strongly suggest that the Universe is spatially flat and dominated by an exotic component with large negative pressure, referred to as dark energy [@de]. The first year result of the Wilkinson Microwave Anisotropy Probe (WMAP) shows that dark energy occupies about $73\%$ of the energy of our Universe, and dark matter about $23\%$. The usual baryon matter which can be described by our known particle theory occupies only about $4\%$ of the total energy of the Universe. Although we can affirm that the ultimate fate of the Universe is determined by the feature of dark energy, the nature of dark energy as well as its cosmological origin remain enigmatic at present. So far the confirmed information about dark energy is still limited and 