On the Star Formation Efficiency in High-redshift Ly alpha Emitters

We present semi-analytical models of high-redshift Ly alpha emitters (LAEs) to constrain the star formation efficiency in those galaxies. Our supernova feedback induced star formation model along with Sheth-Tormman halo mass function correctly reproduces the shape, amplitude and the redshift evolution of UV and Ly alpha luminosity functions of LAEs in the redshift range z = 2 to 7.3. We show that the fraction of Ly alpha emitting galaxies increases with increasing redshifts reaching to unity just after the reionisation. However, we show that star formation efficiency in those LAEs does not show any redshift evolution within the uncertainty in available observations. This would have significant repercussion on the reionisation of the intergalactic medium.