Using a simple method to interpret the luminosity function of Ly \alpha emitters , we explore properties of Ly \alpha emitters from 5.7 \leq z \leq 8.8 with various assumptions about metallicity and stellar mass spectra .
We constrain a mass-to- “ observed light ” ratio , M _ { h } / L _ { band } , where M _ { h } refers to the total mass of the host halo , and L _ { band } refers to the observed luminosity of the source .
For narrow-band surveys , L _ { band } is simply related to the intrinsic Ly \alpha luminosity with a survival fraction of Ly \alpha photons , \alpha _ { esc } .
The mass-to- “ bolometric light ” , M _ { h } / L _ { bol } , can also be deduced , once the metallicity and stellar mass spectrum are given .
The inferred M _ { h } / L _ { bol } is more sensitive to metallicity than to the mass spectrum .
We find the following constraints on a mass-to-light ratio of Ly \alpha emitters from 5.7 \leq z \leq 7 : ( M _ { h } / L _ { bol } ) ( \alpha _ { esc } \epsilon ^ { 1 / \gamma } ) ^ { -1 } = 21 - 38 , 14 - 26 , and 9 - 17 for Z = 0 , 1 / 50 , and 1 ~ { } Z _ { \sun } , respectively , where \epsilon is the “ duty cycle ” of Ly \alpha emitters , and \gamma \sim 2 is a local slope of the cumulative luminosity function , N ( > L ) \propto L ^ { - \gamma } , to which the current data are sensitive .
Only weak lower limits are obtained for z = 8.8 .
Therefore , Ly \alpha emitters are consistent with either starburst galaxies ( M _ { h } / L _ { bol } \sim 0.1 - 1 ) with a smaller Ly \alpha survival fraction , \alpha _ { esc } \epsilon ^ { 1 / \gamma } \sim 0.01 - 0.05 , or normal populations ( M _ { h } / L _ { bol } \sim 10 ) if a good fraction of Ly \alpha photons survived , \alpha _ { esc } \epsilon ^ { 1 / \gamma } \sim 0.5 - 1 .
We find no evidence for the end of reionization in the luminosity functions of Ly \alpha emitters discovered in the current Ly \alpha surveys , including recent discovery of one Ly \alpha emitter at z = 7 .
The data are consistent with no evolution of intrinsic properties of Ly \alpha emitters or neutral fraction in the intergalactic medium up to z = 7 .
No detection of sources at z = 8.8 does not yield a significant constraint yet .
We also show that the lack of detection at z = 8.8 does not rule out the high- z galaxies being the origin of the excess near infrared background .