\contentsline {chapter}{\numberline {1}Introductory stuff}{4} \contentsline {section}{\numberline {1.1}Introduction }{4} \contentsline {section}{\numberline {1.2}Galaxy formation model}{7} \contentsline {chapter}{\numberline {2}Some results}{11} \contentsline {section}{\numberline {2.1}Evolution of the Ly$\alpha $ luminosity function}{11} \contentsline {section}{\numberline {2.2}Observable properties of Ly$\alpha $ emitters }{16} \contentsline {subsection}{\numberline {2.2.1}Ly$\alpha $ equivalent widths}{16} \contentsline {subsection}{\numberline {2.2.2}Broad-band magnitudes}{21} \contentsline {subsection}{\numberline {2.2.3}Sizes of Ly$\alpha $ emitters}{24} \contentsline {section}{\numberline {2.3}Predicted physical properties of Ly$\alpha $ emitters }{26} \contentsline {subsection}{\numberline {2.3.1}Halo masses}{27} \contentsline {subsection}{\numberline {2.3.2}Clustering bias}{27} \contentsline {subsection}{\numberline {2.3.3}Stellar masses}{29} \contentsline {subsection}{\numberline {2.3.4}Metallicities}{30} \contentsline {subsection}{\numberline {2.3.5}Star formation rates}{31} \contentsline {subsection}{\numberline {2.3.6}UV continuum luminosities}{31} \contentsline {section}{\numberline {2.4}The abundance of Ly$\alpha $ emitters at $z>7$}{32} \contentsline {chapter}{\numberline {3}More complicated stuff}{38} \contentsline {section}{\numberline {3.1}Some equations}{38} \contentsline {section}{\numberline {3.2} table}{39} \contentsline {chapter}{\numberline {4}Final stuff}{41} \contentsline {section}{\numberline {4.1}Conclusions}{41}