We make a search for H \alpha emitting galaxies at z \approx 0.24 in the Subaru Deep Field ( SDF ) using the archival data set obtained with the Subaru Telescope .
We carefully select H \alpha emitters in the narrowband filter NB 816 , using B , V , R _ { c } , i ^ { \prime } , and z ^ { \prime } broad-band colors .
We obtain a sample of 258 emitting galaxies with observed equivalent widths of ( H \alpha + [ N ii ] 6548,6584 ) greater than 12 Å .
We also analyze a sample of H \alpha emitters taken from the Sloan Digital Sky Survey ( SDSS ) to constrain the luminous end of H \alpha luminosity function .
Using the same selection criteria as for the SDF , and after excluding AGNs , we obtain 317 H \alpha emitting star-forming galaxies .
Combining these two samples of H \alpha emitters found in both SDF and SDSS , we derive a H \alpha luminosity function with best-fit Schechter function parameters of \alpha = -1.31 ^ { +0.17 } _ { -0.17 } , \log \phi ^ { * } = -2.46 ^ { +0.34 } _ { -0.40 } { Mpc ^ { -3 } } , \log L ^ { * } = 41.99 ^ { +0.08 } _ { -0.07 } { ergs s ^ { -1 } } .
An extinction-corrected H \alpha luminosity density is 4.45 ^ { +2.96 } _ { -1.75 } \times 10 ^ { 39 } { ergs s ^ { -1 } Mpc ^ { -3 } } .
Using the Kennicutt relation between the H \alpha luminosity and star formation rate , the star formation rate density in the survey volume is estimated as 0.035 ^ { +0.024 } _ { -0.014 } ~ { } M _ { \odot } { yr ^ { -1 } Mpc ^ { -3 } } .
The angular two-point correlation function of H \alpha emitters over 875 arcmin ^ { 2 } at z = 0.24 is well fitted by a power-law form with w ( \theta ) = 0.047 ^ { +0.017 } _ { -0.013 } \theta ^ { -0.66 \pm 0.08 } , corresponding to the correlation function of \xi ( r ) = ( r / { 2.6 ^ { +1.0 } _ { -0.8 } Mpc } ) ^ { -1.66 \pm 0.08 } .
The small correlation length of H \alpha emitters may imply the weak clustering of active star-forming galaxies .