The Hα Luminosity Function and Star Formation Rate at [CLC][ITAL]z[/ITAL][/CLC] ≈ 0.24 Based on Subaru Deep Imaging Data

We have carried out a deep imaging survey for Hα emitting galaxies at z≈0.24 using a narrowband filter tuned with the redshifted line. The total sky area covered is 706 arcmin² within a redshift range from 0.234 to 0.252 (δ z=0.018). This corresponds to a volume of 3.9×10³ Mpc³ when Ωₘₐₜₜₑᵣ=0.3, Ω_Λ=0.7, and H₀=70 km s⁻¹ Mpc⁻¹ are adopted. We obtain a sample of 348 Hα emitting galaxies whose observed emission-line equivalent widths are greater than 12 . We find an extinction-corrected Hα luminosity density of 10^39.65+0.08-0.12 ergs s⁻¹ Mpc⁻³. Using the Kennicutt relation between the Hα luminosity and star formation rate, the star formation rate density in the covered volume is estimated as 0.036+0.006-0.012 M_ yr⁻¹ Mpc⁻³. This value is higher by a factor of 3 than the local SFR density.