The Universidad Complutense de Madrid ( UCM ) Survey is a long-term project aiming at finding and analysing star-forming galaxies detected by their H \alpha emission in Schmidt objective-prism plates .
The instrumental set-up limits the volume of the Universe surveyed to a redshift z \lesssim 0.045 .
So far we have discovered several hundred emission-line galaxies ( ELGs ) undergoing star formation at a wide range of levels .
Analyzing a complete sample of ELGs from the UCM survey we have computed the H \alpha luminosity function for the star-forming galaxies in the surveyed volume of the Universe .
A Schechter function provides a good fit to the H \alpha luminosity function with the following parameters : \alpha = -1.3 \pm 0.2 ; L ^ { * } ( { H } \alpha ) = 10 ^ { 42.15 \pm 0.08 } erg s ^ { -1 } and \phi ^ { * } = 10 ^ { -3.2 \pm 0.2 } Mpc ^ { -3 } for H _ { 0 } = 50 km s ^ { -1 } Mpc ^ { -1 } .
Integrating over the full range of luminosities , we obtain an H \alpha luminosity density of 10 ^ { 39.1 \pm 0.2 } erg s ^ { -1 } Mpc ^ { -3 } .
Using the H \alpha emission as a star formation rate ( SFR ) estimator , this translates into a SFR density for the Local Universe of 0.013 ^ { +0.007 } _ { -0.005 } M _ { \odot } yr ^ { -1 } Mpc ^ { -3 } in star-forming galaxies with EW ( H \alpha + [ NII ] ) > 10 Å and z \lesssim 0.045 , for a Scalo Initial Mass Function .
This is the first observational determination of this quantity , which will provide a direct test of current galaxy formation and evolution models .