This paper presents the results from the first wide and deep dual narrow-band survey to select H \alpha and [ O ii ] line emitters at z = 1.47 \pm 0.02 , exploiting synergies between the United Kingdom InfraRed Telescope and the Subaru telescope by using matched narrow-band filters in the H and z ^ { \prime } bands .
The H \alpha survey at z = 1.47 reaches a 3 \sigma flux limit of F _ { { H } \alpha } \approx 7 \times 10 ^ { -17 } erg s ^ { -1 } cm ^ { -2 } ( corresponding to a limiting SFR in H \alpha of \approx 7 M _ { \odot } yr ^ { -1 } ) and detects \approx 200 H \alpha emitters over 0.7 deg ^ { 2 } , while the much deeper [ O ii ] survey reaches an effective flux of \approx 7 \times 10 ^ { -18 } erg s ^ { -1 } cm ^ { -2 } ( SFR in [ O ii ] of \sim 1 M _ { \odot } yr ^ { -1 } ) , detecting \approx 1400 z = 1.47 [ O ii ] emitters in a matched co-moving volume of \sim 2.5 \times 10 ^ { 5 } Mpc ^ { 3 } .
The combined survey results in the identification of 190 simultaneous H \alpha and [ O ii ] emitters at z = 1.47 .
H \alpha and [ O ii ] luminosity functions are derived and both are shown to evolve significantly from z \sim 0 in a consistent way .
The star formation rate density of the Universe at z = 1.47 is evaluated , with the H \alpha analysis yielding \rho _ { SFR } = 0.16 \pm 0.05 M _ { \odot } yr ^ { -1 } Mpc ^ { -3 } and the [ O ii ] analysis \rho _ { SFR } = 0.17 \pm 0.04 M _ { \odot } yr ^ { -1 } Mpc ^ { -3 } .
The measurements are combined with other studies , providing a self-consistent measurement of the star formation history of the Universe over the last \sim 11 Gyrs .
By using a large comparison sample at z \sim 0.1 , derived from the Sloan Digital Sky Survey , [ O ii ] /H \alpha line ratios are calibrated as probes of dust-extinction .
H \alpha emitters at z \sim 1.47 show on average A _ { H \alpha } \approx 1 mag , the same as found by SDSS in the local Universe .
It is shown that although dust extinction correlates with SFR , the relation evolves by about \sim 0.5 mag from z \sim 1.5 to z \sim 0 , with local relations over-predicting the dust extinction corrections at high- z by that amount .
Stellar mass is found to be a much more fundamental extinction predictor , with the same relation between mass and dust-extinction being valid at both z \sim 0 and z \sim 1.5 , at least for low and moderate stellar masses .
The evolution in the extinction-SFR relation is therefore interpreted as being due to the evolution in median specific SFRs over cosmic time .
Dust extinction corrections as a function of optical colours are also derived and shown to be broadly valid at both z \sim 0 and z \sim 1.5 , offering simpler mechanisms for estimating extinction in moderately star-forming systems over the last \sim 9 Gyrs .