We have combined optical and NIR photometry from Pan-STARRS 1 and UKIDSS to search the young ( 5–10 Myr ) star-forming region of Upper Scorpius for wide ( \approx 400–4000 AU ) substellar companions down to \sim 5 M _ { Jup } .
Our search is \approx 4 mag deeper than previous work based on 2MASS .
We identified several candidates around known stellar members using a combination of color selection and spectral energy distribution fitting .
Our followup spectroscopy has identified two new companions as well as confirmed two companions previously identified from photometry , with spectral types of M7.5-M9 and masses of \sim 15–60 M _ { Jup } , indicating a frequency for such wide substellar companions of \sim 0.6 \pm 0.3 % .
Both USco 1610 - 1913B and USco 1612 - 1800B are more luminous than expected for their spectral type compared with known members of Upper Sco .
HIP 77900B has an extreme mass ratio ( M _ { 2 } / M _ { 1 } \approx 0.005 ) and an extreme separation of 3200 AU .
USco 1602 - 2401B also has a very large separation of 1000 AU .
We have also confirmed a low-mass stellar companion , USco 1610 - 2502B ( 730 AU , M5.5 ) .
Our substellar companions appear both non-coeval with their primary stars according to evolutionary models and , as a group , are systematically more luminous than the Upper Sco cluster sequence .
One possible reason for these luminosity discrepancies could be different formation processes or accretion histories for these objects .