Context : Lyman alpha ( Ly \alpha ) emitting galaxies ( LAEs ) are used to probe the distant universe and are therefore important for galaxy evolution studies and for providing clues to the nature of the epoch of reionization .
However , the exact circumstances under which Ly \alpha escapes a galaxy are still not fully understood .

Aims : The Trident project is designed to simultaneously examine Ly \alpha , H \alpha , and Lyman Continuum emission from galaxies at redshift z \sim 2 , thus linking together these three aspects of ionising radiation in galaxies .
In this paper , we outline the strategy of this project and examine the properties of LAEs in the GOODS North field .

Methods : We performed a narrowband LAE survey in GOODS North using existing and two custom made filters at the Nordic Optical Telescope with MOSCA .
We use complementary broad band archival data in the field to make a careful candidate selection and perform optical to near-IR SED fitting .
We also estimate far-infrared luminosities by matching our candidates to detections in Spitzer/MIPS 24 \mu m and Herschel/PACS catalogs .

Results : We find a total of 25 LAE candidates , probing mainly the bright end of the LAE luminosity function with L _ { Ly \alpha } \sim 1 - 15 \times 10 ^ { 42 } erg s ^ { -1 } .
They display a range of masses of \sim 0.5 - 50 \times 10 ^ { 9 } M _ { \odot } , and average ages from a few tens of Myr to 1 Gyr when assuming a constant star formation history .
The majority of our candidates also show signs of recent elevated star formation .
Three candidates have counterparts in the GOODS-Herschel far-IR catalogue , with luminosities consistent with ultra-luminous infrared galaxies ( ULIRGs ) .

Conclusions : The wide range of parameters derived from our SED fitting , as well as part of our sample being detected as ULIRGs , seems to indicate that at these Ly \alpha luminosities , LAEs do not necessarily have to be young dwarfs , and that a lack of dust is not required for Ly \alpha to escape .