The Lyman- \alpha ( Ly \alpha ) emission line has been ubiquitously used to confirm and study high redshift galaxies .
We report on the line morphology as seen in the 2D spectra from the VIMOS Ultra Deep Survey ( VUDS ) in a sample of 914 Ly \alpha emitters from a parent sample of 4192 star-forming galaxies at 2 < z _ { \mathrm { spec } } \lesssim 6 .
The study of the spatial extent of Ly \alpha emission provides insight into the escape of Ly \alpha photons from galaxies .
We classify the line emission as either non-existent , coincident , projected spatial offset , or extended with respect to the observed 2D UV continuum emission .
The line emitters in our sample are classified as \sim 45 \% coincident , \sim 24 \% extended and \sim 11 \% offset emitters . For galaxies with detected UV continuum , we show that extended Ly \alpha emitters ( LAEs ) correspond to the highest equivalent width galaxies ( with an average W _ { \mathrm { Ly \alpha } } \sim - 22 Å ) .
This means that this class of objects is the most common in narrow-band selected samples , which usually select high equivalent width LAEs , < -20 Å .
Extended Ly \alpha emitters are found to be less massive , less star-forming , with lower dust content , and smaller UV continuum sizes ( r _ { 50 } \sim 0.9 kpc ) of all the classes considered here .
We also find that galaxies with larger UV-sizes have lower fractions of Ly \alpha emitters .
By stacking the spectra per emitter class we find that the weaker Ly \alpha emitters have stronger low ionization inter-stellar medium ( ISM ) absorption lines .
Interestingly , we find that galaxies with Ly \alpha offset emission ( median separation of 1.1 _ { -0.8 } ^ { +1.3 } kpc from UV continuum ) show similar velocity offsets in the ISM as those with no visible emission ( and different from other Ly \alpha emitting classes ) .
This class of objects may hint at episodes of gas accretion , bright offset clumps or on-going merging activity into the larger galaxies .