The aim of this paper is to investigate spectral and photometric properties of 854 faint ( i _ { AB } \lesssim 25 mag ) star-forming galaxies ( SFGs ) at 2 < z < 2.5 using the VIMOS Ultra-Deep Survey ( VUDS ) spectroscopic data and deep multi-wavelength photometric data in three extensively studied extragalactic fields ( ECDFS , VVDS , COSMOS ) .
These SFGs were targeted for spectroscopy based on their photometric redshifts .
The VUDS spectra are used to measure the UV spectral slopes ( \beta ) as well as Ly \alpha equivalent widths ( EW ) .
On average , the spectroscopically measured \beta ( –1.36 \pm 0.02 ) , is comparable to the photometrically measured \beta ( –1.32 \pm 0.02 ) , and has smaller measurement uncertainties .
The positive correlation of \beta with the Spectral Energy Distribution ( SED ) -based measurement of dust extinction E _ { s } ( B–V ) emphasizes the importance of \beta as an alternative dust indicator at high redshifts .
To make a proper comparison , we divide these SFGs into three subgroups based on their rest-frame Ly \alpha EW : SFGs with no Ly \alpha emission ( SFG _ { N } ; EW \leq 0Å ) , SFGs with Ly \alpha emission ( SFG _ { L } ; EW > 0Å ) , and Ly \alpha emitters ( LAEs ; EW \geq 20Å ) .
The fraction of LAEs at these redshifts is \sim 10 % , which is consistent with previous observations .
We compared best-fit SED-estimated stellar parameters of the SFG _ { N } , SFG _ { L } and LAE samples .
For the luminosities probed here ( \sim L ^ { * } ) , we find that galaxies with and without Ly \alpha in emission have small but significant differences in their SED-based properties .
We find that LAEs have less dust , and lower star-formation rates ( SFR ) compared to non-LAEs .
We also find that LAEs are less massive compared to non-LAEs , though the difference is smaller and less significant compared to the SFR and E _ { s } ( B–V ) .
When we divide the LAEs based on their Spitzer/IRAC 3.6 \mu m fluxes , we find that the fraction of IRAC-detected ( m _ { 3.6 } \lesssim 25 mag ) LAEs is much higher than the fraction of IRAC-detected narrow band ( NB ) -selected LAEs at z \simeq 2–3 .
This could imply that UV-selected LAEs host a more evolved stellar population , which represents a later stage of galaxy evolution compared to NB-selected LAEs .