Abstract
The aim of this paper is to investigate spectral and photometric properties
of 854 faint ($i_AB$<~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 primarily because of
their photometric redshifts. The VUDS spectra are used to measure the UV
spectral slopes ($\beta$) as well as Ly$\alpha$ equivalent widths (EW). The
spectroscopically measured $\beta$ are, on average, redder (less negative)
compared to the photometrically measured $\beta$. The positive correlation of
$\beta$ with the SED-based measurement of dust extinction E(B-V) emphasizes the
importance of $\beta$ as an alternative dust indicator at high redshifts. For
proper comparison, we divide these SFGs into three sub-groups based on their
rest-frame Ly$\alpha$ EW: SFG_N (EW<=0A), SFG_L (EW>0A), and LAEs (EW=>20A).
The fraction of LAEs at these redshifts is ~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, we find
statistically significant correlations for dust and star-formation rates (SFR),
such that, SFG_L (and LAEs) are less dusty and low star-forming compared to
SFG_N, but the differences are small compared to the large dispersion in these
stellar parameters. We do not observe any significant difference in stellar
mass or UV absolute magnitude. We also observe similar trends of decreasing
dust and SFR with increasing Ly$\alpha$ EW. When we divide the LAEs based on
their Spitzer/IRAC 3.6$\mu$m fluxes, we find that the fraction of IRAC-detected
(m$_3.6$<~25 mag) LAEs is much higher than the fraction of IRAC-detected
NB-selected LAEs at z~2-3. abridged
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