Stellar Populations of Lyman-alpha Emitters at z=4.86: A Comparison to
  $z\sim5$ LBGs
  (abridged) We present a study of stellar population of LAEs at z=4.86 in
GOODS-N and its flanking field. With the publicly available IRAC data in
GOODS-N and further IRAC observations in the flanking fields, we select five
LAEs which are not contaminated by neighboring objects in IRAC images and
construct their observed SEDs with I_c, z', IRAC 3.6micron, and 4.5micron band
photometry. The SEDs cover the rest-frame UV to optical wavelengths. We derive
stellar masses, ages, color excesses, and star formation rates of five LAEs
using SED fitting method. Assuming the constant star formation history, we find
that the stellar masses range from 10^8 to $10^{10} Msun with the median value
of 2.5x10^9 Msun. The derived ages range from very young ages (7.4 Myr) to 437
Myr with a median age of 25 Myr. The color excess E(B-V) are between 0.1-0.4
mag. Star formation rates are 55-209 Msun/yr. A comparison of the stellar
populations is made between three LAEs and 88 LBGs selected at the same
redshift, in the same observed field, and down to the same limit of the
rest-frame UV luminosity. These three LAEs are the brightest and reddest
samples among the whole LAE samples at z=4.86. The LAEs distribute at the
relatively faint part of UV-luminosity distribution of LBGs. Deriving the
stellar properties of the LBGs by fitting their SEDs with the same model
ensures that model difference does not affect the comparison. It is found that
the stellar properties of the LAEs lie on distributions of those of LBGs. On
average, the LAEs show less dust extinction, and lower star formation rates
than LBGs, while the stellar mass of LAEs nearly lies in the middle part of the
mass distribution of LBGs. However, the stellar properties of LAEs and LBGs are
similar at the fixed UV or optical luminosity. We also examine the relations
between the output properties from the SED fitting and the rest-frame Lya
equivalent width.
