Stellar Populations of Lyman Break Galaxies at z=1-3 in the HST/WFC3
  Early Release Science Observations
  We analyze the spectral energy distributions (SEDs) of Lyman break galaxies
(LBGs) at z=1-3 selected using the Hubble Space Telescope (HST) Wide Field
Camera 3 (WFC3) UVIS channel filters. These HST/WFC3 observations cover about
50 sq. arcmin in the GOODS-South field as a part of the WFC3 Early Release
Science program. These LBGs at z=1-3 are selected using dropout selection
criteria similar to high redshift LBGs. The deep multi-band photometry in this
field is used to identify best-fit SED models, from which we infer the
following results: (1) the photometric redshift estimate of these dropout
selected LBGs is accurate to within few percent; (2) the UV spectral slope
(beta) is redder than at high redshift (z>3), where LBGs are less dusty; (3) on
average, LBGs at z=1-3 are massive, dustier and more highly star-forming,
compared to LBGs at higher redshifts with similar luminosities
(0.1L*<~L<~2.5L*), though their median values are similar within 1-sigma
uncertainties. This could imply that identical dropout selection technique, at
all redshifts, find physically similar galaxies; and (4) stellar masses of
these LBGs are directly proportional to their UV luminosities with a
logarithmic slope of ~0.46, and star-formation rates are proportional to their
stellar masses with a logarithmic slope of ~0.90. These relations hold true ---
within luminosities probed in this study --- for LBGs from z~1.5 to 5. The
star-forming galaxies selected using other color-based techniques show similar
correlations at z~2, but to avoid any selection biases, and for direct
comparison with LBGs at z>3, a true Lyman break selection at z~2 is essential.
The future HST UV surveys, both wider and deeper, covering a large luminosity
range are important to better understand LBG properties, and their evolution.
