Abstract
We study the global properties of 51
compact field galaxies with redshifts z ~ 0.2 -
1.3 and apparent magnitudes
I814 < 23.74 in the
flanking fields of the Hubble Deep Field. All
these galaxies have angular half-light radii
re < 0.5 arcsec. Keck
spectra covering ~4000-9000 Å, combined with HST
І814 images and Keck V-band images, were used to
derive redshifts, V606 -
I814 colors, absolute blue
magnitudes (MB), linear
half-light radii
(Re),
blue average surface brightnesses within
Re
(SBe),
velocity widths (σ),
virial masses (M),
mass-to-light ratios
(M/L), excitations
(O[III]/Hβ), and star
formation rates (SFR). The results of this study
can be summarized as follows:
(i):Only
12% of the 51 compact galaxies have
absorption-line dominated spectra, while 88% show
strong, narrow emission lines, similar to the
so-called CNELGs (e.g., Koo, this
volume).(ii):Despite
being very luminous (i.e.,
LB ~
L*; see figure la),
compact emission-line galaxies are low-mass
stellar sytems (i.e., M ≤
1010 Mʘ,
typically; see figure
lb).(iii):Roughly
60% of the compact emission-line galaxies have
colors, sizes, surface brightnesses, luminosities,
velocity widths, excitations, star formation
rates, and mass-to-light ratios characteristic of
young, star-forming HII galaxies (see figures 1
and 2). The remaining 40% form a more
heterogeneous class of evolved starbursts, similar
to local disk starburst
galaxies.(iv):Without
additional star formation, galaxy evolution models
predict that HII-like distant compacts will fade
to resemble today’s spheroidal galaxies such as
NGC 205 (Koo, this
volume).
Spectroscopic Studies of Emission Line Galaxies
