15 research outputs found
WFPC2 Observations of the Hubble Deep Field-South
The Hubble Deep Field-South observations targeted a high-galactic-latitude
field near QSO J2233-606. We present WFPC2 observations of the field in four
wide bandpasses centered at roughly 300, 450, 606, and 814 nm. Observations,
data reduction procedures, and noise properties of the final images are
discussed in detail. A catalog of sources is presented, and the number counts
and color distributions of the galaxies are compared to a new catalog of the
HDF-N that has been constructed in an identical manner. The two fields are
qualitatively similar, with the galaxy number counts for the two fields
agreeing to within 20%. The HDF-S has more candidate Lyman-break galaxies at z
> 2 than the HDF-N. The star-formation rate per unit volume computed from the
HDF-S, based on the UV luminosity of high-redshift candidates, is a factor of
1.9 higher than from the HDF-N at z ~ 2.7, and a factor of 1.3 higher at z ~ 4.Comment: 93 pages, 25 figures; contains very long table
Structures of Local Galaxies Compared to High Redshift Star-forming Galaxies
The rest-frame far-ultraviolet (FUV) morphologies of 8 nearby interacting and
starburst galaxies (Arp 269, M 82, Mrk 8, NGC 520, NGC 1068, NGC 3079, NGC
3310, NGC 7673) are compared with 54 galaxies at z ~ 1.5 and 46 galaxies at z ~
4 observed in the GOODS-ACS field. The nearby sample is artificially redshifted
to z ~ 1.5 and 4. We compare the simulated galaxy morphologies to real z ~ 1.5
and 4 UV-bright galaxy morphologies. We calculate the Gini coefficient (G), the
second-order moment of the brightest 20% of the galaxy's flux (M_20), and the
Sersic index (n). We explore the use of nonparametric methods with 2D profile
fitting and find the combination of M_20 with n an efficient method to classify
galaxies as having merger, exponential disk, or bulge-like morphologies. When
classified according to G and M_20, 20/30% of real/simulated galaxies at z ~
1.5 and 37/12% at z ~ 4 have bulge-like morphologies. The rest have merger-like
or intermediate distributions. Alternatively, when classified according to the
Sersic index, 70% of the z ~ 1.5 and z ~ 4 real galaxies are exponential disks
or bulge-like with n > 0.8, and ~30% of the real galaxies are classified as
mergers. The artificially redshifted galaxies have n values with ~35% bulge or
exponential at z ~ 1.5 and 4. Therefore, ~20-30% of Lyman-break galaxies (LBGs)
have structures similar to local starburst mergers, and may be driven by
similar processes. We assume merger-like or clumpy star-forming galaxies in the
GOODS field have morphological structure with values n -1.7.
We conclude that Mrk 8, NGC 3079, and NGC 7673 have structures similar to those
of merger-like and clumpy star-forming galaxies observed at z ~ 1.5 and 4.Comment: Accepted by The Astronomical Journal May 2009. Changes include an
added explanation of methods in Section
CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)
is designed to document the first third of galactic evolution, over the
approximate redshift (z) range 8--1.5. It will image >250,000 distant galaxies
using three separate cameras on the Hubble Space Telescope, from the
mid-ultraviolet to the near-infrared, and will find and measure Type Ia
supernovae at z>1.5 to test their accuracy as standardizable candles for
cosmology. Five premier multi-wavelength sky regions are selected, each with
extensive ancillary data. The use of five widely separated fields mitigates
cosmic variance and yields statistically robust and complete samples of
galaxies down to a stellar mass of 10^9 M_\odot to z \approx 2, reaching the
knee of the ultraviolet luminosity function (UVLF) of galaxies to z \approx 8.
The survey covers approximately 800 arcmin^2 and is divided into two parts. The
CANDELS/Deep survey (5\sigma\ point-source limit H=27.7 mag) covers \sim 125
arcmin^2 within GOODS-N and GOODS-S. The CANDELS/Wide survey includes GOODS and
three additional fields (EGS, COSMOS, and UDS) and covers the full area to a
5\sigma\ point-source limit of H \gtrsim 27.0 mag. Together with the Hubble
Ultra Deep Fields, the strategy creates a three-tiered "wedding cake" approach
that has proven efficient for extragalactic surveys. Data from the survey are
nonproprietary and are useful for a wide variety of science investigations. In
this paper, we describe the basic motivations for the survey, the CANDELS team
science goals and the resulting observational requirements, the field selection
and geometry, and the observing design. The Hubble data processing and products
are described in a companion paper.Comment: Submitted to Astrophysical Journal Supplement Series; Revised
version, subsequent to referee repor