3,566 research outputs found
Extended Photometry for the DEEP2 Galaxy Redshift Survey: A Testbed for Photometric Redshift Experiments
This paper describes a new catalog that supplements the existing DEEP2 Galaxy
Redshift Survey photometric and spectroscopic catalogs with ugriz photometry
from two other surveys; the Canada-France-Hawaii Legacy Survey (CFHTLS) and the
Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on
the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs.
We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to
provide a more uniform dataset. We have also used this improved photometry to
predict DEEP2 BRI photometry in regions where only poorer measurements were
available previously. In addition, we have included improved astrometry tied to
SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog
contains ~27,000 objects with full ugriz photometry as well as robust
spectroscopic redshift measurements, 64% of which have r > 23. By combining the
secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz
photometry, we have created a catalog that can be used as an excellent testbed
for future photo-z studies, including tests of algorithms for surveys such as
LSST and DES.Comment: 12 pages, 6 figures and 5 tables. Accepted to The Astrophysical
Journal Supplement. Catalogs are publicly available at
http://deep.ps.uci.edu/DR4/photo.extended.htm
Measuring Galaxy Environments with Deep Redshift Surveys
We study the applicability of several galaxy environment measures
(n^th-nearest-neighbor distance, counts in an aperture, and Voronoi volume)
within deep redshift surveys. Mock galaxy catalogs are employed to mimic
representative photometric and spectroscopic surveys at high redshift (z ~ 1).
We investigate the effects of survey edges, redshift precision, redshift-space
distortions, and target selection upon each environment measure. We find that
even optimistic photometric redshift errors (\sigma_z = 0.02) smear out the
line-of-sight galaxy distribution irretrievably on small scales; this
significantly limits the application of photometric redshift surveys to
environment studies. Edges and holes in a survey field dramatically affect the
estimation of environment, with the impact of edge effects depending upon the
adopted environment measure. These edge effects considerably limit the
usefulness of smaller survey fields (e.g. the GOODS fields) for studies of
galaxy environment. In even the poorest groups and clusters, redshift-space
distortions limit the effectiveness of each environment statistic; measuring
density in projection (e.g. using counts in a cylindrical aperture or a
projected n^th-nearest-neighbor distance measure) significantly improves the
accuracy of measures in such over-dense environments. For the DEEP2 Galaxy
Redshift Survey, we conclude that among the environment estimators tested the
projected n^th-nearest-neighbor distance measure provides the most accurate
estimate of local galaxy density over a continuous and broad range of scales.Comment: 17 pages including 16 figures, accepted to Ap
The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. IV. Association with Galaxy Mergers
Double-peaked narrow emission lines in active galactic nucleus (AGN) spectra
can be produced by AGN outflows, rotation, or dual AGNs, which are AGN pairs in
ongoing galaxy mergers. Consequently, double-peaked narrow AGN emission lines
are useful tracers of the coevolution of galaxies and their supermassive black
holes, as driven by AGN feedback and AGN fueling. We investigate this concept
further with follow-up optical longslit observations of a sample of 95 Sloan
Digital Sky Survey (SDSS) galaxies that have double-peaked narrow AGN emission
lines. Based on a kinematic analysis of the longslit spectra, we confirm
previous work that finds that the majority of double-peaked narrow AGN emission
lines are associated with outflows. We also find that eight of the galaxies
have companion galaxies with line-of-sight velocity separations < 500 km/s and
physical separations <30 kpc. Since we find evidence of AGNs in both galaxies,
all eight of these systems are compelling dual AGN candidates. Galaxies with
double-peaked narrow AGN emission lines occur in such galaxy mergers at least
twice as often as typical active galaxies. Finally, we conclude that at least
3% of SDSS galaxies with double-peaked narrow AGN emission lines are found in
galaxy mergers where both galaxies are resolved in SDSS imaging.Comment: 14 pages, 2 figures, ApJ in pres
Dorsomedial Prefrontal Cortex Mediates Rapid Evaluations Predicting the Outcome of Romantic Interactions
Humans frequently make real-world decisions based on rapid evaluations of minimal information; for example, should we talk to an attractive stranger at a party? Little is known, however, about how the brain makes rapid evaluations with real and immediate social consequences. To address this question, we scanned participants with functional magnetic resonance imaging (fMRI) while they viewed photos of individuals that they subsequently met at real-life “speed-dating” events. Neural activity in two areas of dorsomedial prefrontal cortex (DMPFC), paracingulate cortex, and rostromedial prefrontal cortex (RMPFC) was predictive of whether each individual would be ultimately pursued for a romantic relationship or rejected. Activity in these areas was attributable to two distinct components of romantic evaluation: either consensus judgments about physical beauty (paracingulate cortex) or individualized preferences based on a partner's perceived personality (RMPFC). These data identify novel computational roles for these regions of the DMPFC in even very rapid social evaluations. Even a first glance, then, can accurately predict romantic desire, but that glance involves a mix of physical and psychological judgments that depend on specific regions of DMPFC
Kiloparsec-scale Spatial Offsets in Double-peaked Narrow-line Active Galactic Nuclei. I. Markers for Selection of Compelling Dual Active Galactic Nucleus Candidates
Merger-remnant galaxies with kpc-scale separation dual active galactic nuclei
(AGNs) should be widespread as a consequence of galaxy mergers and triggered
gas accretion onto supermassive black holes, yet very few dual AGNs have been
observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan
Digital Sky Survey are plausible dual AGN candidates, but their double-peaked
profiles could also be the result of gas kinematics or AGN-driven outflows and
jets on small or large scales. To help distinguish between these scenarios, we
have obtained spatial profiles of the AGN emission via follow-up long-slit
spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 < z < 0.36
using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit
double AGN emission components with ~kpc projected spatial separations on the
sky, which suggests that they are produced by kpc-scale dual AGNs or kpc-scale
outflows, jets, or rotating gaseous disks. In addition, we find that the
subsample (58%) of the objects with spatially compact emission components may
be preferentially produced by dual AGNs, while the subsample (42%) with
spatially extended emission components may be preferentially produced by AGN
outflows. We also find that for 32% of the sample the two AGN emission
components are preferentially aligned with the host galaxy major axis, as
expected for dual AGNs orbiting in the host galaxy potential. Our results both
narrow the list of possible physical mechanisms producing the double AGN
components, and suggest several observational criteria for selecting the most
promising dual AGN candidates from the full sample of double-peaked narrow-line
AGNs. Using these criteria, we determine the 17 most compelling dual AGN
candidates in our sample.Comment: 12 pages, 8 figures, published in ApJ. Modified from original version
to reflect referee's comment
Images of Pain
An article written in part by Wretha G. Goodpaster and published in the May 2003 issue of Advance: for Imaging and Oncology Administrators, pages 53-57
The DEEP2 Redshift Survey: Lyman Alpha Emitters in the Spectroscopic Database
We present the first results of a search for Lyman-alpha emitters (LAEs) in
the DEEP2 spectroscopic database that uses a search technique that is different
from but complementary to traditional narrowband imaging surveys. We have
visually inspected ~20% of the available DEEP2 spectroscopic data and have
found nine high-quality LAEs with clearly asymmetric line profiles and an
additional ten objects of lower quality, some of which may also be LAEs. Our
survey is most sensitive to LAEs at z=4.4-4.9 and that is indeed where all but
one of our high-quality objects are found. We find the number density of our
spectroscopically-discovered LAEs to be consistent with those found in
narrowband imaging searches. The combined, averaged spectrum of our nine
high-quality objects is well fit by a two-component model, with a second,
lower-amplitude component redshifted by ~420 km/s with respect to the primary
Lyman-alpha line, consistent with large-scale outflows from these objects. We
conclude by discussing the advantages and future prospects of blank-sky
spectroscopic surveys for high-z LAEs.Comment: Accepted for publication in Ap
Keys to successful balanced scorecard implementation and use based on published implementation attempts
In recent years many companies have evolved from being centrally located and managed to decentralized, multi-national companies consisting of many separate entities to be strategically managed. In response to this and other changes, such as the need for better measurement of performance, a strategic management tool was developed called the Balanced Scorecard (BSC). This research provides a tool to guide and evaluate BSC implementation. A meta-synthesis approach was used to examine qualitative BSC data available in the literature that suggested eleven keys to successful BSC implementation and use. These keys are then used to benchmark an implementation in a government logistics organization
The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at z~1
We present measurements of the color and luminosity dependence of galaxy
clustering at z~1 in the DEEP2 Galaxy Redshift Survey. Using volume-limited
subsamples in bins of both color and luminosity, we find that: 1) The
clustering dependence is much stronger with color than with luminosity and is
as strong with color at z~1 as is found locally. We find no dependence of the
clustering amplitude on color for galaxies on the red sequence, but a
significant dependence on color for galaxies within the blue cloud. 2) For
galaxies in the range L/L*~0.7-2, a stronger large-scale luminosity dependence
is seen for all galaxies than for red and blue galaxies separately. The
small-scale clustering amplitude depends significantly on luminosity for blue
galaxies, with brighter samples having a stronger rise on scales r_p<0.5 Mpc/h.
3) Redder galaxies exhibit stronger small-scale redshift-space distortions
("fingers of god"), and both red and blue populations show large-scale
distortions in xi(r_p,pi) due to coherent infall. 4) While the clustering
length, r_0, increases smoothly with galaxy color (in narrow bins), its
power-law exponent, gamma, exhibits a sharp jump from the blue cloud to the red
sequence. The intermediate color `green' galaxy population likely includes
transitional galaxies moving from the blue cloud to the red sequence; on large
scales green galaxies are as clustered as red galaxies but show infall
kinematics and a small-scale correlation slope akin to the blue galaxy
population. 5) We compare our results to a semi-analytic galaxy formation model
applied to the Millenium Run simulation. Differences between the data and the
model suggest that in the model star formation is shut down too efficiently in
satellite galaxies.Comment: 28 pages, 17 figures, emulateapj format, accepted to ApJ, updated to
match published versio
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