1,819 research outputs found
Seeing the sky through Hubble's eye: The COSMOS SkyWalker
Large, high-resolution space-based imaging surveys produce a volume of data
that is difficult to present to the public in a comprehensible way. While
megapixel-sized images can still be printed out or downloaded via the World
Wide Web, this is no longer feasible for images with 10^9 pixels (e.g., the
Hubble Space Telescope Advanced Camera for Surveys [ACS] images of the Galaxy
Evolution from Morphology and SEDs [GEMS] project) or even 10^10 pixels (for
the ACS Cosmic Evolution Survey [COSMOS]). We present a Web-based utility
called the COSMOS SkyWalker that allows viewing of the huge ACS image data set,
even through slow Internet connections. Using standard HTML and JavaScript, the
application successively loads only those portions of the image at a time that
are currently being viewed on the screen. The user can move within the image by
using the mouse or interacting with an overview image. Using an astrometrically
registered image for the COSMOS SkyWalker allows the display of calibrated
world coordinates for use in science. The SkyWalker "technique" can be applied
to other data sets. This requires some customization, notably the slicing up of
a data set into small (e.g., 256^2 pixel) subimages. An advantage of the
SkyWalker is the use of standard Web browser components; thus, it requires no
installation of any software and can therefore be viewed by anyone across many
operating systems.Comment: 4 pages, 2 figures, accepted for publication in PAS
Income and Subjective Financial Well-Being as Determining Factors of Life Satisfaction
The purpose of the investment is to improve the current level of life satisfaction by achieving investment goals. Investors tend to attain high levels of life satisfaction when their investment goals are achieved and lower levels of life satisfaction when goals are far from achievement. The idiosyncratic characteristics of an individual may often hamper the achievement of investment goals and ultimately influence the level of life satisfaction. These characteristics can either contribute towards low life satisfaction or high life satisfaction. Income and the subjective financial well-being play a determining role in whether an investor has a positive or negative life satisfaction. Hence, the aim of this study was to determine whether income and subjective financial well-being have an influence on the life satisfaction of investors. The results of this study reveal that a strong relationship exists between income, financial well-being, and life satisfaction. Investors who perceived themselves, to have high financial well-being were more likely to have high life satisfaction. On the contrary, investors with low perceived financial well-being were more likely to have low life satisfaction. Similar results were observed for income and life satisfaction since a positive relationship was also found
Evolution in the Dust Lane Fraction of Edge-on L* Spiral Galaxies since z=0.8
The presence of a well-defined and narrow dust lane in an edge-on spiral
galaxy is the observational signature of a thin and dense molecular disk, in
which gravitational collapse has overcome turbulence. Using a sample of
galaxies out to z~1 extracted from the COSMOS survey, we identify the fraction
of massive disks that display a dust lane. Our goal is to explore the evolution
in the stability of the molecular ISM disks in spiral galaxies over a cosmic
timescale. We check the reliability of our morphological classifications
against changes in restframe wavelength, resolution, and cosmic dimming with
(artificially redshifted) images of local galaxies from SDSS. We find that the
fraction of L* disks with dust lanes in COSMOS is consistent with the local
fraction (~80%) out to z~0.7. At z=0.8, the dust lane fraction is only slightly
lower. A somewhat lower dust lane fraction in starbursting galaxies tentatively
supports the notion that a high specific star formation rate can efficiently
destroy or inhibit a dense molecular disk. A small subsample of higher redshift
COSMOS galaxies display low internal reddening (E[B-V]), as well as a low
incidence of dust lanes. These may be disks in which the growth of the dusty
ISM disk lags behind that of the stellar disk. We note that at z=0.8, the most
massive galaxies display a lower dust lane fraction than lower mass galaxies. A
small contribution of recent mergers or starbursts to this most massive
population may be responsible. The fact that the fraction of galaxies with dust
lanes in COSMOS is consistent with little or no evolution implies that models
to explain the Spectral Energy Distribution or the host galaxy dust extinction
of supernovae based on local galaxies are still applicable to higher redshift
spirals. It also suggests that dust lanes are long lived phenomena or can be
reformed over very short time-scales.Comment: 14 pages, 9 figures, 2 tables, accepted for publication by Ap
The VIMOS Ultra Deep Survey. Luminosity and stellar mass dependence of galaxy clustering at z~3
We present the study of the dependence of galaxy clustering on luminosity and
stellar mass in the redshift range 2z3.5 using 3236 galaxies with robust
spectroscopic redshifts from the VIMOS Ultra Deep Survey (VUDS). We measure the
two-point real-space correlation function for four volume-limited
stellar mass and four luminosity, M absolute magnitude selected,
sub-samples. We find that the scale dependent clustering amplitude
significantly increases with increasing luminosity and stellar mass indicating
a strong galaxy clustering dependence on these properties. This corresponds to
a strong relative bias between these two sub-samples of b/b=0.43.
Fitting a 5-parameter HOD model we find that the most luminous and massive
galaxies occupy the most massive dark matter haloes with
M = 10 h M. Similar to the
trends observed at lower redshift, the minimum halo mass M depends on
the luminosity and stellar mass of galaxies and grows from M
=10 hM to M=10 hM
from the faintest to the brightest among our galaxy sample, respectively. We
find the difference between these halo masses to be much more pronounced than
is observed for local galaxies of similar properties. Moreover, at z~3, we
observe that the masses at which a halo hosts, on average, one satellite and
one central galaxy is M4M over all luminosity ranges,
significantly lower than observed at z~0 indicating that the halo satellite
occupation increases with redshift. The luminosity and stellar mass dependence
is also reflected in the measurements of the large scale galaxy bias, which we
model as b(L)=1.92+25.36(L/L). We conclude our study
with measurements of the stellar-to-halo mass ratio (SHMR).Comment: 20 pages, 11 figures, A&A in press, v2. revised discussion in sec.
5.5, changed Fig. 4 and Fig. 11, added reference
Morphology and evolution of emission line galaxies in the Hubble Ultra Deep Field
We investigate the properties and evolution of a sample of galaxies selected
to have prominent emission lines in low-resolution grism spectra of the Hubble
Ultra Deep Field (HUDF). These objects, eGRAPES, are late type blue galaxies,
characterized by small proper sizes (R_50 < 2 kpc) in the 4350A rest-frame, low
masses (5x10^9 M_sun), and a wide range of luminosities and surface
brightnesses. The masses, sizes and volume densities of these objects appear to
change very little up to a redshift of z=1.5. On the other hand, their surface
brightness decreases significantly from z=1.5 to z=0 while their mass-to-light
ratio increases two-folds. This could be a sign that most of low redshift
eGRAPES have an older stellar population than high redshift eGRAPES and hence
that most eGRAPES formed at higher redshifts. The average volume density of
eGRAPES is (1.8 \pm 0.3)x10^{-3} Mpc^{-3} between 0.3 < z < 1.5. Many eGRAPES
would formally have been classified as Luminous Compact Blue Galaxies (LCBGs)
if these had been selected based on small physical size, blue intrinsic color,
and high surface brightness, while the remainder of the sample discussed in
this paper forms an extension of LCBGs towards fainter luminosities.Comment: Accepted, to appear in Ap
S-CANDELS: The Spitzer-Cosmic Assembly Near-Infrared Deep Extragalactic Survey. Survey Design, Photometry, and Deep IRAC Source Counts
The Spitzer-Cosmic Assembly Deep Near-Infrared Extragalactic Legacy Survey
(S-CANDELS; PI G. Fazio) is a Cycle 8 Exploration Program designed to detect
galaxies at very high redshifts (z > 5). To mitigate the effects of cosmic
variance and also to take advantage of deep coextensive coverage in multiple
bands by the Hubble Space Telescope Multi-Cycle Treasury Program CANDELS,
S-CANDELS was carried out within five widely separated extragalactic fields:
the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS,
the HST Deep Field North, and the Extended Groth Strip. S-CANDELS builds upon
the existing coverage of these fields from the Spitzer Extended Deep Survey
(SEDS) by increasing the integration time from 12 hours to a total of 50 hours
but within a smaller area, 0.16 square degrees. The additional depth
significantly increases the survey completeness at faint magnitudes. This paper
describes the S-CANDELS survey design, processing, and publicly-available data
products. We present IRAC dual-band 3.6+4.5 micron catalogs reaching to a depth
of 26.5 AB mag. Deep IRAC counts for the roughly 135,000 galaxies detected by
S-CANDELS are consistent with models based on known galaxy populations. The
increase in depth beyond earlier Spitzer/IRAC surveys does not reveal a
significant additional contribution from discrete sources to the diffuse Cosmic
Infrared Background (CIB). Thus it remains true that only roughly half of the
estimated CIB flux from COBE/DIRBE is resolved.Comment: 23 pages, 19 figures, accepted by ApJ
What it means to succeed: Personal perceptions of career success held by senior managers
This research describes the findings of a qualitative study which analyses how senior managers conceptualise and experience career success for themselves. A non-probability voluntary sample of 24 senior managers, using objective
career success criteria, was selected from two international financial institutions located in Johannesburg. This research study entailed semi-structured in-depth interviews that were digitally voice recorded, transcribed verbatim, and analysed
using content analysis. In exploring career success from the perspective of the individual (i.e. the senior manager) and not the organisation, the research attempts to fill the gap in the career literature. Findings demonstrate that although senior managers have general conceptualisations of what career success entail, they have unique personal meanings which they associate with their own career success (e.g. being associated with successful business brands, receiving feedback and recognition and adding value to the organisation). Senior managers also have specific goals set for their future in terms of careers (e.g. owning your own business venture, embracing new opportunities and investing in the community). Talent retention is particularly important among senior managers. Thus, in order to retain them as valuable employees, it is crucial to address and fulfil their career needs accordingly
Identifying dynamically young galaxy groups via wide-angle tail galaxies: A case study in the COSMOS field at z=0.53
We present an analysis of a wide-angle tail (WAT) radio galaxy located in a
galaxy group in the COSMOS field at a redshift of z=0.53 (hereafter CWAT-02).
We find that the host galaxy of CWAT-02 is the brightest galaxy in the group,
although it does not coincide with the center of mass of the system. Estimating
a) the velocity of CWAT-02, relative to the intra-cluster medium (ICM), and b)
the line-of-sight peculiar velocity of CWAT-02's host galaxy, relative to the
average velocity of the group, we find that both values are higher than those
expected for a dominant galaxy in a relaxed system. This suggests that
CWAT-02's host group is dynamically young and likely in the process of an
ongoing group merger. Our results are consistent with previous findings showing
that the presence of a wide-angle tail galaxy in a galaxy group or cluster can
be used as an indicator of dynamically young non-relaxed systems. Taking the
unrelaxed state of CWAT-02's host group into account, we discuss the impact of
radio-AGN heating from CWAT-02 onto its environment, in the context of the
missing baryon problem in galaxy groups. Our analysis strengthens recent
results suggesting that radio-AGN heating may be powerful enough to expel
baryons from galaxy groups.Comment: 8 pages, 6 figures, 1 table. Accepted for publication in Ap
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