7,574 research outputs found
Cosmic Sculpture: A new way to visualise the Cosmic Microwave Background
3D printing presents an attractive alternative to visual representation of
physical datasets such as astronomical images that can be used for research,
outreach or teaching purposes, and is especially relevant to people with a
visual disability. We here report the use of 3D printing technology to produce
a representation of the all-sky Cosmic Microwave Background (CMB) intensity
anisotropy maps produced by the Planck mission. The success of this work in
representing key features of the CMB is discussed as is the potential of this
approach for representing other astrophysical data sets. 3D printing such
datasets represents a highly complementary approach to the usual 2D projections
used in teaching and outreach work, and can also form the basis of
undergraduate projects. The CAD files used to produce the models discussed in
this paper are made available.Comment: Accepted for publication in the European Journal of Physic
Candidate High Redshift and Primeval Galaxies in Hubble Deep Field South
We present the results of colour selection of candidate high redshift
galaxies in Hubble Deep Field South (HDF-S) using the Lyman dropout scheme. The
HDF-S data we discuss were taken in a number of different filters extending
from the near--UV (F300W) to the infrared (F222M) in two different fields. This
allows us to select candidates with redshifts from z~3 to z~12. We find 15
candidate z~3 objects (F300W dropouts), 1 candidate z~4 object (F450W dropout)
and 16 candidate z5 objects (F606W dropouts) in the ~ 4.7 arcmin^2 WFPC-2
field, 4 candidate z~6 (optical dropouts) and 1 candidate z~8 (F110W dropout)
in the 0.84 arcmin^2 NICMOS-3 field. No F160W dropouts are found (z~12). We
compare our selection technique with existing data for HDF-North and discuss
alternative interpretations of the objects. We conclude that there are a number
of lower redshift interlopers in the selections, including one previously
identified object (Treu et al. 1998), and reject those objects most likely to
be foreground contaminants. Even after this we conclude that the F606W dropout
list is likely to still contain substantial foreground contamination. The lack
of candidate very high redshift UV-luminous galaxies supports earlier
conclusions by Lanzetta et al. (1998). We discuss the morphologies and
luminosity functions of the high redshift objects, and their cosmological
implications.Comment: Accepted for publication in MNRA
High spatial resolution observations of CUDSS14A: a SCUBA-selected ultraluminous galaxy at high redshift
The definitive version is available at www.blackwell-synergy.com '. Copyright Blackwell Publishing DOI : 10.1046/j.1365-8711.2000.03822.xWe present a high-resolutionmillimetre interferometric image of the brightest SCUBA- selected galaxy from the Canada-UK deep SCUBA survey (CUDSS). We make a very clear detection at 1.3 mm, but fail to resolve any structure in the source.Peer reviewe
Optical Imaging of Very Luminous Infrared Galaxy Systems: Photometric Properties and Late Evolution
A sample of 19 low redshift (0.03z0.07) very luminous infrared galaxy
(VLIRG: L[8-1000 m] ) systems (30
galaxies) has been imaged in , , and . These objects cover a
luminosity range that is key to linking the most luminous infrared galaxies
with the population of galaxies at large. We have obtained photometry for all
of these VLIRG systems, the individual galaxies (when detached), and their
nuclei, and the relative behavior of these classes has been studied in optical
color-magnitude diagrams. The photometric properties of the sample are also
compared with previously studied samples of ULIRGs. The mean observed
photometric properties of VLIRG and ULIRG samples, considered as a whole, are
indistinguishable at optical wavelengths. This suggests that not only ULIRG,
but also the more numerous population of VLIRGs, have similar rest-frame
optical photometric properties as the submillimeter galaxies (SMG), reinforcing
the connection between low-{\it z} LIRGs -- high-{\it z} SMGs. When the nuclei
of the {\it young} and {\it old} interacting systems are considered separately,
some differences between the VLIRG and the ULIRG samples are found. In
particular, the old VLIRGs are less luminous and redder than old ULIRG systems.
If confirmed with larger samples, this behavior suggests that the late-stage
evolution is different for VLIRGs and ULIRGs. Specifically, as suggested from
spectroscopic data, the present photometric observations support the idea that
the activity during the late phases of VLIRG evolution is dominated by
starbursts, while a higher proportion of ULIRGs could evolve into a QSO type of
object.Comment: 27 pages, 5 figures (degraded to reduce space). Figures 1 and 2 are
multiple page figures (i.e. Fig 1a,b and Fig2a-g
Projecting prevalence by stage of care for prostate cancer and estimating future health service needs: protocol for a modelling study
Introduction Current strategies for the management of prostate cancer are inadequate in Australia. We will, in this study, estimate current service needs and project the future needs for prostate cancer patients in Australia. Methods and analysis First, we will project the future prevalence of prostate cancer for 2010-2018 using data for 1972-2008 from the New South Wales (NSW) Central Cancer Registry. These projections, based on modelled incidence and survival estimates, will be estimated using PIAMOD (Prevalence, Incidence, Analysis MODel) software. Then the total prevalence will be decomposed into five stages of care: initial care, continued monitoring, recurrence, last year of life and long-term survivor. Finally, data from the NSW Prostate Cancer Care and Outcomes Study, including data on patterns of treatment and associated quality of life, will be used to estimate the type and amount of services that will be needed by prostate cancer patients in each stage of care. In addition, Central Cancer Registry episode data will be used to estimate transition rates from localised or locally advanced prostate cancer to metastatic disease. Medicare and Pharmaceutical Benefits data, linked with Prostate Cancer Care and Outcomes Study data, will be used to complement the Cancer Registry episode data. The methods developed will be applied Australia-wide to obtain national estimates of the future prevalence of prostate cancer for different stages of clinical care. Ethics and dissemination This study was approved by the NSW Population and Health Services Research Ethics Committee. Results of the study will be disseminated widely to different interest groups and organisations through a report, conference presentations and peer-reviewed articles.This work is supported by the Prostate Cancer Foundation of Australia (grant number: PCFA – YI 0410). Both David Smith and Xue Qin Yu are supported by an Australian NHMRC Training Fellowship (Ref 1016598, 550002). Mark Clements is supported by an Australian NHMRC Career Development Award (Ref 471491)
INTEGRAL Field Spectroscopy of the Extended Ionized Gas in Arp 220
Integral field optical spectroscopy with the INTEGRAL system has been used to
investigate for the first time the two-dimensional kinematic and ionization
properties of the extended, warm ionized gas in Arp 220 over an area of 28 kpc
by 15 kpc. The structure of the ionized gas is divided into well identified
regions associated with the X-ray emitting plumes and extended lobes. Changes
in the ionization state of the gas along the major axis of the plumes are
detected, in particular in the outer regions of the northwestern plume where
the transition between the main stellar body of the galaxy and a broad, low
surface brightness tidal tail is located. If the plumes are produced by a
starburst-driven galactic wind, the efficiency in the conversion of mechanical
to radiation energy is a factor of at least 10 smaller than in galactic winds
developed in edge-on spirals with well defined rotation and outflowing axis.
The kinematic properties of the lobes are to a first order in agreement with
the predictions of the merger scenario according to which the lobes are
tidal-induced gas condensations produced during the merging process. The
largest velocity gradients and velocity deviations from the systemic velocity
are not associated with the plumes, but with the outer stellar envelope and
broad tidal tails at distances of up to 7.5 kpc, indicating that the large
scale kinematics of the extended ionized gas in Arp 220, is most likely
dominated by the tidal-induced motions, and not by galactic winds associated
with nuclear starbursts.Comment: To appear in Astrophysical Journal. Several values in tables 1 and 2
modified from previous version as the result of updated references. Figures
and content remains unaffecte
Discovery of distant high luminosity infrared galaxies
We have developed a method for selecting the most luminous galaxies detected
by IRAS based on their extreme values of R, the ratio of 60 micron and B-band
luminosity. These objects have optical counterparts that are close to or below
the limits of Schmidt surveys. We have tested our method on a 1079 deg^2 region
of sky, where we have selected a sample of IRAS sources with 60 micron flux
densities greater than 0.2 Jy, corresponding to a redshift limit z~1 for
objects with far-IR luminosities of 10^{13} L_sun. Optical identifications for
these were obtained from the UK Schmidt Telescope plates, using the likelihood
ratio method. Optical spectroscopy has been carried out to reliably identify
and measure the redshifts of six objects with very faint optical counterparts,
which are the only objects with R>100 in the sample. One object is a
hyperluminous infrared galaxy (HyLIG) at z=0.834. Of the remaining, fainter
objects, five are ultraluminous infrared galaxies (ULIGs) with a mean redshift
of 0.45, higher than the highest known redshift of any non-hyperluminous ULIG
prior to this study. High excitation lines reveal the presence of an active
nucleus in the HyLIG, just as in the other known infrared-selected HyLIGs. In
contrast, no high excitation lines are found in the non-hyperluminous ULIGs. We
discuss the implications of our results for the number density of HyLIGs at z<1
and for the evolution of the infrared galaxy population out to this redshift,
and show that substantial evolution is indicated. Our selection method is
robust against the presence of gravitational lensing if the optical and
infrared magnification factors are similar, and we suggest a way of using it to
select candidate gravitationally lensed infrared galaxies.Comment: 6 pages, accepted for publication in A&
Chandra Observations of Extended X-ray Emission in Arp 220
We resolve the extended X-ray emission from the prototypical ultraluminous
infrared galaxy Arp 220. Extended, faint edge-brightened, soft X-ray lobes
outside the optical galaxy are observed to a distance of 10 to 15 kpc on each
side of the nuclear region. Bright plumes inside the optical isophotes coincide
with the optical line emission and extend 11 kpc from end to end across the
nucleus. The data for the plumes cannot be fit by a single temperature plasma,
and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from
bright, diffuse circumnuclear emission in the inner 3 kpc centered on the
Halpha peak, which is displaced from the radio nuclei. There is a close
morphological correspondence between the Halpha and soft X-ray emission on all
spatial scales. We interpret the plumes as a starburst-driven superwind, and
discuss two interpretations of the emission from the lobes in the context of
simulations of the merger dynamics of Arp 220.Comment: Accepted for publication in ApJ; see also astro-ph/0208477 (Paper 1
Chandra Observations of Arp 220: The Nuclear Source
We present the first results from 60ks of observations of Arp 220 using the
ACIS-S instrument on Chandra. We report the detection of several sources near
the galaxy's nucleus, including a point source with a hard spectrum that is
coincident with the western radio nucleus B. This point source is mildly
absorbed (N_H ~ 3 x 10^22 cm^-2) and has an estimated luminosity of 4 x 10^40
erg/s. In addition, a fainter source may coincide with the eastern nucleus A.
Extended hard X-ray emission in the vicinity raises the total estimated nuclear
2-10 keV X-ray luminosity to 1.2 x 10^41 erg/s, but we cannot rule out a hidden
AGN behind columns exceeding 5 x 10^24 cm^-2. We also detect a peak of soft
X-ray emission to the west of the nucleus, and a hard point source 2.5 kpc from
the nucleus with a luminosity of 6 x 10^39 erg/s.Comment: Accepted for publication in Ap
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