3,551 research outputs found
High Spatial Resolution Observations of Two Young Protostars in the R Corona Australis Region
We present multi-wavelength, high spatial resolution imaging of the IRS 7
region in the R Corona Australis molecular cloud. Our observations include 1.1
mm continuum and HCO^+ J = images from the SMA, ^{12}CO J =
outflow maps from the DesertStar heterodyne array receiver on the HHT, 450
m and 850 m continuum images from SCUBA, and archival Spitzer IRAC
and MIPS 24 \micron images. The accurate astrometry of the IRAC images allow us
to identify IRS 7 with the cm source VLA 10W (IRS 7A) and the X-ray source X_W.
The SMA 1.1 mm image reveals two compact continuum sources which are also
distinguishable at 450 m. SMA 1 coincides with X-ray source CXOU
J190156.4-365728 and VLA cm source 10E (IRS 7B) and is seen in the IRAC and
MIPS images. SMA 2 has no infrared counterpart but coincides with cm source VLA
9. Spectral energy distributions constructed from SMA, SCUBA and Spitzer data
yield bolometric temperatures of 83 K for SMA 1 and 70 K for SMA 2. These
temperatures along with the submillimeter to total luminosity ratios indicate
that SMA 2 is a Class 0 protostar, while SMA 1 is a Class 0/Class I
transitional object (L= \Lsun). The ^{12}CO J = outflow map
shows one major and possibly several smaller outflows centered on the IRS 7
region, with masses and energetics consistent with previous work. We identify
the Class 0 source SMA 2/VLA 9 as the main driver of this outflow. The complex
and clumpy spatial and velocity distribution of the HCO^+ J =
emission is not consistent with either bulk rotation, or any known molecular
outflow activity.Comment: 31 pages, 8 figures, Accepted to Ap
Non-Collinear Ferromagnetic Luttinger Liquids
The presence of electron-electron interactions in one dimension profoundly
changes the properties of a system. The separation of charge and spin degrees
of freedom is just one example. We consider what happens when a system
consisting of a ferromagnetic region of non-collinearity, i.e. a domain wall,
is coupled to interacting electrons in one-dimension (more specifically a
Luttinger liquid). The ferromagnetism breaks spin charge separation and the
presence of the domain wall introduces a spin dependent scatterer into the
problem. The absence of spin charge separation and the effects of the electron
correlations results in very different behaviour for the excitations in the
system and for spin-transfer-torque effects in this model.Comment: 6 pages, submitted to Journal of Physics: Conference Series for JEMS
201
Observation of Spin-glass-like Behavior in SrRuO3 Epitaxial Thin Films
We report the observation of spin-glass-like behavior and strong magnetic
anisotropy in extremely smooth (~1-3 \AA) roughness) epitaxial (110) and (010)
SrRuO3 thin films. The easy axis of magnetization is always perpendicular to
the plane of the film (unidirectional) irrespective of crystallographic
orientation. An attempt has been made to understand the nature and origin of
spin-glass behavior, which fits well with Heisenberg model.Comment: 5 pages, 5 Figure
The Association between Contact and Intellectual Disability Literacy, Causal Attributions and Stigma
Background: Contact is seen as a key route to tackling stigma and discrimination. Contact theory states that the quality and type of contact, as well as circumstance of the contact experience, influence the effect of contact on prejudice. The majority of research in intellectual disabilities though has focused on contact as present or absent only. Method: 1264 adult members of the UK general population completed measures of symptom recognition, social distance (as measure of external stigma) and causal beliefs in response to a diagnostically unlabelled vignette, depicting someone with intellectual disabilities. Results: A nuanced contact variable, including frequency of contact and closeness and nature of the contact relationship, explained more of the variance in social distance, compared to the binary variable (contact as present or absent). Only the closeness of the relationship was individually predictive though and the models explained only relatively small amounts of the variance. Structural equation modelling of contact, recognition, social distance and causal beliefs demonstrated that the model including the nuanced variable was an adequate fit for the data. Conclusions: Future research aimed at increasing our understanding of intellectual disability stigma should avoid assessing contact as a binary variable only, but consider other factors, particularly the closeness of contact relationships. Anti-stigma interventions may benefit from focussing on causal attributions as a method of reducing stigma
Non-Markovian Persistence at the PC point of a 1d non-equilibrium kinetic Ising model
One-dimensional non-equilibrium kinetic Ising models evolving under the
competing effect of spin flips at zero temperature and nearest neighbour spin
exchanges exhibiting a parity-conserving (PC) phase transition on the level of
kinks are investigated here numerically from the point of view of the
underlying spin system. The dynamical persistency exponent and the
exponent characterising the two-time autocorrelation function of the
total magnetization under non-equilibrium conditions are reported. It is found
that the PC transition has strong effect: the process becomes non-Markovian and
the above exponents exhibit drastic changes as compared to the Glauber-Ising
case.Comment: 6 pages, Latex, postscript figures include
Spatially resolved spectra of 3C galaxy nuclei
We present and discuss visible-wavelength long-slit spectra of four low
redshift 3C galaxies obtained with the STIS instrument on the Hubble Space
Telescope. The slit was aligned with near-nuclear jet-like structure seen in
HST images of the galaxies, to give unprecedented spatial resolution of the
galaxy inner regions. In 3C 135 and 3C 171, the spectra reveal clumpy emission
line structures that indicate outward motions of a few hundred km s
within a centrally illuminated and ionised biconical region. There may also be
some low-ionisation high-velocity material associated with 3C 135. In 3C 264
and 3C 78, the jets have blue featureless spectra consistent with their
proposed synchrotron origin. There is weak associated line emission in the
innermost part of the jets with mild outflow velocity. These jets are bright
and highly collimated only within a circumnuclear region of lower galaxy
luminosity, which is not dusty. We discuss the origins of these central regions
and their connection with relativistic jets.Comment: 15 pages incl Tables, 12 diagrams, To appear in A
Generalized Dynamic Scaling for Critical Magnetic Systems
The short-time behaviour of the critical dynamics for magnetic systems is
investigated with Monte Carlo methods. Without losing the generality, we
consider the relaxation process for the two dimensional Ising and Potts model
starting from an initial state with very high temperature and arbitrary
magnetization. We confirm the generalized scaling form and observe that the
critical characteristic functions of the initial magnetization for the Ising
and the Potts model are quite different.Comment: 32 pages with15 eps-figure
Exploring the Nature of Weak Chandra Sources near the Galactic Centre
We present results from the first near-IR imaging of the weak X-ray sources
discovered in the Chandra/ACIS-I survey (Wang et al. 2002) towards the Galactic
Centre (GC). These ~800 discrete sources, which contribute significantly to the
GC X-ray emission, represent an important and previously unknown population
within the Galaxy. From our VLT observations we will identify likely IR
counterparts to a sample of the hardest sources, which are most likely X-ray
binaries. With these data we can place constraints on the nature of the
discrete weak X-ray source population of the GC.Comment: In Proc. of ``Interacting Binaries: Accretion, Evolution, and
Outcomes'', eds. L. A. Antonelli et al., AIP, Cefalu, Sicily, 200
ATLBS Extended Source Sample: The evolution in radio source morphology with flux density
Based on the ATLBS survey we present a sample of extended radio sources and
derive morphological properties of faint radio sources. 119 radio galaxies form
the ATLBS-Extended Source Sample (ATLBS-ESS) consisting of all sources
exceeding 30" in extent and integrated flux densities exceeding 1 mJy. We give
structural details along with information on galaxy identifications and source
classifications. The ATLBS-ESS, unlike samples with higher flux-density limits,
has almost equal fractions of FR-I and FR-II radio galaxies with a large
fraction of the FR-I population exhibiting 3C31-type structures. Significant
asymmetry in lobe extents appears to be a common occurrence in the ATLBS-ESS
FR-I sources compared to FR-II sources. We present a sample of 22 FR-Is at
z>0.5 with good structural information. The detection of several giant radio
sources, with size exceeding 0.7 Mpc, at z>1 suggests that giant radio sources
are not less common at high redshifts. The ESS also includes a sample of 28
restarted radio galaxies. The relative abundance of dying and restarting
sources is indicative of a model where radio sources undergo episodic activity
in which an active phase is followed by a brief dying phase that terminates
with restarting of the central activity; in any massive elliptical a few such
activity cycles wherein adjacent events blend may constitute the lifetime of a
radio source and such bursts of blended activity cycles may be repeated over
the age of the host. The ATLBS-ESS includes a 2-Mpc giant radio galaxy with the
lowest surface brightness lobes known to date.Comment: 69 pages, 119 figures, 4 tables, to appear in ApJ
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