2,074 research outputs found
Measuring Extinction Curves of Lensing Galaxies
We critique the method of constructing extinction curves of lensing galaxies
using multiply imaged QSOs. If one of the two QSO images is lightly reddened or
if the dust along both sightlines has the same properties then the method works
well and produces an extinction curve for the lensing galaxy. These cases are
likely rare and hard to confirm. However, if the dust along each sightline has
different properties then the resulting curve is no longer a measurement of
extinction. Instead, it is a measurement of the difference between two
extinction curves. This "lens difference curve'' does contain information about
the dust properties, but extracting a meaningful extinction curve is not
possible without additional, currently unknown information. As a quantitative
example, we show that the combination of two Cardelli, Clayton, & Mathis (CCM)
type extinction curves having different values of R(V) will produce a CCM
extinction curve with a value of R(V) which is dependent on the individual R(V)
values and the ratio of V band extinctions. The resulting lens difference curve
is not an average of the dust along the two sightlines. We find that lens
difference curves with any value of R(V), even negative values, can be produced
by a combination of two reddened sightlines with different CCM extinction
curves with R(V) values consistent with Milky Way dust (2.1 < R(V) < 5.6). This
may explain extreme values of R(V) inferred by this method in previous studies.
But lens difference curves with more normal values of R(V) are just as likely
to be composed of two dust extinction curves with R(V) values different than
that of the lens difference curve. While it is not possible to determine the
individual extinction curves making up a lens difference curve, there is
information about a galaxy's dust contained in the lens difference curves.Comment: 15 pages, 4 figues, ApJ in pres
Approaches and Methods in Architectural Research
This anthology is the proceedings publication from the 2019 NAF Symposium âApproaches and Methods in Architectural Researchâ.Addressing what methods and approaches architects, landscape architects,and urban designers use in their work, why and how, this publication initiatescritical reflection on their relevance, qualities, pitfalls, representations, anddiscursive positionings. \ua0Editors: Anne Elisabeth Toft, Magnus R\uf6nn and Morgan AnderssonContributing authors:Abdulaziz Alshabib, Morgan Andersson, Isabelle Doucet, Susanne Fredholm, Freja Fr\uf6lander, Kiran Maini Gerhardsson, Ellen Kathrine Hansen, Mette Hvass, Thomas H. Kampmann, Karl Kropf, Ann Legeby, Nils Olsson, Jarre Parkatti, Sam Ridgway, Magnus R\uf6nn, Mari Oline Giske Stendebakken, Tony Svensson, Anne Elisabeth Tof
Feeding habits of six anuran (Amphibia: Anura) species in a rainforest fragment in Northeastern Brazil
Probing The Dust-To-Gas Ratio of z > 0 Galaxies Through Gravitational Lenses
We report the detection of differential gas column densities in three
gravitational lenses, MG0414+0534, HE1104-1805, and PKS1830-211. Combined with
the previous differential column density measurements in B1600+434 and
Q2237+0305 and the differential extinction measurements of these lenses, we
probe the dust-to-gas ratio of a small sample of cosmologically distant normal
galaxies. We obtain an average dust-to-gas ratio of E(B-V)/NH =(1.4\pm0.5) e-22
mag cm^2/atoms with an estimated intrinsic dispersion in the ratio of ~40%.
This average dust-to-gas ratio is consistent with the average Galactic value of
1.7e-22 mag cm^2/atoms and the estimated intrinsic dispersion is also
consistent with the 30% observed in the Galaxy.Comment: 14 pages, 4 figures, Accepted by Ap
Phonon-induced quadrupolar ordering of the magnetic superconductor TmNiBC
We present synchrotron x-ray diffraction studies revealing that the lattice
of thulium borocarbide is distorted below T_Q = 13.5 K at zero field. T_Q
increases and the amplitude of the displacements is drastically enhanced, by a
factor of 10 at 60 kOe, when a magnetic field is applied along [100]. The
distortion occurs at the same wave vector as the antiferromagnetic ordering
induced by the a-axis field. A model is presented that accounts for the
properties of the quadrupolar phase and explains the peculiar behavior of the
antiferromagnetic ordering previously observed in this compound.Comment: submitted to PR
Quasicontinuum -decay of Zr: benchmarking indirect () cross section measurements for the -process
Nuclear level densities (NLDs) and -ray strength functions
(SFs) have been extracted from particle- coincidences of the
Zr()Zr and Zr()Zr
reactions using the Oslo method. The new Zr SF data, combined
with photonuclear cross sections, cover the whole energy range from ~MeV up to the giant dipole resonance at ~MeV. The wide-range SF data display structures at ~MeV, compatible with a superposition of the spin-flip
resonance and a pygmy resonance. Furthermore, the SF shows a
minimum at ~MeV and an increase at lower -ray
energies. The experimentally constrained NLDs and SFs are shown to
reproduce known () and Maxwellian-averaged cross sections for
Zr using the {\sf TALYS} reaction code, thus serving as a benchmark
for this indirect method of estimating () cross sections for Zr
isotopes.Comment: 10 pages and 9 figure
The extinction law in high redshift galaxies
We estimate the dust extinction laws in two intermediate redshift galaxies.
The dust in the lens galaxy of LBQS1009-0252, which has an estimated lens
redshift of zl~0.88, appears to be similar to that of the SMC with no
significant feature at 2175 A. Only if the lens galaxy is at a redshift of
zl~0.3, completely inconsistent with the galaxy colors, luminosity or location
on the fundamental plane, can the data be fit with a normal Galactic extinction
curve. The dust in the zl=0.68 lens galaxy for B0218+357, whose reddened image
lies behind a molecular cloud, requires a very flat ultraviolet extinction
curve with (formally) R(V)=12 +- 2. Both lens systems seem to have unusual
extinction curves by Galactic standards.Comment: 15 pages, 3 figures. ApJ in pres
Deep Absorption Line Studies of Quiescent Galaxies at z~2: The Dynamical Mass-Size Relation, and First Constraints on the Fundamental plane
We present dynamical and structural scaling relations of quiescent galaxies
at z=2, including the dynamical mass-size relation and the first constraints on
the fundamental plane (FP). The backbone of the analysis is a new, very deep
VLT/X-shooter spectrum of a massive, compact, quiescent galaxy at z=2.0389. We
detect the continuum between 3700-22000A and several strong absorption features
(Balmer series, Ca H+K, G-band), from which we derive a stellar velocity
dispersion of 318 +/- 53 km/s. We perform detailed modeling of the continuum
emission and line indices and derive strong simultaneous constraints on the
age, metallicity, and stellar mass. The galaxy is a dusty (A_V=0.77
(+0.36,-0.32)) solar metallicity (log(Z/Zsun) = 0.02 (+0.20,-0.41)) post
starburst galaxy, with a mean luminosity weighted log(age/yr) of 8.9 +/- 0.1.
The galaxy formed the majority of its stars at z>3 and currently has little or
no ongoing star formation. We compile a sample of three other z~2 quiescent
galaxies with measured velocity dispersions, two of which are also post
starburst like. Their dynamical mass-size relation is offset significantly less
than the stellar mass-size relation from the local early type relations, which
we attribute to a lower central dark matter fraction. Recent cosmological
merger simulations qualitatively agree with the data, but can not fully account
for the evolution in the dark matter fraction. The z~2 FP requires additional
evolution beyond passive stellar aging, to be in agreement with the local FP.
The structural evolution predicted by the cosmological simulations is
insufficient, suggesting that additional, possibly non-homologous structural
evolution is needed.Comment: Re-submitted to ApJ after implementing the comments of the refere
Distinct nature of static and dynamic magnetic stripes in cuprate superconductors
We present detailed neutron scattering studies of the static and dynamic
stripes in an optimally doped high-temperature superconductor,
LaCuO. We find that the dynamic stripes do not disperse towards the
static stripes in the limit of vanishing energy transfer. We conclude that the
dynamic stripes observed in neutron scattering experiments are not the
Goldstone modes associated with the broken symmetry of the simultaneously
observed static stripes, but rather that the signals originate from different
domains in the sample. These domains may be related by structural twinning, or
may be entirely different phases, where the static stripes in one phase are
pinned versions of the dynamic stripes in the other. Our results explain
earlier observations of unusual dispersions in underdoped
LaSrCuO () and LaBaCuO ().
Our findings are relevant for all compounds exhibiting magnetic stripes, and
may thus be a vital part in unveiling the nature of high temperature
superconductivity
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