209 research outputs found
Quick Starting Dialog Systems with Paraphrase Generation
Acquiring training data to improve the robustness of dialog systems can be a
painstakingly long process. In this work, we propose a method to reduce the
cost and effort of creating new conversational agents by artificially
generating more data from existing examples, using paraphrase generation. Our
proposed approach can kick-start a dialog system with little human effort, and
brings its performance to a level satisfactory enough for allowing actual
interactions with real end-users. We experimented with two neural paraphrasing
approaches, namely Neural Machine Translation and a Transformer-based seq2seq
model. We present the results obtained with two datasets in English and in
French:~a crowd-sourced public intent classification dataset and our own
corporate dialog system dataset. We show that our proposed approach increased
the generalization capabilities of the intent classification model on both
datasets, reducing the effort required to initialize a new dialog system and
helping to deploy this technology at scale within an organization
Weak lensing analysis of CODEX clusters using dark energy camera legacy survey : mass-richness relation
We present the weak-lensing analysis of 279 CODEX clusters using imaging data from 4200 deg(2) of the DECam Legacy Survey (DECaLS) Data Release 3. The cluster sample results from a joint selection in X-ray, optical richness in the range 20 proportional to M-0 (lambda/40)(F lambda). By measuring the CODEX cluster sample as an individual cluster, we obtain the best-fitting values, M-0 = 3.24(-0.27)(+0.29) x 10(14)M(circle dot), and F-lambda = 1.00(-0.22)(+0.22) for the richness scaling index, consistent with a power-law relation. Moreover, we separate the cluster sample into three richness groups; lambda = 20-30, 30-50, and 50-110, and measure the stacked excess surface mass density profile in each group. The results show that both methods are consistent. In addition, we find an excellent agreement between our weak lensing based scaling relation and the relation obtained with dynamical masses estimated from cluster member velocity dispersions measured by the SDSS-IV/SPIDERS team. This suggests that the cluster dynamical equilibrium assumption involved in the dynamical mass estimates is statistically robust for a large sample of clusters.Peer reviewe
Stellar-to-halo mass relation of cluster galaxies
In the hierarchical formation model, galaxy clusters grow by accretion of
smaller groups or isolated galaxies. During the infall into the centre of a
cluster, the properties of accreted galaxies change. In particular, both
observations and numerical simulations suggest that its dark matter halo is
stripped by the tidal forces of the host.
We use galaxy-galaxy weak lensing to measure the average mass of dark matter
haloes of satellite galaxies as a function of projected distance to the centre
of the host, for different stellar mass bins. Assuming that the stellar
component of the galaxy is less disrupted by tidal stripping, stellar mass can
be used as a proxy of the infall mass. We study the stellar to halo mass
relation of satellites as a function of the cluster-centric distance to measure
tidal stripping.
We use the shear catalogues of the DES science verification archive, the
CFHTLenS and the CFHT Stripe 82 (CS82) surveys, and we select satellites from
the redMaPPer catalogue of clusters. For galaxies located in the outskirts of
clusters, we find a stellar to halo mass relation in good agreement with the
theoretical expectations from \citet{moster2013} for central galaxies. In the
centre of the cluster, we find that this relation is shifted to smaller halo
mass for a given stellar mass. We interpret this finding as further evidence
for tidal stripping of dark matter haloes in high density environments.Comment: 15 pages, 14 figure
Perceval: A Software Platform for Discrete Variable Photonic Quantum Computing
We introduce Perceval, an evolutive open-source software platform for
simulating and interfacing with discrete variable photonic quantum computers,
and describe its main features and components. Its Python front-end allows
photonic circuits to be composed from basic photonic building blocks like
photon sources, beam splitters, phase shifters and detectors. A variety of
computational back-ends are available and optimised for different use-cases.
These use state-of-the-art simulation techniques covering both weak simulation,
or sampling, and strong simulation. We give examples of Perceval in action by
reproducing a variety of photonic experiments and simulating photonic
implementations of a range of quantum algorithms, from Grover's and Shor's to
examples of quantum machine learning. Perceval is intended to be a useful
toolkit both for experimentalists wishing to easily model, design, simulate, or
optimise a discrete variable photonic experiment, and for theoreticians wishing
to design algorithms and applications for discrete-variable photonic quantum
computing platforms
Beyond the Ultra-deep Frontier Fields And Legacy Observations (BUFFALO): a high-resolution strong + weak-lensing view of Abell 370
The HST treasury program BUFFALO provides extended wide-field imaging of the
six Hubble Frontier Fields galaxy clusters. Here we present the combined strong
and weak-lensing analysis of Abell 370, a massive cluster at z=0.375. From the
reconstructed total projected mass distribution in the 6arcmin x 6arcmin
BUFFALO field-of-view, we obtain the distribution of massive substructures
outside the cluster core and report the presence of a total of seven
candidates, each with mass . Combining the
total mass distribution derived from lensing with multi-wavelength data, we
evaluate the physical significance of each candidate substructure, and conclude
that 5 out of the 7 substructure candidates seem reliable, and that the mass
distribution in Abell 370 is extended along the North-West and South-East
directions. While this finding is in general agreement with previous studies,
our detailed spatial reconstruction provides new insights into the complex mass
distribution at large cluster-centric radius. We explore the impact of the
extended mass reconstruction on the model of the cluster core and in
particular, we attempt to physically explain the presence of an important
external shear component, necessary to obtain a low root-mean-square separation
between the model-predicted and observed positions of the multiple images in
the cluster core. The substructures can only account for up to half the
amplitude of the external shear, suggesting that more effort is needed to fully
replace it by more physically motivated mass components. We provide public
access to all the lensing data used as well as the different lens models.Comment: 29 pages, 17 figures, 3 table
BUFFALO/Flashlights: Constraints on the abundance of lensed supergiant stars in the Spock galaxy at redshift 1
In this work, we present a constraint on the abundance of supergiant (SG) stars at redshift z ≈ 1, based on recent observations of astrongly lensed arc at this redshift. First we derived a free-form model of MACS J0416.1-2403 using data from the Beyond Ultradeep Frontier Fields and Legacy Observations (BUFFALO) program. The new lens model is based on 72 multiply lensed galaxies thatproduce 214 multiple images, making it the largest sample of spectroscopically confirmed lensed galaxies on this cluster. The largercoverage in BUFFALO allowed us to measure the shear up to the outskirts of the cluster, and extend the range of lensing constraintsup to ∼1 Mpc from the central region, providing a mass estimate up to this radius. As an application, we make predictions for thenumber of high-redshift multiply lensed galaxies detected in future observations with the James Webb Space Telescope (JWST).Then we focus on a previously known lensed galaxy at z = 1.0054, nicknamed Spock, which contains four previously reportedtransients. We interpret these transients as microcaustic crossings of SG stars and explain how we computed the probability of suchevents. Based on simplifications regarding the stellar evolution, we find that microlensing (by stars in the intracluster medium) ofSG stars at z = 1.0054 can fully explain these events. The inferred abundance of SG stars is consistent with either (1) a numberdensity of stars with bolometric luminosities beyond the Humphreys-Davidson (HD) limit (Lmax ≈ 6 × 105 L for red stars), whichis below ∼400 stars kpc−2, or (2) the absence of stars beyond the HD limit but with a SG number density of ∼9000 kpc−2 for starswith luminosities between 105 L and 6 × 105 L. This is equivalent to one SG star per 10 × 10 pc2. Finally, we make predictions forfuture observations with JWST’s NIRcam. We find that in observations made with the F200W filter that reach 29 mag AB, if cool red SG stars exist at z ≈ 1 beyond the HD limit, they should be easily detected in this arc
BUFFALO/Flashlights: Constraints on the abundance of lensed supergiant stars in the Spock galaxy at redshift 1
We present a constraint on the abundance of supergiant (SG) stars at redshift
z approx. 1, based on recent observations of a strongly lensed arc at this
redshift. First we derive a free-form model of MACS J0416.1-2403 using data
from the BUFFALO program. The new lens model is based on 72 multiply lensed
galaxies that produce 214 multiple images, making it the largest sample of
spectroscopically confirmed lensed galaxies on this cluster. The larger
coverage in BUFFALO allows us to measure the shear up to the outskirts of the
cluster, and extend the range of lensing constraints up to ~ 1 Mpc from the
central region, providing a mass estimate up to this radius. As an application,
we make predictions for the number of high-redshift multiply-lensed galaxies
detected in future observations with JWST. Then we focus on a previously known
lensed galaxy at z=1.0054, nicknamed Spock, which contains four previously
reported transients. We interpret these transients as microcaustic crossings of
SG stars and compute the probability of such events. Based on simplifications
regarding the stellar evolution, we find that microlensing (by stars in the
intracluster medium) of SG stars at z=1.0054 can fully explain these events.
The inferred abundance of SG stars is consistent with either (1) a number
density of stars with bolometric luminosities beyond the Humphreys-Davidson
(HD) limit (L ~ ) that is below 400 stars per sq. kpc,
or (2) the absence of stars beyond the HD limit but with a SG number density of
~ 9000 per sq. kpc for stars with luminosities between and
. This is equivalent to one SG star per 10x10 pc. We finally
make predictions for future observations with JWST's NIRcam. We find that in
observations made with the F200W filter that reach 29 mag AB, if cool red SG
stars exist at z~1 beyond the HD limit, they should be easily detected in this
arcComment: 24 pages & 18 figure
Early Science with the Large Millimeter Telescope: Detection of Dust Emission in Multiple Images of a Normal Galaxy at z \u3e 4 Lensed by a Frontier Fields Cluster
We directly detect dust emission in an optically detected, multiply imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1 mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS0717_Az9, is at z \u3e 4 and the strong lensing model (μ=7.5) allows us to calculate an intrinsic IR luminosity of 9.7 × 1010 Le and an obscured star formation rate of 14.6 ± 4.5 Me yr−1. The unobscured star formation rate from the UV is only 4.1 ± 0.3 Me yr−1, which means the total star formation rate (18.7 ± 4.5 Me yr−1) is dominated (75%–80%) by the obscured component. With an intrinsic stellar mass of only 6.9 × 109 Me, MACS0717_Az9 is one of only a handful of z \u3e 4 galaxies at these lower masses that is detected in dust emission. This galaxy lies close to the estimated star formation sequence at this epoch. However, it does not lie on the dust obscuration relation (IRX-β) for local starburst galaxies and is instead consistent with the Small Magellanic Cloud attenuation law. This remarkable lower mass galaxy, showing signs of both low metallicity and high dust content, may challenge our picture of dust production in the early universe
X-ray, lensing and Sunyaev Zel'dovich triaxial analysis of Abell 1835 out to R_{200}
Measuring the intrinsic shape and orientation of dark matter (DM) and
intracluster (IC) gas in galaxy clusters is crucial to constraining their
formation and evolution, and for enhancing the use of clusters as more precise
cosmological probes. Extending our previous works, we present for the first
time results from a triaxial joint analysis of the galaxy cluster Abell 1835,
by means of X-ray, strong lensing (SL) and Sunyaev Zel'dovich (SZ) data. We
parametrically reconstruct the full three-dimensional structure (triaxial shape
and principal axis orientation) of both the DM and the IC gas, and the level of
non-thermal pressure of the IC gas. We find that the intermediate-major and
minor-major axis ratios of the DM are 0.71+/-0.08 and 0.59+/-0.05,
respectively, and the major axis of the DM halo is inclined with respect to the
line of sight at 18.3+/-5.2 deg. We present the first observational measurement
of the non-thermal pressure out to R_{200}, which has been evaluated to be a
few percent of the total energy budget in the internal regions, while reaching
approximately 20% in the outer volumes. We discuss the implications of our
method for the viability of the CDM scenario, focusing on the concentration
parameter C and the inner slope of the DM gamma in order to test the cold dark
matter (CDM) paradigm for structure formation: we measure gamma=1.01+/-0.06 and
C=4.32+/-0.44, values which are close to the predictions of the CDM model. The
combination of X-ray/SL data at high spatial resolution, capable of resolving
the cluster core, with the SZ data, which are more sensitive to the cluster
outer volume, allows us to characterize the level and the gradient of the gas
entropy distribution and non-thermal pressure out to R_{200}, breaking the
degeneracy among the physical models describing the thermal history of the ICM.Comment: MNRAS in press. arXiv admin note: substantial text overlap with
arXiv:1108.076
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