153 research outputs found
Time-dependent calculation of ionization in Potassium at mid-infrared wavelengths
We study the dynamics of the Potassium atom in the mid-infrared, high
intensity, short laser pulse regime. We ascertain numerical convergence by
comparing the results obtained by the direct expansion of the time-dependent
Schroedinger equation onto B-Splines, to those obtained by the eigenbasis
expansion method. We present ionization curves in the 12-, 13-, and 14-photon
ionization range for Potassium. The ionization curve of a scaled system, namely
Hydrogen starting from the 2s, is compared to the 12-photon results. In the
13-photon regime, a dynamic resonance is found and analyzed in some detail. The
results for all wavelengths and intensities, including Hydrogen, display a
clear plateau in the peak-heights of the low energy part of the Above Threshold
Ionization (ATI) spectrum, which scales with the ponderomotive energy Up, and
extends to 2.8 +- 0.5 Up.Comment: 15 two-column pages with 15 figures, 3 tables. Accepted for
publication in Phys. Rev A. Improved figures, language and punctuation, and
made minor corrections. We also added a comparison to the ADK theor
On the evolution of environmental and mass properties of strong lens galaxies in COSMOS
Among the 100 strong lens candidates found in the COSMOS field, 20 with
redshifts in the range [0.34,1.13], feature multiple images of background
sources. Using the multi-wavelength coverage of the field and its spectroscopic
follow-up, we characterize the evolution with redshift of the environment and
of the dark-matter (DM) fraction of the lens galaxies. We present new redshift
of the strong lens candidates. The lens environment is characterized by the
projected 10 closest galaxies around each lens and by the number of galaxies
with a projected distance less than 1Mpc at the lens galaxy redshift. In both
cases, we perform similar measurements on a control sample of twin non-lens
early type galaxies (ETGs). In addition, we identify group members and field
galaxies in the X-ray and optical catalogs of galaxy groups. From those
catalogs, we measure the external shear contribution at the lens galaxy
positions. The systems are then modeled using a SIE plus the external shear due
to the groups. We observe that the average stellar mass of lens galaxies
increases with z and that the environment of lens galaxies is compatible with
that of the twins. During the lens modeling, we notice that, when let free, the
external shear points in a direction which is the mean direction of the
external shear due to groups and of the closest galaxy to the lens. We notice
that the DM fraction of the lens galaxies within the Einstein radius decreases
as the redshift increases. Given these, we conclude that, while the environment
of lens galaxies is compatible with that of non-lens ETGS, their mass
properties evolves significantly with redshift: it is still not clear whether
this advocates in favor of a stronger lensing bias toward massive objects at
high redshift or is simply representative of the high proportion of massive and
high stellar density galaxies at high redshift.Comment: Accepted for publication in A&A. Significant modifications in the
paper but similar conclusion
Theory of mind and peer relationships: the role of social anxiety
Recent research has shown that individual differences in Theory of mind (ToM) during middle childhood are linked with individual differences in childrenâs peer relationships. The present longitudinal study investigated this association more deeply, exploring the potential mediating role played by childrenâs social anxiety. We tested a group of 66 children (11.5 years old at Time 1) three times over one year after their transition to secondary school. Over and above language, SES and stability in individual differences, ToM performance shortly after starting secondary school (Time 1) predicted higher peer acceptance, as well as lower peer rejection, one year later (Time 3) via lower levels of social anxiety over time (Time 2). This study extends our knowledge about the links between social understanding and interpersonal relations in middle childhood. The results suggest that ToM may play an important role in childrenâs adjustment when confronting new social contexts
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 â 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 âź1 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 â 6 Ă 105 L for red stars), whichis below âź400 stars kpcâ2, or (2) the absence of stars beyond the HD limit but with a SG number density of âź9000 kpcâ2 for starswith luminosities between 105 L and 6 Ă 105 L. This is equivalent to one SG star per 10 Ă 10 pc2. Finally, we make predictions forfuture observations with JWSTâs NIRcam. We find that in observations made with the F200W filter that reach 29 mag AB, if cool red SG stars exist at z â 1 beyond the HD limit, they should be easily detected in this arc
Beyond the ultradeep frontier fields and legacy observations (BUFFALO): a high-resolution strong+weak-lensing view of Abell 370
peer reviewe
Combining dark energy survey science verification data with near-infrared data from the ESO VISTA hemisphere survey
We present the combination of optical data from the Science Verification
phase of the Dark Energy Survey (DES) with near infrared data from the ESO
VISTA Hemisphere Survey (VHS). The deep optical detections from DES are used to
extract fluxes and associated errors from the shallower VHS data. Joint 7-band
() photometric catalogues are produced in a single 3 sq-deg DECam
field centred at 02h26m04d36m where the availability of ancillary
multi-wavelength photometry and spectroscopy allows us to test the data
quality. Dual photometry increases the number of DES galaxies with measured VHS
fluxes by a factor of 4.5 relative to a simple catalogue level matching
and results in a 1.5 mag increase in the 80\% completeness limit of the
NIR data. Almost 70\% of DES sources have useful NIR flux measurements in this
initial catalogue. Photometric redshifts are estimated for a subset of galaxies
with spectroscopic redshifts and initial results, although currently limited by
small number statistics, indicate that the VHS data can help reduce the
photometric redshift scatter at both . We present example
DES+VHS colour selection criteria for high redshift Luminous Red Galaxies
(LRGs) at as well as luminous quasars. Using spectroscopic
observations in this field we show that the additional VHS fluxes enable a
cleaner selection of both populations with 10\% contamination from galactic
stars in the case of spectroscopically confirmed quasars and
contamination from galactic stars in the case of spectroscopically confirmed
LRGs. The combined DES+VHS dataset, which will eventually cover almost 5000
sq-deg, will therefore enable a range of new science and be ideally suited for
target selection for future wide-field spectroscopic surveys.We thank the referee, Nicholas Cross, for a very useful report on
this manuscript. MB acknowledges a postdoctoral fellowship via
OLâs Advanced European Research Council Grant (TESTDE).
Funding for the DES Projects has been provided by the U.S.
Department of Energy, the U.S. National Science Foundation, the
Ministry of Science and Education of Spain, the Science and Technology
Facilities Council of the United Kingdom, the Higher Education
Funding Council for England, the National Center for Supercomputing
Applications at the University of Illinois at Urbana-
Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Financiadora de Estudos e Projetos, Fundac¸ Ëao
Carlos Chagas Filho de Amparo `a Pesquisa do Estado do Rio de
Janeiro, Conselho Nacional de Desenvolvimento Cient´Ĺfico e Tecnol
´ogico and the Minist´erio da CiËencia e Tecnologia, the Deutsche
Forschungsgemeinschaft and the Collaborating Institutions in the
Dark Energy Survey.
The Collaborating Institutions are Argonne National Laboratories,
the University of California at Santa Cruz, the University of
Cambridge, Centro de Investigaciones Energeticas, Medioambientales
y Tecnologicas-Madrid, the University of Chicago, University
College London, the DES-Brazil Consortium, the Eidgen¨ossische
Technische Hochschule (ETH) Z¨urich, Fermi National Accelerator
Laboratory, the University of Edinburgh, the University of
Illinois at Urbana-Champaign, the Institut de Ciencies de lâEspai
(IEEC/CSIC), the Institut de Fisica dâAltes Energies, the Lawrence
Berkeley National Laboratory, the Ludwig-Maximilians Universit
¨at and the associated Excellence Cluster Universe, the University
of Michigan, the National Optical Astronomy Observatory,
the University of Nottingham, The Ohio State University, the University
of Pennsylvania, the University of Portsmouth, SLAC National
Laboratory, Stanford University, the University of Sussex,
and Texas A&M University.
The DES participants from Spanish institutions are partially
supported by MINECO under grants AYA2009-13936, AYA2012-
39559, AYA2012-39620, and FPA2012-39684, which include
FEDER funds from the European Union.
We are grateful for the extraordinary contributions of our
CTIO colleagues and the DES Camera, Commissioning and Science
Verification teams in achieving the excellent instrument and
telescope conditions that have made this work possible. The success
of this project also relies critically on the expertise and dedication
of the DES Data Management organisation.
The analysis presented here is based on observations obtained
as part of the VISTA Hemisphere Survey, ESO Progam, 179.A-
2010 (PI: McMahon) and data products from observations made
with ESO Telescopes at the La Silla Paranal Observatory under
programme ID 179.A-2006 (PI: Jarvis).
Data for the OzDES spectroscopic survey were obtained with
the Anglo-Australian Telescope (program numbers 12B/11 and
13B/12). Parts of this research were conducted by the Australian
Research Council Centre of Excellence for All-sky Astrophysics
(CAASTRO), through project number CE110001020. TMD acknowledges
the support of the Australian Research Council through
Future Fellowship, FT100100595.This is the final published version. It first appeared at http://mnras.oxfordjournals.org/content/446/3/2523.abstract
OzDES multifibre spectroscopy for the Dark Energy Survey: three year results and first data release
We present results for the first three years of OzDES, a six-year program to obtain redshifts for objects in the Dark Energy Survey (DES) supernova fields using the 2dF fibre positioner and AAOmega spectrograph on the Anglo-Australian Telescope. OzDES is a multi-object spectroscopic survey targeting multiple types of targets at multiple epochs over a multi-year baseline, and is one of the first multi-object spectroscopic surveys to dynamically include transients into the target list soon after their discovery. At the end of three years, OzDES has spectroscopically confirmed almost 100 supernovae, and has measured redshifts for 17,000 objects, including the redshifts of 2,566 supernova hosts. We examine how our ability to measure redshifts for targets of various types depends on signal-to-noise, magnitude, and exposure time, finding that our redshift success rate increases significantly at a signal-to-noise of 2 to 3 per 1-°Angstrom bin. We also find that the change in signal-to-noise with exposure time closely matches the Poisson limit for stacked exposures as long as 10 hours.We use these results to predict the redshift yield of the full OzDES survey, as well as the potential yields of future surveys on other facilities such as 4MOST, PFS, and MSE. This work marks the first OzDES data release, comprising 14,693 redshifts. OzDES is on target to obtain over 30,000 redshifts over the six-year duration of the survey, including a yield of approximately 5,700 supernova host-galaxy redshifts
Factors shaping prayer frequency among 9- to 11-year-olds
This paper begins by reviewing the evidence from international research concerning the personal and social correlates of prayer frequency during childhood and adolescence. Overall these data continue to support the view that young people who pray not only report higher levels of personal wellbeing but also report higher levels of pro-social attitudes. These findings raise a research question of particular relevance within church schools regarding the factors that predict higher levels of prayer activity among students. The Student Voice Project offers data that can illuminate this research question. Among the 3,101 9- to 11-year old students who participated in the project 11% prayed daily, 9% at least once a week, 32% sometimes, 11% once or twice a year, and 37% never. The present paper tests the power of four sets of predictor variables to account for individual differences in prayer frequency among these students: personal factors (age and sex), psychological factors (using the three dimensional model of personality proposed by Eysenck), church attendance (self, mother, and father), and family discussion about prayer (mother, father, and grandparents). Multiple regression analyses identified the discussion of prayer with the mother as the single most important predictor. These findings locate the development of the practice of prayer within the home, even more than within the church
Development of the social brain from age three to twelve years
Human adults recruit distinct networks of brain regions to think about the bodies and minds of others. This study characterizes the development of these networks, and tests for relationships between neural development and behavioral changes in reasoning about others' minds ('theory of mind', ToM). A large sample of children (n = 122, 3-12 years), and adults (n = 33), watched a short movie while undergoing fMRI. The movie highlights the characters' bodily sensations (often pain) and mental states (beliefs, desires, emotions), and is a feasible experiment for young children. Here we report three main findings: (1) ToM and pain networks are functionally distinct by age 3 years, (2) functional specialization increases throughout childhood, and (3) functional maturity of each network is related to increasingly anti-correlated responses between the networks. Furthermore, the most studied milestone in ToM development, passing explicit false-belief tasks, does not correspond to discontinuities in the development of the social brain.National Science Foundation (U.S.) (Award 1122374)National Science Foundation (U.S.) (Award 095518)National Institutes of Health (U.S.) (Award R01-MH096914-05
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