224 research outputs found
SweetSpot: Near-Infrared Observations of Thirteen Type Ia Supernovae from a New NOAO Survey Probing the Nearby Smooth Hubble Flow
We present 13 Type Ia supernovae (SNe Ia) observed in the restframe
near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared
Camera (WHIRC) on the WIYN 3.5-m telescope. With only 1-3 points per light
curve and a prior on the time of maximum from the spectrum used to type the
object we measure an H-band dispersion of spectroscopically normal SNe Ia of
0.164 mag. These observations continue to demonstrate the improved standard
brightness of SNe Ia in H-band even with limited data. Our sample includes two
SNe Ia at z ~ 0.09, which represent the most distant restframe NIR H-band
observations published to date.
This modest sample of 13 NIR SNe Ia represent the pilot sample for
"SweetSpot" - a three-year NOAO Survey program that will observe 144 SNe Ia in
the smooth Hubble flow. By the end of the survey we will have measured the
relative distance to a redshift of z ~ 0.05 to 1%. Nearby Type Ia supernova (SN
Ia) observations such as these will test the standard nature of SNe Ia in the
restframe NIR, allow insight into the nature of dust, and provide a critical
anchor for future cosmological SN Ia surveys at higher redshift.Comment: 36 pages, 8 figures, Submitted to Ap
Trait Anxiety Is Associated with Negative Interpretations When Resolving Valence Ambiguity of Surprised Faces
The current research examines whether trait anxiety is associated with negative interpretation bias when resolving valence ambiguity of surprised faces. To further isolate the neuro-cognitive mechanism, we presented angry, happy, and surprised faces at broad, high, and low spatial frequency and asked participants to determine the valence of each face. High trait anxiety was associated with more negative interpretations of broad spatial frequency (i.e., intact) surprised faces. However, the modulation of trait anxiety on the negative interpretation of surprised faces disappeared at high and low spatial frequencies. The current study provides evidence that trait anxiety modulates negative interpretations of broad spatial frequency surprised faces. However, the negative interpretation of low spatial frequency surprised faces appears to be a robust default response that occurs regardless of individual differences in trait anxiety
Improving the LSST dithering pattern and cadence for dark energy studies
The Large Synoptic Survey Telescope (LSST) will explore the entire southern
sky over 10 years starting in 2022 with unprecedented depth and time sampling
in six filters, . Artificial power on the scale of the 3.5 deg LSST
field-of-view will contaminate measurements of baryonic acoustic oscillations
(BAO), which fall at the same angular scale at redshift . Using the
HEALPix framework, we demonstrate the impact of an "un-dithered" survey, in
which of each LSST field-of-view is overlapped by neighboring
observations, generating a honeycomb pattern of strongly varying survey depth
and significant artificial power on BAO angular scales. We find that adopting
large dithers (i.e., telescope pointing offsets) of amplitude close to the LSST
field-of-view radius reduces artificial structure in the galaxy distribution by
a factor of 10. We propose an observing strategy utilizing large dithers
within the main survey and minimal dithers for the LSST Deep Drilling Fields.
We show that applying various magnitude cutoffs can further increase survey
uniformity. We find that a magnitude cut of removes significant
spurious power from the angular power spectrum with a minimal reduction in the
total number of observed galaxies over the ten-year LSST run. We also determine
the effectiveness of the observing strategy for Type Ia SNe and predict that
the main survey will contribute 100,000 Type Ia SNe. We propose a
concentrated survey where LSST observes one-third of its main survey area each
year, increasing the number of main survey Type Ia SNe by a factor of
1.5, while still enabling the successful pursuit of other science
drivers.Comment: 9 pages, 6 figures, published in SPIE proceedings; corrected typo in
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From trust in caregivers' support to exploration : the role of openness to negative affect and self-regulation
Attachment theory assumes that trust in caregivers' support and exploration are closely related. Little research tried to investigate this link, nor focuses on mechanisms that might explain this association. The present studies examined whether trust is related to exploration through a serial indirect effect of openness to negative affect and self-regulation. In Study 1, 212 children, aged 8-13, completed questionnaires assessing trust, openness to negative affect, self-regulation and exploration. The results showed that trust predicted exploration, but only to the extent to which openness to negative affect and self-regulation were involved too. Study 2 refined these findings (n = 59, aged 9-12) using a behavioral measure of openness to negative affect and exploration, and with mother-reported self-regulation. Replicating this serial indirect effect of openness to negative affect and self-regulation with multiple informants and methods, the present studies advance our understanding of how trust might foster exploration in preadolescence
Type Ia Supernova Light Curve Inference: Hierarchical Bayesian Analysis in the Near Infrared
We present a comprehensive statistical analysis of the properties of Type Ia
SN light curves in the near infrared using recent data from PAIRITEL and the
literature. We construct a hierarchical Bayesian framework, incorporating
several uncertainties including photometric error, peculiar velocities, dust
extinction and intrinsic variations, for coherent statistical inference. SN Ia
light curve inferences are drawn from the global posterior probability of
parameters describing both individual supernovae and the population conditioned
on the entire SN Ia NIR dataset. The logical structure of the hierarchical
model is represented by a directed acyclic graph. Fully Bayesian analysis of
the model and data is enabled by an efficient MCMC algorithm exploiting the
conditional structure using Gibbs sampling. We apply this framework to the
JHK_s SN Ia light curve data. A new light curve model captures the observed
J-band light curve shape variations. The intrinsic variances in peak absolute
magnitudes are: sigma(M_J) = 0.17 +/- 0.03, sigma(M_H) = 0.11 +/- 0.03, and
sigma(M_Ks) = 0.19 +/- 0.04. We describe the first quantitative evidence for
correlations between the NIR absolute magnitudes and J-band light curve shapes,
and demonstrate their utility for distance estimation. The average residual in
the Hubble diagram for the training set SN at cz > 2000 km/s is 0.10 mag. The
new application of bootstrap cross-validation to SN Ia light curve inference
tests the sensitivity of the model fit to the finite sample and estimates the
prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light
curves are as effective as optical light curves, and, because they are less
vulnerable to dust absorption, they have great potential as precise and
accurate cosmological distance indicators.Comment: 24 pages, 15 figures, 4 tables. Accepted for publication in ApJ.
Corrected typo, added references, minor edit
Early and Late-Time Observations of SN 2008ha: Additional Constraints for the Progenitor and Explosion
We present a new maximum-light optical spectrum of the the extremely low
luminosity and exceptionally low energy Type Ia supernova (SN Ia) 2008ha,
obtained one week before the earliest published spectrum. Previous observations
of SN 2008ha were unable to distinguish between a massive star and white dwarf
origin for the SN. The new maximum-light spectrum, obtained one week before the
earliest previously published spectrum, unambiguously shows features
corresponding to intermediate mass elements, including silicon, sulfur, and
carbon. Although strong silicon features are seen in some core-collapse SNe,
sulfur features, which are a signature of carbon/oxygen burning, have always
been observed to be weak in such events. It is therefore likely that SN 2008ha
was the result of a thermonuclear explosion of a carbon-oxygen white dwarf.
Carbon features at maximum light show that unburned material is present to
significant depths in the SN ejecta, strengthening the case that SN 2008ha was
a failed deflagration. We also present late-time imaging and spectroscopy that
are consistent with this scenario.Comment: ApJL, accepted. 5 pages, 3 figure
The NN2 Flux Difference Method for Constructing Variable Object Light Curves
We present a new method for optimally extracting point-source time
variability information from a series of images. Differential photometry is
generally best accomplished by subtracting two images separated in time, since
this removes all constant objects in the field. By removing background sources
such as the host galaxies of supernovae, such subtractions make possible the
measurement of the proper flux of point-source objects superimposed on extended
sources. In traditional difference photometry, a single image is designated as
the ``template'' image and subtracted from all other observations. This
procedure does not take all the available information into account and for
sub-optimal template images may produce poor results. Given N total
observations of an object, we show how to obtain an estimate of the vector of
fluxes from the individual images using the antisymmetric matrix of flux
differences formed from the N(N-1)/2 distinct possible subtractions and provide
a prescription for estimating the associated uncertainties. We then demonstrate
how this method improves results over the standard procedure of designating one
image as a ``template'' and differencing against only that image.Comment: Accepted to AJ. To be published in November 2005 issue. 16 page, 2
figures, 2 tables. Source code available at
http://www.ctio.noao.edu/essence/nn2
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