Testing Models of Intrinsic Brightness Variations in Type Ia Supernovae, and their Impact on Measuring Cosmological Parameters

For spectroscopically confirmed Type Ia supernovae we evaluate models of intrinsic brightness variations with detailed data/Monte Carlo comparisons of the dispersion in the following quantities: Hubble-diagram scatter, color difference (B-V-c) between the true B-V color and the fitted color (c) from the SALT-II light curve model, and photometric redshift residual. The data sample includes 251 ugriz light curves from the 3-season Sloan Digital Sky Survey-II, and 191 griz light curves from the Supernova Legacy Survey 3-year data release. We find that the simplest model of a wavelength-independent (coherent) scatter is not adequate, and that to describe the data the intrinsic scatter model must have wavelength-dependent variations. We use Monte Carlo simulations to examine the standard approach of adding a coherent scatter term in quadrature to the distance-modulus uncertainty in order to bring the reduced chi2 to unity when fitting a Hubble diagram. If the light curve fits include model uncertainties with the correct wavelength dependence of the scatter, we find that the bias on the dark energy equation of state parameter $w$ is negligible. However, incorrect model uncertainties can lead to a significant bias on the distance moduli, with up to ~0.05 mag redshift-dependent variation. For the recent SNLS3 cosmology results we estimate that this effect introduces an additional systematic uncertainty on $w$ of ~0.02, well below the total uncertainty. However, this uncertainty depends on the samples used, and thus this small $w$-uncertainty is not guaranteed in future cosmology results.Comment: accepted by Ap

Supernova Simulations and Strategies For the Dark Energy Survey

We present an analysis of supernova light curves simulated for the upcoming Dark Energy Survey (DES) supernova search. The simulations employ a code suite that generates and fits realistic light curves in order to obtain distance modulus/redshift pairs that are passed to a cosmology fitter. We investigated several different survey strategies including field selection, supernova selection biases, and photometric redshift measurements. Using the results of this study, we chose a 30 square degree search area in the griz filter set. We forecast 1) that this survey will provide a homogeneous sample of up to 4000 Type Ia supernovae in the redshift range 0.05<z<1.2, and 2) that the increased red efficiency of the DES camera will significantly improve high-redshift color measurements. The redshift of each supernova with an identified host galaxy will be obtained from spectroscopic observations of the host. A supernova spectrum will be obtained for a subset of the sample, which will be utilized for control studies. In addition, we have investigated the use of combined photometric redshifts taking into account data from both the host and supernova. We have investigated and estimated the likely contamination from core-collapse supernovae based on photometric identification, and have found that a Type Ia supernova sample purity of up to 98% is obtainable given specific assumptions. Furthermore, we present systematic uncertainties due to sample purity, photometric calibration, dust extinction priors, filter-centroid shifts, and inter-calibration. We conclude by estimating the uncertainty on the cosmological parameters that will be measured from the DES supernova data.Comment: 46 pages, 30 figures, resubmitted to ApJ as Revision 2 (final author revision), which has subtle editorial differences compared to the published paper (ApJ, 753, 152). Note that this posting includes PDF only due to a bug in either the latex macros or the arXiv submission system. The source files are available in the DES document database: http://des-docdb.fnal.gov/cgi-bin/ShowDocument?docid=624

Search for muonic decays of the antiproton at the Fermilab Antiproton Accumulator

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on six antiproton decay modes which contain a final-state muon. At the 90% C.L. we find that tau/B(mu gamma) > 5.0 x 10^4 yr, tau/B(mu pi0) > 4.8 x 10^4 yr, tau/B(mu eta) > 7.9 x 10^3 yr, tau/B(mu gamma gamma) > 2.3 x 10^4 yr, tau/B(mu K0S > 4.3 x 10^3 yr, and tau/B(mu K0L) > 6.5 x 10^3 yr.Comment: 8 pages + 3 Postscript figure

Leading with heart: Academic leadership during the COVID-19 crisis

The COVID-19 pandemic has impacted every sphere of life. It has brought into sharp focus not only the critical role that leaders have to play in taking charge of their organisations and employees, but the complexity of that leadership role, too. The authors of this paper are both psychologists who occupy leadership positions in a university. The paper briefly explores the evolution of leadership theory, leadership in times of crises, generally, and leadership during the time of COVID-19. In addition, one of the authors offers a personal note on the leadership experience during COVID-19. What became clear during the reflections was that empathy, vulnerability, self-awareness and agility were some of the qualities needed during this crisis. In addition, the psychodynamic concept of containment appears very relevant in managing the affective intensity experienced by staff and students. Leaders were expected to not only fully understand the meaning of empathy and compassion, but to know how to sincerely demonstrate these qualities to staff and students alike

Meaning of becoming mother and son/daughter through massage

Objective: Revealing the experience of mothers when massaging their children to know the phenomenon in the context of a mother-child healthy development. Method: This is a qualitative study with a phenomenological approach carried out with 11 women who massaged their children and answered the guiding question: What did the experience of massaging your child mean to you? Results: The experience of massaging their children meant the development of their being a mother and of being a son/daughter, in addition to developing the attachment relationship between them. The massage can operationalize this integrality, become a tool of communication, stimulation and promotion of secure attachment, by promoting the loving interaction between mother and child. Conclusion: This practice should be considered as an option in the programs that promote the comprehensive health of the mother and child