Signatures of the Youngest Starbursts: Optically-thick Thermal Bremsstrahlung Radio Sources in Henize 2-10

VLA radio continuum imaging reveals compact (<8 pc) ~1 mJy radio sources in the central 5" starburst region of the blue compact galaxy Henize 2-10. We interpret these radio knots as extremely young, ultra-dense HII regions. We model their luminosities and spectral energy distributions, finding that they are consistent with unusually dense HII regions having electron densities, 1500 cm^-3 < n_e < 5000 cm^-3, and sizes of 3-8 pc. Since these H II regions are not visible in optical images, we propose that the radio data preferentially reveal the youngest, densest, and most highly obscured starforming events. Energy considerations imply that each of the five \HII regions contains ~750 O7V equivalent stars, greater than the number found in 30 Doradus in the LMC. The high densities imply an over-pressure compared to the typical interstellar medium so that such objects must be short-lived (<0.5 Myr expansion timescales). We conclude that the radio continuum maps reveal the very young (<0.5 Myr) precursors of ``super starclusters'' or ``proto globular clusters'' which are prominent at optical and UV wavelengths in He 2-10. If the ultra-dense HII regions are typical of those which we predict will be found in other starbursting systems, then super starclusters spend 15% of their lifetime in heavily-obscured environments, similar to Galactic ultra-compact HII regions. This body of work leads us to propose that massive extragalactic star clusters (i.e. proto globular clusters) with ages <10^6 yr may be most easily identified by finding compact radio sources with optically-thick thermal bremsstrahlung spectral signatures.Comment: AASTeX, 8 figures 2 included with psfig in text; other 6 in jpeg format; Postscript versions of figures may be found at http://zem.ucolick.org/chip/Research/young_clusters.html -- Accepted for publication in the Astrophysical Journa

Stellar Winds and Embedded Star Formation in the Galactic Center Quintuplet and Arches Clusters: Multifrequency Radio Observations

A multi-frequency, multi-configuration study has been made of the compact radio sources in the Galactic Center Quintuplet and Arches stellar clusters using the Very Large Array. Ten radio sources have been detected in the Quintuplet cluster. The majority of these radio sources have rising spectral indices and are positionally coincident with young massive stars that are known to have powerful stellar winds. We conclude that the three most compact of these sources are produced by stellar wind emission; thus, mass-loss rates can be derived and have an average value of 3 x 10^-5 solar masses/year. The remainder of the sources are likely to be a combination of stellar wind emission and free-free emission from surrounding ionized gas. In three cases, the radio sources have no stellar counterpart and the radio emission is thought to arise from compact or ultra-compact HII regions. If so, these sources would be the first detections of embedded massive stars to be discovered in the Galactic center clusters. The radio nebula associated with the Pistol star resembles the nebula surrounding the LBV star Eta Carina and may be related to the stellar wind of the Pistol star. Ten compact radio sources are detected in the Arches cluster and are interpreted to be stellar wind sources, consistent with previous findings. Several of the sources show moderate variability (10-30%) in their flux density, possibly related to a nonthermal component in the wind emission. A number of radio sources in both clusters have X-ray counterparts, which have been interpreted to be the shocked, colliding winds of massive binary systems.Comment: 24 pages, 6 figures; Accepted for publication in the Astronomical Journa

Retired A Stars and Their Companions VI. A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD200964

We report radial velocity measurements of the G-type subgiants 24 Sextanis (=HD90043) and HD200964. Both are massive, evolved stars that exhibit periodic variations due to the presence of a pair of Jovian planets. Photometric monitoring with the T12 0.80m APT at Fairborn Observatory demonstrates both stars to be constant in brightness to <= 0.002 mag, thus strengthening the planetary interpretation of the radial velocity variations. 24 Sex b,c have orbital periods of 453.8 days and 883~days, corresponding to semimajor axes 1.333 AU and 2.08 AU, and minimum masses (Msini) 1.99 Mjup and 0.86 Mjup, assuming a stellar mass 1.54 Msun. HD200964 b,c have orbital periods of 613.8 days and 825 days, corresponding to semimajor axes 1.601 AU and 1.95 AU, and minimum masses 1.85 Mjup and 0.90 Mjup, assuming M* = 1.44 Msun. We also carry out dynamical simulations to properly account for gravitational interactions between the planets. Most, if not all, of the dynamically stable solutions include crossing orbits, suggesting that each system is locked in a mean motion resonance that prevents close encounters and provides long-term stability. The planets in the 24 Sex system likely have a period ratio near 2:1, while the HD200964 system is even more tightly packed with a period ratio close to 4:3. However, we caution that further radial velocity observations and more detailed dynamical modelling will be required to provide definitive and unique orbital solutions for both cases, and to determine whether the two systems are truly resonant.Comment: AJ accepte

Optical and ultraviolet spectroscopic analysis of SN 2011fe at late times

We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349, and 578 days post-maximum light, as well as an ultraviolet spectrum obtained with Hubble Space Telescope at 360 days post-maximum light. We compare these observations with synthetic spectra produced with the radiative transfer code PHOENIX. The day +100 spectrum can be well fit with models which neglect collisional and radiative data for forbidden lines. Curiously, including this data and recomputing the fit yields a quite similar spectrum, but with different combinations of lines forming some of the stronger features. At day +205 and later epochs, forbidden lines dominate much of the optical spectrum formation; however, our results indicate that recombination, not collisional excitation, is the most influential physical process driving spectrum formation at these late times. Consequently, our synthetic optical and UV spectra at all epochs presented here are formed almost exclusively through recombination-driven fluorescence. Furthermore, our models suggest that the ultraviolet spectrum even as late as day +360 is optically thick and consists of permitted lines from several iron-peak species. These results indicate that the transition to the "nebular" phase in Type Ia supernovae is complex and highly wavelength-dependent.Comment: 22 pages, 21 figuress, 1 table, submitted to MNRA

Monte Carlo Simulation of Massive Absorbers for Cryogenic Calorimeters

There is a growing interest in cryogenic calorimeters with macroscopic absorbers for applications such as dark matter direct detection and rare event search experiments. The physics of energy transport in calorimeters with absorber masses exceeding several grams is made complex by the anisotropic nature of the absorber crystals as well as the changing mean free paths as phonons decay to progressively lower energies. We present a Monte Carlo model capable of simulating anisotropic phonon transport in cryogenic crystals. We have initiated the validation process and discuss the level of agreement between our simulation and experimental results reported in the literature, focusing on heat pulse propagation in germanium. The simulation framework is implemented using Geant4, a toolkit originally developed for high-energy physics Monte Carlo simulations. Geant4 has also been used for nuclear and accelerator physics, and applications in medical and space sciences. We believe that our current work may open up new avenues for applications in material science and condensed matter physics.United States. Dept. of Energy (SLAC National Accelerator Laboratory. Contract DE-AC02-76SF00515

Managing physical and mental health conditions: Consumer perspectives on integrated care

Despite the growing trend of integrating primary care and mental health services, little research has documented how consumers with severe mental illnesses (SMI) manage comorbid conditions or view integrated services. We sought to better understand how consumers perceive and manage both mental and physical health conditions and their views of integrated services. We conducted semi-structured interviews with consumers receiving primary care services integrated in a community mental health setting. Consumers described a range of strategies to deal with physical health conditions and generally viewed mental and physical health conditions as impacting one another. Consumers viewed integration of primary care and mental health services favorably, specifically its convenience, friendliness, and knowledge of providers, and collaboration between providers. Although integration was viewed positively, consumers with SMI may need a myriad of strategies and supports to both initiate and sustain lifestyle changes that address common physical health problems

Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars

We present an analysis of ~5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass subgiants (1.5 < M*/Msun < 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26 (+9,-8)%, which is significantly higher than the ~5-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to {0.2, 0.3, 0.5, 0.6, 1.3} MJup within {0.1, 0.3, 0.6, 1.0, 3.0} AU. To compare the properties of planets around intermediate-mass stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN ~ M^{alpha}P^{beta} dlnM dlnP, the observed planet frequency, and the detection limits we derived. We find that the values of alpha and beta for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4 sigma level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (~ 50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets.Comment: Accepted by the Astrophysical Journal; 15 pages, 15 figure

Temporospatial shifts in Sandhill Crane staging in the Central Platte River Valley in response to climatic variation and habitat change

Over 80% of the Mid-Continent Sandhill Crane (Antigone canadensis) Population (MCP), estimated at over 660,000 individuals, stops in the Central Platte River Valley (CPRV) during spring migration from mid-February through mid-April. Research suggests that the MCP may be shifting its distribution spatially and temporally within the CPRV. From 2002 to 2017, we conducted weekly aerial surveys of Sandhill Cranes staging in the CPRV to examine temporal and spatial trends in their abundance and distribution. Then, we used winter temperature and drought severity measures from key wintering and early migratory stopover locations to assess the impacts of weather patterns on annual migration chronology in the CPRV. We also evaluated channel width and land cover characteristics using aerial imagery from 1938, 1998, and 2016 to assess the relationship between habitat change and the spatial distribution of the MCP in the CPRV. We used generalized linear models, cumulative link models, and Akaike’s information criterion corrected for small sample sizes (AICc) to compare temporal and spatial models. Temperatures and drought conditions at wintering and migration locations that are heavily used by Greater Sandhill Cranes (A. c. tabida) best predicted migration chronology of the MCP to the CPRV. The spatial distribution of roosting Sandhill Cranes from 2015 to 2017 was best predicted by the proportion of width reduction in the main channel since 1938 (rather than its width in 2016) and the proportion of land cover as prairie-meadow habitat within 800 m of the Platte River. Our data suggest that Sandhill Cranes advanced their migration by an average of just over 1 day per year from 2002 to 2017, and that they continued to shift eastward, concentrating at eastern reaches of the CPRV. Climate change, land use change, and habitat loss have all likely contributed to Sandhill Cranes coming earlier and staying longer in fewer reaches of the CPRV, increasing their site use intensity. These historically unprecedented densities may present a disease risk to Sandhill Cranes and other waterbirds, including Whooping Cranes (Grus americana). Our models suggest that conservation actions may be maintaining Sandhill Crane densities in areas that would otherwise be declining in use. We suggest that management actions intended to mitigate trends in the distribution of Sandhill Cranes, including wet meadow restoration, may similarly benefit prairie- and braided river–endemic species of concern. Más del 80% de la población de grullas canadienses (Antigone canadensis), de la zona central del continente (MCP por sus siglas en inglés), estimada en más de 660,000, descansa en el valle central del Río Platte (CPRV por sus siglas en inglés) durante su migración de primavera, desde mediados de febrero hasta mediados de abril. Diversos estudios indican que su distribución espacial y temporal podría estar cambiando dentro del CPRV. Desde el año 2002 hasta el 2017 realizamos sondeos aéreos semanales de grullas canadienses en el CPRV para estudiar las tendencias temporales y espaciales relacionadas a su abundancia y distribución. Usamos mediciones de temperatura durante el invierno y de la severidad de la sequía de lugares claves de invernada y de sitios de descanso durante su migración temprana para evaluar el impacto de los patrones climáticos en la cronología migratoria anual del CPRV. También analizamos la amplitud del canal y las características de la cubierta terrestre usando imágenes aéreas de 1938, 1998 y 2016 con el fin de evaluar la relación entre el cambio de hábitat y la distribución espacial de la MCP en el CPRV. Utilizamos modelos lineales generalizados, modelos de enlace acumulativo y el criterio de información de Akaike adecuados a muestras pequeñas (AICc), para comparar modelos temporales y espaciales. Las condiciones climáticas y de sequía en los sitios de invernada y migración más usados por la grulla canadiense mayor (A. c. tabida) predijeron mejor la cronología migratoria de la MCP en el CPRV. La reducción de la amplitud del canal principal desde 1938, junto con el porcentaje de cubierta terrestre como hábitat de pradera dentro de los 800 m del río Platte, fue el mejor predictor de la distribución espacial de la grulla canadiense desde el año 2015 hasta el 2017. Nuestros estudios indican que las grullas canadienses adelantaron su migración en un promedio poco más de un día por año entre el 2002 y el 2017 y que continuaron desplazándose hacia el este, concentrándose en los extremos orientales del CPRV. El cambio climático, el cambio de uso del suelo y la pérdida del hábitat probablemente contribuyeron a la migración temprana de esta especie y a su permanencia más prolongada en algunos sectores del CPRV, aumentando la intensidad del uso del sitio. Estas densidades sin precedentes podrían presentar un riesgo de enfermedad para la grulla canadiense y otras aves acuáticas, incluidas las grullas trompeteras (Grus americana). Nuestros modelos indican que las medidas actuales de conservación podrían ser la causa de preservación de la densidad poblacional de la grulla canadiense en áreas en las que, de otra forma, su presencia estaría disminuyendo. Sugerimos que las medidas de control destinadas a mitigar la tendencia de distribución de la grulla canadiense, incluyendo la restauración de los prados húmedos, pueden beneficiar de igual manera a las especies endémicas, praderas y ríos trenzados de nuestro interés

Snowmass CF1 Summary: WIMP Dark Matter Direct Detection

As part of the Snowmass process, the Cosmic Frontier WIMP Direct Detection subgroup (CF1) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The charge to CF1 was (a) to summarize the current status and projected sensitivity of WIMP direct detection experiments worldwide, (b) motivate WIMP dark matter searches over a broad parameter space by examining a spectrum of WIMP models, (c) establish a community consensus on the type of experimental program required to explore that parameter space, and (d) identify the common infrastructure required to practically meet those goals.Comment: Snowmass CF1 Final Summary Report: 47 pages and 28 figures with a 5 page appendix on instrumentation R&