Early Results from the Wisconsin H-Alpha Mapper Southern Sky Survey

After a successful eleven-year campaign at Kitt Peak, we moved the Wisconsin H-Alpha Mapper (WHAM) to Cerro Tololo in early 2009. Here we present some of the early data after a few months under southern skies. These maps begin to complete the first all-sky, kinematic survey of the diffuse H-alpha emission from the Milky Way. Much of this emission arises from the Warm Ionized Medium (WIM), a significant component of the ISM that extends a few kiloparsecs above the Galactic disk. While this first look at the data focuses on the H-alpha survey, WHAM is also capable of observing many other optical emission lines, revealing fascinating trends in the temperature and ionization state of the WIM. Our ongoing studies of the physical conditions of diffuse ionized gas will continue from the southern hemisphere following the H-alpha survey. In addition, future observations will cover the full velocity range of the Magellanic Stream, Bridge, and Clouds to trace the ionized gas associated with these neighboring systems.Comment: 4 pages, 2 figures. To appear in "The Dynamic ISM: A celebration of the Canadian Galactic Plane Survey," ASP Conference Serie

The First Detection of Diffuse Interstellar [OII] Emission and Confirmation That Variations in [NII]/Hα Trace Variations in Temperature

Using a newly developed Spatial Heterodyne Spectrometer (SHS), we have obtained the first radial velocity resolved emission-line profiles of diffuse [OII] λ3726 and λ3729 doublet emission from the warm (104 K) ionized component of our Galaxy\u27s interstellar medium (WIM). These [OII] lines are a principal coolant for this widespread, photoionized gas and are a tracer of variations in the gas temperature resulting from unidentified heating processes that appear to be acting within the Galaxy\u27s disk and halo

Detection of Diffuse Interstellar [O II] Emission from the Milky Way Using Spatial Heterodyne Spectroscopy

Using a newly developed spatial heterodyne spectrometer (SHS), we have obtained the first radial velocity resolved emission-line profiles of diffuse [O II] 3726 and 3729 angstrom emission lines from the warm (10,000 K) ionized component of our Galaxy\u27s interstellar medium. These [O II] lines are a principal coolant for this widespread, photoionized gas and are a potential tracer of variations in the gas temperature resulting from unidentified heating processes that appear to be acting within the Galaxy\u27s disk and halo. By spectrally isolating for the first time Galactic [O II] from atmospheric [O II] emission, we were able to detect interstellar [O II] out to 20 degrees from the Galactic equator with intensities that range from tens of rayleighs near the Galactic plane to less than 1 rayleigh at high Galactic latitudes. The [O II] line profiles clearly show structure indicating emission along the lines of sight from both local and more distant interstellar gas. Comparisons of the [O II] intensities with the intensities of [N II] 6584 angstrom and H-alpha 6563 angstrom observed with WHAM indicate that the observed variations in [N II]/H-alpha and [O II]/H-alpha in the diffuse interstellar gas are consistent with variations in temperature and confirm the value of the [O II] observations as a temperature diagnostic for the WIM

First Performance Results of a New Field-Widened Spatial Heterodyne Spectrometer for Geocoronal Hα Research

A new, high-resolution field-widened spatial heterodyne spectrometer (FW-SHS) designed to observe geocoronal Balmer α (Hα, 6563 Å) emission was installed at Pine Bluff Observatory (PBO) near Madison, Wisconsin. FW-SHS observations were compared with an already well-characterized dual-etalon Fabry-Perot Interferometer (PBO FPI) optimized for Hα, also at PBO. The FW-SHS is a robust Fourier transform instrument that combines a large throughput advantage with high spectral resolution and a relatively long spectral baseline (~10 times that of the PBO FPI) in a compact, versatile instrument with no moving parts.Coincident Hα observations by FW-SHS and PBO FPI were obtained over similar integration times, resolving powers (~67,000 and 80,000 at Hα) and fields of view (1.8° and 1.4°, respectively). First light FW-SHS observations of Hα intensity and temperature (Doppler width) versus viewing geometry (shadow altitude) show excellent relative agreement with the geocoronal observations previously obtained at PBO by FPI. The FW-SHS has a 640 km/s (14 Å) spectral band pass and is capable of determining geocoronal Hα Doppler shifts on the order of 100 m/s with a temporal resolution on the order of minutes. These characteristics make the FW-SHS well suited for spectroscopic studies of relatively faint (~12–2 R), diffuse-source geocoronal Hα emission from Earthˈs upper thermosphere and exosphere and the interstellar medium in our Galaxy. Current and future FW-SHS observations extend long-term geocoronal hydrogen observation data sets already spanning three solar minima. This paper describes the FW-SHS first light performance and Hα observational results collected from observing nights across 2013 and 2014

Visible charge exchange recombination spectroscopy on TFTR

Visible charge exchange recombination spectroscopy is routinely used to measure the time evolution of the ion temperature (T{sub i}) and toroidal rotation velocity (v{sub {phi}}) profiles on TFTR. These measurements are made with the CHERS diagnostic, a fiber-optically coupled spectrometer equipped with a two-dimensional photodiode array detector which provides both spectral and spatial resolution. The instrumentation, data analysis techniques, and examples of T{sub i} and v{sub {phi}} measurements are described. Recently, CHERS has been used to perform impurity transport experiments: radial profiles of diffusivities and convective velocities for helium and iron have been deduced from measurements of the time evolutions of He{sup 2+} and Fe{sup 24+} profiles following impurity injection. Examples of these measurements are given. 12 refs., 8 figs

SMART Research: Toward Interdisciplinary River Science in Europe

Interdisciplinary science is rapidly advancing to address complex human-environment interactions. River science aims to provide the methods and knowledge required to sustainably manage some of the planet’s most important and vulnerable ecosystems; and there is a clear need for river managers and scientists to be trained within an interdisciplinary approach. However, despite the science community’s recognition of the importance of interdisciplinary training, there are few studies examining interdisciplinary graduate programs, especially in science and engineering. Here we assess and reflect on the contribution of a 9-year European doctoral program in river science: ‘Science for MAnagement of Rivers and their Tidal Systems’ Erasmus Mundus Joint Doctorate (SMART EMJD). The program trained a new generation of 36 early career scientists under the supervision of 34 international experts from different disciplinary and interdisciplinary research fields focusing on river systems, aiming to transcend the boundaries between disciplines and between science and management. We analyzed the three core facets of the SMART program, namely: (1) interdisciplinarity, (2) internationalism, and (3) management-oriented science. We reviewed the contents of doctoral theses and publications and synthesized the outcomes of two questionnaire surveys conducted with doctoral candidates and supervisors. A high percentage of the scientific outputs (80%) were interdisciplinary. There was evidence of active collaboration between different teams of doctoral candidates and supervisors, in terms of joint publications (5 papers out of the 69 analyzed) but this was understandably quite limited given the other demands of the program. We found evidence to contradict the perception that interdisciplinarity is a barrier to career success as employment rates were high (97%) and achieved very soon after the defense, both in academia (50%) and the private/public sector (50%) with a strong international dimension. Despite management-oriented research being a limited (9%) portion of the ensemble of theses, employment in management was higher (22%). The SMART program also increased the network of international collaborations for doctoral candidates and supervisors. Reflections on doctoral training programs like SMART contribute to debates around research training and the career opportunities of interdisciplinary scientists

Development and characterization of the readout system for POLARBEAR-2

POLARBEAR-2 is a next-generation receiver for precision measurements of the polarization of the cosmic microwave background (Cosmic Microwave Background (CMB)). Scheduled to deploy in early 2015, it will observe alongside the existing POLARBEAR-1 receiver, on a new telescope in the Simons Array on Cerro Toco in the Atacama desert of Chile. For increased sensitivity, it will feature a larger area focal plane, with a total of 7,588 polarization sensitive antenna-coupled Transition Edge Sensor (TES) bolometers, with a design sensitivity of 4.1 uKrt(s). The focal plane will be cooled to 250 milliKelvin, and the bolometers will be read-out with 40x frequency domain multiplexing, with 36 optical bolometers on a single SQUID amplifier, along with 2 dark bolometers and 2 calibration resistors. To increase the multiplexing factor from 8x for POLARBEAR-1 to 40x for POLARBEAR-2 requires additional bandwidth for SQUID readout and well-defined frequency channel spacing. Extending to these higher frequencies requires new components and design for the LC filters which define channel spacing. The LC filters are cold resonant circuits with an inductor and capacitor in series with each bolometer, and stray inductance in the wiring and equivalent series resistance from the capacitors can affect bolometer operation. We present results from characterizing these new readout components. Integration of the readout system is being done first on a small scale, to ensure that the readout system does not affect bolometer sensitivity or stability, and to validate the overall system before expansion into the full receiver. We present the status of readout integration, and the initial results and status of components for the full array.Comment: Presented at SPIE Astronomical Telescopes and Instrumentation 2014: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII. Published in Proceedings of SPIE Volume 915

GMC Collisions as Triggers of Star Formation. III. Density and Magnetically Regulated Star Formation

We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation sub-grid models. Two such models are explored: (1) Density-Regulated, i.e., fixed efficiency per free-fall time above a set density threshold; (2) Magnetically- Regulated, i.e., fixed efficiency per free-fall time in regions that are magnetically supercritical. Variations of parameters associated with these models are also explored. In the non-colliding simulations, the overall level of star formation is sensitive to model parameter choices that relate to effective density thresholds. In the GMC collision simulations, the final star formation rates and efficiencies are relatively independent of these parameters. Between non-colliding and colliding cases, we compare the morphologies of the resulting star clusters, properties of star-forming gas, time evolution of the star formation rate (SFR), spatial clustering of the stars, and resulting kinematics of the stars in comparison to the natal gas. We find that typical collisions, by creating larger amounts of dense gas, trigger earlier and enhanced star formation, resulting in 10 times higher SFRs and efficiencies. The star clusters formed from GMC collisions show greater spatial sub-structure and more disturbed kinematics

Modeling Atmospheric Emission for CMB Ground-based Observations

Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3D-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the POLARBEAR-I project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations