A5015178198- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Superconducting and THz Device Technology
- Atmospheric Ozone and Climate
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Calibration and Measurement Techniques
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- Molecular Spectroscopy and Structure
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Spectroscopy and Laser Applications
- Spacecraft and Cryogenic Technologies
- Planetary Science and Exploration
- Scientific Research and Discoveries
- Advanced Thermodynamic Systems and Engines
- Optical Polarization and Ellipsometry
- Geophysics and Sensor Technology
Northwestern University
2015-2024
Northwestern Medicine
2019
Western University of Health Sciences
2018
Arizona State University
2018
University of Toronto
2014
Cardiff University
2014
University of British Columbia
2008
University of Massachusetts Amherst
1992-2008
Goddard Space Flight Center
2008
University of Chicago
1989-2008
The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitationalwave background from inflation in polarization cosmic microwave (CMB). CLASS multi-frequency array four telescopes operating high-altitude site Atacama Desert Chile. will survey 70% sky frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen straddle Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad coverage ensures that can...
High-resolution Airborne Wide-band Camera (HAWC[Formula: see text]) is the facility far-infrared imager and polarimeter for SOFIA, NASA’s Stratospheric Observatory Infrared Astronomy. It designed to cover portion of infrared spectrum that completely inaccessible ground-based observatories which essential studies astronomical sources with temperatures between tens hundreds degrees Kelvin. Its ability make polarimetric measurements aligned dust grains provides a unique new capability studying...
We present results for Vela C obtained during the 2012 flight of Balloon-borne Large Aperture Submillimeter Telescope Polarimetry (BLASTPol). mapped polarized intensity across almost entire extent this giant molecular cloud, in bands centered at 250, 350, and 500 {\mu}m. In initial paper, we show our {\mu}m data smoothed to a resolution 2.5 arcminutes (approximately 0.5 pc). that mean level fractional polarization p most its spatial variations can be accounted using an empirical...
The Probe of Inflation and Cosmic Origins (PICO) is a proposed probe-scale space mission consisting an imaging polarimeter operating in frequency bands between 20 800 GHz. We describe the science achievable by PICO, which has sensitivity equivalent to more than 3300 Planck missions, technical implementation, schedule cost.
We present an introduction to observing procedures and principles of analysis used in far‐infrared polarimetry. The are those for single‐dish observations thermal emission from aligned dust grains. discuss techniques removing backgrounds reducing evaluating errors. required interpreting polarization maps spectra terms opacity, field structure, variations temperature polarizing efficiency.
One of the key problems in star formation research is to determine role magnetic fields. Starting from atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate a volume several hundred pc across order form typical molecular cloud. Star usually occurs cloud cores, have linear sizes below and densities nH2 > 10^5 cm. With current technologies, it hard probe fields at scales lying between accumulation length size range corresponds many levels turbulent eddy...
We present the first detection of polarization around Class 0 low-mass protostar L1157-mm at two different wavelengths. show polarimetric maps large scales (10'' resolution 350 μm) from SHARC-II Polarimeter and smaller (12–45 1.3 mm) Combined Array for Research in Millimeter-wave Astronomy (CARMA). The observations are consistent with each other inferred magnetic field lines aligned outflow. CARMA suggest a full hourglass morphology centered about core; this is only second well-defined...
We present 350 micron polarization observations of four low-mass cores containing Class 0 protostars: L483, L1157, L1448-IRS2, and Serp-FIR1. This is the second paper in a larger survey aimed at testing magnetically regulated models for core-collapse. One key prediction these that mean magnetic field core should be aligned with symmetry axis (minor axis) flattened YSO inner envelope (aka pseudodisk). Furthermore, exhibit pinched or hour-glass shaped morphology as gravity drags inward towards...
The Probe of Inflation and Cosmic Origins (PICO) is an imaging polarimeter that will scan the sky for 5 years in 21 frequency bands spread between 799 GHz. It produce full-sky surveys intensity polarization with a final combined-map noise level 0.87 $\mu$K arcmin required specifications, equivalent to 3300 Planck missions, our current best-estimate would have 0.61 (6400 missions). PICO either determine energy scale inflation by detecting tensor scalar ratio at $r=5\times 10^{-4}~(5\sigma)$,...
Abstract The dust emission polarization spectrum—how the percentage changes with wavelength—serves as a probe of grain properties in star-forming regions. In this paper, we present 89–214 μ m spectrum measurements obtained from SOFIA/HAWC+ for three clouds: OMC1, M17, and W3. We find that all clouds have an overall decreasing increasing wavelength (i.e., “falling spectrum”). use SOFIA Herschel data to create column density temperature maps each cloud. fit slope at sky position cloud, using...
We have observed the linear polarization of 450 μm continuum emission from Galactic center, using a new polarimetric detector system that is operated on 2 m telescope at South Pole. The resulting map extends ~170 pc along plane and ~30 in latitude, thus covers significant fraction central molecular zone. Our shows this region permeated by large-scale toroidal magnetic fields. consider our results together with radio observations show evidence poloidal fields center Faraday rotation...
We report the detection of polarized emission in vicinity Galactic center for 158 positions within eight different pointings Hertz polarimeter operating on Caltech Submillimeter Observatory. These include locations 2' offset to east, northeast, and northwest M-0.02-0.07; southeast 20 km s-1 cloud (M-0.13-0.08); CO 0.02-0.02, M0.07-0.08; M0.11-0.08. use these data conjunction with previous far-infrared submillimeter polarization results find that direction inferred magnetic field is related...
A focal plane imaging array receiver is described which covers the 86-115 GHz frequency range for radio astronomical observations. The 3*5 element uses cryogenic Schottky diode mixers with integrated HEMT IF amplifiers. cold quasi-optical filter selects desired sideband, and terminates image at 20 K. Polarization interleaving used to minimize size on sky. LO power provided by a tripled YIG tuned oscillator. average noise temperature of pixels varies from 250-350 K SSB depending frequency....
view Abstract Citations (92) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of submillimeter polarization in the Orion nebula. Hildebrand, R. H. ; Dragovan, M. Novak, G. Linear has been observed radiation (270 microns) from two regions Orion: one centered Kleinmann-Low nebula and 1.5 arcmin south The observations were performed September 1983 January 1984 with NASA Kuiper Airborne Observatory (KAO). polarizations measured for both...
We report new 350 μm polarization observations of the thermal dust emission from cores surrounding low-mass, Class 0 young stellar objects L1527, IC348-SMM2, and B335. have inferred magnetic field directions these used them together with results in literature to determine whether magnetically regulated core-collapse star formation models are consistent observations. These predict a pseudo-disk its symmetry axis aligned core field. The also pinch structure on scale less than or comparable...
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary its Herschel/SPIRE heritage focal plane allows simultaneous observation at 250, 350, 500 {\mu}m. We flew 2010 again 2012. Both were long duration Antarctic flights. Here we present polarimetry of nearby filamentary dark cloud Lupus I obtained during flight. Despite...
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was a suborbital experiment designed to map magnetic fields in order study their role star formation processes. BLASTPol made detailed polarization maps of number molecular clouds during its successful flights from Antarctica 2010 and 2012. We present the next-generation instrument (BLAST-TNG) that will build off success previous continue as unique test bed new technologies. With 16-fold increase mapping...
Abstract We report new polarimetric and photometric maps of the massive star-forming region OMC-1 using HAWC+ instrument on Stratospheric Observatory for Infrared Astronomy. present continuum measurements this at 53, 89, 154, 214 μ m angular resolutions 5″, 8″, 14″, 19″ four bands, respectively. The enable computation improved spectral energy distributions region. find that longer wavelengths, inferred magnetic field configuration matches “hourglass” seen in previous studies, indicating...
We present results from the Austral Winter 2003 observing campaign of SPARO, a 450 micron polarimeter used with two-meter telescope at South Pole. mapped large-scale magnetic fields in four Giant Molecular Clouds (GMCs) Galactic disk: NGC 6334, Carina Nebula, G333.6-0.2 and G331.5-0.1. find statistically significant correlation inferred field directions orientation plane. Specifically, three GMCs (NGC 6334 is exception) have mean that are within 15 degrees The simplest interpretation...
We have used the SHARP polarimeter at Caltech Submillimeter Observatory to map polarization wavelengths of 350 and 450 micron in a ~2 x 3 arcmin region Orion Molecular Cloud. The covers brightest OMC-1 ridge including Kleinmann-Low (KL) nebula submillimeter source Orion-south. ratio 450-to-350 is ~ 1.3 +/- 0.3 outer parts cloud drops by factor 2 towards KL. consistent with measurements other clouds similar confirms previous placing minimum dusty molecular wavelength micron.
We investigate the polarization modulation properties of a variable-delay modulator (VPM). The VPM modulates via variable separation between polarizing grid and parallel mirror. find that in limit where wavelength is much larger than diameter metal wires comprise grid, phase delay derived from geometric mirror sufficient to characterize device. However, outside this range, additional parameters describing geometry must be included fully response. In paper, we report test results at...
Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM and troublesome contaminant CMB polarization. In each case, an understanding significance polarization signal requires well-calibrated physical models grains. Despite decades progress theory observation, polarized remain largely underconstrained. During its 2012 flight, balloon-borne telescope BLASTPol obtained simultaneous broad-band polarimetric maps translucent molecular cloud at 250, 350, 500...
Abstract We present far-infrared polarimetry observations of M82 at 53 and 154 μ m NGC 253 89 m, which were taken with High-resolution Airborne Wideband Camera-plus (HAWC+) in mode on the Stratospheric Observatory for Infrared Astronomy. The polarization clearly shows a magnetic field geometry perpendicular to disk hot dust emission. For combination nuclear region, but closer parallel away from nucleus. fractional (154 m) ranges 7% (3%) off nucleus 0.5% (0.3%) near A simple interpretation...
Abstract Sensitive wide-field observations of polarized thermal emission from interstellar dust grains will allow astronomers to address key outstanding questions about the life cycle matter and energy driving formation stars evolution galaxies. Stratospheric balloon-borne telescopes can map this at far-infrared wavelengths near peak spectrum—wavelengths that are inaccessible ground. In paper we sensitivity achievable by a Super Pressure Balloon polarimetry mission, using as an example...