78 research outputs found
The SuperBIT Hardware Design and a Constraint of the Tensor to Scalar Ratio r from the Spider I Polarized CMB Maps
No full text]Scientific ballooning experiments offer a number of advantages over space and ground based alternatives: they are lower cost, faster to deploy, and easily upgraded in contrast with satellites. As well, the ballooning environment, while quite harsh, has the benefit of raising the experiment above 99% of the atmosphere, as opposed to ground based experiments which are subject to seeing and absorptivity of the atmosphere even when atop the highest mountains. The subjects of this thesis are two examples of scientific ballooning experiments; Spider I, a cosmic microwave background experiment, and SuperBIT, an optical and near-UV observatory. The Spider I experiment is designed to constrain the tensor to scalar ratio, r; a parameter informing the allowed potential energy of the inflationary epoch thought to precede the standard cosmological model, ΛCDM. This thesis contains an analysis of the Spider CMB maps for a constraint on the parameter r, and includes the development of a bin to bin correlation transfer matrix, as well as the development of an auto-spectrum null-test procedure used for data qualification. The SuperBIT experiment is designed for cluster-galaxy weak gravitational lensing measurements to provide calibration data for future satellite experiments which are hoped will break the 1.5σ contention between the leading measurements of the cosmological parameters Ω M and σ8 taken from CMB data compared with that of other low redshift, Sunayev Zel’dovich measurements. To date no lensing data has been taken; however, a long duration flight is tentatively scheduled for 2021. This thesis contains a description of my contributions to the development of the SuperBIT hardware systems and optics.Ph.D.2022-11-30 00:00:0
Mapping Submillimetre Polarization with BLASTPol
No full textBLASTPol observes the linearly polarized emission from interstellar dust. Dust polarization traces magnetic fields, and submillimetre wavelengths can see into the dense molecular clouds in which stars are born. With this measurement, BLASTPol can help resolve long-standing questions about the role of magnetic fields in the beginning of star formation.BLASTPol is a 1.8 m telescope with 288 Herschel/SPIRE-heritage bolometric detectors at 250 μm, 350 μm, and 500 μm. Polarimetric capability was added with photolithographed grids and a stepped half-wave plate. This work outlines the instrument, with a focus on the BLASTbus electronics system for detector readout, telescope attitude control, and cryogenic housekeeping.In December 2010 and in December 2012, BLASTPol had two long duration balloon flights. An improved map making procedure has been used for reducing the 2012 dataset to maps of the polarized sky. The overall data analysis procedure is described, along with details of the map maker characterization. Finally, maps are presented for the seven targets observed during the 2012 flight. The 14 square degree map of the Vela~C giant molecular cloud is of particularly high quality and will be used in several upcoming studies of dust physics and star formation.Ph.D
Mapping Submillimetre Polarization with BLASTPol
No full textBLASTPol observes the linearly polarized emission from interstellar dust. Dust polarization traces magnetic fields, and submillimetre wavelengths can see into the dense molecular clouds in which stars are born. With this measurement, BLASTPol can help resolve long-standing questions about the role of magnetic fields in the beginning of star formation.BLASTPol is a 1.8 m telescope with 288 Herschel/SPIRE-heritage bolometric detectors at 250 μm, 350 μm, and 500 μm. Polarimetric capability was added with photolithographed grids and a stepped half-wave plate. This work outlines the instrument, with a focus on the BLASTbus electronics system for detector readout, telescope attitude control, and cryogenic housekeeping.In December 2010 and in December 2012, BLASTPol had two long duration balloon flights. An improved map making procedure has been used for reducing the 2012 dataset to maps of the polarized sky. The overall data analysis procedure is described, along with details of the map maker characterization. Finally, maps are presented for the seven targets observed during the 2012 flight. The 14 square degree map of the Vela~C giant molecular cloud is of particularly high quality and will be used in several upcoming studies of dust physics and star formation.Ph.D
Polarimetry from the Stratosphere with Spider and BLASTPol
No full textThis thesis presents the hardware development and flight performance of two balloon-borne experiments. The Spider experiment is a millimetre-wavelength polarimeter designed to measure B-mode polarization in the Cosmic Microwave Background at degree scales. This pattern is the imprint of the primordial gravitational waves predicted to have been produced by inflation. The BLASTPol experiment is a submillimetre-wavelength polarimeter designed to measure the linearly-polarized emission from aligned dust grains in Galactic molecular clouds, inferring the directions of the magnetic fields there. One goal of this measurement is to understand the role of magnetic fields in the earliest stages of star formation.
Spider had a Long-Duration Balloon flight around Antarctica in January 2015. BLASTPol had two such flights, in December 2010 and 2012. Analysis of Spider data is underway. Results of BLASTPol 2012 data analysis are presented herein.
The design and performance of the Spider pointing control system is presented. A new pivot motor control mode was developed, in which the servo drive controlled motor velocity, not current. This mode enabled sinusoidal azimuth scans at a peak speed of 5 deg/s, with a peak acceleration of 0.5 (deg/s)/s, in flight. The pointing stability in flight was 1'' to 2'' RMS. A new elevation drive system was designed and built for Spider.
The Spider observing strategy is presented. It enabled observation of a 10% patch of sky, avoiding the sun and Galactic plane, with uniform coverage in declination, and good cross-linking.
A model of the BLASTPol 2012 PSF was developed, allowing centroiding, flat-fielding, and map deconvolution. The latter was attempted in Fourier space, and using the Lucy-Richardson method.
A net linear polarization of the dust emission in the Carina Nebula was measured by BLASTPol. The mean fractional polarization is 6.75% +/- 0.015%, 6.84% +/- 0.016% and 7.06% +/- 0.019%, at 250, 350, and 500 μm respectively. A falling polarization spectrum was found, in contrast with the V-shaped spectrum measured in other molecular clouds. The median ratios of the fractional polarization between bands have been measured to be 1.0155 +/- 0.00035 between 250 and 350 μm, and 0.9376 +/- 0.00056 between 500 and 350 μm.Ph.D
Polarimetry from the Stratosphere with Spider and BLASTPol
No full textThis thesis presents the hardware development and flight performance of two balloon-borne experiments. The Spider experiment is a millimetre-wavelength polarimeter designed to measure B-mode polarization in the Cosmic Microwave Background at degree scales. This pattern is the imprint of the primordial gravitational waves predicted to have been produced by inflation. The BLASTPol experiment is a submillimetre-wavelength polarimeter designed to measure the linearly-polarized emission from aligned dust grains in Galactic molecular clouds, inferring the directions of the magnetic fields there. One goal of this measurement is to understand the role of magnetic fields in the earliest stages of star formation.
Spider had a Long-Duration Balloon flight around Antarctica in January 2015. BLASTPol had two such flights, in December 2010 and 2012. Analysis of Spider data is underway. Results of BLASTPol 2012 data analysis are presented herein.
The design and performance of the Spider pointing control system is presented. A new pivot motor control mode was developed, in which the servo drive controlled motor velocity, not current. This mode enabled sinusoidal azimuth scans at a peak speed of 5 deg/s, with a peak acceleration of 0.5 (deg/s)/s, in flight. The pointing stability in flight was 1'' to 2'' RMS. A new elevation drive system was designed and built for Spider.
The Spider observing strategy is presented. It enabled observation of a 10% patch of sky, avoiding the sun and Galactic plane, with uniform coverage in declination, and good cross-linking.
A model of the BLASTPol 2012 PSF was developed, allowing centroiding, flat-fielding, and map deconvolution. The latter was attempted in Fourier space, and using the Lucy-Richardson method.
A net linear polarization of the dust emission in the Carina Nebula was measured by BLASTPol. The mean fractional polarization is 6.75% +/- 0.015%, 6.84% +/- 0.016% and 7.06% +/- 0.019%, at 250, 350, and 500 μm respectively. A falling polarization spectrum was found, in contrast with the V-shaped spectrum measured in other molecular clouds. The median ratios of the fractional polarization between bands have been measured to be 1.0155 +/- 0.00035 between 250 and 350 μm, and 0.9376 +/- 0.00056 between 500 and 350 μm.Ph.D
Probing cosmic inflation with the Spider experiment
No full textSpider is a balloon-borne cosmic microwave polarimeter designed to operate for up to two weeks on
a Long Duration Balloon platform. From above 99.5% of the atmosphere, Spider flew over Antarctica
for 16 days observing the sky with over two thousand detectors housed inside a 1300 L liquid helium
cryostat, distributed amongst 6 telescopes that span two frequency channels: 95 GHz and 150 GHz. By
focusing its observing time over a 10% patch of the sky at high galactic latitude, Spider targets the
degree-scale BB spectrum in search of the pattern that would have been imprinted by gravitational
waves propagating in the early universe, a key prediction of inflation.
In order to probe the physics of the very early universe the experiment needs to operate in the harsh
environment of the upper atmosphere for multiple days. This work discusses at length the detailed
thermal modeling and analysis leading up to the 2015 flight which ensured the correct thermal operation
of every component while at 36 km of altitude. The flight is followed by a data analysis that will
ultimately produce a constraint on the amplitude of the primordial gravitational wave background from
bandpowers of the BB spectrum of the CMB. In order to measure the CMB itself, contamination to the
BB spectrum by polarized galactic foreground emission needs to be quantified. To improve its ability
to characterize polarized foregrounds, Spider will have a second flight in 2018-2019 which will add
a 285 GHz frequency channel. In this work, we explore a component separation technique involving
Planck HFI data. A power spectrum estimator used to produce bandpower estimates from maps is also
discussed.Ph.D.2019-12-19 00:00:0
Probing cosmic inflation with the Spider experiment
No full textSpider is a balloon-borne cosmic microwave polarimeter designed to operate for up to two weeks on
a Long Duration Balloon platform. From above 99.5% of the atmosphere, Spider flew over Antarctica
for 16 days observing the sky with over two thousand detectors housed inside a 1300 L liquid helium
cryostat, distributed amongst 6 telescopes that span two frequency channels: 95 GHz and 150 GHz. By
focusing its observing time over a 10% patch of the sky at high galactic latitude, Spider targets the
degree-scale BB spectrum in search of the pattern that would have been imprinted by gravitational
waves propagating in the early universe, a key prediction of inflation.
In order to probe the physics of the very early universe the experiment needs to operate in the harsh
environment of the upper atmosphere for multiple days. This work discusses at length the detailed
thermal modeling and analysis leading up to the 2015 flight which ensured the correct thermal operation
of every component while at 36 km of altitude. The flight is followed by a data analysis that will
ultimately produce a constraint on the amplitude of the primordial gravitational wave background from
bandpowers of the BB spectrum of the CMB. In order to measure the CMB itself, contamination to the
BB spectrum by polarized galactic foreground emission needs to be quantified. To improve its ability
to characterize polarized foregrounds, Spider will have a second flight in 2018-2019 which will add
a 285 GHz frequency channel. In this work, we explore a component separation technique involving
Planck HFI data. A power spectrum estimator used to produce bandpower estimates from maps is also
discussed.Ph.D.2019-12-19 00:00:0
Probing Interstellar Grain Alignment with Balloon-borne Submillimeter Observations
No full textThe role that magnetic fields play in regulating star formation is one of the outstanding issues in star formation theory. Magnetic fields in star-forming clouds in our galaxy can be observed by tracing the polarized emission from interstellar dust grains. However the mechanism by which the dust grains align with the magnetic fields is not fully understood. Grain alignment theories (e.g. radiative alignment torques) make predictions for the observed spectrum of the polarized emission, so observations at multiple wavelengths can be used to test these theories. The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) observes polarized dust at 250um, 350um and 500um while suspended from a balloon in the stratosphere above Antarctica. BLASTPol maps the dust polarization signal over entire molecular clouds, with enough angular resolution to trace the cloud sub-structures and protostellar cores. BLASTPol uses an attitude reconstruction system consisting of multiple sensors, including star cameras, sun sensors and rate gyroscopes. This system allows BLASTPol to point in-flight at specific regions on the sky, and allows the telescope’s attitude to be reconstructed post-flight. A similar system was built for SPIDER, a balloon-borne telescope that observes the polarization of the CMB.
The analysis pipeline used to produce science maps is discussed, and science results are presented from BLASTPol’s 2012 observations of the Vela C molecular cloud. The polarization spectrum shows a minimum at 350um, similar to the measurements of previous experiments observing other molecular clouds. No strong correlation is seen between he shape of the polarization spectrum and either the temperature or density of the dust. Analysis of the maps is ongoing, and future work will focus on the diffuse dust in the cloud, which is more suitable to compare with dust models.Ph.D
Design, Implementation, and Operational Methodologies for Sub-Arcsecond Attitude Determination, Control, and Stabilization of the Super-pressure Balloon-borne Imaging Telescope (SuperBIT)
No full textScientific balloon-borne instrumentation offers an attractive, competitive, and effective alternative to space-borne missions when considering the overall scope, cost, and development timescale required to design and launch scientific instruments. In particular, the balloon-borne environment provides a near-space regime that is suitable for a number of modern astronomical and cosmological experiments, where the atmospheric interference suffered by ground-based instrumentation is negligible at stratospheric altitudes. This work is centered around the analytical strategies and implementation considerations for the attitude determination and control of SuperBIT, a scientific balloon-borne payload capable of meeting the strict sub-arcsecond pointing and image stability requirements demanded by modern cosmological experiments. Broadly speaking, the designed stability specifications of SuperBIT coupled with its observational efficiency, image quality, and accessibility rivals state-of-the-art astronomical observatories such as the Hubble Space Telescope.
To this end, this work presents an end-to-end design methodology for precision pointing balloon-borne payloads such as SuperBIT within an analytical yet implementationally grounded context. Simulation models of SuperBIT are analytically derived to aid in pre-assembly trade-off and case studies that are pertinent to the dynamic balloon-borne environment. From these results, state estimation techniques and control methodologies are extensively developed, leveraging the analytical framework of simulation models and design studies. This pre-assembly design phase is physically validated during assembly, integration, and testing through implementation in real-time hardware and software, which bridges the gap between analytical results and practical application. SuperBIT attitude determination and control is demonstrated throughout two engineering test flights that verify pointing and image stability requirements in flight, where the post-flight results close the overall design loop by suggesting practical improvements to pre-design methodologies.
Overall, the analytical and practical results presented in this work, though centered around the SuperBIT project, provide generically useful and implementationally viable methodologies for high precision balloon-borne instrumentation, all of which are validated, justified, and improved both theoretically and practically. As such, the continuing development of SuperBIT, built from the work presented in this thesis, strives to further the potential for scientific balloon-borne astronomy in the near future.Ph.D
Design, Implementation, and Operational Methodologies for Sub-Arcsecond Attitude Determination, Control, and Stabilization of the Super-pressure Balloon-borne Imaging Telescope (SuperBIT)
No full textScientific balloon-borne instrumentation offers an attractive, competitive, and effective alternative to space-borne missions when considering the overall scope, cost, and development timescale required to design and launch scientific instruments. In particular, the balloon-borne environment provides a near-space regime that is suitable for a number of modern astronomical and cosmological experiments, where the atmospheric interference suffered by ground-based instrumentation is negligible at stratospheric altitudes. This work is centered around the analytical strategies and implementation considerations for the attitude determination and control of SuperBIT, a scientific balloon-borne payload capable of meeting the strict sub-arcsecond pointing and image stability requirements demanded by modern cosmological experiments. Broadly speaking, the designed stability specifications of SuperBIT coupled with its observational efficiency, image quality, and accessibility rivals state-of-the-art astronomical observatories such as the Hubble Space Telescope.
To this end, this work presents an end-to-end design methodology for precision pointing balloon-borne payloads such as SuperBIT within an analytical yet implementationally grounded context. Simulation models of SuperBIT are analytically derived to aid in pre-assembly trade-off and case studies that are pertinent to the dynamic balloon-borne environment. From these results, state estimation techniques and control methodologies are extensively developed, leveraging the analytical framework of simulation models and design studies. This pre-assembly design phase is physically validated during assembly, integration, and testing through implementation in real-time hardware and software, which bridges the gap between analytical results and practical application. SuperBIT attitude determination and control is demonstrated throughout two engineering test flights that verify pointing and image stability requirements in flight, where the post-flight results close the overall design loop by suggesting practical improvements to pre-design methodologies.
Overall, the analytical and practical results presented in this work, though centered around the SuperBIT project, provide generically useful and implementationally viable methodologies for high precision balloon-borne instrumentation, all of which are validated, justified, and improved both theoretically and practically. As such, the continuing development of SuperBIT, built from the work presented in this thesis, strives to further the potential for scientific balloon-borne astronomy in the near future.Ph.D
- …
