Browsing by Department "Physics And Astronomy"

Now showing 1 - 19 of 19

Active Inner Veto for Improved SuperCDMS SNOLAB Dark Matter Search Sensitivity
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/329; DOE-Office Of Science
The goal of this project was to develop and study a new geometry of cryogenic detector that could act as an active veto surrounding a smaller, inner cryogenic detector. This drastically reduces the background event rates, enabling more effective rare event searches. An annular germanium detector was fabricated with athermal phonon sensors and successfully tested. A threshold of better than 10keV was desired; 4keV was demonstrated.
Calibrating Astronomical Instruments To Improve The Science Gained From The Large Synoptic Survey Telescope
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/670; National Science Foundation
The future Large Synoptic Survey Telescope (LSST) of the United States will revolutionize astronomy by obtaining images of objects observed repeatedly over long periods of time. These observations will be extremely accurate. In order to get the best science from these observations, two types of additional, supporting observations will also be used: observations that have been made using different telescopes and instruments in the past, and observations that will be made with other telescopes and instruments in the future. For all of these supporting observations to be useful, they must be as accurate as the observations that will be taken using the LSST. For this project, the astronomers will calibrate the telescopes, instruments, and sky conditions of the observatories where the other observations are or will be made. This project serves the national interest, as it ensures that the data acquired with the new telescope will contribute the best scientific results possible, promoting the progress of observational astronomy. The astronomers are from Texas A & M University, which draws most of its students from a heavily Hispanic population. The investigators intend to employ two graduate students and 8 - 10 undergraduate students. The Large Synoptic Survey Telescope (LSST) project will produce an enormous amount of photometric data that will revolutionize the field of astronomy. One of the LSST goals is to provide an unprecedented level of photometric accuracy: <0.5%. Existing and on-going data from other telescopes will be used for comparison and follow-up observations with the new LSST observations. These observations, however, will need to be very well calibrated. The investigators will use existing equipment to provide accurate spectrophotometric calibration of imaging systems at observatories around the world. The calibration will include in-situ measurements of the telescopes, optics, filters, and detectors, providing detailed knowledge of the transmission profiles of the instruments. The atmospheric transmission above the observatory sites will also be measured. Together, these measurements will help to enable exceptionally accurate photometric calibration of these systems. Based on similar measurements of the DECam instrument and the Cerro Tololo Inter-American Observatory location, the investigators estimate that the proposed work should allow for accuracy of ~0.2% across large surveys and all spectral bands.
Collaborative Research: Quantum Cascade Laser Transceivers for Terahertz Wireless Communication
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/626; National Science Foundation
The terahertz is a region of the electromagnetic spectrum lying between microwaves and the infrared range, also known as the "terahertz gap" due to the lack of suitable technologies for its generation and manipulation. On the one hand, conventional electronic devices used to produce microwaves cannot operate at higher frequencies, while on the other hand optical sources such as terahertz lasers typically require cryogenic operation, which is impractical. Thus, novel approaches are needed to develop convenient terahertz sources. The goal of this project is to demonstrate a new class of terahertz sources based on a high-power mid-infrared semiconductor laser (so-called quantum cascade laser) designed to generate a comb of frequencies separated by precisely equidistant terahertz frequency intervals. The resulting terahertz radiation sources will show room temperature operation, narrow linewidth, and wide tunability. These would be attractive for many applications, especially remote sensing. Indeed, hundreds of chemicals from gases to drugs, explosives, and biomolecules have telltale absorption and emission features in the terahertz range. Terahertz sensing would allow one to monitor the ozone depletion, climate change, and environmental pollution. It would give insights into the formation and decay of stars in our galaxy and beyond. Such terahertz sources would also be very valuable in the studies of materials, since many fundamental excitations in matter such as plasma oscillations and sound waves exhibit resonances in the terahertz. The core of the proposed new device architecture consists of a mid-infrared quantum cascade laser generating an optical frequency comb with a terahertz spacing between longitudinal modes, named a harmonic frequency comb. However, instead of using infrared light emitted from the laser as in typical frequency combs, here the intracavity beating of the optical modes constituting the comb is exploited to generate a coherent terahertz signal at room temperature. The focus of this project is to demonstrate such new terahertz sources for sensing applications. These devices will benefit from unprecedented compactness, having a footprint smaller than 1 square centimeter. Thanks to the nature of a frequency comb, they will generate terahertz tones with narrow linewidth (in the Hz range) and high stability. Moreover, they will be able to operate at room temperature with a broad tuning range, from microwaves to the terahertz region, as a result of the fast electron dynamics of the laser. By connecting and synchronizing an array of such devices, it will be possible to coherently scale up the emitted power and enable terahertz beam control, such as beam steering and shaping. Because of these unique features, the proposed sources will rival and potentially outperform other existing systems for terahertz sensing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Collaborative Research: Compact Room Temperature Operated THz Emitters-With Scalable Architecture and Low Electric Power Consumption
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/626; National Science Foundation
Abstract Title: Compact and efficient room temperature operated terahertz emitters for industrial, medical and home security applications. Nontechnical: Terahertz sensing is an enabling technology for noninvasive detection of biological and chemical hazardous agents, cancer detection, detection of mines and explosives, security screening in buildings, airports, and other public space, as well as short-range covert communications in terahertz transmission windows of the atmosphere. Currently available terahertz sources are either bulky or require cryogenic cooling leading to high costs, high complexity, and often low reliability. The proposed novel design concept aims to address most of the deficiencies of the current state-of-the-art terahertz emitter technology. The target device implementation will be similar in terms of the complexity, reliability and size to widely used standard inexpensive near infrared diode lasers. The success of the proposed effort will enable wide deployment of terahertz imaging and spectroscopic sensors for the security screening, medical diagnostics, and industrial monitoring applications. The project requires strongly correlated effort between theory and experiment including extensive modeling, optimization of the device fabrication methodologies as well as detailed characterization and field testing of the novel laser emitters. The research effort is integrated with educational and outreach plans aimed at enhancing education opportunities at the New York and Texas public universities and local communities. Technical: The main goal of the project is the development of high-power diode lasers with built-in resonant nonlinearity for efficient intra-cavity difference frequency generation in the terahertz spectral range. The gain sections based on asymmetric coupled quantum wells utilize the unique band alignment that can be realized in an antimonide material system. Laser modes generated at two closely spaced wavelengths near 2 microns will serve as an intracavity pump field for difference frequency generation. The antimonide-based diode lasers emitting in that spectral region demonstrate some of the lowest threshold current densities ever achieved for semiconductor lasers, excellent temperature stability, and watt level output power, all at room temperature. The expected electrical power input necessary for the proposed device operation with micro to milliwatt terahertz output level will be two to three orders of magnitude lower than those of existing technologies. The proposed research offers experimental and theoretical studies of the fundamental problem of resonant optical nonlinearities in antimonide-based quantum-well systems in a wide range of carrier populations from nondegenerate to highly degenerate. The future development of the proposed devices will include fabrication of widely tunable terahertz emitters as well as integration with silicon photonics. Transfer of the technology to the arsenide or silicon platform will enable epi-side down mounting of large area arrays of the terahertz emitters to scale up the output terahertz power to tens of milliwatt level and perform terahertz beam shaping.
Collaborative Research: Galaxy Growth in Different Environments in the Early Universe from z=1.9 to 3.5
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/461; National Science Foundation
The team will assemble optical and infrared observations of hundreds of thousands of galaxies. The observations pick out galaxies about 10 to 12 billion years back in time. This period is known to be one of hectic change for galaxies. The team will study how these changes depend on whether a galaxy has many neighbors, or no neighbors at all. This important topic could not be studied before because not enough observations were available. The team will release their assembled catalog to the public. Senior team members will train junior members. The team will give public talks, offer residential workshops to teachers and develop a three-dimensional show for a children's science museum. In a tour de force, the team will combine data from five deep, wide-area galaxy surveys that include both photometry and integral-field-unit spectroscopy. They will use the combined data to study galaxy evolution over the full range of galactic environments at redshifts z ~ 1.9 to 3.5. These are key redshifts for galaxy evolution, as they probe the assembly of massive galaxies, the peaks in star formation and black-hole accretion, and the collapse of the largest proto-clusters of galaxies. The team will amass photometry for about 600,000 galaxies and spectroscopy for about 260,000 galaxies. Using this dataset, the team will conduct statistically meaningful analyses that were heretofore impossible.
Elucidating the Local Supermassive Black Hole â€“ Galaxy Connection
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/212; National Science Foundation
Part 1 Supermassive black holes, weighing a million to several billion solar masses, reside at the centers of most, if not all, massive galaxies. Although the black hole's gravitational influence is limited to a very small region at the center of the galaxy, surprisingly the black hole mass has been found to strongly correlate with the properties of the larger host galaxy. This suggests that black holes are essential components of galaxies, with the growth of one somehow affecting the growth of the other. Our understanding of the underlying physics, however, is limited by the current sample of galaxies. In particular, black hole mass determinations have been made in galaxies that are not representative of the global population. Our program seeks to address this troublesome bias by measuring black hole masses in 31 local galaxies using state-of-the-art observational and dynamical modeling methods. The proposed research will yield the largest uniform black hole survey carried out to date. By specifically targeting galaxies with sizes and luminosities that are not well represented in the existing sample, the PI will obtain a more complete census of local black holes in a wider range of galaxies. Forgoing the approach that has been used for years of measuring a few black holes at a time, and instead examining large, homogenous datasets of carefully selected samples is the ideal way to achieve a breakthrough in our understanding of how black holes and galaxies grow and evolve together. The project also incorporates an educational component, reaching a potentially large number of people who may never opt to attend a science event on their own. The PI will organize and coordinate the presentation of interactive physics and astronomy demonstrations during First Fridays in downtown Bryan, TX. During First Fridays, the public gather to take in culture through live music, street performances, and art exhibitions. The outreach activity will engage the public while they partake in their normal activities and show that science is relevant to their everyday lives. The program will further provide undergraduate students with the opportunity to interact with department members at all levels, which is particularly useful for retaining beginning undergraduates who may not yet feel at home and connected to the department. Part 2 Over the past two decades it has become increasingly clear that supermassive black holes are essential components of galaxies. About 100 black hole mass measurements in nearby galaxies have been made to date, leading to the establishment of tight correlations between the mass of a central black hole and its host galaxy's large-scale properties. Our understanding of the underlying physics driving the empirical relations, however, is limited by the current sample of galaxies. In particular, black hole mass determinations have been made in galaxies that are not representative of the global population. Instead, galaxies with small sizes at a given luminosity have been preferentially targeted, as they are generally the easiest to observe and model. The project seeks to address this troublesome bias by weighing black holes in 31 local galaxies using adaptive optics integral field spectroscopy from the Gemini North telescope, Hubble Space Telescope imaging, wide-field integral field spectroscopy from McDonald Observatory, and state-of-the-art dynamical models. The proposed research will yield the largest uniform black hole survey carried out to date, and will significantly enhance the diversity of black hole hosts by targeting galaxies with sizes and luminosities that are not well represented in the existing sample. This benchmark study will produce a more complete census of black holes in a wide range of galaxies that have experienced diverse evolutionary pasts, and will provide a deeper understanding of black hole-galaxy co-evolution. Detailed investigations of large, carefully selected samples using a homogenous approach is the ideal way to make major progress in the field prior to the next generation of extremely large telescopes. The program also incorporates an educational component, reaching a potentially large number of people who may never opt to attend a science event on their own. Using the lessons learned from a previous pilot program, the PI will organize and coordinate the presentation of interactive physics and astronomy demonstrations during First Fridays in downtown Bryan, TX. During First Fridays, the public gather to take in culture through live music, street performances, and art exhibitions. The outreach activity will engage the public while they partake in their normal activities and show that science is relevant to their everyday lives. Beyond reaching an untapped audience, the program will provide undergraduate students with the opportunity to interact with department members at all levels, which is particularly useful for retaining beginning undergraduates who may not yet feel at home and connected to the department. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Elucidating the Local Supermassive Black Hole Galaxy Connection
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/212; National Science Foundation
Part 1 Supermassive black holes, weighing a million to several billion solar masses, reside at the centers of most, if not all, massive galaxies. Although the black hole's gravitational influence is limited to a very small region at the center of the galaxy, surprisingly the black hole mass has been found to strongly correlate with the properties of the larger host galaxy. This suggests that black holes are essential components of galaxies, with the growth of one somehow affecting the growth of the other. Our understanding of the underlying physics, however, is limited by the current sample of galaxies. In particular, black hole mass determinations have been made in galaxies that are not representative of the global population. Our program seeks to address this troublesome bias by measuring black hole masses in 31 local galaxies using state-of-the-art observational and dynamical modeling methods. The proposed research will yield the largest uniform black hole survey carried out to date. By specifically targeting galaxies with sizes and luminosities that are not well represented in the existing sample, the PI will obtain a more complete census of local black holes in a wider range of galaxies. Forgoing the approach that has been used for years of measuring a few black holes at a time, and instead examining large, homogenous datasets of carefully selected samples is the ideal way to achieve a breakthrough in our understanding of how black holes and galaxies grow and evolve together. The project also incorporates an educational component, reaching a potentially large number of people who may never opt to attend a science event on their own. The PI will organize and coordinate the presentation of interactive physics and astronomy demonstrations during First Fridays in downtown Bryan, TX. During First Fridays, the public gather to take in culture through live music, street performances, and art exhibitions. The outreach activity will engage the public while they partake in their normal activities and show that science is relevant to their everyday lives. The program will further provide undergraduate students with the opportunity to interact with department members at all levels, which is particularly useful for retaining beginning undergraduates who may not yet feel at home and connected to the department. Part 2 Over the past two decades it has become increasingly clear that supermassive black holes are essential components of galaxies. About 100 black hole mass measurements in nearby galaxies have been made to date, leading to the establishment of tight correlations between the mass of a central black hole and its host galaxy's large-scale properties. Our understanding of the underlying physics driving the empirical relations, however, is limited by the current sample of galaxies. In particular, black hole mass determinations have been made in galaxies that are not representative of the global population. Instead, galaxies with small sizes at a given luminosity have been preferentially targeted, as they are generally the easiest to observe and model. The project seeks to address this troublesome bias by weighing black holes in 31 local galaxies using adaptive optics integral field spectroscopy from the Gemini North telescope, Hubble Space Telescope imaging, wide-field integral field spectroscopy from McDonald Observatory, and state-of-the-art dynamical models. The proposed research will yield the largest uniform black hole survey carried out to date, and will significantly enhance the diversity of black hole hosts by targeting galaxies with sizes and luminosities that are not well represented in the existing sample. This benchmark study will produce a more complete census of black holes in a wide range of galaxies that have experienced diverse evolutionary pasts, and will provide a deeper understanding of black hole-galaxy co-evolution. Detailed investigations of large, carefully selected samples using a homogenous approach is the ideal way to make major progress in the field prior to the next generation of extremely large telescopes. The program also incorporates an educational component, reaching a potentially large number of people who may never opt to attend a science event on their own. Using the lessons learned from a previous pilot program, the PI will organize and coordinate the presentation of interactive physics and astronomy demonstrations during First Fridays in downtown Bryan, TX. During First Fridays, the public gather to take in culture through live music, street performances, and art exhibitions. The outreach activity will engage the public while they partake in their normal activities and show that science is relevant to their everyday lives. Beyond reaching an untapped audience, the program will provide undergraduate students with the opportunity to interact with department members at all levels, which is particularly useful for retaining beginning undergraduates who may not yet feel at home and connected to the department. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Examining the Assembly History of the Universe Using Large Grism Datasets
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/461; NASA-Washington
Astronomy is entering an age of large surveys and massive data sets. It is important that we adapt and develop methods that will work with these data sets in a statistically sophisticated way. The spatially resolved data sets of space-based slitless grism spectra in the near-IR, taken from the Hubble Space Telescope (HST) and the next generation of space telescopes (JWST and WFIRST), provide highly valuable data on distant galaxies. Gathering this data from the ground is especially challenging given that all rest-optical features shift above ~ 1 µm where studies from ground-based telescopes are subject to higher backgrounds and a high density of telluric emission lines in wavelength space. Slitless grism data provide spectral data from each object in the field, allowing us to constrain stellar population parameters with higher confidence with population statistics. The CANDELS Lyman-a Emission At Reionization survey (PI: C. Papovich) covers 12 fields in the GOODS-North and GOODS-South Deep regions of CANDELS, averaging ~ 400 objects per field. The methods I developed in Estrada-Carpenter et al. 2019 show that grism data on its own is capable of providing constraints on the stellar populations of massive quiescent galaxies. The studies I propose include measuring the (light- weighted) ages, star-formation, and chemical evolution histories of quiescent and star-forming galaxies at z > 1 using existing HST/ WFC3 G102/G141 grism data and photometric data that already exist in the CANDELS/GOODS fields (and possibly other fields). These data will allow me to study the variation of stellar population parameters as a function of mass and activity. I then plan to use these constraints to derive at what redshift this population of quiescent galaxies would have formed and quenched, identify the star- forming progenitors and use analyses of both populations to understand how galaxies form stars, quench, and assemble. I am an expert in grism analysis and am very familiar with all the difficulties that come from working with these complex data sets. I have already built a similar tools to analyze HST/WFC3 G102 grism spectra for my previous project. My fitting methods includes applying a forward modeling technique which accounts for the morphological broadening seen in grism data. I will update these methods to accommodate the inclusion of additional datasets. For my proposed research I will use the high-performance cluster computers at Texas A&M, which I have previous experience with. I will use Flexible Stellar Population Synthesis models to model my galaxies. These models include the ability to create non-parametric start-formation and chemical evolution histories. In my previous work I used a predefined grid which I marginalized over. I am currently working with a nested sampling algorithm, which allows me to fit many more parameters. All the HST data needed for this study are available (and my adviser is the PI of the main dataset). I will analyze these data, and also adapt the fitting tools to work with data from JWST and WFIRST, which will move this analysis method into the 21st century and enable a larger range of science. This proposal supports the mission of NASA by achieving the goal to "Explore the origin and evolution of the galaxies, stars and planets that make up our universe" as well as seeking to "understand how the universe has evolved since the Big Bang, and how its constituents were produced" (as seen in Chapter 4.4 of the NASA SMD 2014 Science Plan).
M-theory, Superspace and Higher Spin Theories
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/391; National Science Foundation
This award funds the research activities of Professors Katrin Becker, Melanie Becker, and Ergin Sezgin at Texas A&M University. String theory provides a framework for describing gravity in a way which is consistent with the laws of quantum mechanics. However, string theories generally require that there exist extra dimensions beyond those of width, length, and height. Such extra dimensions must be rolled into very small spaces, and the shapes of these spaces determine which elementary particles are predicted by string theory. For these reasons, it is important to understand the detailed shapes of these extra dimensions. Likewise, combining Einstein's theory of gravity with quantum mechanics involves a hypothetical particle --- the so-called "graviton" --- which transmits gravitational interactions and carries two units of spin. However, string theory can also give rise to remarkable extensions of Einstein's theory which involve higher-spin analogues of the graviton. For these reasons, string theory can have profound consequences for early-universe physics. In their research, Professors Becker, Becker, and Sezgin aim to investigate these and other fundamental questions involving the connections between string theory, gravity, and higher-spin theories. As such, this project advances the national interest by promoting progress in fundamental science within the United States. This project is also envisioned to have significant broader impacts. Not only will this research further develop the interface between string theory and mathematics, but it will also provide an arena for the critical training for postdocs and students. Professors Becker, Becker, and Sezgin will also give public lectures on their research results and organize scientific workshops to help advance the field. More technically, Professors Becker, Becker, and Sezgin aim to construct the full spacetime effective action of different string theory and M-theory compactifications to all orders in the slope parameter and its formulation in superspace. Their goal is to use physical ideas and methods to solve long-standing problems in mathematics. Further, Professors Becker, Becker, and Sezgin will study the holographic description of higher-spin theory, its coupling to matter, spontaneous symmetry breaking, cosmological solutions and their consequences for early-universe physics. They will also study specific aspects of a geometrical description of duality symmetries of strings and branes within a framework known as exceptional field theory. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
New Color Centers in Diamond: Towards Broadband Quantum Memories
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/318; National Science Foundation
Information technologies are among the main pillars of society, and information security is becoming more important. One direction for improving the security of future information systems is to utilize quantum communication lines. Based on laws of nature, such lines do not allow non-traceable copying of the information transmitted. But the same physics that makes them secure (i.e. the non-cloning theorem) also forbids the use of classical repeaters, which in turn limits communication distance and speed. This issue may be overcome by using quantum repeaters, the key ingredient of which is a quantum memory device. The aim of this project is to develop a novel solid-state quantum memory based on quantum states of color centers in diamond. This project will utilize theoretical and experimental advances developed at Texas A&M University both for the memory access protocol and for its physical implementation. This research project will strengthen the US presence in the field of optical ensemble-based solid-state quantum memories. It will also help train the next generation of scientists in this dynamically developing interdisciplinary field of research. Graduate and undergraduate students will get involved in the investigations through participation in the experiments, developing theoretical models, programming, collecting and interpreting experimental data, and numerical simulations. The investigators will also incorporate the obtained results into courses. This project focuses on new color centers, namely, Germanium Vacancies and Silicon Vacancies in diamond (GeV and SiV) for pioneering experimental realization of an ensemble based broadband quantum memory in diamond. This realization will be achieved using a new approach to quantum memory based on a discrete spatial chirp of a control field that has recently been suggested by the co-PIs. The outcome of this work, a single-photon solid-state interface, will be a milestone on the way to a scalable universal optical quantum computer. In comparison to existing technologies, like rare-earth doped crystals and nitrogen vacancy centers in diamond (NV), SiV and GeV have stronger optical interaction and less spectral diffusion (and inhomogeneous linewidths). The stronger zero-phonon line gives more efficient interaction of a single photon with a single silicon-vacancy, while a narrow inhomogeneous line broadening favors ensemble-based quantum memories. Other advantages of GeV and SiV are the presence of polarization selection rules and large (160 GHz and 50 GHz accordingly) energy level splitting in the ground state. The last one allows for large storage bandwidth. It is worth pointing out that multi-GHz vs MHz bandwidth is a key advantage of an optical over RF quantum networks (i.e. superconducting circuits (SCC)). The only disadvantage of GeV and SiV is a shorter electron-spin coherence time. However, it has been shown that this can be dramatically increased, up to 13 ms, by cooling SiV down to 100 mK. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
REU SITE: Astronomical Research and Instrumentation at Texas A&M University
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/370; National Science Foundation
Texas A&M University (TAMU) will host a summer REU (Research Experiences for Undergraduates) program in astronomy. Students will complete individual research projects with a faculty mentor. They will also benefit from interaction with summer students in 14 other TAMU REU programs, such as the REU Summer Scholars Program (weekly informal lunch discussions focusing on ethnic minority issues) and the university-wide summer REU Poster Session. This program will benefit society by enhancing the education of undergraduates through research and professional development programs, by involving them in the development of advanced astronomical instrumentation, and by extending these opportunities to students from institutions otherwise unable to offer such experiences, which will be a primary focus of the recruitment efforts. The summer will begin with a 3-day workshop that will give them a hands-on introduction to data visualization and computational data analysis. Students will also have the opportunity to design, construct, test, and deploy a variety of instruments to be used at astronomical observatories around the world. TAMU astronomy faculty are involved in most of the current and future large-scale observational astronomy collaborations. All of the REU students have the opportunity to spend one week observing at McDonald Observatory in west Texas, and they will be invited to participate in public outreach activities.
Seeing Core-Collapse Supernovae in the Ultraviolet
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Washington
Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves .Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and ground-based optical/NIR spectra to create timeseries bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction). The templates will improve the photometric classification and distance bias modeling for Type Ia supernova cosmology, while the extinction and temperature constraints will improve the use of type IIP supernovae as a distinct distance indicator on their own.
Seeing Core-Collapse Supernovae in the Ultraviolet
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Washington
Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves. Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and groundbased optical/NIR spectra to create time-series bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction). The templates will improve the photometric classification and distance bias modeling for Type Ia supernova cosmology, while the extinction and temperature constraints will improve the use of type IIP supernovae as a distinct distance indicator on their own.
Studies of Atomic Hydrogen Contained in Solid Molecular Hydrogen Isotopes
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/676; National Science Foundation
Non-technical Abstract The quantum mechanical phenomena of Bose Einstein Condensation leads to many fascinating and important effects. In 4He it leads to a superfluid where the liquid can flow with viscosity and transport heat without loss. In some metals it leads to superconductivity where electric currents are carried without loss - offering the potential for power distribution without the losses that occur in current power lines. BEC has also been observed in super-cooled atoms which could lead to more precise atomic clocks that power the global positioning system. Other, yet to be discovered systems, may show equally fascinating and important behavior. In this project we will attempt to produce a Bose Einstein Condensate in hydrogen atoms embedded in solid molecular hydrogen. The studies will take place at ultra-low temperature (below 0.1 degrees above absolute zero) and utilize microwave magnetic resonance techniques. This work will provide training in state-of-the-art low temperature and microwave techniques which are relevant in many areas of physics such as quantum computing. An active outreach program is pursued. Meetings with graduate students, visits by junior college students and participation in science fairs continues. For example, the principal investigator gives public lectures at the Texas A & M Physics and Engineering Festival with demonstrations. The festival is typically attended by more than 5000 students from all over the state of Texas and beyond. Technical Abstract The properties of hydrogen atoms embedded in solid molecular hydrogen films are studied by electron spin resonance in a high magnetic field (4.6 Tesla, resonant frequency 130 GHz) corresponding to 2mm waves. The spectrometer for these measurements is fully operational. A dilution refrigerator is now in place to cool the samples to temperatures below 100 mK. The large departure of the polarization of the nuclear spins from the Boltzmann distribution observed previously are investigated down to lower temperatures and at higher hydrogen atom concentrations in an attempt to reach full Bose-Einstein condensation. Although in previous experiments the spin-lattice relaxation was found to be several hours, it was not possible to fully saturate the transition between the two lowest hyperfine states. This anomalous behavior is fully investigated. Hole burning experiments in a magnetic field gradient also are performed to determine the hydrogen atom mobility as Bose-Einstein condensation occurs. Finally, the effect of different film substrates on the departure from Boltzmann statistics of hydrogen atoms are studied.
Supernova Key Project: Swift Response to New Transients
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Goddard Space Flight Center
This proposal describes a multi-year, Swift Key Project to observe all nearby (d < 35 Mpc) transients (mostly expected to be SNe) with Swift within 24 hour of discovery (even before they are spectroscopically classified). The proposed investigation aims to obtain early UV and X-ray data on 60 transients in a distance-limited sample. This program will acquire a type-blind sample of all nearby SN, which would be useful to search for the early shocks in unbiased samples for both Type Ia (shocked companions) and CC SNe (shock breakouts). For Type Ia SNe, the proposed program would be effective in detecting UV emission from the shocked companion. For CCSN the proposed program would be effective in detecting shock breakout and cooling. These results would be useful for constraining the nature of the SN progenitors and their environments. This program is the first attempt to comprise a complete distance-limited SN sample in UV (for a given 2-yr period).
Swift and SIRAH: UV to NIR observations of Type Ia Supernovae Beyond the Twilight Zone
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/230; NASA-Shared Services Center
While Swift observations have uncovered a large diversity in the UV luminosities of Type Ia Supernovae (SNe Ia), the physical origin of the diversity of these standard candles and the cosmological impact is still unknown. We propose to observe a sample of twenty-four Type Ia Supernovae (SNe Ia) in the nearby Hubble flow with Swift’s Ultra-Violet/Optical Telescope (UVOT). In coordination with the Hubble Space Telescope’s (HST) SIRAH program, these SNe will have well-measured peak absolute magnitudes encompassing the UV, optical, and near-infrared (NIR). Analysis of these observations will show whether the physical cause of the UV dispersion already observed in the UV peak magnitudes and colors also has an impact on the optical luminosities, thereby affecting the usefulness of SNe Ia as standard candles. The sensitivity of the UV to many of the systematic uncertainties (metallicity, extinction, viewing angle, etc) may allow the identification and correction of differences between otherwise “standard” candles. This program capitalizes on Swift’s unique strengths of rapid response, short term scheduling, and UV capabilities to improve our understanding of the standard candles essential to studies of the expanding universe.
Test & Evaluation for the IARPA Quantum Enhanced Optimization Program
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/519; NASA-Ames Research Center
The IARPA Quantum Enhanced Optimization (QEO) program requires cost-effective, state-of-art, objective, and programmatically flexible Test and Evaluation (T&E) capabilities to validate that performer results are precise and accurate as reported, relative to the Program goals. To this end, Texas A&M University (TAMU) is uniquely suited to work as NASA's subcontractor for the T&E effort. In particular, TAMU and NASA have shared and unique capabilities, as well as validation roles and objectives. These include expertise in error models, the effects of noise on classical benchmarks, enhancement models, projections, and corroboration of results, precision requirements vs mis-specification, as well as quantum advantage via tailored problems based on spin glasses, CSPs, and current applications of interest to IARPA. TAMU provides IARPA through NASA a highly-responsive and authoritative means to quantify the deepest significance of performer results relative to QEO goals, and their broader significance to the community and future IARPA interests.
The Carnegie Supernova Project - Pushing the Precision of Type Ia Supernovae as Cosmological Standard Candles
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/457; National Science Foundation
This award funds research on an extensive dataset that will provide firm tests of the types of stars that end their life as Type Ia supernovae. The researchers will recalibrate data to higher precision and gain a better understanding of systematic errors and uncertainties. Results from this work will help provide tests of general relativity and improve our understanding of dark energy. Graduate students and postdoctoral researchers will be trained and mentored in research. Public outreach programs incorporating research results will be carried out at the home institutions of the PIs. The final reduced data will be made available to the astronomical community. This project will be accomplished by completing data reduction of optical and near-infrared wavelength images to produce final light curves of supernova explosions. They will also complete data reduction of near-infrared spectra of supernova explosions with an emphasis on improved removal of telluric absorption. They will produce new spectral templates for the community, analyze host galaxy properties, and produce Hubble diagrams. Finally, they will compare theory with observation and look for evidence of interaction with non-degenerate companions or circumstellar material. They will also probe the explosion physics as a function of luminosity and light curve decline rate. The dataset will also be used to improve the precision of using supernova Type Ia data as distance indicators for constraining the nature of dark energy.
Ultrafast Spectroscopy for Stand-off Detection of Explosive Devices
Physics And Astronomy; TAMU; https://hdl.handle.net/20.500.14641/550; DOD-Navy-Office of Naval Research
The major goal of this project is to develop new approaches to real-time detection of explosives, based on remote atmospheric superradiance and lasing, and stand-off coherent Raman spectroscopy. Our enhanced technique will allow rapid remote spectroscopic detection of chemicals, with the possibility of fast scanning of a wide area for Improvised Explosive Devices (IED's) and related trace chemicals. The ultimate target species are specific chemical constituents of common "home-made" devices originating from materials such as fertilizer, gunpowder and hydrogen peroxide. For this purpose, we will develop methods and techniques based on approaches we have previously used for remote identification and sensing of chemicals, on the ground and in the atmosphere. The techniques developed are expected to have sufficient sensitivity for detecting explosive chemical signature of substances such as ammonium nitrate, triacetone triperoxide, ethylene glycol, and urea nitrate, for example, at a safe remote distance. As an ultimate goal, we envision the possibility of producing a short-pulse fiber laser -based device that can be reliably deployed in the field. Implementation in the field may utilize spectrum databases and algorithms to quickly determine the constituent molecules and atoms in a sample under investigation. Moreover, a high-energy laser-based device may provide means initiating ignition and detonation of detected explosives from a safe distance. Extension of nonlinear spectroscopic techniques to the stand-off detection mode would enhance the optical return and permit the extraction a highly directional species-selective signal without the trade-off between the detection distance and input laser power that occurs with incoherent techniques. Stand-off optical sensing requires that the wave-vector of one or more impinging or generated laser fields is inverted, so that the beam propagates back towards the observer, providing an optical signature of the target volume. In dense optical media strong nonlinearities enable artificial nonlinear mirrors, based for example on phase-conjugation schemes or on plasma reflection. In low-density gaseous media, on the other hand, in the absence of back-scattering/-reflection at hard surfaces, it is extremely challenging to achieve wave-vector inversion, producing a coherent beam that retraces its way back to the laser. This difficulty is due to momentum conservation which strongly prohibits wave-vector reversal, while the optical nonlinearities in the gas phase are too weak to enable it. To acquire a coherent stand-off signal from a gas volume without the use of back-scattering/reflecting surfaces, one needs to provide a spatially-coherent back-propagating beam originating from the gas itself. Hence the objective of the proposed work is to develop a laser-like source of directional radiation from a remotely-pumped region of air, that will provide a coherent probe beam for nonlinear spectroscopy of target species. We aim to consider and evaluate backward air-lasing, superradiance, and quantum amplification by superradiant emission of radiation (QASER). The utilization of the bright coherent backward-propagating optical beam in remote spectroscopy applications will result in a dramatic improvement of the detection sensitivity compared to the standard light detection and ranging techniques. We will use nonlinear spectroscopy and supplement the backward-generated light by additional laser pulses sent in the forward direction. The end goal is to induce a coherent, directional, signal beam that carries the molecular fingerprint straight back toward the detector. Molecular excitations produced by pairs of photons - one from the backward air-laser beam and the other from the forward interrogation laser - provide a sensitive molecular detection mechanism. Examples include two-photon absorption (TPA ) and stimulated Raman scattering (SRS). For gas molecules, both TPA and SRS will show species-specific (fingerprint-like) structure of vibrational and rotational energy levels.