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Real-Time Rfi Mitigation In Radio Astronomy, Emily Ramey, Nick Joslyn, Richard Prestage, Michael Lam, Luke Hawkins, Tim Blattner, Mark Whitehead 2019 Washington University in St. Louis

Real-Time Rfi Mitigation In Radio Astronomy, Emily Ramey, Nick Joslyn, Richard Prestage, Michael Lam, Luke Hawkins, Tim Blattner, Mark Whitehead

Senior Honors Papers / Undergraduate Theses

As the use of wireless technology has increased around the world, Radio Frequency Interference (RFI) has become more and more of a problem for radio astronomers. Preventative measures exist to limit the presence of RFI, and programs exist to remove it from saved data, but the use of algorithms to detect and remove RFI as an observation is occurring is much less common. Such a method would be incredibly useful for observations in which the data must undergo several rounds of processing before being saved, as in pulsar timing studies. Strategies for real-time mitigation have been discussed and tested with ...


Arecibo Message, Joshua P. Tan 2019 CUNY La Guardia Community College

Arecibo Message, Joshua P. Tan

Open Educational Resources

This two week assignment asks students to interpret and analyze the 1974 Arecibo Message sent by Drake and Sagan. Week 1 introduces the concepts behind the construction of the message and engages with a critical analysis of the architecture and the contents of the message. Week 2 asks students to develop software in a Jupyter Notebook (available for free from the Anaconda Python Distribution) to interpret messages that were similar to those produced by Drake and Sagan.


Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft 2019 Macalester College

Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft

Macalester Journal of Physics and Astronomy

We present neutral hydrogen (HI) observations from the Very Large Array (VLA) telescope of the galaxies Haro 11, Pox 186, and VCC 1313. 24 hours of deep spectral line observation at the 21 cm line were obtained from the program 17B-287 of Haro 11, the primary galaxy studied in this capstone, and 176 and 203 respective minutes of archival VLA data at the 21 cm line were obtained from the program AS0832 of Pox 186 and VCC 1313, the secondary and tertiary sources of study for this capstone. Haro 11 is one of a very small number of local dwarf ...


Binary Neutron Star Merger Rates. Predictions From Observations Of Dwarf Galaxies And Observable Rates With Ground-Based Gravitational-Wave Detectors, Karen Perez Sarmiento 2019 Macalester College

Binary Neutron Star Merger Rates. Predictions From Observations Of Dwarf Galaxies And Observable Rates With Ground-Based Gravitational-Wave Detectors, Karen Perez Sarmiento

Macalester Journal of Physics and Astronomy

Binary Neutron Star (BNS) mergers are interesting events in the field of multi-messenger astronomy since they are sources of detectable gravitational wave signals and electromagnetic transients. Here I introduce a new method to calculate a conservative, lower-limit for the rate of BNS merger events that is proportional to the stellar mass and is based on evidence of an r-process event in the dwarf galaxy Reticulum II. Two estimates of the stellar mass in the nearby universe were made using a Schechter Mass Function and a modified version of the 2MASS Extended Source Catalog (2MASS XSC). The BNS merger event rates ...


Uv Led System For Pl Measurements On Gan Samples, Dona H. Pantova 2019 Macalester College

Uv Led System For Pl Measurements On Gan Samples, Dona H. Pantova

Macalester Journal of Physics and Astronomy

Gallium Nitride materials are direct bandgap semiconductors with important applications, such as in the production of light-emitting diodes and transistors. The process of photoluminescence, in which excited electron and holes emit electro-magnetic radiation when they recombine, can be used to study the structure and quality of Gallium Nitride materials. Due to the size of the bandgap in these materials (3.4eV), ultraviolet light is required to create electron-hole pairs in GaN. We designed and built a system, which uses ultraviolet light, to take measurements on GaN samples provided by a local company, Lightwave Photonics, who were interested in the quality ...


Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina 2019 Macalester College

Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina

Macalester Journal of Physics and Astronomy

In this work, we study the electrical properties of transparent conducting oxides using physical and optical techniques. The objective is to characterize the conductivity of a series of cadmium oxide zinc-oxide thin films with varying cadmium concentrations using three methods. The Hall Effect estimates carrier concentration, sheet conductivity, and carrier mobility. Optical methods, such as FTIR spectroscopy, can provide estimates of the plasma frequency, which describes a metal’s transition from being transparent to opaque to light. THz spectroscopy extracts the complex conductivity of materials in the far infrared spectrum and provides insights on the optical transport properties of conductors ...


Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach 2019 Macalester College

Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach

Macalester Journal of Physics and Astronomy

The solar cycle has a profound effect on both terrestrial and extra-terrestrial operations. Understanding the history of the solar cycle is necessary for studying long term trends, however older data is difficult to calibrate due to the sparsity of observations. In this paper we propose a new method for calibrating sunspot number data that does not rely on observational overlap. Initial testing shows promise in this method’s success, though more work must be done to ensure calibration consistency across all observers.


Recent Evolution Of The Eta Carinae Supernova Imposter System, Greta L. Helmel 2019 Macalester College

Recent Evolution Of The Eta Carinae Supernova Imposter System, Greta L. Helmel

Macalester Journal of Physics and Astronomy

The supernova imposter Eta Carinae and its surrounding Homunculus reflection nebula have been of great interest for the last several decades. As the most massive star known in our Galaxy, this object is of particular importance in understanding high mass loss episodes and final stages in the evolution of other similarly massive stars in the later stages of their lives. Observations using the STIS CCD Instrument have been taken over the past 20 years for both the central star and the Homunculus as part of the Hubble Space Telescope (HST) Treasury Program on Eta Carinae. Recent changes in the spectra ...


The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford 2019 Macalester College

The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford

Macalester Journal of Physics and Astronomy

We present H I spectral line images of the nearby dwarf galaxy NGC 3239. The galaxy’s curious morphology suggests that it is a post-merger system. We propose that NGC 3239 is a merger because it has multiple tidal tails, an enhanced velocity dispersion throughout the disk, and widespread star formation. We have produced kinematic moment maps corresponding to the H I column density, radial velocity, and velocity dispersion. Further, position velocity (P-V) slices of the galaxy were taken and three-color images were made using the SDSS G, R, and I, filters for comparison with the moment maps. These slices ...


Tik-Means: Transformation-Infused K-Means Clustering For Skewed Groups, Nicholas S. Berry, Ranjan Maitra 2019 Iowa State University

Tik-Means: Transformation-Infused K-Means Clustering For Skewed Groups, Nicholas S. Berry, Ranjan Maitra

Ranjan Maitra

The K-means algorithm is extended to allow for partitioning of skewed groups. Our algorithm is called TiK-Means and contributes a K-means type algorithm that assigns observations to groups while estimating their skewness-transformation parameters. The resulting groups and transformation reveal general-structured clusters that can be explained by inverting the estimated transformation. Further, a modification of the jump statistic chooses the number of groups. Our algorithm is evaluated on simulated and real-life datasets and then applied to a long-standing astronomical dispute regarding the distinct kinds of gamma ray bursts.


Multivariate T-Mixture-Model-Based Cluster Analysis Of Batse Catalogue Establishes Importance Of All Observed Parameters, Confirms Five Distinct Ellipsoidal Sub-Populations Of Gamma-Ray Bursts, Souradeep Chattopadhyay, Ranjan Maitra 2019 Iowa State University

Multivariate T-Mixture-Model-Based Cluster Analysis Of Batse Catalogue Establishes Importance Of All Observed Parameters, Confirms Five Distinct Ellipsoidal Sub-Populations Of Gamma-Ray Bursts, Souradeep Chattopadhyay, Ranjan Maitra

Ranjan Maitra

Determining the kinds of gamma-ray bursts (GRBs) has been of interest to astronomers for many years. We analysed 1599 GRBs from the Burst and Transient Source Experiment (BATSE) 4Br catalogue using t-mixture-model-based clustering on all nine observed parameters (T50, T90, F1, F2, F3, F4, P64, P256, and P1024) and found evidence of five types of GRBs. Our results further refine our earlier findings by providing groups that are more distinct. Using the classification scheme of past authors that employed duration, total fluence (Ft = F1 + F2 + F3 ...


Gaussian-Mixture-Model-Based Cluster Analysis Finds Five Kinds Of Gamma-Ray Bursts In The Batse Catalogue, Souradeep Chattopadhyay, Ranjan Maitra 2019 University of Calcutta

Gaussian-Mixture-Model-Based Cluster Analysis Finds Five Kinds Of Gamma-Ray Bursts In The Batse Catalogue, Souradeep Chattopadhyay, Ranjan Maitra

Ranjan Maitra

Clustering methods are an important tool to enumerate and describe the different coherent kind of gamma-ray bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent associated assumptions, the inclusion of variables in clustering, nature of initialization methods used or the iterative algorithm or the criterion used to judge the optimal number of groups supported by the data. We analysed GRBs from the Burst and Transient Source Experiment (BATSE) 4Br Catalog using k-means and Gaussian-mixture-models-based clustering methods and found that after accounting for all the above factors, all ...


Machine Learning Pipeline For Exoplanet Classification, George Clayton Sturrock, Brychan Manry, Sohail Rafiqi 2019 Southern Methodist University

Machine Learning Pipeline For Exoplanet Classification, George Clayton Sturrock, Brychan Manry, Sohail Rafiqi

SMU Data Science Review

Planet identification has typically been a tasked performed exclusively by teams of astronomers and astrophysicists using methods and tools accessible only to those with years of academic education and training. NASA’s Exoplanet Exploration program has introduced modern satellites capable of capturing a vast array of data regarding celestial objects of interest to assist with researching these objects. The availability of satellite data has opened up the task of planet identification to individuals capable of writing and interpreting machine learning models. In this study, several classification models and datasets are utilized to assign a probability of an observation being an ...


Thornado-Hydro: Generalizing Discontinuous Galerkin Methods For A Nuclear Equation Of State For Supernova Hydrodynamics, Brandon Lynn Barker, Eirik Endeve, Anthony Mezzacappa 2019 University of Tennessee, Knoxville

Thornado-Hydro: Generalizing Discontinuous Galerkin Methods For A Nuclear Equation Of State For Supernova Hydrodynamics, Brandon Lynn Barker, Eirik Endeve, Anthony Mezzacappa

Chancellor’s Honors Program Projects

No abstract provided.


Median Energy Imaging Of Supernova Remnants With Chandra X-Ray Observatory, Anne Blackwell 2019 College of William and Mary

Median Energy Imaging Of Supernova Remnants With Chandra X-Ray Observatory, Anne Blackwell

Undergraduate Honors Theses

Supernova remnants (SNRs) play an important role in shaping the energy density, chemical enrichment, and interstellar medium (ISM) of galaxies, and in our understanding of stellar evolution. Due to the high plasma temperatures of SNRs, they primarily emit X-rays. Using data collected with the Chandra observatory, we study a novel statistical imaging analysis technique to probe the underlying structure and physical properties of DEM L71, a SNR in the Large Magellanic Cloud. We used the statistical properties of the photons within an image pixel, such as the median energy, to make images of the energetics across the SNR. We have ...


Induced Magnetic Dipole On Jupiter’S Moon Europa, Luke Francis, Michele Zanolin 2019 Embry-Riddle Aeronautical University

Induced Magnetic Dipole On Jupiter’S Moon Europa, Luke Francis, Michele Zanolin

Student Works

Physics can have some of the most unique and extraordinary applications of basic principles applied on a larger scale. This paper will explore the properties of induced magnetic dipoles and will examine this phenomenon directly from Jupiter's moon, Europa. These properties will be used to determine if there is liquid water beneath its icy surface and how this conclusion was verified. This will be accomplished using the concepts of magnetic dipoles and induced currents. Recent missions have also revealed estimates of the depth of Europa's subsurface ocean. There have been many measurements taken of Europa's magnetic field ...


Keynote: Keck Observatory Laser Show: Technology That’S Improving Our Vision Of The Universe, Marc Kassis 2019 W. M. Keck Observatory

Keynote: Keck Observatory Laser Show: Technology That’S Improving Our Vision Of The Universe, Marc Kassis

Carroll College Student Undergraduate Research Festival

The W. M. Keck Observatory uses two adaptive optics systems equipped with laser guide star technology to take the “twinkle” out of star light. The adaptive optics technology sharpens images taken with the two twin 10 meter diameter Keck Observatory telescopes that are currently the largest optical and near-infrared telescopes on the planet. Forward thinking Keck scientists are constantly innovating and adding new technology to the telescopes to keep it at the cutting edge of research astronomy, and this includes updates to our adaptive optics systems that reveal unprecedented detail of astronomical objects. During this presentation, you will get a ...


Cloud Coalescence: A Dynamical Instability Affecting Multiphase Environments, Tim Walters, Daniel Proga 2019 Los Alamos National Laboratory

Cloud Coalescence: A Dynamical Instability Affecting Multiphase Environments, Tim Walters, Daniel Proga

Physics & Astronomy Faculty Publications

Mass and size distributions are the key characteristics of any astrophysical object, including the densest clumps comprising the cold phase of multiphase environments. In our recent papers, we showed how individual clouds of various sizes form and evolve in active galactic nuclei. In particular, we showed that large clouds undergo damped oscillations as a response to their formation process. Here we follow up this investigation, addressing how different size clouds interact. We find that smaller clouds become trapped in the advective flows generated by larger clouds. The explanation for this behavior leads to a rather remarkable conclusion: even in the ...


Non-Isobaric Thermal Instability, Tim Walters, Daniel Proga 2019 Los Alamos National Laboratory

Non-Isobaric Thermal Instability, Tim Walters, Daniel Proga

Physics & Astronomy Faculty Publications

Multiphase media have very complex structure and evolution. Accurate numerical simulations are necessary to make advances in our understanding of this rich physics. Because simulations can capture both the linear and nonlinear evolution of perturbations with a relatively wide range of sizes, it is important to thoroughly understand the stability of condensation and acoustic modes between the two extreme wavelength limits of isobaric and isochoric instability as identified by Field. Partially motivated by a recent suggestion that large non-isobaric clouds can "shatter" into tiny cloudlets, we revisit the linear theory to survey all possible regimes of thermal instability. We uncover ...


Using Atran Telluric Correction To Investigate The 3Μm-Region, Lucas Trent McClure 2019 University of Tennessee, Knoxville

Using Atran Telluric Correction To Investigate The 3Μm-Region, Lucas Trent Mcclure

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

Small-bodies of the Solar System, such as asteroids, provide an abundant amount of information about planetary formation and evolution. In particular, the characterization of asteroids is vital to understanding the distribution and abundance of water throughout the Solar System. Recent findings in asteroid spectroscopy have provided evidence for the surface presence of water-ice and hydroxide, likely due to silicates on asteroid surfaces interacting with H+ ions from the solar wind. To investigate surface hydration, astronomers analyze the 3µm region, where an absorption feature is exhibited. Atmospheric water, however, affects the quality of the data around this particular region, but a ...


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