Sam Frederick     About     Projects

Projects

Publications

  1. “Modeling Magnetohydrodynamic Equilibrium in Magnetars with Applications to Continuous Gravitational Wave Production”. S.G. Frederick, K.L. Thompson, M.P. Kuchera. Monthly Notices of the Royal Astronomical Society, Volume 503, Issue 2, May 2021, Pages 2764–2775. DOI: 10.1093/mnras/stab625.

  2. “Correction and Accuracy of PurpleAir PM2.5 Measurements for Extreme Wildfire Smoke”. K.K. Barkjohn, A.L. Holder, S.G. Frederick, A.L. Clements. Sensors 2022, 22, 9669. DOI: 10.3390/s22249669

Presentations (* presenter)

  1. “Air Sensors: PurpleAir, AirNow Fire and Smoke Map, and Air Sensor Use Internationally”. K.K. Barkjohn, S.G. Frederick, A.L. Holder, A.L. Clements, Embassy Air Quality Fellows Program, U.S. Department of State. (Virtual, Dec 2020). EPA Science Inventory Link.

  2. “Yearlong performance of Six PM Air Sensor Models Across Seven U.S. Sites”. K.K. Barkjohn*, C. Johnson, S.G. Frederick, R. Yaga, B. Thomas, W. Schoppman, A.L. Clements. American Association for Aerosol Research. (Virtual, Oct 2020). EPA Science Inventory Link.

  3. “Leveraging a PurpleAir Sensor Network to Inform Air Quality Action in Phoenix, Arizona”. I. VonWald*, K.K. Barkjohn, S.G. Frederick, S. Kimbrough, B. Davis, N. Peterson, I. Domsky, R. Pope, A. Clements. American Association for Aerosol Research. (Virtual, Oct 2020). EPA Science Inventory Link.

  4. “Long-Term Performance of Five Air Sensor Models Across Seven U.S. Sites”. K.K. Barkjohn*, S.G. Frederick, C. Johnson, R. Yaga, B. Thomas, W. Schoppman, A.L. Clements. Air Sensor International Conference Fall webinar series. (Virtual, Oct 2020). EPA Science Inventory Link.

  5. “Performance Evaluations of Air Sensors at EPA’s AIRS Site”. S.G. Frederick*, K.K. Barkjohn, C. Johnson, R. Yaga, A.L. Clements. U.S. EPA PM2.5 Implementation Workgroup. (Virtual, Aug 2020).

  6. “PurpleAir PM2.5 U.S. Correction and Performance During Smoke Events”. K.K. Barkjohn*, A.L Holder, S.G. Frederick, A.L. Clements, International Smoke Symposium. (Virtual, Apr 2020). EPA Science Inventory Link.

  7. “Performance Evaluations of PM2.5 Sensors in Research Triangle Park”. S.G. Frederick*, K.K. Barkjohn, C. Johnson, R. Yaga, A.L. Clements. U.S. EPA Air Sensor Brownbag Webinar. (RTP, NC, Jan 2020). EPA Science Inventory Link.

  8. “Modeling Structural and Magnetic Field Stability in Magnetars with Applications to Continuous Gravitational Wave Production”. S.G. Frederick*. Thesis Defense, Davidson College Department of Physics. (Davidson, Apr 2019).

  9. “Highly Magnetic Stars and Continuous Gravitational Wave Production”. S.G. Frederick*, K.L. Thompson, M.P. Kuchera. Public talk, Charlotte Amateur Astronomers’ Club. (Charlotte, NC, Mar 2019).

  10. “Modeling Stability of Magnetic Fields in Magnetars”. S.G. Frederick*, K.L. Thompson, M.P. Kuchera. Davidson College Department of Physics Winter Symposium. (Davidson, Dec 2018).

  11. “Radio Observations of Intermittent Pulsars and Interstellar Clouds”. S.G. Frederick*, K.L. Thompson. Davidson College Department of Physics Winter Symposium. (Davidson, Dec 2017)

Poster Presentations (* presenter)

  1. “Performance Evaluations of Six PM2.5 Sensors in Research Triangle Park, NC”. S.G. Frederick*, K.K. Barkjohn, C. Johnson, I. VonWald, A.L. Clements. American Association for Aerosol Research. (Virtual, Oct 2020). EPA Science Inventory Link.

  2. “Impacts of Data Completeness on Hourly Averaged PurpleAir PM2.5 Concentrations During Smoke Events”. S.G. Frederick*, K.K. Barkjohn, A.L. Holder, A.L. Clements. American Association for Aerosol Research. (Virtual, Oct 2020) EPA Science Inventory Link.

  3. “Performance Evaluations of Six PM2.5 Sensors in Research Triangle Park, NC”. S.G. Frederick*, K.K. Barkjohn, C. Johnson, R. Yaga, A.L. Clements. Air Pollution Monitoring for Communities Grantee Meeting. (RTP, NC, Feb 2020).

  4. “PurpleAir PM2.5 U.S. Correction and Performance During Smoke Events”. K. Johnson*, A. Holder, S. Frederick, A. Clements. Air Pollution Monitoring for Communities Grantee Meeting. (RTP, NC, Feb 2020).

  5. “Modeling Structural and Magnetic Field Stability in Magnetars”. S. Frederick*, K.L. Thompson, M.P. Kuchera. Meeting of the American Astronomical Society. (Seattle, WA, Jan 2019). EPA Science Inventory Link.

  6. “HI Observations of Intermittent Pulsars”. S. Frederick*, K. Thompson. North Carolina Astronomers’ Meeting. (Guilford Technical Community College, Guilford, NC, Sep 2018).

  7. “HI Observations of Intermittent Pulsars”. S. Frederick*, K.L. Thompson. Davidson College Alenda Lux Research Symposium. (Davidson, NC, May 2018).

  8. “Analysis of Particle Trajectories around Schwarzschild and Extreme-Kerr Black Holes”. S. Frederick*. Davidson College Alenda Lux Research Symposium. (Davidson, NC, May 2017)

  9. “Determining the Excitation Temperature of M57 via Spectral Analysis”. S. Frederick*. Quadrennial SPS Physics Congress. (San Francisco, CA, Nov 2016)

Honors Thesis in Physics - Davidson College, May 2019

Modeling Magnetohydrodynamic Equilibrium in Magnetars with Applications to Continuous Gravitational Wave Detection

  • Constructed a C-based computational model for magnetar stellar structure with strong magnetic fields by implementing magnetohydrodynamic simulation via the PLUTO code for astrophysical gas dynamics.
  • Quantified structural deformation due to magnetic field strength via measurement of stellar ellipticity by evaluating changes to the principal moments of inertia of the star.
  • Determined estimates for continuous gravitational wave strain resulting from stellar deformation assuming axisymmetric deformations orthogonal to the rotational axis.
  • Found simulation results to be within reasonable prediction of published wave strain estimates for highly-magnetic pulsar sources.