Ph.D. University of Michigan, United States, 2019
Field: Atmospheric, Oceanic, and Space Sciences and Scientific Computing (Dual Degree)
Dissertation: Probing the Universe with Space Based Low Frequency Radio Measurements
Chair : J. Kasper Committee: J. Lazio, M. Liemohn, W. Manchester, S. Veerapaneni
M.S. University of Michigan, United States, 2017
Field: Atmospheric, Oceanic, and Space Sciences
B.S. Alma College, Michigan, United States, 2014
Field: Mathematics and Computer Science, with Honors, Summa Cum Laude
Senior Thesis: Incompleteness: What We Can’t Prove
Multidisciplinary Design Program (MDP) Heliophysics Instrumentation Group, ENGR 255/355
Focus on Low Frequency Radio Applications for Space Science, in support of the SunRISE mission's student collaboration.
KEY WORDS: Heliophysics, Radio Astronomy, Radio Interferometry, Solar Radio Bursts, Coronal Mass Ejections, Low Frequency Astrophysics, MHD Simulations, Lunar Science, Scientific Computing, Machine Learning
Dr. Alexander Hegedus is a leading expert in simulating and interpreting measurements from space-based low frequency radio arrays. He is a part of several concept array teams that are at various stages of development including SunRISE, RELIC, PRIME, Synchrotron, and FARSIDE. These arrays have a wide range of scientific targets, including solar type II and III radio bursts, radio galaxies, exoplanets, Earth’s transient magnetospheric emissions like auroral kilometric radiation, Earth’s background synchrotron emission from its radiation belts, and early universe cosmology. Dr. Hegedus has a top to bottom understanding of these low frequency radio measurements, with experience spanning from instrumentation to calibration to imaging and data analysis.
One space-based radio array furthest along in development that Dr. Hegedus is integrally involved with is SunRISE, a 6 spacecraft concept array with a primary focus on imaging solar Type II and III radio bursts. His research involves showing how the mission could achieve its main scientific objective of discerning between different theories of radio burst generation/solar energetic particle acceleration within Coronal Mass Ejections (CMEs) via imaging with a synthetic aperture created with the separate receivers across the 6 spacecraft. SunRISE was selected and began Phase B in 2020, with the University of Michigan slated to host the Science Operations Center (SOC) that will process and deliver all of the mission’s data for the 12 month mission over mid 2023-2024. Dr. Hegedus was designated as a Co-Investigator and the SOC lead for the SunRISE mission. As a postdoctoral research fellow at the University of Michigan, Dr. Hegedus has already begun to lay the groundwork for the SOC, profiling the science pipeline for the full volume of data expected to be generated by the mission, and procuring the proper resources for the computational needs of the pipeline and the storage of its output data. The SOC will eventually deliver all its data to the NASA Space Physics Data Facility to be archived in 3 months intervals over the course of the mission.
Dr. Hegedus also has experience with handling massive amounts of MHD simulation data, with the aim of teasing out the location of burst emission from recreations of past major space weather events. Dr. Hegedus introduced a technique to identify the likely source location of the emission by comparing the observed dynamic spectrum from a single spacecraft against synthetic spectra made from hypothesized emitting regions within a numerical simulation of a CME. He also extended the framework to score these synthetic spectra by their similarity to the type II frequency profile derived from Wind/WAVES data. He found that simulated areas with 4x enhanced entropy and de Hoffmann Teller velocity > 1.3x the shock speed are found to produce synthetic spectra similar to spacecraft observations. One promising long-term goal of applying this framework is finding a common set of thresholds of plasma parameters that create synthetic type II spectra that match observed spectra across many recreated simulations of major CMEs. Such findings would be valuable information for constraining physical theories of particle acceleration at CMEs, and also immediately applicable to space weather operations to those at the Space Weather Prediction Center and their peers. A set of key thresholds that mark the site of type II burst generation and particle acceleration would help enable more reliable space weather prediction, especially with the use of faster than real time simulations of incoming CMEs on the horizon. This thread of research was in partnership with Dr. Manchester of the University of Michigan, who ran the MHD simulations and, like Dr. Hegedus, is a Co-Investigator on the SunRISE mission. These types of studies will be made even more powerful once SunRISE is launched and is able to provide additional bounds on the location of burst emission within CMEs.
Dr. Hegedus also has adapted his pipeline for simulating the performance of radio arrays on the lunar surface. He is involved in several concept arrays including the PRIME, FARSIDE, and Synchrotron arrays. One of his first author papers in Radio Science showcases this pipeline for the science case of imaging the synchrotron emission from Earth’s radiation belts. This synchrotron emission has only ever been imaged at higher frequencies for Jupiter, and a low frequency array in space would be necessary to do the same for Earth. Dr. Hegedus demonstrated how a large-scale array on the lunar near side could make daily images of this background emission, providing a unique proxy measurement of the global energetic electron distribution in Earth’s magnetosphere. This paper was well received, and Dr. Hegedus was invited to write a book chapter in the upcoming textbook, Magnetospheric Imaging: Understanding the Space and Environment through Global Measurements, edited by Gallagher, D., Colado-Vega, Y., Wing, S., and Frey, H.
Dr. Hegedus is also a Co-Investigator on PRIME, the Prototype Radio Interferometer on the Moon for Exoplanet studies, which is currently under review for the NASA call for Payloads and Research Investigations on the Surface of the Moon (PI Dr. Jack Burns of University of Colorado, Boulder). Dr. Hegedus is also involved with studies for FARSIDE, a concept array to go to the lunar far side, whose chief scientific target is the absorption troughs of the redshifted neutral hydrogen 21-cm signal in the 10-40 MHz range to probe the so called “Dark Ages” and constrain cosmological models of the early universe. He has been working closely with the science and engineering teams, simulating the performance of different array configurations across different deployment strategies.
Dr. Hegedus has also applied these lunar arrays to the scientific objective of localizing transient emission from energetic electrons in Earth’s magnetosphere through tracking a variety of emissions, including Auroral Kilometric Radiation and Medium Frequency Bursts. He showed that smaller arrays like PRIME will be able to coarsely localize radio loud transient emission such as solar radio bursts and emission from Earth’s magnetosphere. Medium sized (10 km, 128 element) arrays such as FARSIDE have the sensitivity to conduct novel cosmological measurements on the radio quiet far side, but a similar configuration on the nearside could precisely localize the bright transients to within kilometers of their plane of sky location, yielding an unprecedented view of local electron instabilities for any events that are beamed towards the Moon. Filling in the 10 km array even past FARSIDE specifications could increase the sensitivity to a point where daily images of the Earth’s synchrotron emission could be made. This could provide both local and global measurements of energetic electrons in the Earth’s magnetosphere to an unprecedented degree.
Multidisciplinary Design Program Supervisor, University of Michigan, 2020-2021
SunRISE, Co-Investigator, Science Operation Center Lead
Parker Solar Probe, Radio Science Working Group, Co-Chair
Network for Exploration and Space Science, Collaborator
Michigan Postdoctoral Association of the College of Engineering – Executive Committee, 2019 – 2021
Alexander Hegedus is a Postdoctoral Research Fellow at the Climate and Space Sciences and Engineering Department at University of Michigan. He earned his dual degree PhD in Atmospheric Oceanic and Space Sciences & Scientific Computing from University of Michigan in 2019. He received his Bachelors in Mathematics & Computer Science in 2014 from Alma College, and his Masters in Atmospheric , Oceanic, and Space Sciences from University of Michigan in 2016.
In the early stages of his PhD (2014-2015), Dr. Hegedus gained experience with ground-based radio receivers including the Owens Valley Long Wavelength Array (OVRO-LWA) with Dr. Lincoln Greenhill of the Center for Astrophysics at Harvard, the Green Bank Telescope (GBT) as part of the NRAO summer school, and the Very Large Array (VLA). He acquired hands on experience in the assembly of LWA antennas, taking data with them, and analyzing that data with industry standard software packages. His experience includes the use of PRESTO for analyzing pulsar data, as well as Common Astronomy Software Applications (CASA) for general imaging. He also worked with single spacecraft radio measurements, including those from the Wind, STEREO, and Parker Solar Probe (PSP) to plot their detections of solar radio bursts. Dr. Hegedus continues to be active in PSP circles as the Co-Chair of the Radio & Solar Energetic Particle Working Group where he helps moderate monthly meetings on scientific progress from the spacecraft.
He interned at JPL in the summer of 2016 & 2017, working with multiple teams on different space based array concepts. His presentation Simulating 3D Spacecraft Constellations for Low Frequency Radio Imaging won an Outstanding Student Paper Award (OSPA) at the American Geophysical Union Fall Meeting in 2016. Alex is a Co-Investigator and head of the Science Operations Center for SunRISE, a recently funded NASA Heliophysics Mission of Opportunity that will launch 6 satellites into GEO orbit in 2023 to create the first synthetic aperture in space. He is also the Heliophysics/Astrophysics representative on the Lunar Exploration Analysis Group. His research interests include Heliophysics, Radio Astronomy, Lunar Science, Scientific Computing, and Machine Learning.
Outstanding Student Paper Award, American Geophysical Union 2016
Romero-Wolf, A., Hegedus, A., Kasper, J., and Lazio, J., “Prospects for Low Frequency Radio Astronomy with the Sun Radio Interferometer Space Experiment,” in prep Astronomy & Astrophysics
Hegedus, A., Manchester, W., and Kasper, J., “Tracking the Source of Solar Type II Bursts through Comparisons of Simulations and Radio Data,” submitted The Astrophysical Journal
Hegedus, A.M., “Imaging Earth’s Magnetospheric Transient and Background Synchrotron Emission with Lunar Near Side Radio Arrays,” Magnetospheric Imaging: Understanding the Space and Environment through Global Measurements, Gallagher, D., Colado-Vega, Y., Wing, S., and Frey, H., eds, Elsevier, 2020 (in press).
Werner, C., […], Hegedus, A., et al., “Expression of the of the androgen receptor governs radiation resistance in a subset of glioblastomas vulnerable to anti-androgen therapy,” Molecular Cancer Therapeutics, (2020). 10.1158/1535-7163.MCT-20-0095
Hegedus, A. M. “Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface”, The Journal of Visualized Experiments, (2020). https://dx.doi.org/10.3791/61540
Huang, J., […], Hegedus, A.M., et al., “Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with the First Parker Solar Probe Observations,” The Astrophysical Journal Supplement Series, 246(2):70 (2020). 10.3847/1538-4365/ab74e0
Krupar, V., […], Hegedus, A. M., et al., “Density fluctuations in the solar wind based on type III radio bursts observed by parker solar probe,” The Astrophysical Journal Supplement Series, 246(2):57 (2020). 10.3847/1538-4365/ab65bd
Pulupa, M., […], Hegedus, A. M., et al., “Statistics and polarization of type III radio bursts observed in the inner heliosphere,” The Astrophysical Journal Supplement Series, 246(2):49 (2020). 10.3847/1538-4365/ab65bd
Hegedus, A., Nenon, Q., Brunet, A., Kasper, J., Sicard, A., Cecconi, B., MacDowall, R., Baker, D., “Measuring the Earths Synchrotron Emission from Radiation Belts with a Lunar Near Side Radio Array”, Radio Science, 56, (2020). 10.1029/2019RS006891
Hegedus, A., Kasper, J., Lazio, J., Romero-Wolf, A., and Manchester, W., “The Data Processing Pipeline and Science Analysis of the Sun Radio Interferometer Space Experiment,” 2019 IEEE Aerospace Conference Proceedings, Big Sky, MT, (2019). 10.1109/AERO.2019.8741697
Hegedus, A., Soriano, M., Kurum, A., and Kasper, J., “Correlators for Synthetic Apertures in Space,” IEEE Aerospace Conference Proceedings, Big Sky, MT, (2019). 10.1109/AERO.2019.8742024
Alibay, F., Hegedus, A., et al. “SunRISE Status: Concept Development Update,” 2018 IEEE Aerospace Conference Proceedings, Big Sky, MT, (2018). 10.1109/AERO.2018.8396371
Belov, K., […], Hegedus, A., et al. “A space-based decametric wavelength radio telescope concept,” Experimental Astronomy (2018). https://doi.org/10.1007/s10686-018-9601-6
Cranmer, M., […], Hegedus, A., et al. “Bifrost: A Python/C++ Framework for High-Throughput Stream Processing in Astronomy,” Journal of Astronomical Instrumentation Vol. 6, No. 4 (2017). 10.1142/S2251171717500076