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Dr. Nithyanandan Thyagarajan

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Dr. Nithyanandan Thyagarajan Address National Radio Astronomy Observatory Webpage https://tnithyanandan.wordpress.com/ 1003 Lopezville Rd E-mail [email protected] Socorro, NM 87801, USA Phone +1 (575) 835-7095 Education 2004-2011 PhD in Astronomy, Columbia University, New York, NY, USA. Thesis Advisor: Prof. David J. Helfand Ph.D. dissertation available for download at https://tnithyanandan.wordpress.com/ 2006-2007 M.Phil. in Astronomy, Columbia University, New York, NY, USA 2004-2006 M.A. in Astronomy, Columbia University, New York, NY, USA 2000-2004 Bachelor of Technology in Electrical Engineering, IIT Madras, India. Thesis Advisor: Prof. Harishankar Ramachandran Professional Experience Sep 2017 - National Radio Astronomy Observatory, Socorro, NM, USA Present Jansky Postdoctoral Fellow Collaborations: Hydrogen Epoch of Reionization (HERA), Square Kilometre Array (SKA), Murchison Widefield Array (MWA) Oct 2016 - Arizona State University, School of Earth and Space Exploration, Tempe, AZ, USA Aug 2017 Assistant Research Scientist Collaborations: Hydrogen Epoch of Reionization (HERA), Square Kilometre Array (SKA), Murchison Widefield Array (MWA) Sep 2013 - Arizona State University, School of Earth and Space Exploration, Tempe, AZ, USA Sep 2016 Post-doctoral Research Associate Collaborations: Hydrogen Epoch of Reionization (HERA), Square Kilometre Array (SKA), Murchison Widefield Array (MWA) May 2011 - Raman Research Institute, Bangalore, India Jul 2013 Pancharatnam Post-doctoral Fellow Collaborations: Murchison Widefield Array (MWA) 1 of 14 Research Grants • Principal investigator of a $600,000 grant proposal funded by the National Science Foundation (NSF) Advanced Technologies and Instrumentation (ATI) division for “First Deployment of an E-Field Parallel Imaging Correlator with the LWA” at Sevilleta LWA station in collaboration with Prof. Greg Taylor (UNM), Prof. Gregg Hallinan (Caltech), Prof. Aaron Parsons (Berkeley), Prof. Judd Bowman (ASU), Prof. Miguel Morales (UW), Prof. Ralph Wijers (U. Amsterdam, AARTFAAC-LOFAR) and Prof. Dan Werthimer (Berkeley). Peer-reviewed Publications 1. Thyagarajan, N., Beardsley, A. P., Bowman, J. D., & Morales, M. F., Monthly Notices of the Royal Astronomical Society, 467, 715 (2017), “A Generic and Efficient E-field Parallel Imag- ing Correlator for Next-Generation Radio Telescopes” 2. Thyagarajan, N., Parsons, A. R., DeBoer, D. R., Bowman, J. D., et al., The Astrophysical Journal, 825, 9 (2016), “Effects of Antenna Beam Chromaticity on Redshifted 21 cm Power Spec- trum and Implications for Hydrogen Epoch of Reionization Array” 3. Beardsley, A. P., Thyagarajan, N., Morales, M. F., & Bowman, J. D., Monthly Notices of the Royal Astronomical Society (2017), “An Efficient Feedback Calibration Algorithm for Di- rect Imaging Radio Telescopes” 4. Thyagarajan, N., Jacobs, D. C., Bowman, J. D., et al., The Astrophysical Journal Letters, 807, 28 (2015), “Confirmation of Wide-field Signatures in Redshifted 21 cm Power Spectra” 5. Thyagarajan, N., Jacobs, D. C., Bowman, J. D., et al., The Astrophysical Journal, 804, 14 (2015), “Foregrounds in Wide-Field Redshifted 21 cm Power Spectra” 6. Thyagarajan, N., Udaya Shankar, N., Subrahmanyan, R., et al., The Astrophysical Journal, 776, 6 (2013), “A Study of Fundamental Limitations to Statistical Detection of Redshifted HI from the Epoch of Reionization” 7. Thyagarajan, N., Helfand, D. J., White, R. L., & Becker, R. H., The Astrophysical Journal, 742, 49 (2011), “Variable and Transient Radio Sources in the FIRST Survey” 8. DeBoer, D. R., Parsons, A. R., …Thyagarajan, N., et al. [54 authors], Publications of the As- tronomical Society of Pacific, 129, 045001 (2017), “Hydrogen Epoch of Reionization Array (HERA)” 9. Kapinska, A. D., Staveley-Smith, L., Crocker, R., …Thyagarajan, N., et al. [70 authors], The Astrophysical Journal, 838, 68 (2017), “Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies” 10. Patra, N., Parsons, A. R., DeBoer, D. R., Thyagarajan, N., et al., arXiv:1701.03209 (2017), Exper- imental Astronomy (in press), “The Hydrogen Epoch of Reionization Array Dish III : Mea- suring Chromaticity of Prototype Element with Reflectometry” 11. Nunhokee, C. D., Bernardi, G., Kohn, S. A., Aguirre, J. E., Thyagarajan, N., et al., The Astrophys- ical Journal (2017), “Constraining polarized foregrounds for eor experiments II: Simula- tions of polarization leakage in the avoidance scheme” 12. Kittiwisit, P.,Bowman, J. D., Jacobs, D. C., Thyagarajan, N. & Beardsley, A. P., arXiv:1708.00036 (2017), Monthly Notices of the Royal Astronomical Society (Accepted, in press), “Sensitivity of the Hydrogen Epoch of Reionization Array and its Build-out Stages to One-point Statistics from Redshifted 21 cm Observations” 2 of 14 13. Paul, S., Sethi, S. K., …Thyagarajan, N., et al. [54 authors], The Astrophysical Journal, 833, 213 (2016), “Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization” 14. Beardsley, A. P.,Hazelton, B. J., …Thyagarajan, N., et al. [66 authors], The Astrophysical Jour- nal, 833, 102 (2016), “First Season MWA EoR Power Spectrum Results at Redshift 7” 15. Neben, A., Bradley, R. F., …Thyagarajan, N., et al. [29 authors], The Astrophysical Journal, 826, 199 (2016), “The Hydrogen Epoch of Reionization Array Dish I: Beam Pattern Mea- surements and Science Implications” 16. Ewall-Wice, A., Bradley, R. F., …Thyagarajan, N., et al. [27 authors], The Astrophysical Jour- nal, 831, 196 (2016), “The HERA Dish II: Electromagnetic Simulations and Science Impli- cations” 17. Ewall-Wice, A., Dillon, J. S., …Thyagarajan, N., et al. [65 authors], Monthly Notices of the Royal Astronomical Society, 460, 4320 (2016), “First limits on the 21 cm power spectrum during the epoch of X-ray heating” 18. Lenc, E., Gaensler, B. M., …Thyagarajan, N., et al. [79 authors], The Astrophysical Journal, 830, 38 (2016), “Low frequency observations of linearly polarized structures in the interstellar medium near the south Galactic pole” 19. Carroll, P.,Line, J., …Thyagarajan, N., et al. [64 authors], The Monthly Notices of the Royal As- tronomical Society, 461, 4151 (2016), “A high reliability survey of discrete Epoch of Reion- ization foreground sources in the MWA EoR0 field” 20. Jacobs, D. C., Hazelton, B. J., …Thyagarajan, N., et al. [64 authors], The Astrophysical Journal, 825, 114 (2016), “The Murchison Widefield Array 21 cm Power Spectrum Analysis Method- ology” 21. Pober, J. C., Hazelton, B. J., …Thyagarajan, N., et al. [68 authors], The Astrophysical Journal, 819, 8 (2016), “The Importance of Widefield Foreground Removal for 21 cm Cosmology: A Demonstration with Early MWA Epoch of Reionization Observations” 22. Offringa, A. R., Trott, C. M., …Thyagarajan, N., et al. [41 authors], The Monthly Notices of the Royal Astronomical Society, 458, 1057 (2016), “Parametrising Epoch of Reionization fore- grounds: A deep survey of low-frequency point-source spectra with the MWA” 23. Trott, C. M., Pindor, B., …Thyagarajan, N., et al. [52 authors], The Astrophysical Journal, 818, 139 (2016), “CHIPS: The Cosmological HI Power Spectrum Estimator” 24. Dillon, J. S., Neben, A. R., …Thyagarajan, N., et al. [55 authors], Physical Review D, 91, 123011 (2015), “Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data” 25. Offringa, A. R., Wayth, R. B., …Thyagarajan, N., et al. [65 authors], Publications of the Astro- nomical Society of Australia, 32, 8 (2015), “The Low-Frequency Environment of the Murchi- son Widefield Array: Radio-Frequency Interference Analysis and Mitigation” Ph.D. Dissertation (2011): “Investigations in Time and of Space Using the FIRST Survey: Ra- dio Source Variability and the Evolution of FR II Quasars”, ProQuest Dissertations and Theses, Publication Number: AAT 3443779 Research Experience 3 of 14 2017 - Investigation of Novel and Alternate Approaches to Redshifted 21 cm Cosmology Present Collaborators: Prof. Chris L. Carilli (NRAO), Prof. Judd Bowman (ASU), Prof. Aaron Parsons (UC Berkeley), & HERA Collaboration Despite having theoretical sensitivity to make a high significance EoR detection, current EoR experiments using redshifted 21 cm observations at low frequencies such as MWA, PAPER, and LOFAR are severely limited by spectral systematics arising out of leakage from bright foregrounds, wide-field effects, reflections, non-redundancies and heterogeneous behavior among antennas, calibration errors, etc. I am investigating closure phase quan- tity as an alternate method to study spectral separability of the EoR signal and some of these systematics. Since closure quantities are independent of antenna-based calibration and calibration errors, they are immune to many of the aforementioned limitations. 2016 - Array Layout Specifications for HERA and SKA Present Collaborators: Prof. Judd Bowman (ASU), Prof. David DeBoer (UC Berkeley), Prof. Aaron Parsons (UC Berkeley), HERA & SKA Collaborations. Radio instruments have a lot of potential in this era of precision cosmology. Examples in- clude the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA). Construction of these arrays have already begun or will commence shortly. In- accuracies in layout will lead to loss of any assumed redundancy, baseline-dependent chromaticity, and significant mis-estimates and mis-subtraction of foreground contam- ination. Using Precision Radio Interferometry Simulator (PRISim), I am developing per- formance specifications
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