Ue-Li Pen

Ue-Li Pen profile picture
Academia Sinica
Research Associate Faculty
Areas of research:
Cosmology
(519) 569-7600 x6282
If you are interested in pursuing a MSc degree, please apply to the Perimeter Scholars International (PSI) masters program. If you are interested in working with me as a PhD student, please send me an email at [email protected] or submit an application directly to my department at the University of Toronto and indicate that you would like to be supervised by me. Perimeter Institute is committed to diversity within its community and I welcome applications from underrepresented groups.
In the modern era where much of astrophysics operates in giant collaborations (e.g. CMB-S4, LIGO, EHT), my niche has been to explore short term innovative initiatives with large growth potential. 21cm cosmology is such an example, where I initiated the CHIME telescope in Canada, whose advantage in survey speed has changed the FRB field This exciting new development is leading to large samples of coherent light sources, essentially lasers at cosmological distances, which probe space-time with a strain h~10^{-26}, the most precise probe available. New theoretical developments arose, including application of Picard-Lefschetz theory to address the wave optics path integrals, represented in a series of papers with Turok, Feldbrugge, Foreman, Jow and others. Cosmological opportunity lies in the smallest scales, with discovery space due to the large number of observable modes. Recently, we developed a theory of directed angular momentum, using the signed orientation of the galaxy on the sky as classified by spiral winding in the citizen-science galaxy zoo. This opens the potential to probe early helicity and non-Gaussianity, far beyond current constraints.
  • Director, Academia Sinica Institute of Astronomy & Astrophysics, 2021 Fall
  • Director, CITA, 2016-2019
  • Professor, CITA, 2011-Present
  • Associate Professor, CITA, 2003-2011
  • Assistant Professor, CITA, 1998-2003
  • Junior Fellow, Harvard University, 1995-1998
  • Lancelot Berkeley Prize (Shared)
  • Governor-General"s Innovation Awards (2020) (shared with the CHIME collaboration)
  • 1/347 share of EHT breakthrough prize
  • Simons Research Award (deferred from 2019 due to admin duties).
  • Humboldt Research Award - Alexander von Humboldt-Stiftung - 89,603, Humboldt Foundation, Prize / Award, The award is valued at euro 60,000.
  • Chime/Frb Collaboration, A., Bridget C., Bandura, K., Bhardwaj, M., Boyle, P. J., Brar, C., Breitman, D., Cassanelli, T., Chatterjee, S., Chawla, P., Cliche, J.-F., Cubranic, D., Curtin, A. P., Deng, M., Dobbs, M., Dong, F. A., Fonseca, E., Gaensler, B. M., Giri, U., Good, D. C., . . . Zwaniga, A. (2022). Sub-second periodicity in a fast radio burst. Nature, 607, 256-259. https://doi.org/10.1038/s41586-022-04841-8
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . Zhao, S.-S. (2022). First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric. The Astrophysical Journal, 930, L17. https://doi.org/10.3847/2041-8213/ac6756
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Carlos Algaba, J., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . White, C. (2022). First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole. The Astrophysical Journal, 930, L16. https://doi.org/10.3847/2041-8213/ac6672
  • Farah, J., Galison, P., Akiyama, K., Bouman, K. L., Bower, G. C., Chael, A., Fuentes, A., Gómez, J. L., Honma, M., Johnson, M. D., Kofuji, Y., Marrone, D. P., Moriyama, K., Narayan, R., Pesce, D. W., Tiede, P., Wielgus, M., Zhao, G.-Y., Alberdi, A., . . . Collaboration, E. H. T. (2022). Selective Dynamical Imaging of Interferometric Data. The Astrophysical Journal, 930, L18. https://doi.org/10.3847/2041-8213/ac6615
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . Zeballos, M. (2022). First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way. The Astrophysical Journal, 930, L12. https://doi.org/10.3847/2041-8213/ac667410.3847/2041-8213/ac667510.3847/2041-8213/ac6429
  • Wielgus, M., Marchili, N., Martí-Vidal, I., Keating, G. K., Ramakrishnan, V., Tiede, P., Fomalont, E., Issaoun, S., Neilsen, J., Nowak, M. A., Blackburn, L., Gammie, C. F., Goddi, C., Haggard, D., Lee, D., Moscibrodzka, M., Tetarenko, A. J., Bower, G. C., Chan, C.-k., . . . Zhao, S.-S. (2022). Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign. The Astrophysical Journal, 930, L19. https://doi.org/10.3847/2041-8213/ac6428
  • Georgiev, B., Pesce, D. W., Broderick, A. E., Wong, G. N., Dhruv, V., Wielgus, M., Gammie, C. F., Chan, C.-k., Chatterjee, K., Emami, R., Mizuno, Y., Gold, R., Fromm, C. M., Ricarte, A., Yoon, D., Joshi, A. V., Prather, B., Cruz-Osorio, A., Johnson, M. D., . . . Zhao, S.-S. (2022). A Universal Power-law Prescription for Variability from Synthetic Images of Black Hole Accretion Flows. The Astrophysical Journal, 930, L20. https://doi.org/10.3847/2041-8213/ac65eb
  • Broderick, A. E., Gold, R., Georgiev, B., Pesce, D. W., Tiede, P., Ni, C., Moriyama, K., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., . . . Zhao, S.-S. (2022). Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI. The Astrophysical Journal, 930, L21. https://doi.org/10.3847/2041-8213/ac6584
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . Wouterloot, J. G. A. (2022). First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration. The Astrophysical Journal, 930, L13. https://doi.org/10.3847/2041-8213/ac6675
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . Zhao, S.-S. (2022). First Sagittarius A* Event Horizon Telescope Results. III. Imaging of the Galactic Center Supermassive Black Hole. The Astrophysical Journal, 930, L14. https://doi.org/10.3847/2041-8213/ac6429
  • Collaboration, E. H. T., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Bach, U., Baczko, A.-K., Ball, D., Baloković, M., Barrett, J., Bauböck, M., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Bouman, K. L., . . . Chang, D. O. (2022). First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass. The Astrophysical Journal, 930, L15. https://doi.org/10.3847/2041-8213/ac667410.3847/2041-8213/ac667210.3847/2041-8213/ac6736
  • Motloch, P., Pen, U.-L., & Yu, H.-R. (2022). Correlating galaxy shapes and initial conditions: An observational study. Physical Review D, 105, 083504. https://doi.org/10.1103/PhysRevD.105.083504
  • Motloch, P., Pen, U.-L., & Yu, H.-R. (2022). Observational search for primordial chirality violations using galaxy angular momenta. Physical Review D, 105, 083512. https://doi.org/10.1103/PhysRevD.105.083512
  • Zhu, H.-M., Mao, T.-X., & Pen, U.-L. (2022). Cosmic Tidal Reconstruction with Halo Fields. The Astrophysical Journal, 929, 5. https://doi.org/10.3847/1538-4357/ac5a47
  • Baker, D., Brisken, W., van Kerkwijk, M. H., Main, R., Pen, U.-L., Sprenger, T., & Wucknitz, O. (2022). Interstellar interferometry: precise curvature measurement from pulsar secondary spectra. Monthly Notices of the Royal Astronomical Society, 510, 4573-4581. https://doi.org/10.1093/mnras/stab3599
  • Wolz, L., Pourtsidou, A., Masui, K. W., Chang, T.-C., Bautista, J. E., Müller, E.-M., Avila, S., Bacon, D., Percival, W. J., Cunnington, S., Anderson, C., Chen, X., Kneib, J.-P., Li, Y.-C., Liao, Y.-W., Pen, U.-L., Peterson, J. B., Rossi, G., Schneider, D. P., . . . Zhao, G.-B. (2022). H I constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps. Monthly Notices of the Royal Astronomical Society, 510, 3495-3511. https://doi.org/10.1093/mnras/stab3621
  • Cassanelli, T., Leung, C., Rahman, M., Vanderlinde, K., Mena-Parra, J., Cary, S., Masui, K. W., Luo, J., Lin, H.-H., Bij, A., Gill, A., Baker, D., Bandura, K., Berger, S., Boyle, P. J., Brar, C., Chatterjee, S., Cubranic, D., Dobbs, M., . . . Tendulkar, S. P. (2022). Localizing FRBs through VLBI with the Algonquin Radio Observatory 10 m Telescope. The Astronomical Journal, 163, 65. https://doi.org/10.3847/1538-3881/ac3d2f
  • WKirsten, F., Marcote, B., Nimmo, K., Hessels, J. W. T., Bhardwaj, M., Tendulkar, S. P., Keimpema, A., Yang, J., Snelders, M. P., Scholz, P., Pearlman, A. B., Law, C. J., Peters, W. M., Giroletti, M., Paragi, Z., Bassa, C., Hewitt, D. M., Bach, U., Bezrukovs, V., . . . Vlemmings, W. (2022). A repeating fast radio burst source in a globular cluster. Nature, 602, 585-589. https://doi.org/10.1038/s41586-021-04354-w
  • Satapathy, K., Psaltis, D., Özel, F., Medeiros, L., Dougall, S. T., Chan, C.-K., Wielgus, M., Prather, B. S., Wong, G. N., Gammie, C. F., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Baczko, A.-K., Ball, D., . . . Zhao, S.-S. (2022). The Variability of the Black Hole Image in M87 at the Dynamical Timescale. The Astrophysical Journal, 925, 13. https://doi.org/10.3847/1538-4357/ac332e
  • Marthi, V. R., Bethapudi, S., Main, R. A., Lin, H.-H., Spitler, L. G., Wharton, R. S., Li, D. Z., Gautam, T., Pen, U.-L., & Hilmarsson, G. H. (2022). Burst properties of the highly active FRB20201124A using uGMRT. Monthly Notices of the Royal Astronomical Society, 509, 2209-2219. https://doi.org/10.1093/mnras/stab3067
  • Collaboration, C. F., Amiri, M., Andersen, B. C., Bandura, K., Berger, S., Bhardwaj, M., Boyce, M. M., Boyle, P. J., Brar, C., Breitman, D., Cassanelli, T., Chawla, P., Chen, T., Cliche, J.-F., Cook, A., Cubranic, D., Curtin, A. P., Deng, M., Dobbs, M., . . . Zwaniga, A. V. (2021). The First CHIME/FRB Fast Radio Burst Catalog. The Astrophysical Journal Supplement Series, 257, 59. https://doi.org/10.3847/1538-4365/ac33ab
  • Jow, D. L., Lin, F. X., Tyhurst, E., & Pen, U.-L. (2021). Imaginary images and Stokes phenomena in the weak plasma lensing of coherent sources. Monthly Notices of the Royal Astronomical Society, 507, 5390-5402. https://doi.org/10.1093/mnras/stab2337
  • Lin, F. X., Lin, H.-H., Luo, J., Main, R., McKee, J., Pen, U.-L., Simard, D., & van Kerkwijk, M. H. (2021). Profile changes associated with dispersion measure events in PSR J1713+0747. Monthly Notices of the Royal Astronomical Society, 508, 1115-1127. https://doi.org/10.1093/mnras/stab2529
  • Bij, A., Lin, H.-H., Li, D., van Kerkwijk, M. H., Pen, U.-L., Lu, W., Main, R., Peterson, J. B., Quine, B., & Vanderlinde, K. (2021). Kinematics of Crab Giant Pulses. The Astrophysical Journal, 920, 38. https://doi.org/10.3847/1538-4357/ac1589
  • Marthi, V. R., Simard, D., Main, R. A., Pen, U.-L., van Kerkwijk, M. H., Vanderlinde, K., Gupta, Y., Roberts, C., & Quine, B. M. (2021). Scintillation of PSR B1508+55 - the view from a 10 000-km baseline. Monthly Notices of the Royal Astronomical Society, 506, 5160-5169. https://doi.org/10.1093/mnras/stab1970
  • Switzer, E. R., Barrentine, E. M., Cataldo, G., Essinger-Hileman, T., Ade, P. A. R., Anderson, C. J., Barlis, A., Beeman, J., Bellis, N., Bolatto, A. D., Breysse, P. C., Bulcha, B. T., Chevres-Fernanadez, L.-R., Cho, C., Connors, J. A., Ehsan, N., Glenn, J., Golec, J., Hays-Wehle, J. P., . . . Yung, L. Y. A. (2021). Experiment for cryogenic large-aperture intensity mapping: instrument design. Journal of Astronomical Telescopes, Instruments, and Systems, 7, 044004. https://doi.org/10.1117/1.Jatis.7.4.044004
  • Hong-Ming Zhu, Tian-Xiang Mao, Ue-Li Pen(2021).Cosmic Tidal Reconstruction with Halo Fields.arXiv: 2108.01575
  • VR Marthi, S Bethapudi, RA Main, H-H Lin, LG Spitler, RS Wharton, DZ Li, TG Gautam, U-L Pen, GH Hilmarsson.(2021). Burst properties of the highly active FRB 20201124A using uGMRT.arXiv: 2108.00697
  • Tomas Cassanelli, Calvin Leung, Mubdi Rahman, Keith Vanderlinde, Juan Mena-Parra, Savannah Cary, Kiyoshi W Masui, Jing Luo, Hsiu-Hsien Lin, Akanksha Bij, Ajay Gill, Daniel Baker, Kevin Bandura, Sabrina Berger, Patrick J Boyle, Charanjot Brar, Shami Chatterjee, Davor Cubranic, Matt Dobbs, Emmanuel Fonseca, Deborah C Good, Jane F Kaczmarek, Victoria K Kaspi, Thomas L Landecker, Adam E Lanman, Dongzi Z Li, James W MacKee, Bradley W Meyers, Daniele Michilli, Arun Naidu, Cherry Ng, Chitrang Patel, Aaron B Pearlman, Ue-Li P Pen, Ziggy Pleunis, Brendan Quine, Andre Renard, Pranav Sanghavi, Kendrick M Smith, Ingrid Stairs, Shriharsh P Tendulkar.(2021). Localizing FRBs through VLBI with the Algonquin Radio Observatory 10-m Telescope. arXiv: 2107.05659
  • FRB Collaboration.(2021). Sub-second periodicity in a fast radio burst. arXiv: 2107.08463
  • Artem Tuntsov, Ue-Li Pen, Mark Walker.(2021). Down-drifting, bandwidth and beaming of fast radio bursts. arXiv: 2107.13549
  • FRB Collaboration.(2021). The First CHIME/FRB Fast Radio Burst Catalog. arXiv: 2106.04352.
  • F Kirsten, B Marcote, K Nimmo, JWT Hessels, M Bhardwaj, SP Tendulkar, A Keimpema, J Yang, MP Snelders, P Scholz, AB Pearlman, CJ Law, WM Peters, M Giroletti, DM Hewitt, U Bach, V Bezukovs, M Burgay, ST Buttaccio, JE Conway, A Corongiu, R Feiler, O Forssén, MP Gawroński, R Karuppusamy, MA Kharinov, M Lindqvist, G Maccaferri, A Melnikov, OS Ould-Boukattine, Z Paragi, A Possenti, G Surcis, N Wang, J Yuan, K Aggarwal, R Anna-Thomas, GC Bower, R Blaauw, S Burke-Spolaor, T Cassanelli, TE Clarke, E Fonseca, BM Gaensler, A Gopinath, VM Kaspi, N Kassim, TJW Lazio, C Leung, D Li, HH Lin, KW Masui, R Mckinven, D Michilli, A Mikhailov, C Ng, A Orbidans, UL Pen, E Petroff, M Rahman, SM Ransom, K Shin, KM Smith, IH Stairs, W Vlemmings.(2021). A repeating fast radio burst source in a globular cluster. arXiv: 2105.11445
  • Akanksha Bij, Hsiu-Hsien Lin, Dongzi Li, Marten H van Kerkwijk, Ue-Li Pen, Wenbin Lu, Robert Main, Jeffrey B Peterson, Brendan Quine, Keith Vanderlinde.(2021). Kinematics of Crab Giant Pulses. arXiv: 2105.08851
  • Laura Wolz, Alkistis Pourtsidou, Kiyoshi W Masui, Tzu-Ching Chang, Julian E Bautista, Eva-Maria Müller, Santiago Avila, David Bacon, Will J Percival, Steven Cunnington, Chris Anderson, Xuelei Chen, Jean-Paul Kneib, Yi-Chao Li, Yu-Wei Liao, Ue-Li Pen, Jeffrey B Peterson, Graziano Rossi, Donald P Schneider, Jaswant Yadav, Gong-Bo Zhao.(2021). HI constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps. arXiv: 2102.04946
  • Daniel Baker, Walter Brisken, Marten H van Kerkwijk, Robert Main, Ue-Li Pen, Tim Sprenger, Olaf Wucknitz.(2021). Interstellar Interferometry: Precise Curvature Measurement from Pulsar Secondary Spectra. arXiv: 2101.04646.
  • Giuseppe Cataldo, Peter AR Ade, Christopher J Anderson, Alyssa Barlis, Emily M Barrentine, Nicholas G Bellis,et al. (2020) Overview and status of EXCLAIM, the experiment for cryogenic large-aperture intensity mapping. International Society for Optics and Photonics. Volume 11453, Page 114530H
  • Pen, Ue-Li. (2020). Nonlinear Reconstruction: the Cosmic Web Inside Out. the Lorentz Center workshop. Leiden University, Netherlands. Lorentz Center.
  • Luo, J.; Pen, U.; Van Kerkwijk, M.; Demorest, P.; Main, R. (2020). Is the Black Widow Pulsar Eclipsed by its Companion?. Bulletin of the American Astronomical Society. 235th American Astronomical Society meeting, Honolulu, United States. American Astronomical Society.
  • Pen. Ue-Li. (2019). The CHIME Telescope. Arecibo IPS Workshop. Puerto Rico.
  • Pen. Ue-Li. (2019). Cosmology and fundamental physics with FRBs. Cosmological Frontiers in Fundamental Physics 2019. Waterloo, Canada. Perimeter Institute.
  • Pen. Ue-Li. (2019). Synergy of Plasma Lensing and Gravitational Lensing. Gravity meets Plasma workshop. South-Western Institute for Astronomy Research, China.
  • Pen. Ue-Li. (2019). Interstellar Scintillation Theory and Experimentation: the Potential of 1-D Scintillation Screens in the Interstellar Medium. Scintillating Science: Cutting-Edge Science Achieved Through the Observations of Radio Scintillation Conference. South Africa National Space Agency , South Africa.
  • Pen. Ue-Li. (2019). 21cm intensity mapping: current results and future potential. Future of Canadian Radio Astronomy Workshop. the Dominion Radio Astrophysical Observatory, British Columbia, Canada.
  • Ue-Li Pen(2022)"BURSTT: Taiwan all sky FRB survey" , IAU-369 New projects talk
  • Ue-Li Pen(2022)"Probing the universe with Fast Radio Bursts", Canadian Institute for Theoretical Astrophysics(CITA)
  • Ue-Li, Pen (2022)"From GRBs, Baryogenesis to FRBs", Astrophysics in the Next Decade: From the First Stars to Intelligent Life(CIERA conference)
  • Ue-Li, Pen (2022)"Turok-Witten-Picard-Lefschetz quantum mechanics and quantum gravity"National Taiwan University. April 11, 2022
  • Ue-Li, Pen (2022) "Classical Mechanics, Quantum Mechanics, Quantum Cosmology: How the universe may have begun" National Yang Ming Chiao Tung University. March 3, 2022
  • Ue-Li, Pen (2022) "Classical Mechanics, Quantum Mechanics, Quantum Cosmology: new view on the universe" National Changhua University of Education.
  • Ue-Li, Pen (2022) "FRB Physics". National Central University.
  • Ue-Li, Pen(2022). "Why do spiral galaxies rotate, and what can we learn from that?". Astronomy on Tap. Taipei, Taiwan. Jan 21, 2022. 22 minutes.
  • Ue-Li, Pen(2022). "Classical and quantum completeness of transient black hole space times". National Taiwan University, Taipei, Taiwan
  • Ue-Li Pen(2021). "Picard-Lefschetz Path Integrals for astrophysical lensing: imaging stars, planets and dark matter". National Taiwan University, Taipei, Taiwan.
  • Ue-Li, Pen(2021). "Broadbeam Radio Survey Telescope (BRST)". Science at Low Frequencies(SALF)
  • Ue-Li, Pen(2021). "FRB Physics". National Taiwan Normal University, Taipei, Taiwan.
  • Ue-Li, Pen (2021). "FRBs: Coherent probes of space-time". FRB 2021(Virtual), International Conference.
  • Ue-Li, Pen (2021). "FRBs: Coherent probes of space-time".CITA, Toronto, Canada.
  • "the Stockert Radioteleskop upgrade". Dunlap Institute for Astronomy and Astrophysics, University of Toronto. Toronto, Canada. Apr., 20. 20 mins.