Pinchen Fan

Research

I work on several radio and laser SETI projects that are supported via a NASA Exoplanet Research Program grant (Science PI: Pinchen Fan, Admin PI: Jason Wright):

  1. I characterized the patterns of NASA’s Deep Space Network (Fan et al., 2025 ApJL 990 L1), and found that our deep-space transmissions were more frequent during Earth-Sun conjunctions, along the ecliptic plane, and during conjunctions of Earth and another solar system planet.
  2. I am developing a laser search pipeline to look for laser emissions from planet-hosting M-dwarfs. We use stellar spectra taken with the Habitable-Zone Planet Finder on the 10-meter Hobby-Eberly Telescope.
  3. I will search for radio transmissions from 1) non-transitting exoplanets during planet-star conjunctions and 2) transiting exoplanets at random times and/or during planet-star or planet-planet conjunctions.

Selected Publications

Please see my CV or my NASA ADS Library for the complete list of publications.

Pinchen Fan and Jason T. Wright and T. Joseph W. Lazio, Detecting Extraterrestrial Civilizations That Employ an Earth-level Deep Space Network, The Astrophysical Journal Letters, 990, L1 (2025)

We analyzed the transmission logs of NASA’s Deep Space Network (DSN) over the last 20 years (2005-2025). We found that an external observer would see DSN transmissions more frequently, compared to the average transmission duty cycle, when they observe around Earth-Sun conjunctions (4x the average), if the solar system is edge-on (transiting system) in their line of sight (20x the average), or if they look when one of the solar system planet is behind another (400,000x the average in the Earth-Mars case). Thus, radio and laser SETI should prioritize transiting systems and search during planet-star or planet-planet conjuctions.

Sofia Z Sheikh, Macy J Huston, Pinchen Fan, Jason T Wright, Thomas Beatty, Connor Martini, Ravi Kopparapu, Adam Frank, Earth Detecting Earth: At What Distance Could Earth’s Constellation of Technosignatures Be Detected with Present-day Technology?, The Astronomical Journal, 169, 118 (2025)

We calulated the detectability of various present-day Earth technosignatures using only humanity’s state-of-the-art detectors. We found that, although infrequent celestially targeted radio transmissions using humanity’s largest antenna were still the most detectable technosignature, constant transmissions between ground stations and deep-space spacecraft could be detected across interstellar ditances.

Anarya Ray, Pinchen Fan, Vincent F. He, Malachy Bloom, Suyu Michael Yang, Jay D. Tasson, Jolien D. E. Creighton, Measuring Gravitational Wave Speed and Lorentz Violation with the First Three Gravitational-Wave Catalogs, Physical Review D, 110, 12 (2024)

We used LIGO O3 gravitational-wave (GW) data to measure the speed of GWs. We showed that the 90% credible interval of the speed of GWs included the speed of light. We then used the data to simultaneously measure the nine coeffieints for Lorentz violation in the nondispersive, nonbirefringent limit of the gravitational section of the Standard Model Extension. The 90% credible intervals for all nine coefficients were consistent with zero. These results showed no violation of general relavitity.

Muhammed Saleem et al. (including Pinchen Fan), Demonstration of Machine Learning-assisted real-time noise regression in gravitational wave detectors, Classical and Quantum Gravity, 41, 19 (2024)

We used machine learning to reduce the noise levels in the LIGO gravitational-wave (GW) detectors in real-time by accounting for various instrumental noise and powerline noise around 60 Hz. I used GstLAL, a low-latency GW search pipeline, to evaluate the performance of the algorithm. With a latency of 1-2 seconds, our pipeline enhances the signal-to-noise ratio of potential events without doing any harm to underlying astrophysical events.

Selected Media Coverage