Wu Po-Feng 吳柏鋒
Assistant Professor
Graduate Institute of Astrophysics, National Taiwan University
Email: wupofeng [at] phys.ntu.edu.tw
I am an assistant professor in the Graduate Institute of Astrophysics at National Taiwan University.
My research fields is galaxy evolution, especially with large extra-galactic survey.
Research
Quenching of star formation across cosmic time
My research focuses on a fundamental question in astrophysics: how do galaxies stop forming stars? I am especially interested in the mechanisms driving a rapid transformation. This process, known as “quenching,” is a critical step in galaxy evolution. I use multi-wavelength imaging and spectroscopic data (e.g., VLT, HST, JWST, and ALMA) to investigate the interplay between galaxy's structure, formation histories, gas content, and central supermassive black hole in shutting down star formation from the local universe to the epoch of formation of first massive quiescent galaxies.
On-going Projects
LEGA-C survey
The Large Early Galaxy Census (LEGA-C) is a Public Spectroscopic Survey of ~3000 K-band selected galaxies at redshifts z = 0.6 − 1.0 with stellar masses log(M/Msun) > 10, an 128-night survey conducted with VIMOS on ESO’s Very Large Telescope. Each galaxy receives 20-hour long integration time in order to acheive a signal-to-noise ratio comparable to SDSS spectra in the nearby Universe.
These deep, high-resolution slit spectra provide very detailed data of stellar continua for galaxies ~7 Gyrs ago and are able to characterize fundamental properties of stellar populations: stellar ages, metallicities, stellar velocity dispersion, dynamical masses, as well as stellar rotation. These are keys for the study of galaxy evolution, but so far only available for representative galaxy samples in the nearby universe, at lookback time approximately 1 Gyr. The survey stretches the baseline in cosmic time, allows us to study how galaxies evolve through the 2nd half of the Universe.
Prime Focus Spectrograph Galaxy Evolution survey
The Prime Focus Spectrograph (PFS) on the Subaru Telescope is a next-generation survey instrument. It uses 2,400 fibers to simultaneously capture spectra from numerous objects over a wide field of 1.3 square degree. Its extensive spectral coverage, spanning visible to near-infrared light (380 nm to 1260 nm), enables groundbreaking studies in galaxy evolution, cosmology, and dark energy.
Starting from Year 2025, the consortium starts a 360-night, 5-year survey project. I involve in the Galaxy Evolution component, a major undertaking to create a comprehensive census of galaxy growth. It will chart the development of galaxies across a vast cosmic timeline, from the era of reionization (z∼7) to the peak of cosmic star formation (z∼2) and the main epoch of the massive quiescent galaxy formation (z<1). By observing hundreds of thousands of galaxies, the survey will trace the assembly of stellar mass and the influence of the cosmic web on how galaxies form and mature.
Recent work
Ejective Feedback in the early Universe
The emergence of massive quiescent galaxies in the first billion years of the Universe is a puzzle. How galaxies can grow so fast and rapidly stop growing? Using spectra taken by the James Webb Space Telescope, I reveal a massive gas flow escaping from a massive galaxy at redshift z=4, when the Universe was only 1.5 billion year-old. This discovery suggests that "ejective feedback" is at work to help suppresing the growth of galaxies in the early Universe.
This work is published in Wu 2025, ApJ, 978, 131.
Article: phys.org.