Research

1. Probing galaxy formation in the cosmic web

TBW (c.f. the JWST program links).

2. Galactic winds beyond the local universe

Galactic winds are the outflowing gas ejected from galaxies. They are considered to have a prominent impact on galaxy formation especially in the early Universe. However, much has yet to be known regarding the origins and physical properties of these winds.

My thesis research is motivated by one question: How and where do galactic winds occur within galaxies in the early Universe? I aim at answering the question using the spectroscopic data from a Keck observing program, HALO7D (PI: R. Guhathakurta, UC Santa Cruz), which includes around 200 $z \sim 1$ star-forming galaxies with deep exposures by the DEep Imaging Multi-Object Spectrograph (DEIMOS).

I led a case study of the cool phase of galactic winds from a massive star-forming galaxy at $z \sim 1$ (Wang et al. 2022). Our study indicates that the winds are most likely launched from a spatially extended area which includes both the inner and outer regions of the galaxy. We also find that spatially extended star formation is the most probable driver of the observed extended winds.

It might be common for the massive star-forming galaxies at $z \gtrsim 1$ to have winds launched from the entire galaxies. This is supported by a separate study, in which we find that spatially extended star formation is common among massive star-forming galaxies at $z \sim 1$ (Wang et al. 2017). Studying the winds of a larger sample of galaxies in the future will help us better understand where the stellar feedback is directly “in action” and what roles galactic winds play in the formation of galaxy bulges, disks, and metallicity gradients.

3. “Slitlet-Stepping”: a novel mode of spatially-resolved spectroscopic observations with JWST

I have been involved in a study to develop a novel observing mode for the JWST NIRSpec instrument. The mode, ‘‘Slitlet-Stepping’’, will enable spatially resolved spectroscopic observations of at least 30 galaxies simultaneously, by making use of the Mirco-Shutter Assembly on the NIRSpec. The mode is at least 10 times as efficient as the NIRSpec IFU mode which only targets at one galaxy at a single time. The high efficiency will open up great opportunities for large galaxy surveys with JWST in the near future.

I am currently co-leading an effort to implement this mode to the upcoming observations of our approved JWST program (PI: Susan Kassin), one of the largest General Observers programs in Cycle 1 for galaxy science.

4. The dust attenuation law for galaxies at $z\sim 1$

Accurate measurements of the galaxy star formation rates are essential for us to understand how galaxies form. However, a significant fraction of the star formation can be obscured by dust. The obscured star formation needs to be inferred indirectly by assuming a certain dust attenuation law if no far-infrared photometry is available, which is often the case for the galaxies observed at high redshifts.

In Wang et al. (2018), we find that the dust attenuation law is dependent on the galaxy inclination, which can lead to systematic errors up to 0.3 dex in the inferred star formation rates. By introducing an inclination correction, our study brings more accurate measurements of star formation rates at $z\sim 1$ and above. Details about this study can be found from my talk at the STScI/JHU Galaxy Journal Club.