Overview

The general topic of my research is to explore what we can learn about the nature of dark matter (DM) from the first stars, black holes, and galaxies formed during the Epoch of Reionization and Cosmic Dawn (redshift 5-30), which can be more sensitive to DM physics on small scales (< kpc) than their present-day counterparts. The basic idea is to make theoretical predictions on the observational signatures of early star/galaxy/structure formation in different candidate DM models, which, combined with current observations, can place new constraints on DM models, and also provide guidance for future observations/experiments designed to shed light on the nature of DM. The major challenges arise from the potential degeneracy between DM and baryonic physics, as well as uncertainties in theoretical models of baryonic processes at Cosmic Dawn, such as star formation (e.g., mass distribution and multiplicity), stellar evolution and feedback (e.g., rotation, winds, supernovae, and binary interactions). In light of this, I work generally in three directions:

• Improve modelling of baryonic physics during early star/galaxy/structure formation 

• Explore new probes of Cosmic Dawn and correlations between probes that may break the degeneracy between DM and baryonic physics

• Implement DM and baryonic physics self-consistently in simulations and semi-analytical models to predict the unique effects and observational signatures of DM at Cosmic Dawn

In a word, the goal is to make robust and self-consistent theoretical predictions for the "most useful" probes of Cosmic Dawn. This is a challenging and fascinating task given the rich physics and phenomena (see the "roadmap" below) involved across a broad range of scales (from < AU to > Mpc). 

My recent work focuses on star clusters and (binaries of) massive stars at Cosmic Dawn as progenitors of X-ray binaries, compact object mergers, and massive black hole seeds, and sources of stellar feedback (e.g., winds, ionization, supernova explosion and metal enrichment), which are expected to have unique observational signatures in terms of gravitational waves, spectra of high-z galaxies and AGN, and the 21-cm signal and reionization. I have also been investigating the effects of primordial black holes on early star/galaxy/structure formation, motivated by gravitational wave observations of massive binary black hole mergers and the detection of extraordinarily massive, old galaxies and overmassive black holes by JWST. 

My research topics are grouped into 4 themes below (linked to individual pages with more detailed information). You can visit the Recent page for my most recent results and check this ads page to see a list of my publications (19 as 1st author, h-index=17). 

Compact object mergers and X-ray binaries at Cosmic Dawn

Clusters and binaries of the first stars

Probes of early star formation

Early structure/star formation in different dark matter models