Research

Binary Black Hole

BBHs are of interest for multiple topics in astrophysics ranging from the detection of gravitational waves to galaxy evolution and cosmology. While the formation of massive BBHs from galaxy mergers is almost inevitable, direct evidence remains uncertain. We develop new techniques to identify BBHs on different scales across the universe. For more info, check out papers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14.


Black Hole Feedback

Black holes may play a key role in shaping the galaxies in which we live. Theory of galaxy formation and evolution invokes black hole “feedback” to reproduce the observed galaxy properties. However, the physics of feedback remains poorly understood. We solve these puzzles using observations of AGN host galaxies. For more info, see papers 1, 2, 3, 4, 5, 6.


Black Hole Seed

How exactly the seeds of supermassive black holes formed is still unknown. Observations of small black holes in low-mass galaxies hold important clues to the answer of seed formation. However, small black holes are difficult to find particularly in low-mass galaxies where star formation tends to wash out the ionizational fingerprints of accreting black holes. We circumvent the problem using accretion variability recorded by the highly sensitive multi-epoch imaging from the Dark Energy Survey. Stay tuned for more updates!


Black Hole Tide

When stars wander too close to a black hole, tides break them apart producing luminous flares. Observations of these flares tell us about properties of the black holes. We develop new techniques to identify such tidal disruption events through their astrochemical fingerprints. For more info, see paper here.


Machine Learning Black Hole

Measuring black hole mass is critical for many areas of astrophysical research from cosmology to galaxy evolution. We know about half a million black holes with a mass measured by traditional approaches using spectroscopic observations, representing decades of state-of-the-art community efforts. However, LSST will discover ~a billion new black holes, for the majority of which spectroscopic observations will not be practical. We are building deep learning algorithms to seek out an alternative way for estimating black hole mass using only the accretion disk time series. Stay tuned for more updates!


Fundamental Physics

Lying at the intersection of physics and astronomy, black holes provide an ideal laboratory to study some of the most fundamental questions regarding the physical laws of the universe. One test of Einstein’s General Relativity is gravitational redshift. AGN broad emission lines arise from a region close to the black hole where gas is photo-ionized. The proximity of the broad line region to the black hole causes significant special- and general-relativistic effects on the emission lines.  For more info, see paper.


Exoplanets, Baby Galaxies, and the Cosmic Microwave Background

Our work extends to planets outside our Solar System, distant galaxies in the early universe, and thermal relics from the Big Bang. Check out our papers on exoplanet atmosphere and structure evolution (1, 2, 3), chemical abundances and physical conditions in high-redshift galaxies (paper), and statistical properties of the cosmic microwave background (1, 2).