# Astrophysics Seminar

### Polar Disks and Planets Around Eccentric Orbit Binaries

Misaligned disks in binaries were commonly thought to evolve to a coplanar
state. However, recent theory and observations have surprisingly shown that disks around
eccentric orbit binaries can evolve to a polar state in which the disk is...

### Towards an accurate cosmological measurements with optical clusters

Tomomi Sunayama

Galaxy clusters are the most massive gravitationally self-bound objects in the Universe. These clusters form at the rare high peaks of the primordial density fluctuations, and they subsequently trace the growth of structure in the Universe as they...

### Fireball in Fast Radio Bursts

Kunihito Ioka

Fast radio bursts (FRBs) are the brightest radio transients in the universe. Since the unexpected discovery in the 21st century, their extreme nature is one of the biggest mysteries of astrophysics. FRBs are also unique probes of the universe...

One of the strongest predictions of the standard cold dark matter paradigm is the hierarchy of structure down to Earth-mass scales.  However, individual self-bound clumps of dark matter--"halos"--are difficult to detect directly.  Instead, we use...

### From Panchromatic Images to Stellar Ages and Beyond

Joshua Speagle

Large-area surveys such as Gaia have given us an unprecedented amount of data on stars in the Milky Way. One of the largest ongoing challenges in understanding the present-day structure and formation history of our Galaxy (i.e. Galactic archaeology)...

### Genesis, dynamics, and dissipation of turbulent magnetic fields

Astronomical observations indicate that coherent, dynamically important magnetic fields are ubiquitous in the Universe. However, neither the origin problem -- what are the physical mechanisms that generate the initial seed'' magnetic fields —- nor...

### Pushing the frontiers of gravitational encounters and collisionless dynamics

Uddipan Banik

Gravity plays the central role in structure formation and evolution in astronomical scales. Despite the apparently simple inverse square law for the gravitational force in the non-relativistic regime, the dynamics of self-gravitating many-body...

### Stellar Basins

I will describe the phenomenology of stellar basins: volumetric stellar emission into gravitationally bound orbits of weakly coupled particles such as axions, moduli, hidden photons, and fermions. While only a tiny fraction of the instantaneous...

### Lessons from Astrophysical Models of Sgr A* and the Event Horizon Telescope

The Event Horizon Telescope (EHT) collaboration has recently published the first image of the near-horizon region around the supermassive black hole at the center of our Milky Way galaxy, Sgr A*. In addition to providing new constraints on general...