Astrophysics Seminars

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...

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)...

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...

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...

Our understanding of astrophysical black holes is predicated on the Kerr solution to Einstein’s equations. A promising avenue for testing the Kerr hypothesis is to detect the shadow a black hole casts on the surrounding emission and compare its size...

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...

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...

Following the collision of two compact objects, an accretion disk forms and from it matter is ejected that sources the universe's heavy elements and that is observable as a kilonova. The amount of ejecta, the types of elements that form, and the...

Close binaries are the origin of many extraordinary events in the Universe, including type Ia supernovae and gravitational wave events. On the other extreme, wide binaries are easily disrupted by gravitational perturbations, making them a unique...

The identity of dark matter remains a mystery, despite decades of theorizing and detection efforts. This includes the mechanism for its primordial production, its interactions with itself or with visible matter, and the very nature of dark matter...