IAS/PU Joint Astrophysics Colloquium

The Continuing Search for Planet Nine

Matthew Holman
Harvard-Smithsonian Center for Astrophysics
October 15, 2019

Several lines of evidence, both theoretical and observational, indicate that additional planets in the outer solar system remain to be discovered.  Most recently, attention has been focused on 'Planet Nine',a few Earth mass planet with a moderate inclination at a distance of a few hundred AU (Trujillo & Sheppard 2014, Batygin & Brown 2016, Brown & Batygin 2016).  I will review this evidence for the existence of this body and will present a variety of approaches that are being used to find it.

Kinematics of Circumgalactic Gas

Crystal Martin
University of California, Santa Barbara
November 27, 2018

Most of the baryons associated with galaxy halos reside in the
circumgalactic medium. A significant fraction of the mass is at
temperatures well below the halo virial temperature.  What holds
the cool CGM up?  I will present new measurements of the kinematics
of circumgalactic gas.  The data show that much of the low-ionization
CGM rotates in the same direction as the galactic disk, suggesting
substantial centrifugal support.  Disturbances from galactic winds

New Results in Tests of Gravity with Radio Pulsars

Michael Kramer
Max Planck Institute for Radio Astronomy
October 23, 2018

We are living in a golden era for testing gravitational physics with precision experiments. This talk will present new results using a variety of tests with radio pulsars. These results will be placed in context of other experiments (including LIGO, EHT etc), and I will demonstrate how pulsars continue to provide unique constraints on gravity and fundamental physics in general, and how they complement other methods.