The Physics Department Astrophysics Seminar is held at
**1:45pm on Wednesdays** in Room 2165 of the New Physics Building.

**September 6:** Shun-Pei Miao (NCKU)

**Title: ** Electrodynamic Effects of Inflationary Gravitons

**Abstract: ** I begin by describing the origin of big IR effects during primordial inflation. I then review a series of works on EM + GR
from flat space to de Sitter, commenting in particular on the issue of gauge dependence. Finally, I make a conjecture for resolving the issue,
and present the latest work which has been done to test this conjecture.

**September 27:** *Special Event: Academic Jobs Panel*

**October 4:** Richard Woodard (UF Physics)

**Title: ** MOND Cosmology

**Abstract: ** MOND is a phenomenological model which modifies the extreme weak field regime of Newtonian gravity so as to explain galactic rotation curves without dark matter. If correct, it must be the non-relativistic, static limit of some relativistic modified gravity theory.
I show how the only possible metric-based modification of gravity is nonlocal, and I construct the action using the Tully-Fisher relation and
weak lensing. Then I explore the consequences of this model for cosmology. This talk is based on three arXiv papers: 1106.4984, 1405.0393
and 1608.07858.

**October 11:** Adrian Hamers (IAS)

**Title: ** Dynamics around supermassive black holes: from mpc to kpc

**Abstract: ** We consider orbital dynamics at various scales around supermassive black holes (MBHs) with masses comparable to the MBH in the Milky Way Galactic Center (GC). First, we address the relativistic regime within a few mpc from the MBH. In this regime, orbital diffusion is affected by relativistic precession which has implications for the evolution of stars like the S-stars, and for the rates of inspirals of compact objects onto the MBH (i.e., EMRIs). Second, we consider the X-ray and near-IR flares that are observed from the MBH in the GC on an approximately daily basis. A proposed origin for these flares is the tidal disruption of large (> 10 km radius) planetesimals, and we study the dynamics of such planetesimals in the GC at the parsec scale, giving clues into their origin. Lastly, we venture to larger scales of up to a kpc from the MBH and consider relaxation of objects, in particular binary stars, due to transient nuclear spiral arms. We show how this relaxation process can enhance the disruption rates of stellar binaries, with implications for the orientation of hypervelocity stars originating from the GC.

**October 17:** Special Event (12:45pm, Bryant Space Center Rm. 217)

**Title: ** Discussion of LIGO results

**Abstract: ** Steve Eikenberry will lead a discussion about the discovery of a binary neutron star merger by LIGO. (*Note the unusual time and location.*)

**October 25:** Cole Miller (Univ. of Maryland)

**Title: ** When Neutron Stars Collide

**Abstract: ** On August 17, gravitational waves and gamma rays from a merger of two neutron stars reached the Earth. Over the next several weeks, astronomers studied this event across the electromagnetic spectrum, leading to remarkable confirmation of predictions and also some fascinating new puzzles to consider. I will share some perspectives about the importance of the observations in many subjects: from tests of theories of strong gravity to the structure of neutron stars to the nature of short gamma-ray bursts and the production of heavy elements. I will also speculate about the return we can expect from gravitational wave observing runs in the coming years.

**November 8:** Steffen Aksteiner (Princeton)

**November 15:** Desika Narayanan (UF Astronomy)

**November 22:** *No seminar -- Thanksgiving week*

**November 29:** Jack Hewitt (Univ. of North Florida)

Students may receive credit for attending this seminar by
registering for PHY 6391.

**Astronomy Department Colloquium**
Fall 2017
Spring 2018

**Other Physics Department Seminars and Events**

2010–2011, 2011–2012, 2012–2013, 2013–2014, 2014–2015, 2015–2016 2016–2017

Questions, comments, suggestions: lblecha@ufl.edu, bernard@phys.ufl.edu, fry@phys.ufl.edu.