Mr Chris Hamilton

email ch783 [at] cam  [dot] ac [dot] uk

Career

  • 2017-date: PhD student in Astrophysics, Department of Applied Mathematics and Theoretical Physics & Emmanuel College, University of Cambridge
  • 2013-2017: 3 years of Physics, then 4th year Masters in Mathematical and Theoretical Physics, Merton College, University of Oxford

Research

I am a second year PhD student in the Astrophysics group at DAMTP, working with Dr Roman Rafikov.  I am interested in all aspects of theoretical astrophysics, with particular emphasis on the dynamics of galaxies, galactic nuclei, globular clusters, binary systems, etc.

Dynamics of binaries

During my PhD I have developed a general secular theory describing the secular dynamical evolution of any binary orbiting an arbitrary axisymmetric potential (Hamilton & Rafikov 2019a,b).  The formalism brings several separate problems into a simple unified framework, including the hierarchical three-body (Lidov-Kozai) problem and the problem of Oort comets torqued by the Galactic tide. 

We demonstated that large-amplitude eccentricity oscillations typified by the Lidov-Kozai mechanism - and often invoked to explain the abundance of black hole mergers, blue stragglers, and hot jupiters - are in fact quite general whenever a wide binary orbits an axisymmetric host system (e.g. a globular cluster). 

Compact object mergers driven by cluster tides

The dynamical effect uncovered in Hamilton & Rafikov (2019a,b) suggested that compact object (black hole / neutron star) binaries in globular and nuclear clusters might be torqued to such high eccentricity by the tidal potential of their host cluster that they emit gravitational radiation and eventually merge, providing a new channel for LIGO graviational wave events.  We have quantified this effect under the assumption that the binary responds secularly to the smooth cluster potential alone (Hamilton & Rafikov 2019c).  Our future work will involve refining this simple model in several ways, in particular by accounting for stellar flybys.

Kinetic theory of self-gravitating systems

I am also generally interested in the kinetic theory of long-range interacting systems, be they gravitational or plasma. I have applied the (gravitational) Balescu-Lenard equation to spherical stellar systems (Hamilton et al. 2018, MNRAS). We argued that secular evolution of globular clusters must be strongly influenced by the presence of large scale collective modes amplified by self-gravity as opposed to two-particle (Chandrasekhar-style) scattering.

Selected Publications

  • Hamilton, C. & Rafikov, R. R. (2019), "Compact object binary mergers driven by cluster tides: a new channel for LIGO/Virgo gravitational wave events" ArXiV preprint https://arxiv.org/abs/1907.00994

Teaching

  • Michaelmas Term 2017: Part II Cosmology supervisions
  • Lent Term 2018: Part II Statistical Physics supervisions
  • Easter Term 2018: Part II Cosmology revision; Part II Statistical Physics revision
  • Michaelmas Term 2018: Part II Cosmology supervisions
  • Easter Term 2019: Part II Cosmology revision