Research Events
For the Public
Northwestern University

CIERA Special Seminars 2015-2016

*Tech = Technological Institute (2145 Sheridan Road)
**Db = Dearborn Observatory (2131 Tech Drive)

Fall Quarter 2015

  Date/Time      Visitor Host
  Sept. 15
  Tech F160

Adrian Hamers
    Leiden Observatory
    Secular dynamics of high-order multiple systems
     applications to circumbinary planets and Hot Jupiters

We present a new efficient method to study the long-term dynamics of hierarchical multiple systems such as high-multiplicity stellar systems and multiplanet systems, without restrictions on the number of bodies nor on the hierarchical configuration. We apply this method to hierarchical quadruple systems consisting of a hierarchical triple orbited by a fourth body, in different contexts. First, we consider the general dynamics, and we characterise the behavior of the system in terms of a ratio of Kozai-Lidov (KL) time-scales applied to different binary pairs. Second, we apply the method to explain the currently observed lack of transiting circumbinary planets around short-period binaries. Finally, we present preliminary integrations of multiplanet systems, in which secular chaos gives rise to high eccentricities and tidal shrinkage in the innermost planet's orbit, giving a pathway for producing Hot Jupiters. Our new method allows for much faster and longer integrations compared to previous direct N-body integrations, making it an excellent tool for better understanding the conditions for producing Hot Jupiters in multiplanet systems through secular chaos.

Fabio Antonini
  Oct. 8
  Tech F160

Andrew W. Smith
    University of Maryland, College Park and NASA/GSFC
    Revealing The Violent Universe: Current Results and The Future of Gamma-ray Astronomy

The last 10 years have seen a dramatic explosion of important science results from space based instruments (~0.3-300 GeV) such as Fermi-LAT and AGILE, as well as ground based instruments (~100-5000 GeV) such as VERITAS, HESS, and MAGIC. These instruments have provided an in-depth exploration of particle acceleration in the the most energetic known cosmic sources (supernova remnants, gamma-ray bursts, pulsars, AGN, and the center of our own Galaxy), as well as providing important clues to the mystery of high energy cosmic ray origins. In this talk I will review the most important recent results from these instruments as well as providing a preview of the next generation of both ground and space based gamma-ray observatories. The future for ground based instruments is already being cemented with the completion of the HAWC array in Mexico, as well as the upcoming CTA array planned for both the Northern and Southern Hemispheres. The successor to Fermi-LAT is also in the works, with several mature mission concepts progressing forward already. I will review some of these concepts and provide an outlook for the future of this exciting and dynamic field.

Farhad Yusef-Zadeh
  Nov. 23
  Tech F160

Morgan MacLeod
    University of California, Santa Cruz

Fabio Antonini


Winter Quarter 2016

  Date/Time      Visitor Host
  Jan. 14
  Tech F160

Ian Stephens
    Boston University

Giles Novak and Farhad Yusef-Zadeh



For more information, contact: ciera@northwestern.edu

Past CIERA Special Seminars