Colloquium Abstracts

Monday, 2:00 pm, NRAO Auditorium


Ph.D. Candidate Gareth Jones

Title:  A Multi-Faceted Study of Three Forms of Galactic Formation in the Early Universe


While observations of the early universe have focused on bright, highly starbursting galaxies, star formation activity in the early universe was dominated by main sequence galaxies. Observations of the former group have been accumulating for decades, but the latter are only recently observable using modern instruments. In this work, we apply the Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to observe specific examples of each galactic class, in order to explore three modes of galaxy formation: smooth accretion, satellite accretion, and massive mergers. Using the molecular gas tracer CO and a broad set of continuum measurements, we characterize the gas mass and distribution, star formation, and dust temperature of the two archetypal massively merging Hyper-Luminous IR Galaxies (HyLIRGs) BRI1202-0725 & BRI1335-0417. We then examine the [CII] emission of the Lyman-Break Galaxy (LBG) WMH5, which shows two infalling gas clouds, implying ongoing formation via filamentary accretion. Finally, we apply a classical suite of dynamical characterization tools to [CII] observations of three MS galaxies and three starbursts, resulting in rotation curves and dynamical masses for each. By examining each of these sources in detail, we find that galaxies in the early (i.e., z > 4) universe formed via a broad range of interactions, ranging from cold-mode accretion to major mergers. As these instruments continue observing, and with the future advent of JWST and perhaps the ngVLA, stronger constraints may be placed on the behavior of the galaxies in the epoch of initial galaxy formation.


Thursday, 2:00 pm, Workman 101


Ph.D. Candidate Samuel Collopy




Three models of finite temperature non-Abelian gauge fields are
studied on four-dimensional products of spheres. Yang-Mills theory is
studied on S
2 and the Einstein Universe, S
. Quantum
gravity is also studied on the Einstein Universe. In all three models,
the quantum fields are considered to be a perturbation over a
covariantly constant background. DeWitt’s background field method is
used to calculate the one-loop effective action as a function of the
radii of the spheres, and the stability of the constant background
configuration is examined. The effective action is used to compute the
heat capacity and entropy, and the thermodynamic properties of the
systems are analyzed.

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