Ph.D Defense: Rodrigo Negreiros

Defense – Wednesday 21st October at 2:00pm in the Education and Business Administration Building, Room 110 there will be a Ph.D. Thesis Defense presented by Rodrigo Negreiros who will talk on “Numerical Study of the Properties of Compact Stars”. Free Coffee and Cake served from 1.30pm in P-145A. This is the first Ph.D. defense supervised by the Dept. of Physics. There will be a live broadcast of the talk (restricted to Windows® systems only).


Compact stars are formed in catastrophic astrophysical events such as supernova explosions and binary stellar collisions. It is estimated that galaxies like our Milky Way contain between 108 to 1010 compact stars, which permanently harbor compressed ultra-dense nuclear matter in their interiors. This key feature together with the ongoing progress in observational astrophysics, make compact stars superb astrophysical laboratories for a wide range of intriguing physical studies. Several such studies are performed in this thesis. The first activity concerns the widely unknown nuclear equation of state and the core composition of compact stars. Particular attention is payed to the possible presence hyperons in the cores of neutron stars as well as to stars made of unconfined up, down and strange quarks (strange quark stars). The second activity aims at investigating the structure and stability of rapidly rotating compact stars, performed for a broad collection of equations of state computed in part one of the thesis. The third activity focuses on the thermal evolution of compact stars, driven by neutrino emission from their cores and by photon emission from the surfaces. Is is shown that the thermal behavior depends very strongly on the stellar core composition, which govern the neutrino emission rates. Moreover, it is found that the thermal evolution of neutron stars is significantly different that of strange quark stars, specifically if strange quark matter forms a color superconductor, as predicted by theory. The studies performed in this thesis are key for our understanding of the thermal evolution of isolated rotating neutron stars (pulsars), anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs), and provide most valuable information about the phase diagram of isospin-asymmetric ultra-dense nuclear matter which cannot be probed in high-energy collision experiments.

Committee Members:

Prof. Fridolin Weber (Chair, Dept. of Physics, SDSU),

Prof. Calvin Johnson (Dept. of Physics, SDSU),

Prof. Michael Bromley (Dept. of Physics, SDSU),

Prof. Allon Percus (Claremont Graduate University), and

Prof. Ali Nadim (Keck Graduate Institute and Claremont Graduate University)


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