Mon Feb 26, 2018

Nuclear Physics Seminar: Dr. Mark Roberts, Woods Hole Oceanographic Institution

4:00 PM - 5:00 PM
124 Nieuwland Science Hall

Why does an Oceanography Institution have a Particle Accelerator?

Dr. Mark Roberts
National Ocean Sciences AMS Facility
Woods Hole Oceanographic Institution

Hosted by Prof. Peaslee

Posted In: Nuclear Seminar

Tue Feb 27, 2018

Astrophysics Seminar: Dr. Gen Chiaki, Georgia Tech

12:30 PM - 1:30 PM
184 Nieuwland Science Hall

Formation criterion and process of extremely metal-poor stars: the role of first supernovae

Dr. Gen Chiaki
Postdoctoral Researcher, Georgia Tech

Metal-poor stars are living fossils with records of the metal enrichment in the early Universe. They are classified primarily into C-enhanced metal-poor (CEMP) stars and C-normal metal-poor (CNMP) stars according to their carbon abundances. Recently, the new classification of CEMP stars is presented. Their carbon and iron abundances show lower limits of A_cr(C) ~ 6 and [Fe/H]_cr ~ -5, respectively. This suggests the critical elemental abundances above which thermal emission cooling of carbon and silicate grains operates to induce the fragmentation of their parent gas clouds, and low-mass stars are likely to be formed. Since the dust cooling rate depends on the condensation efficiency of metal and grain size distribution with a given metallicity, we estimate them from the observed lower-limits of carbon and iron abundances. Then, we derive the critical condition of the formation of EMP stars. The different classes of CEMP stars are well-explained as the difference of main grain species for their formation.

     We also present results of numerical simulations of the metal-enrichment process and EMP star formation. From their small metal content, they are considered to acquire heavy elements from a single or several supernovae (SNe) of first-generation (Pop III) stars. We simulate the feedback effects of photoionization and SNe with a range of masses of Pop III stars and hosting minihalos (MHs). For pair-instability supernovae (PISNe) with large explosion energy ~30x10^{51} erg, the ejected gas reaches to the neighboring halos, i.e., external enrichment (EE) takes place in all relevant mass range of MHs. Yet, the metals cannot penetrate into the central part of halos, and the resulting metallicity is [Fe/H] < -5. This is consistent with no observational sign of PISNe among EMP stars. For core-collapse supernovae (CCSNe) with normal explosion energy ~1x10^{51} erg, the ejected gas falls back into minihalos and internal enrichment (IE) occurs. The metallicities in the recollapsing region are -5 < [Fe/H] < -3 in most cases. We can conclude that IE by CCSNe can explain the metallicity range and elemental abundance ratios of EMP stars.

Posted In: Astrophysics Seminar

Particle Physics Seminar: Prof. Radovan Dermisek, Indiana University

4:00 PM - 5:00 PM
415 Nieuwland Science Hall

Understanding parameters of the standard model from the MSSM extended by a complete vectorlike family

Prof. Radovan Dermisek
Theoretical Particle Physics
Indiana University…

Posted In: Particle Physics Seminar

Wed Feb 28, 2018

Physics Colloquium: Prof. John LoSecco, University of Notre Dame

4:00 PM - 5:00 PM
118 Nieuwland Science Hall

Title TBA

Prof. John LoSecco
Department of Physics
University of Notre Dame…

Posted In: Colloquia

Mon Mar 5, 2018

Nuclear Physics Seminar: Dr. Nicole Vassh, University of Notre Dame

4:00 PM - 5:00 PM
124 Nieuwland Science Hall

Title TBA

Dr. Nicole Vassh, Postdoc
University of Notre Dame

Hosted by Prof. Surman

Posted In: Nuclear Seminar

Tue Mar 6, 2018

Astrophysics Seminar: Dr. MacKenzie Warren, MSU

12:30 PM - 1:30 PM
184 Nieuwland Science Hall

Title TBA

Dr. MacKenzie Warren
(ND PhD)
MSU

Hosted by Prof. Mathews

Posted In: Astrophysics Seminar

Particle Physics Seminar: Dr. Hooman Davoudiasl, Brookhaven National Laboratory

4:00 PM - 5:00 PM
415 Nieuwland Science Hall

Long range dark matter forces and new views on old problems

Dr. Hooman Davoudiasl
Brookhaven National Laboratory

Hosted by Prof. Delgado

Posted In: Particle Physics Seminar

Wed Mar 7, 2018

Physics Colloquium: Dr. Eric Chaisson, Harvard-Smithsonian Center for Astrophysics

4:00 PM - 5:00 PM
118 Nieuwland Science Hall

The Rise of Complexity in Nature

Dr. Eric Chaisson
Harvard-Smithsonian Center for Astrophysics

Director’s Fellow, 2017-18, Institute for Advanced Study, University of Notre Dame

 

Nature writ large is a mess. Yet, underlying unities pervade the long and storied, albeit meandering, path from the early Universe to civilization on Earth.  Evolution is one of those unifiers, incorporating physical, biological, and cultural changes within a broad and inclusive cosmic-evolutionary scenario.  Complexity is another such unifier, delineating the growth of structure, function, and diversity within and among galaxies, stars, planets, life, and society.

 

This talk will summarize a research agenda now underway not only to search for unity in Nature but also, potentially and more fundamentally, to quantify both unceasing evolution and increasing complexity by modeling energy, whose flows through non-equilibrium systems arguably grant opportunities for evolution to create evermore complexity.

Posted In: Colloquia

Mon Mar 19, 2018

Nuclear Physics Seminar: Dr. Amy Roberts

4:00 PM - 5:00 PM
124 Nieuwland Science Hall

Title TBA

Dr. Amy Roberts
(ND PhD)
University of Colorado Denver

Hosted by Dr. deBoer

Posted In: Nuclear Seminar

Tue Mar 20, 2018

Astrophysics Seminar: Prof. Robert Scherrer, Vanderbilt University

12:30 PM - 1:30 PM
184 Nieuwland Science Hall

The cosmological Lithium Problem

Prof. Robert Scherrer
Vanderbilt University

Hosted by Prof. Mathews

Posted In: Astrophysics Seminar

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