Events at Physics |
Events on Tuesday, April 26th, 2022
- Thesis Defense
- Hunting for cosmic neutrino sources from Giga- to Exa-electronvolt with IceCube
- Time: 2:00 pm
- Place: B343 Sterling
- Speaker: Alex Pizzuto, Physics PhD Graduate Student
- Abstract: Ever since the first observation of cosmic rays over a century ago, the origins of these high-energy particles has remained a mystery. Identifying and understanding the sources of these cosmic rays could provide invaluable insight into not only astrophysics but also fundamental particle physics. The IceCube Neutrino Observatory, a cubic-kilometer neutrino telescope instrumented at the geographic South Pole, has made remarkable progress on this front -- first with the detection of a diffuse astrophysical neutrino flux in 2013, and later with the identification of a particular flaring blazar as a promising neutrino source. However, the sources of the vast majority of the diffuse neutrino flux remain unidentified. The goal of this thesis is to identify astrophysical neutrino sources despite our limited detection threshold. We show how analyzing neutrino data with new techniques can reveal an immense deal about the nature of the universe's most energetic particle accelerators. After providing a description of the state of the field and a quick overview of the general analysis techniques used, we present a variety of analyses focused on searching for neutrino emission from promising classes of astrophysical transients. Although all of these analyses resulted in non-detections, we are hopeful that the tools presented here will assist with the identification of cosmic neutrino sources in the years to come.
- Host: Justin Vandenbroucke
- Theory Seminar (High Energy/Cosmology)
- Euclidean Wormholes: Conceptual Issues and Applications
- Time: 4:00 pm
- Place: Chamberlin 5280
- Speaker: Pablo Soler Gomis, CTPU - Institute for Basic Science
- Abstract: An important open question in the study of quantum gravity is whether topologically non trivial spacetime configurations (Euclidean wormholes) should be taken into account in the path integral. If present, they can generate phenomenologically relevant couplings and play an important role, e.g. in breaking axionic shift symmetries. At the same time, they pose deep conceptual problems such as the appearance of random couplings in the effective action or conflicts with holography. I will introduce in this talk some of the basic features of Euclidean wormholes and their phenomenological applications, focusing in particular on axionic wormholes and the role played by (massive) dilatons in their construction.
- Host: George Wojcik
- Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
- From SNe to SNRs: Hunting Legacies of Supernova Explosions in Supernova Remnants
- Time: 6:00 pm - 7:00 pm
- Place: virtual - Join Zoom Meeting Meeting ID: 912 3071 4547
- Speaker: Hiro Nagataki, RIKEN ABBL
- Abstract: Progress of theories for core-collapse supernovae is remarkable, including developments of multi-dimensional hydro simulations. Observational confirmations are mandatory to understand the explosion mechanism of core-collapse supernovae completely. Direct observations will be done by neutrinos and gravitational waves for a future supernova that will happen in Milky Way or very nearby galaxies. Such a nearby supernova should occur in the future, but the supernova rate is roughly 1 event per century per galaxy. The youngest supernova found in Milky Way is Cassiopeia A, whose age is about 350 yrs old. The youngest supernova in Large Magellanic Cloud is SN1987A which is 35 yrs old. Therefore, we cannot predict when the next nearby supernova will happen. In this talk, I would like to present our unique approach to finding observational evidence of the explosion mechanism of core-collapse supernovae in young supernova remnants. We did 3-dimensional hydro simulations that covered from supernova explosion phase to the supernova remnant phase. Such multi-D simulations with a wide range of scales (in time and length) have never been done before. We could demonstrate that such simulations are possible thanks to excellent international collaborations. This talk will mainly present a detailed comparison between our simulations and SN1987A. I will shortly show that such comparison is meaningful for Cassiopeia A and Type Ia supernova remnants, too. Join Zoom Meeting Meeting ID: 912 3071 4547
- Host: Baha Balantekin