[phas-dept] Mar. 22 (Thursday) 4 PM - Physics and Astronomy Colloquium

[Heungman Park]

Spring 2018 Colloquium

Department of Physics & Astronomy, TAMU-Commerce

Mar 22, Thursday, 4-5 PM in Science Building 127

(coffee and cookies will be served at 3:50 PM)

Astrophysics, Particle physics

Astrophysical Neutrinos:
What do they tell us about cosmic accelerators?
Dr. Spencer Klein

Lawrence Berkeley National Laboratory & Univ. of California at Berkeley


[https://urldefense.proofpoint.com/v2/url?u=https-3A__lh3.googleusercontent.com_jzwdsLW8OFMq-5FCVsrMbCdo0o7ZFhOqdxASVks9W2e1m06BpR8O-2Dc1zbB623ti6qPk4hPQi52-2DK-2DQEWMNI4YoihhzDTA7UzhiVASP3e41mj3yteraNntXjcC-2D6SB9It7CzzgHTgrS&d=DwIFAw&c=oqyuZuih6ykib6aKiBq22_bich4AVfYGoLertJN0bEc&r=hjwEO_XYlnwAQWUGeaCrW47w4mK-Al28-BKyRvaivBs&m=cLaxFSjy7Ck-ZI7bZmbD2NEzsgiBFjU7-oa_VUDEEgc&s=mjjOoKDPG5qTKEij8kdHdhMous8R4pBnpfT2pu8GUW0&e=]


Dr. Klein earned his BA in 1982 from the University of California, San Diego, and his PhD from Stanford University in 1988 for dissertation work on 29 GeV e^+e^- collisions.  From there, he moved into astroparticle physics, with postdocs at Boston University, on MACRO [Monopole, Astrophysics and Cosmic-Ray Observatory] and UC Santa Cruz on Cygnus, Milagro and the Landau-Pomeranchuk Effect. In 1994, he moved to Lawrence Berkeley National Lab, to work on heavy-ion collisions with the STAR detector at RHIC, where he is currently a senior scientist; he also has an appointment as a research physicist at UC Berkeley.  His current interests include neutrino astroparticle physics with IceCube and ARIANNA, and ultra-peripheral collisions with STAR and ALICE. He has a blog, https://urldefense.proofpoint.com/v2/url?u=http-3A__antarcticaneutrinos.blogspot.com_&d=DwIFAw&c=oqyuZuih6ykib6aKiBq22_bich4AVfYGoLertJN0bEc&r=hjwEO_XYlnwAQWUGeaCrW47w4mK-Al28-BKyRvaivBs&m=cLaxFSjy7Ck-ZI7bZmbD2NEzsgiBFjU7-oa_VUDEEgc&s=T7c-XV80gFuVseg02rQf17SID-CM6bHC9cj8bwWIGXc&e=<https://urldefense.proofpoint.com/v2/url?u=http-3A__antarcticaneutrinos.blogspot.com_&d=DwMD-g&c=oqyuZuih6ykib6aKiBq22_bich4AVfYGoLertJN0bEc&r=oW0cJCgG9kL3hewogz7V9J0OTS6PpWhN7lR7LkypiUg&m=bWkJAZEO0ukALOJYk3Regz6yFroh-BPacNvZW1fm9Wk&s=JyeH7OJEXwl4lcSeDtFx7TAl8rIJsop9EAee699DLVw&e=>.


Abstract

The existence of cosmic-rays with energies well above 10^20 electron volts (16 Joules) is a long-standing mystery; producing them requires either enormously powerful astrophysical accelerators, or something exotic.  One way to shed light on cosmic-rays accelerators is to search for their signal in another channel - neutrinos! The IceCube detector has observed a diffuse flux of astrophysical neutrinos, extending to energies well above 1 PeV (10^15 eV).  This flux has been observed by multiple analyses using independent datasets, with high significance.  This flux is near the maximum predicted ("Waxman-Bahcall bound") from astrophysical accelerators. Most popular source models, involving gamma-ray bursts, active galactic nuclei (galactic centers containing supermassive black holes), and even star-forming galaxies are disfavored to varying degrees.    In this talk, I will discuss the IceCube results in the context of cosmic-ray physics and give the status of different classes of source models. I will conclude by discussing some possible future experiments.

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