Talk detail

Participant	Chen, Pisin
Institution	Leung Center for Cosmology and Particle Astrophysics - R806, New Physics Building, No.1. Sec.4, Roosevelt Rd. - Taipei - - Taiwan

Session	GB3	Accepted		Order	Time
Talk	Oral abstract	Title	Did Gamma Ray Burst Induce Cambrian Explosion?
Coauthors
Abstract	One longstanding mystery in bio-evolution since Darwin's time is the origin of the Cambrian explosion that happened around 540 million years ago (Mya), where an extremely rapid increase of species occurred. Here we suggest that a nearby GRB event 500 parsecs away, which should occur about once per 5 Gy, might have triggered the Cambrian explosion. Due to a relatively lower cross section and the conservation of photon number in Compton scattering, a substantial fraction of the GRB photons can reach the sea level and would induce DNA mutations in organisms protected by a shallow layer of water or soil, thus expediting the bio-diversication. This possibility of inducing genetic mutations is unique among all candidate sources for major incidents in the history of bio- evolution. A possible evidence would be the anomalous abundance of certain nuclear isotopes with long half-lives transmuted by the GRB photons in geological records from the Cambrian period. Our notion also imposes constraints on the evolution of exoplanet organisms and the migration of panspermia.
Pdf file

Session	HE2	Accepted		Order	Time
Talk	Oral abstract	Title	Radiowave Detection of Ultra High Energy Cosmic Neutrinos and Cosmic Rays
Coauthors
Abstract	Ultra high energy cosmic rays (UHECR) with energies >1020 eV have been observed. Yet their origin remains a mystery. Where and how were they generated and accelerated? Traversing cosmic distance, UHECRs would necessarily interact with CMB photons and produce ultra high energy cosmic neutrinos (UHECN). Such cosmogenic, GZK (Greisen-Zatsepin-Kuzmin) neutrinos are guaranteed to exist, but have never been observed. The investigations in both UHECR and UHECN would help to shed much light on our understanding of the highest energy universe as well as providing us rich discovery potentials in neutrino physics. It is commonly agreed that such events can best be observed by detecting the radio wave signals emitted by their induced shower particles, based on the Askaryan effect in ice or the geo-synchrotron emission in air. In this talk we review the science potentials, the detection methods, and the status of the ongoing radiowave-based projects such as the balloon-borne ANITA, the ground-based ARA and ARIANNA in Antarctica, and TAROGE in Taiwan.
Pdf file