Review on ultra-high-energy cosmic rays

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Our review on open questions in ultra-high-energy cosmic rays is now out:

Open Questions in Cosmic-Ray Research at Ultrahigh Energies, 1903.06714

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We wrote this review following the 2018 workshop at MIAPP: “The High Energy Universe: Gamma Ray, Neutrino, and Cosmic Ray Astronomy”.  The review will be published in Frontiers.

The figure above is a Hillas plot by Foteini Oikonomou, Fig. 10 in the paper.

Astro2020 neutrino white papers

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The US decadal survey in Astronomy and Astrophysics (more information here) requested science white paper for their panel to review.  The recommendations of the panel will help guide decision-making in the next ten years.

A group of us(*) consisting of experimentalists and theorists from across the field have submitted two white papers on high-energy cosmic neutrinos to the survey.  The papers are each endorsed by  >300 members of the community.

Take a look for yourself:

Fundamental Physics with High-Energy Cosmic Neutrinos, 1903.04333

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Astrophysics Uniquely Enabled by Observations of High-Energy Neutrinos, 1903.04334

panorama_HESE7yr

(*) Markus Ackermann, Markus Ahlers, Luis Anchordoqui, Mauricio Bustamante, Amy Connolly, Cosmin Deaconu, Darren Grant, Peter Gorham, Francis Halzen, Albrecht Karle, Kumiko Kotera, Marek Kowalski, Miguel A. Mostafa, Kohta Murase, Anna Nelles, Angela Olinto, Andres Romero-Wolf, Abigail Vieregg, Stephanie Wissel

Long-range neutrino interaction paper picked as PRL Editors’ Suggestion

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Our paper ‘Universe’s Worth of Electrons to Probe Long-Range Interactions of High-Energy Astrophysical Neutrinos’ was published on Physical Review Letters:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.061103

It was selected as a PRL Editors’ Suggestion.  You can read the synopsis on the APS Physics page here:

Synopsis: Neutrino Probes of Long-Range Interactions

Link to the arXiv version of the paper: 1802.02042

Recovering the neutrino flavor composition at neutrino sources

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In a new paper with Markus Ahlers, we introduce a method to infer the flavor composition of high-energy astrophysical neutrinos at their sources, based on measurements of the flavor composition at Earth:

Inferring the flavor of high-energy astrophysical neutrinos at their sources
Mauricio Bustamante, Markus Ahlers

To do this, we effectively revert the effect of flavor oscillations, while taking into account uncertainties in the neutrino mixing parameters.

We apply the method to flavor measurements published by IceCube, and to projections for the near-future IceCube upgrade and the more distant IceCube-Gen2.

In the illustrative, physically motivated case where there is no production of tau neutrinos at the sources, we can recover the fraction of electron neutrinos produced at the sources:

posterior_pdf_flavor_ratios_source_hard_no_tau_icecube_combined

Presently (“IceCube 2015”), we find that neutrino production by the decay of high-energy pions is compatible with the flavor and oscillation data, with a slight preference for sources harboring strong magnetic fields which make intermediate muons lose energy by synchrotron radiation.  In the future, the IceCube ugprade and IceCube-Gen2 have the potential to single out the neutrino production mechanism