RUB Research School

Detail

  1. You are here:
  2. Startseite
  3. About
  4. Map of International Research Activities (MIRA)
  5. Detail
Back

Author
Name Hellrung, Jonas
Research field Neutrino Astronomy
Career stage doctoral researcher
Home university/institution Ruhr-Universität Bochum (RUB)
Department/Research unit at home university/institution Physics and Astronomy
Chair/Working group at home institution Theoretical Physiscs IV

International activity
Country United States
Location Madison, Wisconsin
University University of Wisconsin-Madison
Fund Research School PR.INT
Type of activity research stay
Period starts 16-09-2024
ends 26-10-2024
Keywords Neutrinos, Astronomy, Cosmic Rays, Astroparticle Physics
Report Cosmic rays (CRs) are high-energy particles, mostly protons, which are travelling through the Universe. The origin of most of the particles is still a mystery. We can only measure the properties of CRs here on Earth, and we cannot be sure if our observation is dominated by sources of CRs in our neighborhood or if the properties are similar across the Milky Way. However, we can indirectly study the properties of CRs in the whole Galaxy by understanding the properties of Galactic diffuse emission:

While traveling through the Galaxy, CRs can interact with particles of the interstellar gas to produce neutrinos. Neutrinos are elementary particles with no electric charge and very small masses. These properties make them a good probe for the distribution of CRs in our Galaxy, because they travel on a straight line and are very rarely absorbed.

However, for the same reasons, neutrinos are very hard to detect. Neutrino detectors are using huge volumes to compensate for the small interaction probability. The first detector finding astrophysical neutrinos is the IceCube Neutrino Observatory located at the South Pole. It consists of more than 5000 light detectors, distributed within a cubic kilometer of clear ice. In 2023, IceCube presented the first observation of a neutrino flux coming from the Milky Way. This opens the opportunity for further studies of Galactic diffuse neutrino emission to understand the distribution of CRs in the Milky Way.

My project is a statistical analysis of the Galactic neutrino flux. I want to test different models for this flux, assuming different CR propagation models and distributions. I want to combine different types of neutrino events to increase the number of included events and the sensitivity to the Galactic neutrino flux.

During my stay I worked on upgrading a framework for a combined fit of long tracklike neutrino events and more spherical cascade events. The framework was developed in the IceCube Collaboration to exploit the advantages of both event types in one analysis. I want to use this framework to analyze the Galactic neutrino flux.

In recent years, a new cascade event selection (DNNCascade) has been established, which includes almost 3 times more astrophysical neutrinos than the selection used in the first version of the combined fit. As this increases the sensitivity to the Galactic neutrino flux, I want to use this sample for my analysis. Before the sample can be used, it has to be included into the software and it has to be shown, that the data can be described well by simulations. This is important because in the analysis simulations are used to calculate the expected number of events which is then compared to the data.

For this I visited Assistant Professor Dr. Lu Lu and her group at the University of Wisconsin-Madison for 6 weeks in September and October 2024. The University is the leading institution within the IceCube Collaboration, which RUB is also a member of. Dr. Lu Lu and her students want to use the same framework to answer other astrophysical questions. They have been working on a better agreement between simulations and data, while I am experienced with the combined fit software. During my visit we combined this expertise to upgrade the framework.
During my visit, the IceCube Fall Collaboration Meeting also took place in Madison. This was a good opportunity to present the status of my analysis to the collaboration and discuss open problems.
Back