Identification of cosmic ray sources amongst jetted active galaxies

Welcome to the webpage of the joint FWF-ARRS project

Cosmic Rays (CRs) are energetic, mostly charged particles of cosmic origin. A dedicated method is developed in this project with the goal to determine to which extent ultra-high energy (UHE, ≥ 10 EeV) CRs originate from jetted active galactic nuclei.

Recent measurement results favor conventional scenarios of the UHECR production at astrophysical sites. Prominent jet outflows in powerful active galactic nuclei (AGN) provide suitable conditions for charged particle acceleration up to UHEs, and are thus considered prime contributors to the observed UHECR flux. During CR acceleration, hadronic interactions occur where photons and neutrinos are produced. As neutral messengers, they provide information about the CR source location in the sky, and the physical conditions at the CR production site, while the charged CRs suffer from loss of directional information by deflections in cosmic magnetic fields. To reach the project goal, we employ a multi-messenger, multi-wavelength (MWL) approach including measurements of 1) UHECRs by the Pierre Auger Observatory, 2) gamma-rays of high- (HE, ≥ 100 MeV), by the Fermi-LAT detector, and very-high energy (VHE, ≥ 30 GeV), by ground-based Cherenkov telescopes, and 3) VHE neutrinos by the IceCube experiment.

In the proposed multistep procedure, all nearby AGN are first classified according to their capability to accelerate particles to UHEs. For this purpose, we use MWL measurements of the AGN electromagnetic spectra, complemented with AGN emission models to build a list of suitable AGN candidates for UHECR acceleration. Auger data indicate that the CR flux composition at extreme energies trends from light towards intermediate mass nuclei. Therefore current state-of-the-art AGN emission models will be extended (by the Austrian project team under the lead of Dr. A. Reimer) to include injection, transport and radiative losses of particle distributions of heavy nuclei composition. The Slovenian project team (led by Dr. S. Vorobiov) will develop and perform subsequent simulations of possible UHECR arrival directions for various cosmic magnetic field configurations, based on the AGN candidate list. The resulting UHECR patterns expected at Earth will be cross-correlated with Auger data. The signatures of the produced photon and neutrino emission will be analyzed and their relation to Fermi-LAT and IceCube data investigated as well. Finally, characteristic UHECR features stemming from AGN jets, and verifiable by the near-future Cherenkov Telescope Array (CTA), will be predicted.

This project benefits from the participation of numerous world leading scientists from Italy and Poland. It is expected to lead to valuable results towards identifying the sources of the UHECRs and optimizing the CTA observation strategies for this science case.


July 3, 2023
Our abstract was accepted as a talk at the TeV Particle Astrophysics (TeVPA) conference. Anita Reimer will present our work on low-luminosity jetted AGN as particle multi-messenger sources, covering several aspects of our project. The conference will take place in Naples, from September 11th to 15th 2023.

June 28, 2023
Today, the team had the chance to visit Victor Franz Hess' Observatory, at the Hafelekar summit. Our colleague Emmerich Kneringer led the visit for us and we are grateful to have had this opportunity to discover the workstation of the Nobel Price Laureate of 1936! Here are two pictures of the team members in front of the observatory:


June 28, 2023
Today marks the launch of the last face-to-face meeting of this project. For this occasion, we gather in Innsbruck for 3 days of discussion. We are looking forward to exchanging exciting ideas!

June 22, 2023
Margot Boughelilba submitted a paper to ApJL, in collaboration with Anita Reimer. In this paper, they study the parsec-scale core composition of FR0s.

June 13, 2023
Two abstracts, from members of our team, were accepted as talks at the XVIII International Conference on Topics in Astroparticle and Underground Physics (TAUP). Anita Reimer will present our work on low-luminosity jetted AGN as particle multi-messenger sources, while Serguei Vorobiov and Jon Paul Lundquist will present their results on the multi-messenger properties of cosmic rays produced by FR 0s and propagating towards Earth. The conference will take place in Vienna, from August 28th to September 1st 2023.

March 31, 2023
Paolo Da Vela left University of Innsbruck. He is now employed at INAF OAS Bologna and will continue to contribute to our collaboration.

February 6, 2023
Margot Boughelilba is now working fully for the project at the University of Innsbruck. She will work on modelling the FR0 radio-galaxies that we identified as possible cosmic-ray accelerators.

December 26, 2022
The third circular of the next ICRC2023 conference that will take place in Nagoya, Japan from July 26 to August 3 has been published. The deadline for the submission of the abstract is February 10, 2023. The team will discuss in the next video call about the abstracts to be submitted.

December 14-16, 2022
The winter project meeting took place in Vipava. During these days the team discussed about the status of the
 cosmic rays propagation study from FR0 galaxies and set the publication strategy. Also the recent developments of the AGN jet modeling as well as recent results from Pierre Auger Observaotry and CTA have been revised and discussed. The team also decided for a last collaboration meeting to be held in Innsbruck in Spring 2023.

November 16, 2022
Fermi/LAT collaboration published the fourth catalog of Active Galactic Nuclei data release 3. Among the new sources discovered as gamma-ray emitters  the FR0 source 55267 It is the first confirmed association between a gamma ray source and a FR0 galaxy. This is relevant for our planned broadband FR0 source modeling using the code we are developing.

November 4, 2022
Icecube published a study aimed to look for neutrino emission from astrophysical sources. This study is based on data collected from 2011 and 2020. Evidence of significant neutrino emission from the nearby Seyfert 2 galaxy has been reported.

 August 29-September 2 , 2022
Lukas Merten (previous project postdoc, now project collaborator) visited the Innsbruck group where we had intense discussions and joint work on the nuclear cosmic ray propagation code we are developing.

 April 20-22 , 2022
Collaboration meeting (hybird) hosted in Innsbruck

January 28, 2022
We selected, among the FR0 galaxies, two very good candidates to be observed with the X-ray satellite Nustar (sensitive in the energy range 3-80 keV) and submitted a proposal to ask for new data to be taken in next observations cycle.

January 1, 2022
Lukas Merten left University of Innsbruck. He is now employed at Rhur University Bochum (RUB) and will continue to contribute to our collaboration.

October 20-22, 2022
After more than one year the team had the chance to meet (at least partially) in person. The collaboration meeting took place in Vipava (Slovenia) in a hybrid form.  During the meeting several points have been discussed: recent developments about multimessenger astronomy, cosmic ray propagation as well as AGN jet modeling. During the discussions the team agreed on requesting new X-ray data for the sources selected for the project, FR0 galaxies, to have a better multiwavelength coverage. This will be done at the beginning of 2022. The schedule of the meeting can be found on the meeting page.

September 1, 2021
During this week the joint meeting of the Austrian and Swiss physical societies (ÖPG and SPS) is taking place in Innsbruck. The project team used the opportunity to present our research to a broad (non-astroparticle) community with a talk (see our publications).

July 30, 2021
The latest results from our project have been presented in various forms at the 37th International Cosmic Ray Conference (ICRC) during the last two weeks, where we received valuable feedback by colleagues from all around the world. Our findings have also been published in Proceedings of Science (see our publications). Here, the project team presented an early study on the propagation of UHECR from FR-0s to our Galaxy.

May 1, 2021
Paolo Da Vela is now engaging full time in the project team. With his expertise in high energy gamma ray physics he will help to model candidate source regions, e.g. FR 0 radio galaxies.

February 14, 2021
The first article of the project team was published and is freely avalaible. We could show that based on a hybrid acceleration scenario, combining Fermi I order and gradual shear acceleration, UHECRs can be accelerated in FR 0 jets and escape the prevailing photon target fields. This is a first step in examing the FR 0 contribution to the observed UHECR flux.

December 09, 2020
Today we presented our work on FR 0 radio galaxies as possible UHECR source candidates at the international YITP workshop "Connecting high-energy astroparticle physics for origins of cosmic rays and future perspectives” that was hosted as a hybrid event in Kyoto, JAP. The abstract and our slides will become available on the workshop homepage.

May 14, 2020
Yesterday the remote face-2-face meeting ended after two days full of inspiring discussions. The complete team virtually gathered for four sessions dedicated to the fields of the research project: multimessenger observation, a source catalogue, source physics, and multimessenger propagation. The full schedule can be found on the meeting page.
Although the meeting was a great success, still all participants are hoping to meet in person on the next possible occasion.

April 7, 2020
Today the project team has decided to postpone the face2face meeting in Nova Gorica due to the severe Covid-19 outbreak. Although the bi-yearly in-person meetings are an important factor for the success of the project, they are unfortunatly not possible under the given circumstances. The scheduled meeting will now be transformed to a virtual meeting to allow for the essential exchange of ideas. It is planned to make up for the F2F-meeting in Nova Gorica at a later point in time.

March 3, 2020
We are happy to announce that two new members joined our research team in February. Margot Boughelilba, a PhD student in Innsbruck, will work on a numerical simulation to describe cosmic ray physics inside the jets. The Slovenian team is strengthened by Jon Paul Lundquist, who is helping to improve the modelling of the cosmic ray transport from the sources to Earth.

November 11, 2019
The webpage was officially launched today. We will keep you updated on this existing project here on this page. Get to know the collaborators or learn about the resources that will become available for the scientific community during the project.

October 15, 2019
The kick-off meeting of the project is about to take place in Innsbruck very soon (October 28-30, 2019). At this first face-to-face appointment all members of the international team will get to know each other and start discussion on science of cosmic rays originating in active galaxies. More information on the meeting can be found at the collaboration meeting page.

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