The origin of cosmic rays (CRs) with up to 10^20 eV energies is one of the most important questions in astrophysics to date. One way to track down CR sources and study CR propagation is to look for the products of cosmic ray interactions, in particular gamma rays and high-energy (TeV-PeV) neutrinos. The neutrinos, indeed, are characteristic of hadronic interactions and thus would be an unambiguous signature of the presence of cosmic rays. The detection of coincident neutrino and photon signals would allow locating and characterizing CR interaction sites. During the past two years, the discovery by IceCube of neutrinos emitted from the NGC 1068 galaxy and from the galactic plane has demonstrated the capability of current and upcoming experiments to not identify astrophysical neutrinos but also to discover and study specific sources. The observation of NGC1068 has also highlighted the link between neutrinos and hard X rays for opaque sources. Thus, IceCube’s discoveries have opened a new research program in astrophysics, in which combined studies between next-generation neutrino and X-ray/gamma-ray experiments will be essential.

The SVOM and KM3NeT groups at APC are looking for a Ph. D. student to investigate the potential of accreting black holes (in particular gamma-ray bursts, GRBs, and Active Galactic Nuclei, AGNs) to accelerate cosmic rays. A GRBs is an extremely violent transient cosmic phenomenon resulting from the fusion of two neutron stars or from an extreme supernova while an AGN is composed of a supermassive black hole accreting matter from its environment and sometimes also exhibiting relativistic jets.

Since June 2024, these astrophysical sources are being monitored by the SVOM telescope, which can observe them in the optical to gamma-ray range with multiple instruments. APC is currently playing a key role in the commissioning and exploitation of the ECLAIRs telescope, which probes the hard X- and gamma-rays. If GRBs accelerate cosmic rays, they could also produce high-energy neutrinos. APC is currently involved in the KM3NeT neutrino experiment which is currently both being built and taking data in the Mediterranean Sea (completion expected in 2027). A key asset of KM3NeT is its excellent resolution, which could allow the experiment to identify coincidences between SVOM observations and neutrinos, thereby providing evidence for a new class of CR sources. 

The goal of the Ph. D. student will be to search for coincidences between KM3NeT and SVOM observations, employing two strategies. First, the student will identify high-energy neutrino events and use them to identify time windows and sky regions of interest for SVOM observations. Second, the student will perform a joint search for neutrinos (KM3NeT) and X-rays or gamma-rays (ECLAIRs). In this joint search, the student will exploit the space (and time) coincidences expected between the neutrino and photon events to relax the selection cuts at KM3NeT and SVOM. In addition to event selection, a key component of this work will be constraining the properties of entire GRB and AGN populations. To this end, the student will have to investigate state-of-the-art cosmic-ray emission models and identify relevant parameters. This thesis would therefore be an excellent opportunity for the candidate to work on both modelling and multi-messenger data analysis.

The student will be part of both the SVOM and KM3NeT collaborations. We therefore expect them to participate in collaboration meetings (travelling 3-4 times per year), and take part in the data processing, detector monitoring, and maintenance activities. 

Some experience with Python programming (optionally also C++) and with data analysis would be highly appreciated. Whenever possible, we strongly encourage candidates to also join us in advance for a master's project on a similar topic.