Space Science Research Projects

Study of neutrino blazars under a self-consistent physical paradigm, bridging the gap between first-principle simulations and multi-messenger signatures.Overview Blazars, relativistic jets from active galactic nuclei pointing very close to our line of sight, are among the most powerful cosmic particle accelerators in the Universe. They exhibit very bright, highly variable, nonthermal-dominated emission across the entire electromagnetic spectrum, indicating extreme particle acceleration in compact regions, often referred to as the blazar zone. Recently, NSF-funded IceCube have detected a very high energy neutrino event potentially in association with a flaring blazar TXS 0506+056 detected by Fermi. This exciting multi-messenger discovery provides the first observational evidence that extragalactic cosmic rays and neutrinos may originate from the blazar zone. Finding more neutrino blazars becomes one of the top scientific questions in the multi-messenger astronomy and a key element of NSF’s “Window on the Universe”. Intellectual Merit Neutrino blazars have proved to be difficult to identify with blind surveys of all blazars. IceCube has performed extended correlation studies, but mostly yielded insignificant correlations. Therefore, neutrino blazars are likely to be characterized by special physical conditions, which make them a rare population of blazars. This proposed program attempts to address overarching questions connected to the physical conditions favorable for proton acceleration to multi PeV energy, explore the relation between neutrino emission and electromagnetic signatures, and uncover the characteristic radiation patterns that can distinguish neutrino blazars. To address these questions, it is proposed to study neutrino blazars combining MHD, PIC, particle transport, and polarized radiation transfer simulations. These simulations are designed to track the cosmic ray acceleration and transport, thus identify temporal correlation between neutrinos and multi-wavelength signatures as well as characteristic radiation patterns for neutrino blazars. This approach therefore leverages current observational efforts to reveal underlying blazar zone physics, and provides solid predictions for future multi-messenger discoveries. Broader Impacts The proposed research will offer research opportunities for undergraduate students at Purdue University. They will work under the advisory of the Co-PIs and Collaborator to gain experience on the exciting frontiers of multi-messenger astrophysics and relativistic jet physics. The wide context of the proposal equally allows for analytical and numerical projects as well as comparison with observations, so that undergraduates can pick the opportunity that fits their main interest. The Co-PI will also participate in outreach with high school students via the Saturday Morning Astrophysics Program at Purdue University. This is a successful monthly program for Indiana middle and high school students offered within the outreach activities of the Physics and Astronomy department. A new annual activity will be introduced connected to the topic of special relativity. It will involve presentations by the faculty and graduate students where the main concepts will be highlighted. The students will then be involved with hands-on, table-top activities where they can absorb these concepts. This outreach activity will culminate with a half-day Astrophysics Camp for students in the third year of the project.