Search for neutrino signatures in the high-energy activity of blazars

  • Date: –15:00
  • Location: Online: Zoom
  • Lecturer: Ankur Sharma, Uppsala universitet
  • Organiser: Division of Astronomy and Space Physics, Department of Physics and Astronomy
  • Contact person: Sofia Ramstedt
  • Seminarium

Blazars are among the most powerful steady sources in the Universe. The conditions in their doppler boosted jets can support cosmic ray acceleration and production of high-energy neutrinos. Multi-messenger searches for neutrinos from blazars have traditionally focused on their gamma-ray emission, which can be simultaneously produced in photohadronic interactions. This approach proved vital in the identification of a candidate neutrino emitting blazar in 2017 by IceCube and other collaborations, with observations from Fermi-LAT and MAGIC playing important roles. Follow-up observations of this source by X-ray satellites proved helpful in constraining its SED, since X-rays originating from the hadronically co-produced gamma-rays absorbed in the source, can be correlated with the neutrino flux.

 

In this talk, my previous work characterising the gamma-ray activity of a sample of blazars in spatial coincidence with IceCube high-energy neutrinos will be presented. I will describe the identification of long-duration flares and estimation of the level of activity by calculating gamma-ray duty cycles. For sources with relevant flares, neutrino “light curves” obtained under the assumption of (Fermi-LAT) gamma-ray data produced through photo-pion cascades, will be discussed in the context of constraining the minimum flare duration for detecting very high-energy neutrinos from these blazars. I will also provide an overview of my planned analysis using X-ray selected blazars with IceCube data, and a study of catalogs used to select these sources.