Towards the Next-Generation Gamma-Ray Observatory

Deutsches Elektronen-Synchrotron DESY
Notkestraße 85
22607 Hamburg

Humboldt Universität zu Berlin
Department Physik
Newtonstr. 15
D-12489 Berlin

The Universe is home to countless stunning and beautiful phenomena, some of which are almost inconceivably violent and energetic. Supermassive black holes and galactic binary systems are two examples of these marvels. They generate streams of matter and energy moving away from their accreting black holes with velocities close to the speed of light. These powerful flows, so-called jets, produce gamma-rays, an extremely high-energy form of electromagnetic radiation, billions of times more energetic than visible light. What is happening in astrophysical jets to produce these high-energy radiation? How do black holes form jets? Where in these jet are particles accelerated to energies far beyond to what is possible with Earth-based accelerators? These are the core questions addressed by the proposed Helmholtz Young Investigators Group.

Astrophysical jets are most powerful at high-energies. Very high-energy gamma-ray observation is likely to be the key to understanding the underlying physics of particle acceleration in jets, but current-generation instruments are not sensitive enough to answer the fundamental questions. The Cherenkov Telescope Array (CTA), a next-generation gamma-ray observatory being built by European institutions, will be a unique tool for the Young Investigators Group to explore the high-energy nature of astrophysical jets. This gamma-ray telescope will dwarf its predecessors, MAGIC, H.E.S.S. and VERITAS, in nearly all respects - sensitivity, angular resolution and energy coverage. CTA is expected to deliver first astrophysical data in 2014.

The proposed Young Investigators Group will prepare for the science phase and help transfering the vast knowledge gained in current generation instruments to CTA. The first stage of this preparatory phase focuses on significantly improving the sensitivity of CTA through implementation of sophisticated methods for background suppression at the telescope design, trigger, and analysis level. The group will develop innovative observing strategies to observe multiple sources simultaneously and most effectively. The group will also use various realistic testbeds to exercise the power of the envisaged methods for background suppression and sensitivity enhancement. This will be done by applying for observation time as external investigator at existing telescopes and working on the data obtained. Such observations will also provide physics data as an important ingredient of PhD theses to be written within the group.

CTA will be a versatile instrument which will allow the exploration of many different science topics. The proposed Young Investigators Group will also pursue a program to search for evidence of a gamma-ray annihilation signal of dark matter - the nature of dark matter is one of the most important questions in science in the 21st century. While this aspect of the program is more exploratory than jet studies, a positive result would have unrivaled impact on astronomy and particle physics, and upper limits will be the most constraining available in
this energy range.

The program of the proposed Young Investigators Group will be carried out in close collaboration with experimental and theoretical groups at DESY, Humboldt University, the astronomy groups at Potsdam University and AIP Potsdam, and the high-energy astrophysics group at Leeds University. The program will stimulate education and training of students and young researchers. This research plan addresses key questions of the Helmholtz research field “Structure of Matter”.