The recently detected gamma-ray emission from Starburst galaxies is most commonly considered to be diffuse emission arising from strong interactions of accelerated cosmic rays. Mannheim et al. (2012), however, have argued that a population of individ
ual pulsar-wind nebulae (PWNe) could be responsible for the detected TeV emission. Here we show that the Starburst environment plays a critical role in the TeV emission from Starburst PWNe, and perform the first detailed calculations for this scenario. Our approach is based on the measured star-formation rates in the Starburst nuclei of NGC 253 and M 82, assumed pulsar birth periods and a simple model for the injection of non-thermal particles. The two-zone model applied here takes into account the high far-infrared radiation field, and different densities and magnetic fields in the PWNe and the Starburst regions, as well as particle escape. We confirm that PWNe can make a significant contribution to the TeV fluxes, provided that the injection spectrum of particles is rather hard and that the average pulsar birth period is rather short (~35 ms). The PWN contribution should lead to a distinct spectral feature which can be probed by future instruments such as CTA.
The past decade has seen a dramatic improvement in the quality of data available at both high (HE: 100 MeV to 100 GeV) and very high (VHE: 100 GeV to 100 TeV) gamma-ray energies. With three years of data from the Fermi Large Area Telescope (LAT) and
deep pointed observations with arrays of Cherenkov telescope, continuous spectral coverage from 100 MeV to $sim10$ TeV exists for the first time for the brightest gamma-ray sources. The Fermi-LAT is likely to continue for several years, resulting in significant improvements in high energy sensitivity. On the same timescale, the Cherenkov Telescope Array (CTA) will be constructed providing unprecedented VHE capabilities. The optimisation of CTA must take into account competition and complementarity with Fermi, in particularly in the overlapping energy range 10$-$100 GeV. Here we compare the performance of Fermi-LAT and the current baseline CTA design for steady and transient, point-like and extended sources.
