PANGU: A High Resolution Gamma-Ray Space Telescope

Abstract

We describe the instrument concept of a high angular resolution telescope dedicated to the sub-GeV (from 10 MeV to 1 GeV) gamma-ray photon detection. This mission, named PANGU (PAir-productioN Gammaray Unit), has been suggested as a candidate for the joint small mission between the European Space Agency (ESA) and the Chinese Academy of Science (CAS). A wide range of topics of both astronomy and fundamental physics can be attacked with PANGU, covering Galactic and extragalactic cosmic-ray physics, extreme physics of a variety of extended (e.g. supernova remnants, galaxies, galaxy clusters) and compact (e.g. black holes, pulsars, gamma-ray bursts) objects, solar and terrestrial gamma-ray phenomena, and searching for dark matter decay and/or annihilation signature etc. The unprecedented point spread function can be achieved with a pairproduction telescope with a large number of thin active tracking layers to precisely reconstruct the pair-produced electron and positron tracks. Scintillating fibers or thin silicon micro-strip detectors are suitable technology for such a tracker. The energy measurement is achieved by measuring the momentum of the electrons and positrons through a magnetic field. The innovated spectrometer approach provides superior photon pointing resolution, and is particular suitable in the sub-GeV range. The level of tracking precision makes it possible to measure the polarization of gamma rays, which would open up a new frontier in gamma-ray astronomy. The frequent full-sky survey at sub-GeV with PANGU's large field of view and significantly improved point spread function would provide crucial information to GeV-TeV astrophysics for current/future missions including Fermi, DAMPE, HERD, and CTA, and other multi-wavelength telescopes.

Time-dependent neutrino emission from Mrk 421 during flares and predictions for IceCube

“…IBIS/INTEGRAL [66] and future, e.g. PANGU [67], γ-ray satellites operating in the 1-100 MeV energy range. In addition, the Bethe-Heitler emission is expected to be highly polarized and, as such, its modeling constitutes a prediction that may be tested by future γ-ray polarimeters, such as ASTROGAM 2 and AdEPT [68].…”

γ-Ray polarimetry with conversions to e+e− pairs: Polarization asymmetry and the way to measure it

“…For thick wafers (≈ 500 µm [47,48,49,50,51,52]), the effective polarization asymmetry, and therefore the dilution factor, are still low because multiple scattering remains an issue. It's only if very thin wafers can be made, held and launched (≈ 150 µm [53]) that there is some hope of a sizeable sensitivity to polarization (see Figs. 5 and 6 of Ref.…”

MeV astronomy with Herwig?

“…Alongside strong efforts in direct detection searches [4][5][6], one of the leading constraints in the MeV to GeV range is expected to be set by indirect detection [7]. Besides the existing GeVscale gamma-ray and cosmic-ray observatories [8][9][10][11][12], several proposed MeV gamma-ray telescopes such as e-A [13] and AMEGO [14] and concept telescopes [15][16][17][18] herald a new era in astronomy. A wealth of hidden sector models in the sub-GeV range can be tested.…”