The e-ASTROGAM mission (exploring the extreme Universe with gamma rays in the MeV-GeV range)

Abstract: e-ASTROGAM (`enhanced ASTROGAM') is a breakthrough Observatory mission dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. In the largely unexplored MeV-GeV domain, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on Galactic ecosystems. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and the promise of eLISA. Keywords: High-energy gamma-ray astronomy, High-energy astrophysics, Nuclear Astrophysics, Compton and Pair creation telescope, Gamma-ray bursts, Active Galactic Nuclei, Jets, Outflows, Multiwavelength observations of the Universe, Counterparts of gravitational waves, Fermi, Dark Matter, Nucleosynthesis, Early Universe, Supernovae, Cosmic Rays, Cosmic antimatter.

Overview of the e-ASTROGAM Mission

The paper discusses the e-ASTROGAM mission, a proposed space observatory dedicated to studying the Universe through gamma rays in the MeV–GeV energy range. The mission aims to advance the field of high-energy gamma-ray astronomy with a new, sensitive instrument capable of unprecedented angular and energy resolution, as well as polarimetric capability. This observatory will offer insights into the nature of various high-energy astrophysical phenomena, including gamma-ray bursts (GRBs), active galactic nuclei (AGN), cosmic rays, and supernovae, with a focus on detecting and analyzing emissions up to several GeV.

Mission Components and Objectives

The e-ASTROGAM mission is designed around a payload consisting of a silicon tracker, a calorimeter, and an anticoincidence system, allowing for refined gamma-ray detection and analysis. The silicon tracker and calorimeter work together to measure the energy and interaction position of gamma rays, while the anticoincidence system helps differentiate gamma-ray signals from background noise induced by charged particles.

This mission's core scientific objectives address three primary topics: understanding the processes in extreme astrophysical environments, the role of cosmic rays in galaxy evolution, and the study of nucleosynthesis and chemical enrichment in the Galaxy. The mission is expected to discover new sources in gamma-ray astronomy by improving point-source sensitivity over its predecessors by up to two orders of magnitude, providing new insights into the particle acceleration processes and the nature of cosmic antimatter sources.

Scientific Implications and Future Prospects

Processes at the Heart of the Extreme Universe: e-ASTROGAM will probe the transition from low-energy phenomena to less understood extreme processes. In particular, its polarimetric capabilities could elucidate the composition of relativistic jets and outflows, lending insight into the mechanisms powering gamma-ray bursts and AGN jets.

Cosmic Ray Origin and Effects: Higher sensitivity to cosmic-ray emissions will refine our understanding of particle diffusion and star formation dynamics within the Galaxy. e-ASTROGAM could effectively discriminate between astrophysical and dark matter signals, providing critical data on positron emissions and cosmic antimatter.

Nucleosynthesis and Galactic Chemical Evolution: By significantly improving line sensitivity, e-ASTROGAM will offer a clearer understanding of isotope formation in stars and their distribution across the Galaxy. Such data will enhance models of supernova activity and inform precision cosmology applications.

Observational Capabilities & Mission Design

During its proposed lifetime, e-ASTROGAM will operate with a wide field of view, detecting transients and nova emissions alongside steady sources like pulsars and magnetars. By maintaining flexible observation strategies, this mission will open significant opportunities in multi-messenger astronomy, providing complementary data to established observatories.

Using a carefully designed payload, the mission aligns with present technological capabilities while leveraging innovations in silicon detector technology, ensuring long-term operational efficiency and robust data quality.

Overall, e-ASTROGAM promises to be an insightful addition to astrophysical research, poised to refine theories about the high-energy Universe significantly, expand our observatory capabilities in the MeV–GeV regime, and pave the way for future discoveries in gamma-ray astronomy.