The Crab Pulsar and Nebula as Seen in Gamma-Rays

Slightly more than 30 years ago, Whipple detection of the Crab Nebula was the start of Very High Energy gamma-ray astronomy. Since then, gamma-ray observations of this source have continued to provide new surprises and challenges to theories, with the detection of fast variability, pulsed emission up to unexpectedly high energy, and the very recent detection of photons with energy exceeding 1 PeV. In this article, we review the impact of gamma-ray observations on our understanding of this extraordinary accelerator.

35 Years of Ground-Based Gamma-ray Astronomy

This paper provides a brief, personal account of the development of ground-based gamma-ray astronomy, primarily over the last 35 years, with some digressions into the earlier history of the field. Ideas related to the imaging of Cherenkov events and the potential for the use of arrays were in existence for some time before the technical expertise required for their exploitation emerged. There has been occasional controversy, great creativity and some heroic determination—all of it part of establishing a new window into the universe.

Half-a-century of gamma-ray astrophysics at the Max-Planck Institute for Extraterrestrial Physics

Gamma-ray astronomy has been one of the prime scientific research fields of the Max-Planck Institute for Extraterrestrial Physics (MPE) from its beginning. Over the years, the entire gamma-ray energy range accessible from space was explored. The purpose of this review article is to summarise the achievements of the gamma-ray group at MPE during the last 50+ years. This covers a substantial part of the general history of space-based gamma-ray astronomy, for which both, general review articles (e.g. Pinkau in Exp Astron 5: 157, 2009; Schönfelder in AN 323: 524, 2002; Trimble in AIP Conf Proc 304: 40, 1994) and a detailed tabular list of events and missions (Leonard and Gehrels in https://heasarc.gsfc.nasa.gov/docs/history, version 1.0.8, 2009), have been compiled. Here, we describe the gamma-ray activities at MPE from the beginning till the present, reviewing the tight interplay between new technological developments towards new instruments and scientific progress in understanding gamma-ray sources in the sky. This covers (i) the early development of instruments and their tests on half a dozen balloon flights, (ii) the involvement in the most important space missions at the time, i.e. ESA’s COS-B satellite, NASA’s Compton Gamma-ray Observatory and Fermi Space Telescope, as well as ESA’s INTEGRAL observatory, (iii) the participation in several other missions such as TD-1, Solar Maximum Mission, or Ulysses, and (iv) the complementary ground-based optical instruments OPTIMA and GROND to enhance selected science topics (pulsars, gamma-ray bursts). With the gradual running-out of institutional support since 2010, gamma-ray astrophysics as a main research field has now come to an end at MPE.

Evolution of Data Formats in Very-High-Energy Gamma-ray Astronomy

Most major scientific results produced by ground-based gamma-ray telescopes in the last 30 years have been obtained by expert members of the collaborations operating these instruments. This is due to the proprietary data and software policies adopted by these collaborations. However, the advent of the next generation of telescopes and their operation as observatories open to the astronomical community, along with a generally increasing demand for open science, confront gamma-ray astronomers with the challenge of sharing their data and analysis tools. As a consequence, in the last few years, the development of open-source science tools has progressed in parallel with the endeavour to define a standardised data format for astronomical gamma-ray data. The latter constitutes the main topic of this review. Common data specifications provide equally important benefits to the current and future generation of gamma-ray instruments: they allow the data from different instruments, including legacy data from decommissioned telescopes, to be easily combined and analysed within the same software framework. In addition, standardised data accessible to the public, and analysable with open-source software, grant fully-reproducible results. In this article, we provide an overview of the evolution of the data format for gamma-ray astronomical data, focusing on its progression from private and diverse specifications to prototypical open and standardised ones. The latter have already been successfully employed in a number of publications paving the way to the analysis of data from the next generation of gamma-ray instruments, and to an open and reproducible way of conducting gamma-ray astronomy.

GAMMA-RAY BURSTS: A PERSONAL VIEW

The first observations in gamma-ray astronomy were made in the late 1960's, primarily by balloon-borne observations. In the early 1970's, gamma-ray bursts were discovered, completely by accident, by satellites looking for man-made nuclear explosions in space. The celestial nature of these events were soon confirmed by other satellites. The first large detector system designed for cosmic gamma-ray bursts observations was the BATSE instrument on the Compton Gamma-Ray Observatory. Some of the details of the instrumentation onboard ballons and satellites and the gamma-ray bursts observational properties they determined are presented.

A compact instrument for gamma-ray burst detection on a CubeSat platform I

The Educational Irish Research Satellite 1 (EIRSAT-1) is a 2U CubeSat being developed under ESA’s Fly Your Satellite! programme. The project has many aspects, which are primarily educational, but also include space qualification of new detector technologies for gamma-ray astronomy and the detection of gamma-ray bursts (GRBs). The Gamma-ray Module (GMOD), the main mission payload, is a small gamma-ray spectrometer comprising a 25 mm × 25 mm × 40 mm cerium bromide scintillator coupled to an array of 16 silicon photomultipliers. The readout is provided by IDE3380 (SIPHRA), a low-power and radiation tolerant readout ASIC. GMOD will detect gamma-rays and measure their energies in a range from tens of keV to a few MeV. Monte Carlo simulations were performed using the Medium Energy Gamma-ray Astronomy Library to evaluate GMOD’s capability for the detection of GRBs in low Earth orbit. The simulations used a detailed mass model of the full spacecraft derived from a very high-fidelity 3D CAD model. The sky-average effective area of GMOD on board EIRSAT-1 was found to be 10 cm2 at 120 keV. The instrument is expected to detect between 11 and 14 GRBs, at a significance greater than 10σ (and up to 32 at 5σ), during a nominal one-year mission. The shape of the scintillator in GMOD results in omni-directional sensitivity which allows for a nearly all-sky field of view.