Gamma-ray astronomy
A huge number of gamma ray emitting high-energy systems like black holes, stellar coronas, neutron stars, white dwarf stars, remnants of supernova, clusters of galaxies, including the Crab Nebula and the Vela pulsar (the most powerful source so far), have been identified, alongside an overall diffuse gamma-ray background along the plane of the Milky Way galaxy.
Cosmic radiation with the highest energy triggers electron-photon cascades in the atmosphere, while lower-energy gamma rays are only detectable above it.
Gamma-ray bursts, like GRB 190114C, are transient phenomena challenging our understanding of high-energy astrophysical processes, ranging from microseconds to several hundred seconds.
Gamma rays are difficult to detect due to their high energy and their blocking by the Earth’s atmosphere, necessitating balloon-borne detectors and artificial satellites in space.
Early experiments in the 1950s and 1960s used balloons to carry instruments to access altitudes where the atmospheric absorption of gamma rays is low, followed by the launch of the first gamma-ray satellites: SAS 2 (1972) and COS-B (1975).
These were defense satellites originally designed to detect gamma rays from secret nuclear testing, but they luckily discovered puzzling gamma-ray bursts coming from deep space.
This interdisciplinary field involves collaboration among physicists, astrophysicists, and engineers in projects like the High Energy Stereoscopic System (H.E.S.S.
As GeV gamma rays are important in the study of extra-solar, and especially extragalactic, astronomy, new observations may complicate some prior models and findings.
Technological advancements, including advanced mirror designs, better camera technologies, improved trigger systems, faster readout electronics, high-performance photon detectors like Silicon photomultipliers (SiPMs), alongside innovative data processing algorithms like time-tagging techniques and event reconstruction methods, will enhance spatial and temporal resolution.
The ground-based Cherenkov Telescope Array project, a next-generation gamma ray observatory which will incorporate many of these improvements and will be ten times more sensitive, is planned to be fully operational by 2025.
Studied since the mid-1980s with instruments on board a variety of satellites and space probes, including Soviet Venera spacecraft and the Pioneer Venus Orbiter, the sources of these enigmatic high-energy flashes remain a mystery.
Solar flares create massive amounts of radiation across the full electromagnetic spectrum from the longest wavelength, radio waves, to high energy gamma rays.
These gamma rays can be observed and allow scientists to determine the major results of the energy released, which is not provided by the emissions from other wavelengths.
The extremely low photon fluxes at such high energies require detector effective areas that are impractically large for current space-based instruments.
Gamma radiation in the TeV range emanating from the Crab Nebula was first detected in 1989 by the Fred Lawrence Whipple Observatory at Mt.
Modern Cherenkov telescope experiments like H.E.S.S., VERITAS, MAGIC, and CANGAROO III can detect the Crab Nebula in a few minutes.
[14] The supernova SN1987A in the Large Magellanic Cloud (LMC) was discovered on February 23, 1987, and its progenitor, Sanduleak -69 202, was a blue supergiant with luminosity of 2-5×1038 erg/s.
The Compton Gamma Ray Observatory (CGRO) was designed to take advantage of the major advances in detector technology during the 1980s, and was launched in 1991.
By identifying the first non-gamma ray counterparts to gamma-ray bursts, it opened the way for their precise position determination and optical observation of their fading remnants in distant galaxies.
These bubbles of high-energy radiation are suspected as erupting from a massive black hole or evidence of a burst of star formations from millions of years ago.
[17] In 2011 the Fermi team released its second catalog of gamma-ray sources detected by the satellite's Large Area Telescope (LAT), which produced an inventory of 1,873 objects shining with the highest-energy form of light.
The gamma-ray burst occurred as some giant stars exploded at the ends of their lives before collapsing into black holes, in the direction of the constellation Sagitta.
