Session R10: Future Gamma-ray Space Missions

Live

The All sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission that will provide ground breaking new capabilities for multi-messenger astrophysics - identifying and studying the astrophysical objects that produce gravitational waves and neutrinos; along with a rich menu of additional science in astrophysical jets, compact objects, dark matter and nuclear line spectroscopy. AMEGO will cover the energy range from 200 keV to over 20 GeV, with more than an order of magnitude improvement in sensitivity relative to previous missions. AMEGO provides breakthrough capabilities in three areas of MeV astrophysics: nuclear line spectroscopy will provide new insight into the currently topical area of element formation in dynamic environments; polarization capabilities will uniquely probe conditions and processes in astrophysical jets and in the magnetospheres and winds of compact objects; a wide field of view and broad energy range provide outstanding capability in time domain and multi-messenger astrophysics with excellent synergies with observations at other wavelengths.   

Live

The electromagnetic spectrum from a few hundred keV to $>$100 MeV remains one of the most under-explored. Recent breakthroughs in multimessenger astrophysics have revealed that it is paramount in the study of sources that have unique signatures in the gamma-ray regime. The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a mission concept targeting multimessenger science in this energy range. The AMEGO instrument comprises four subsystems: a tracker, a low-energy calorimeter, a high-energy calorimeter, and a plastic scintillator anticoincidence detector. I will discuss the development of the AMEGO prototype instrument, with the ultimate goal of a balloon flight in 2021. This prototype will validate the overall instrument design under flight-like conditions and demonstrate the ability to take data in the presence of high background. In this contribution, I will discuss the current status of the prototype and preliminary results.   

Live

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) mission concept is a combined Compton and pair-production telescope designed to survey the sky from ~200 keV to > 10 GeV with high continuum sensitivity, polarization sensitivity, and the ability to measure nuclear lines. AMEGO comprises a multi-layer double-sided silicon tracker for measuring particle tracks and the energy of Compton recoil electrons, a CZT imaging calorimeter which enables nuclear line spectroscopy, a CsI calorimeter to increase the energy range of the instrument, and a plastic scintillator anticoincidence detector for rejecting cosmic ray events. ComPair, the AMEGO prototype, is currently under development and will undergo beam tests in 2020 and a short-duration balloon flight is planned for late 2021. In this contribution, we present the prototype tracker subsystem which comprises seven layers of double-sided silicon detectors read out using a custom analogue front-end. We will also discuss the motivation behind the detector design and readout electronics in the context of the full AMEGO mission.   

Live

The European Space Observatory INTEGRAL has been providing excellent results on X-ray and $\gamma $--ray astronomy since 2002. However, the nature of the Galactic Center (GC) region excessive $\gamma $-ray radiation, in particular 511 keV positron annihilation line is still a mystery. I will present a concept of a potential $\gamma $-ray telescope with the major objectives: a) understand the nature of the GC supermassive black hole environment and other heavily populated sky regions, including the 511 keV positron annihilation line, by creating an intensity map with high spectral and spatial resolution; b) probe the origin of the Fermi Bubbles by extracting the diffuse MeV spectrum from the base of the bubbles; c) explore Galactic chemical evolution and sites of explosive element synthesis by conducting high-sensitivity measurements of nuclear lines. A telescope will also be capable to detect gamma-ray bursts and measure polarization. The instrument is based on a novel CdZnTe Imager and deployable coded aperture mask. The unique feature of proposed instrument is that it operates simultaneously in two modes, high-angular resolution enabled by coded aperture mask, and in Compton telescope mode, enabled by CdZnTe Imager.   

Live

The Lunar Occultation eXplorer (LOX) will leverage the power of temporal modulation to transform our understanding of the nuclear cosmos (0.1--10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms like Compton telescopes to mitigate mission complexity, technology development, and cost constraints, while delivering sensitivity (\textless ${10}^{-7}$cm$^{\mathrm{-2}}$ s$^{\mathrm{-1}}$ MeV$^{\mathrm{-1}})$, continuous all-sky monitoring, and sub-degree localization capabilities. LOX will operate from lunar orbit, using the Moon as an occulting disk to modulate astrophysical source signatures via repeated eclipses. Simplicity is a hallmark of this efficient and validated approach. LOX's lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by SWaP resources. Data analyses rely only on spacecraft ephemerides and a rigorous statistical framework rather than kinematic reconstruction, and its operational profile mimics low-resource planetary investigations. LOX is a low-risk, high-heritage implementation benefitting from decades of lunar exploration. The mission concept, validation from the Moon/Mars, and high-priority science goals will be reviewed to highlight what LOX can reveal about matter and energy lifecycles in our galaxy and beyond.   

Live

We report observations of the first astrophysical sources detected from the Moon and Mars at MeV energies. Our detections of the Crab Nebula and Cygnus X-1 demonstrate the efficacy of the Planetary and Lunar Occultation Technique (PLOT) as a paradigm for gamma-ray astronomy, and build upon ``first light'' demonstration of the technique by Miller {\&} Lawrence (2016). NASA's Lunar Prospector and Mars Odyssey Gamma-Ray Spectrometers served as proxies for a dedicated PLOT-based mission, and together provided modest (12{\%} FWHM@0.662 MeV) and high-resolution (\textless 0.4{\%} FWHM@1.332 MeV) spectra, respectively, for over 10 years. Long-term monitoring and spectral characterizations of the detected sources verifies basic tenets and validates the performance of the occultation methodology, reinforces its feasibility as an alternative astronomical detection paradigm for nuclear astrophysics investigations, and is an illustration of the fundamental benefits of the Moon (and Mars) as a platform for science. We will report details of the analysis methodology, present new insights into the behavior of the detected sources, contrast the benefits of lunar vs. Martian operating environments, and discuss the relevance of these results to the development of the Lunar Occultation eXplorer (LOX) mission concept.   

Live

A new era of multi-messenger astronomy broke ground after the first simultaneous detection of a short gamma-ray burst (SGRB) with a gravitational-wave (GW) signal. Coincident detections enable electromagnetic observations that probe many areas of astrophysics such as jet physics, neutron star equation of state, speed of gravity, and heavy element production. In order to increase the number of SGRB-GW simultaneous detections, the gamma-ray community needs broad-band sky coverage and continued sensitivity. BurstCube, a CubeSat for Gravitational Wave Counterparts, aims to expand sky coverage of the current suite of GRB monitors in order to detect and localize gamma-ray bursts (GRBs). BurstCube is designed with four Cesium Iodide scintillators coupled to arrays of silicon photo-multipliers (SiPMs) on a 6U CubeSat bus (a single U corresponds to cubic unit approx. 10 cm on each side) that are optimized for gamma-rays between 50 keV and 1 MeV, the ideal energy range for GRB prompt emission. BurstCube will compliment current gamma-ray observatories in the detection of GRBs as well as provide astronomical context to gravitational wave events detected by Advanced LIGO, Advanced Virgo, and KAGRA. We present the BurstCube scientific objectives and mission design.   

BurstCube, a CubeSat for Gravitational Wave Counterparts: Instrument Design

The recent detection of Gravitational Waves (GWs) has increased the need for multi-messenger astronomy to further our understanding of the nature and source of GWs as well as to probe fundamental physics questions such as neutron star equation of state, speed of gravity, and heavy element production.   \underline {BurstCube}, a \underline {CubeSat} for Gravitational Wave Counterparts,  will expand sky coverage of the current suite of gamma-ray bursts (GRB) monitors in order to detect and localize GRBs and search for simultaneous detections with GWs. \underline {BurstCube} is designed to fly on a 6U CubeSat and consists of four Cesium Iodide (CsI) scintillators coupled to large-area arrays of silicon photo-multipliers (SiPMs) with sensitivity to gamma-rays between 50 keV and 1 MeV.  The four CsI crystals are oriented to allow for localization of GRBs.  We discuss the BurstCube instrument design, associated front-end electronics, and preliminary performance characteristics.    

Not Participating

Joint detections between gravitational waves and gamma-ray bursts (GRBs) enables multi-messenger science and allows for constraints on the neutron star equation of state, tests of fundamental physics, and insight into the origin of the prompt emission. To increase the likelihood of these coincident detections, full sky coverage in the gamma-ray regime is needed. BurstCube will expand sky coverage and assist current observatories, such as \textit{Swift} and\textit{ Fermi}, in the detection and localization of GRBs within the energy range of 50 keV to 1 MeV. BurstCube, a 6U (10 x 20 x 30 cm) CubeSat comprised of four Cesium Iodide scintillators coupled to arrays of silicon photo-multipliers (SiPMs), is currently undergoing flight build and will reach launch readiness in the fall of 2021. We present the performance, current status of the mission, and future calibration of the instrument.