跨越软伽马射线能区：利用 Compton Spectrometer and Imager (COSI) 和 Background and Transient Observer (BTO) 中的同时探测来理解天体物理暂现源
Across the soft gamma-ray regime: utilizing simultaneous detections in the Compton Spectrometer and Imager (COSI) and the Background and Transient Observer (BTO) to understand astrophysical transients
Hannah C. Gulick, Eliza Neights, Samer Al Nussirat, Claire Tianyi Chen, Kaylie Ching, Cassandra Dove, Alyson Joens, Carolyn Kierans, Hubert Liu, Israel Martinez… 展开作者
Hannah C. Gulick, Eliza Neights, Samer Al Nussirat, Claire Tianyi Chen, Kaylie Ching, Cassandra Dove, Alyson Joens, Carolyn Kierans, Hubert Liu, Israel Martinez, Tomas Mician, Shunsaku Nagasawa, Shreya Nandyala, Isabel Schmidtke, Derek Shah, Andreas Zoglauer, Kazuhiro Nakasawa, Tadayuki Takahashi, Juan-Carlos Martinez Oliveros, John A. Tomsick
备注：
12 pages of text with an additional 2 pages for acknowledgments and citations. 9 figures. 1 table
Compton Spectrometer and Imager (COSI) 是一项 NASA 资助的 Small Explorer (SMEX) 任务，计划于 2027 年发射。COSI 将搭载一台宽视场伽马射线望远镜，旨在对 0.2--5 MeV 范围内的整个天空进行观测。该仪器使用锗探测器，将以卓越的能量分辨率和度级别的定位能力，提供天体物理源的成像、光谱分析和偏振测量。除了主仪器外，COSI 还将搭载一个名为 Background and Transient Observer (BTO) 的学生合作项目。BTO 将把 COSI 的通带扩展到低于 200 keV 的能量范围，从而实现跨越 30 keV--2 MeV 共享能段的光谱分析。BTO 仪器将由两个 NaI 闪烁体和学生设计的读出电子设备组成。利用 COSI 和 BTO 仪器的光谱信息，将能够对诸如伽马射线暴的能量峰值反转、磁星耀斑的特征以及一系列暂现现象的事件频率等物理现象进行约束。在本文中，我们介绍了 BTO 的预期科学产出，并评论了 COSI 和 BTO 任务的共享产出。我们包含了利用 BTO 的光谱响应进行的伽马射线暴、磁星巨型耀斑和地球伽马射线闪的模拟。此外，我们估计了 BTO 的伽马射线暴探测率，发现 BTO 每年将探测到约 150 个伽马射线暴，其中大部分事件为长暴。
英文摘要：
The Compton Spectrometer and Imager (COSI) is a NASA funded Small Explorer (SMEX) mission slated to launch in 2027. COSI will house a wide-field gamma-ray telescope designed to survey the entire sky in the 0.2--5 MeV range. Using germanium detectors, the instrument will provide imaging, spectroscopy, and polarimetry of astrophysical sources with excellent energy resolution and degree-scale localization capabilities. In addition to the main instrument, COSI will fly with a student collaboration project known as the Background and Transient Observer (BTO). BTO will extend the COSI bandpass to energies lower than 200 keV, thus enabling spectral analysis across the shared band of 30 keV--2 MeV range. The BTO instrument will consist of two NaI scintillators and student-designed readout electronics. Using spectral information from both the COSI and BTO instruments, physics such as the energy peak turnover in gamma-ray bursts, the characteristics of magnetar flares, and the event frequency of a range of transient phenomena will be constrained. In this paper, we present the expected science returnables from BTO and comment on the shared returnables from the COSI and BTO missions. We include simulations of gamma-ray bursts, magnetar giant flares, and terrestrial gamma-ray flashes using BTO's spectral response. Additionally, we estimate BTO's gamma-ray burst detection rate and find that BTO will detect ~150 gamma-ray bursts per year, with most of these events being long bursts.
Signal processing and data acquisition system for the BTO detectors onboard COSI
Space Sciences Laboratory, University of California, Berkeley（加州大学伯克利分校空间科学实验室）；International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP, WPI), KEK（高能加速器研究机构量子场测量系统国际中心）；Department of Physics, Nagoya University（名古屋大学物理学系）；The Hakubi Center for Advanced Research, Kyoto University（京都大学博古利高级研究中心）；Department of Physics, Kyoto University（京都大学物理学系）
The Compton Spectrometer and Imager (COSI) is a balloon-borne, soft-gamma ray imager, spectrometer, and polarimeter with sensitivity from 0.2 to 5 MeV. Utilizing a compact Compton telescope design with twelve cross-strip, high-purity germanium detectors, COSI has three main science goals: study the 511 keV positron annihilation line from the Galactic plane, image diffuse emission from stellar nuclear lines, and perform polarization studies of gamma-ray bursts and other extreme astrophysical environments. COSI has just completed a successful 46-day flight on NASA's new Super Pressure Balloon, l…
In this Astro2020 APC White Paper, we describe a Small Explorer (SMEX) mission concept called the Compton Spectrometer and Imager. COSI is a Compton telescope that covers the bandpass often referred to as the "MeV Gap" because it is the least explored region of the whole electromagnetic spectrum. COSI provides a significant improvement in sensitivity along with high-resolution spectroscopy, enabling studies of 511 keV electron-positron annihilation emission and measurements of several radioactive elements that trace the Galactic history of supernovae. COSI also measures polarization of gamma-r…
The Compton Spectrometer and Imager (COSI) is a 0.2-5 MeV Compton telescope capable of imaging, spectroscopy, and polarimetry of astrophysical sources. Such capabilities are made possible by COSI's germanium cross-strip detectors, which provide high efficiency, high resolution spectroscopy and precise 3D positioning of photon interactions. Science goals for COSI include studies of 0.511 MeV emission from antimatter annihilation in the Galaxy, mapping radioactive elements from nucleosynthesis, determining emission mechanisms and source geometries with polarization, and detecting and localizing …
The Compton Spectrometer and Imager (COSI) is a balloon-borne compact Compton telescope designed to survey the 0.2-5 MeV sky. COSI's energy resolution of $\sim$0.2% at 1.8 MeV, single-photon reconstruction, and wide field of view make it capable of studying astrophysical nuclear lines, particularly the 1809 keV $γ$-ray line from decaying Galactic $^{26}$Al. Most $^{26}$Al originates in massive stars and core-collapse supernova nucleosynthesis, but the path from stellar evolution models to Galaxy-wide emission remains unconstrained. In 2016, COSI had a successful 46-day flight on a NASA superpr…
A long duration gamma-ray burst, GRB 160530A, was detected by the Compton Spectrometer and Imager (COSI) during the 2016 COSI Super Pressure Balloon campaign. As a Compton telescope, COSI is inherently sensitive to the polarization of gamma-ray sources in the energy range 0.2-5.0 MeV. We measured the polarization of GRB 160530A using 1) a standard method (SM) based on fitting the distribution of azimuthal scattering angles with a modulation curve, and 2) an unbinned, maximum likelihood method (MLM). In both cases, the measured polarization level was below the $99\%$ confidence minimum detectab…
The Compton Spectrometer and Imager (COSI) is a balloon-borne gamma-ray (0.2-5 MeV) telescope designed to study astrophysical sources. COSI employs a compact Compton telescope design utilizing 12 high-purity germanium double-sided strip detectors and is inherently sensitive to polarization. In 2016, COSI was launched from Wanaka, New Zealand and completed a successful 46-day flight on NASA's new Super Pressure Balloon. In order to perform imaging, spectral, and polarization analysis of the sources observed during the 2016 flight, we compute the detector response from well-benchmarked simulatio…
The Compton Spectrometer and Imager (COSI) is a balloon-borne gamma-ray (0.2-5 MeV) telescope with inherent sensitivity to polarization. COSI's main goal is to study astrophysical sources such as $γ$-ray bursts, positron annihilation, Galactic nucleosynthesis, and compact objects. COSI employs a compact Compton telescope design utilizing 12 high-purity cross strip germanium detectors (size: $8\times8\times1.5$ cm$^3$, 2 mm strip pitch). We require well-benchmarked simulations to simulate the full instrument response used for data analysis, to optimize our analysis algorithms, and to better und…
The Compton Spectrometer and Imager (COSI) is a balloon-borne compact Compton telescope designed to survey the $γ$-ray sky from 0.2 to 5 MeV. COSI's wide field-of-view (FOV) and excellent energy resolution from high-purity germanium detectors make it uniquely capable of probing this under-explored energy regime. In particular, it can facilitate understanding of stellar nucleosynthesis through studies of diffuse emission from the radioisotope $\mathrm{^{26}Al}$ at 1.809 MeV. In 2016, COSI was launched from Wanaka, New Zealand on a NASA superpressure balloon and flew for 46 days. The flight was …
Predictions for Short Gamma-Ray Burst Detections by COSI
The George Washington University（乔治华盛顿大学）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；Louisiana State University（路易斯安那州立大学）；INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所-博洛尼亚天体物理与空间科学观测站）；Clemson University（克莱姆森大学）；Johannes Gutenberg-Universität Mainz（约翰内斯·古腾堡大学美因茨分校）；University of California Berkeley（加州大学伯克利分校）；NASA Marshall Space Flight Center（NASA马歇尔太空飞行中心）；National Tsing Hua University（国立清华大学）
Localization and Confidence Region Estimation of Short GRBs with the COSI BGO Shield Using a HEALPix-Based Deep Learning Approach
INAF/OAS Bologna（意大利国家天体物理研究所博洛尼亚天文台）；Louisiana State University（路易斯安那州立大学）；George Washington University（乔治华盛顿大学）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；University of Maryland, College Park（马里兰大学帕克分校）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（NASA/戈达德太空飞行中心空间科学与技术研究探索中心）；University of Bologna（博洛尼亚大学）；Johannes Gutenberg-Universität Mainz（美因茨约翰内斯古腾堡大学）；George Mason University（乔治梅森大学）；INAF/OA Catania（意大利国家天体物理研究所卡塔尼亚天文台）；U.S. Naval Research Laboratory（美国海军研究实验室）；Clemson University（克莱姆森大学）
The balloon-borne Compton Spectrometer and Imager (COSI) had a successful 46-day flight in 2016. The instrument is sensitive to photons in the energy range $0.2$-$5$ MeV. Compton telescopes have the advantage of a unique imaging response and provide the possibility of strong background suppression. With its high-purity germanium detectors, COSI can precisely map $γ$-ray line emission. The strongest persistent and diffuse $γ$-ray line signal is the 511 keV emission line from the annihilation of electrons with positrons from the direction of the Galactic centre. While many sources have been prop…
The signature of positron annihilation, namely the 511 keV $γ$-ray line, was first detected coming from the direction of the Galactic center in the 1970's, but the source of Galactic positrons still remains a puzzle. The measured flux of the annihilation corresponds to an intense steady source of positron production, with an annihilation rate on the order of $\sim10^{43}$~e$^{+}$/s. The 511 keV emission is the strongest persistent Galactic $γ$-ray line signal and it shows a concentration towards the Galactic center region. An additional low-surface brightness component is aligned with the Gala…
Detectability of Polarized Gamma-ray Emission from Blazar Flares with COSI
Louisiana State University（路易斯安那州立大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）；Clemson University（克莱姆森大学）；Johannes Gutenberg-Universität Mainz（美因茨约翰内斯古腾堡大学）；University of Maryland, College Park（马里兰大学帕克分校）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；NASA Marshall Space Flight Center（美国宇航局马歇尔太空飞行中心）；Foundation for Research（研究基金会）
Sub-MeV gamma-ray lines from an endothermic interpretation of the LZ recoil candidate
Southeastern Universities Research Association (SURA)（东南大学研究协会）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；International Institute of Physics, Federal University of Rio Grande do Norte（北里奥格兰德联邦大学物理国际研究所）；Observatório Nacional（国家天文台）
本文提出重暗物质内热上散射解释 LZ 高能核反冲候选事件，并指出其辐射衰变产生亚 MeV 伽马射线线，可被 COSI 探测，为验证该解释提供机会。
