Time evolution of storms producing terrestrial gamma-ray flashes using era5 reanalysis data, gps, lightning and geo-stationary satellite observations

In this article, we report the first investigation over time of the atmospheric conditions around terrestrial gamma-ray flash (TGF) occurrences, using GPS sensors in combination with geostationary satellite observations and ERA5 reanalysis data. The goal is to understand which characteristics are favorable to the development of these events and to investigate if any precursor signals can be expected. A total of 9 TGFs, occurring at a distance lower than 45 km from a GPS sensor, were analyzed and two of them are shown here as an example analysis. Moreover, the lightning activity, collected by the World Wide Lightning Location Network (WWLLN), was used in order to identify any links and correlations with TGF occurrence and precipitable water vapor (PWV) trends. The combined use of GPS and the stroke rate trends identified, for all cases, a recurring pattern in which an increase in PWV is observed on a timescale of about two hours before the TGF occurrence that can be placed within the lightning peak. The temporal relation between the PWV trend and TGF occurrence is strictly related to the position of GPS sensors in relation to TGF coordinates. The life cycle of these storms observed by geostationary sensors described TGF-producing clouds as intense with a wide range of extensions and, in all cases, the TGF is located at the edge of the convective cell. Furthermore, the satellite data provide an added value in associating the GPS water vapor trend to the convective cell generating the TGF. The investigation with ERA5 reanalysis data showed that TGFs mainly occur in convective environments with unexceptional values with respect to the monthly average value of parameters measured at the same location. Moreover, the analysis showed the strong potential of the use of GPS data for the troposphere characterization in areas with complex territorial morphologies. This study provides indications on the dynamics of con-vective systems linked to TGFs and will certainly help refine our understanding of their production, as well as highlighting a potential approach through the use of GPS data to explore the lightning activity trend and TGF occurrences.publishedVersio

The AGILE Pipeline for Gravitational Waves Events Follow-up

The first direct detection of gravitational waves (GW) by Advanced LIGO detectors in September 2015 has drawn the attention of the astrophysical community that is now searching for the electromagnetic counterparts of the detected GW events. The AGILE (Astro-Rivelatore Gamma a Immagini Leggero) mission is primarily devoted to the high-energy astrophysical study of gamma-ray sources in the 30 MeV to 30 GeV energy range. The capability of the AGILE satellite for the discovery of transients is unique: the actual spinning configuration of the satellite, together with a large field of view and a good sensitivity of F =(1-2) ×10-8ergcm-2 s-1 for 100s integrations, provides a coverage of 80% of the sky, with each position exposed for 100 seconds, 200 times a day. The AGILE team signed a memorandum of understanding (MoU) with the LIGO/Virgo collaboration to follow the GW notices provided through the GCN network. In this paper we describe our automated pipeline that reacts to LIGO/Virgo GW notices and performs different kind of automated analysis to boost the search for of GW event counterparts

A FPGA-based digital readout system for a multi-channel X and gamma-ray spectrometer

The XGS project aims to develop a multi-channel broadband X and gamma -ray spectrometer for space applications. The experiment envisages the use of solid-state Silicon Drift Detectors coupled to inorganic scintillator bars. A prototype is under development in the framework of an INAF funded project, in which the detector signal will be digitized by a fast ADC and further digitally processed. An overview of the system architecture and the test equipment currently under development based on low-cost commercial system-on-chip FPGA boards will be given

The Gamma-Flash data acquisition system for observation of terrestrial gamma-ray flashes

Gamma-Flash is an Italian project funded by the Italian Space Agency (ASI) and led by the National Institute for Astrophysics (INAF), devoted to the observation and study of high-energy phenomena, such as terrestrial gamma-ray flashes and gamma-ray glows produced in the Earth's atmosphere during thunderstorms. The project's detectors and the data acquisition and control system (DACS) are placed at the "O. Vittori" observatory on the top of Mt. Cimone (Italy). Another payload will be placed on an aircraft for observations of thunderstorms in the air. This work presents the architecture of the data acquisition and control system and the data flow.Comment: 4 pages, 1 figure, Astronomical Data Analysis Software and System XXXII (2022

The wide field monitor and spectrometer instrument on board the ASTENA satellite mission concept

The ASTENA mission concept under study in the framework of the H2020 AHEAD project includes a wide field monitor and spectrometer (WFM/S), mainly dedicated to GRBs. The instrument, composed by different units, is sensitive in the range 1 keV - 20 MeV. The total isotropic detection area will be 3.0 m2 with a FOV of about 1.35 sr. The WFM will allow the detection and spectroscopic and polarimetric characterization of all classes of GRBs. Each module is a coded mask telescope that will allow the source localization within few arcmin up to 50-100 keV. The detector core is based on the coupling of low-noise, solid-state Silicon Drift Detectors (SDDs) with CsI(Tl) scintillator bars. Low-energy and highenergy photons are discriminated using the on-board electronics. The instrument design and preliminary experimental characterizations are reported and discussed

PixDD: a multi-pixel silicon drift detector for high-throughput spectral-timing studies

The Pixelated silicon Drift Detector (PixDD) is a two-dimensional multi-pixel X-ray sensor based on the technology of Silicon Drift Detectors, designed to solve the dead time and pile-up issues of photon-integrating imaging detectors. Read out by a two-dimensional self-triggering Application-Specific Integrated Circuit named RIGEL, to which the sensor is bump-bonded, it operates in the 0:5 — 15 keV energy range and is designed to achieve single-photon sensitivity and good spectroscopic capabilities even at room temperature or with mild cooling (< 150 eV resolution at 6 keV at 0 °C). The paper reports on the design and performance tests of the 128-pixel prototype of the fully integrated system

The large area detector onboard the eXTP mission

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we will provide an overview of the LAD instrument design, its current status of development and anticipated performance