Andrea Giuliani (AG) has been part of the AGILE Science Team since 2001. During this period he has been involved in both technical aspects of the research activities, such as event selection and reconstruction with the GRID (Gamma Ray Imager Detector) instrument, and scientific aspects, among which modeling the gamma-ray emission of the interstellar medium and data analysis of gamma sources detected by AGILE, especially cosmic-ray accelerators (SNRs and PWNs) and GRBs.
Scientific software development for AGILE: AG is responsible for the event reconstruction software for the AGILE GRID. Since the gamma-ray detectors are based on the detection of photon pair production, the reconstruction software covers a special role in the instrument performances (efficiency, angular and energetic resolution). AG has developed a software code for track identification and reconstruction using the AGILE tracker, based on the kalman filter technique (KALMA). This software is the official tool used at the ASDC (ASI Science Data Center) and provides both energy and direction of the gamma-ray observed by AGILE. A simplified version of this algorithm (KALMEX) has been implemented in the AGILE on-board software in order to reject earth albedo events, as described in [4].
AG is also involved in the study of background rejection for the GRID instrument. The background is mainly due to charge particles which produce an event rate some orders of magnitude higher than the cosmic gamma-ray one. The algorithm developed by AG is able to discriminate signal events from background on the basis of topological characteristics of the event classes. This tool is part of the official software package and is part of the AGILE on-ground event selection pipeline.
Moreover AG has contributed to the development of DHSIM, a software which allows for the simulation of the AGILE on-board trigger logic. This tool has been extensively used to optimize the parameters of the on-board algorithms.
AG has participated to the Monte Carlo simulation of the AGILE data for a complete orbit. The simulation includes both the gamma-ray events as produced by cosmic sources, and the background events as induced by charged particles and albedo photons.
This Monte Carlo simulation, which has required about 1000 hours in CPU time, consists of about 10 million events and is the largest AGILE simulated event archive.
AG took part in the integration of the Tracker and Anticoincidence systems with the Satellite Payload Shell started in September 2005. During these phases a continuous monitoring of the system performances was required. This activity was carried on by AG both at the IASF institute in Milan and in the different laboratories in which the integration took place, such as Laben laboratories in Vimodrone (Milano), the C. Gavazzi Space laboratory in Tortona (Alessandria) and the IABG laboratory in Ottobrunn (Munich). During November 2005, AGILE was calibrated on a beam test facility at the INFN National Laboratories in Frascati (Rome). The satellite instrumentation has been irradiated with high energy particles beams (photons, electrons and positrons) provided by the LINAC accelerator.
AG has contributed to the test beam organization concerning the optimization of the irradiation configurations, such as beam incidence angles, positions and energy, and has participated to the data taking.
AG was involved in the analysis of both the data acquired during the AGILE calibration campaign in 2005 and the cosmic muon data taking with the tracker during the apparatus assembling. This data allowed for the determination of the tracker performances, such as efficiency and spatial resolution. Moreover comparison with simulated events has been used for validation of the Monte Carlo software.
After the launch of AGILE, in April 2007, AG has coordinated the study of the in-flight calibration data, obtaining the characterization of the AGILE gamma-ray imager, such as effective area, point spread function and energetic response matrix. As for now, AG is responsible for the GRID calibration.
The model of the 
-rays emission interstellar medium : AG has elaborated the model of the gamma-ray emission of the interstellar medium of the Galaxy used in the AGILE scientific software.
This work is described in his PhD thesis (title: ``Gamma-Ray emission from the galactic plane: a new model for AGILE''), and in [3].
The model gives an estimation of the Galactic gamma emissivity on a grid which is a tridimensional representation of the whole Galaxy. The gamma emissivity is obtained by calculating the interaction of cosmic rays with the interstellar medium (mainly molecular clouds and HI clouds) through bremsstrahlung and p-p interaction, and the interaction of cosmic rays with interstellar radiation field (infrared and optic-UV) through inverse Compton. The interstellar gas distribution has been obtained from recent radio surveys, while spectra and distribution of both cosmic rays and radiation fields are obtained from numerical models. AG is now chair of the AGILE working group ``Diffuse and Dark Matter".
Analysis and modeling of Galactic Cosmic-Rays Accelerators : AG is leading the analysis on the gamma-ray emission of SNRs observed by AGILE. This analysis produced the first unambiguous detection of emission from these objects in the high-energy gamma-rays band (100 MeV - 10 GeV). Indeed, thanks to the diffuse emission model (more accurate than the past models) and to the good angular resolution of AGILE, it was possible to resolve the morphology of several SNRs. The paper on the SNR IC443 [19] presents this investigation.
Moreover, AG has built a software able to model the gamma-ray emission from SNR, simulating the physics processes which cause acceleration and diffusion of cosmic rays close to these objects. The results were presented in the paper [9], in which the variation of the spatially resolved spectrum of the SNRs W28 is analyzed and interpreted. A similar approach has been used by AG in order to derive the expected gamma-ray emission from the PWN Vela X as reported in the paper [13] published on Science.
The most prominent result of the investigation on Galactic CR accelerators, is the discovery of the first clear evidence of protons acceleration in a supernova remnant (the SNR W44).
This result was published in [2] and reported by an INAF/ASI press release and several national newspapers.
AG is also CoPI of the accepted proposal ``A mini-survey at 5-8 GHz of Gamma-Ray selected SNRs'' at the radiotelescope of Medicina (Bologna). This investigation is aimed to disentangle the leptonic component in the non-thermal spectrum of SNRs seen in gamma-ray band.
Study of the gamma-ray emission from GRBs: AG is first author of the study on the gamma-ray emission of the GRB 080514B [8]. This has been the first GRB observed with a gamma-ray telescope of new generation. This has allowed to observe for the first time some peculiarity in the light curve, as the so-called ``delayed emission'', subsequently confirmed by other GRB observation performed by the Fermi telescope. The GRB 080514B has also been the first one for which the redshift could be measured [16]. An ASI press release has been issued reporting these results.
AG led the analysis on the GRB 090510, the first short GRB seen in the high-energy gamma ray band [6].
The analysis revealed that the gamma-ray emission above 30 MeV is described by a power-law time decay of the flux of the type t
and the spectrum was remarkably different from that of the prompt phase.
AG is also first author of the preliminary analysis of the remarkable GRB 100724B [10].
Finally AG has analyzed the XMM observations of the bright afterglow of GRB 120711A [7]. These observations collected the largest dataset ever for a GRB afterglow. In order to exploit the richness of these data AG implemented a dedicated software for the spectral characterization. The search for spectral lines didn't find any significative signal but the resulting upper-limits resulted to be the best ever derived for an X-rays GRB afterglow.
Other studies of high-energy sources: AG also performed a study on the SED of the blazar 3C 279 observed by AGILE while flaring during July 2007 [5]. This study has been carried on using a multi-wavelength approach, combining gamma rays, X-rays, optics and radio data and using a theoretical model for the different components of the blazar SED.
AG has also actively participated in the study of other galactic and extragalactic sources seen by AGILE such as, for example, the gamma-ray pulsar PSRJ2021+3651, identified thanks to the AGILE data, for which AG obtained the flux and the spectrum as described in [11].
AG produced the hadronic model used for the interpretation of the gamma-ray flares seen by AGILE from Cyg-X3 [14,18].
AG participates to the study of the Terrestrial Gamma-ray flare with the AGILE/GRID tracker, creating a dedicate software for the reconstruction of events with incoming direction outside the field of view of the instrument [12].
AG has also been involved in the creation of the AGILE catalog of gamma-ray sources [15].
Moreover, AG participated to the analysis of the dust halo around the X-ray sources 1E 1547.0-5408 [20] and Swift J1834.9-0846 [1] deriving the distance of the molecular clouds in the direction of these sources using the CO-line radio data.
Study of feasibility for future high-energy experiments : AG also participated to the NHXM team with the organization and analysis of Montecarlo simulations in order to evaluate the background rate in the Low and High energy detectors as a function of the design of the instrument and the anticoincidence [17].
AG is now member of the collaboration GAMMA 400 for the realization of a gamma-ray space telescope devoted to the observation in the largely unexplored band E
100 MeV.
For this experiment AG provided event reconstruction software of the gamma-ray photons converting in the tracker.
AG also developed the scientific sky simulator for GAMMA 400.
Work for the CTA and ASTRI collaborations : AG has joined the ASTRI collaboration in autumn 2013 and started working on both the software development and scientific studies. AG wrote the software package used for the scientific simulation ASTRISIM, optimized for the ASTRI Mini-array, precursor of the CTA instrument. It produces the expected events collected with an ASTRI observation, convolving the spectra of the gamma-ray sources with the instrument response files. AG coordinates the ASTRI scientific simulation activities, as described above, and is also responsible for the Supernova Remnants simulations, in order to study the ASTRI prospects for SNRs observations. The results of this work has been presented in several meetings (e.g. the CTA Consortium Meeting held in Turku, Finland, 4-8 May 2015)
Milano,
9 March 2016