456 results on '"Di Cocco P"'
Search Results
2. AGILE gamma-ray detection of the exceptional GRB 221009A
- Author
-
Tavani, M., Piano, G., Bulgarelli, A., Foffano, L., Ursi, A., Verrecchia, F., Pittori, C., Casentini, C., Giuliani, A., Longo, F., Panebianco, G., Di Piano, A., Baroncelli, L., Fioretti, V., Parmiggiani, N., Argan, A., Trois, A., Vercellone, S., Cardillo, M., Antonelli, L. A., Barbiellini, G., Caraveo, P., Cattaneo, P. W., Chen, A. W., Costa, E., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Feroci, M., Gianotti, F., Labanti, C., Lazzarotto, F., Lipari, P., Lucarelli, F., Marisaldi, M., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Pilia, M., Rapisarda, M., Rappoldi, A., Rubini, A., Soffitta, P., Trifoglio, M., Vittorini, V., and D'Amico, F.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Gamma-ray emission in the MeV-GeV range from explosive cosmic events is of invaluable relevance to understanding physical processes related to the formation of neutron stars and black holes. Here we report on the detection by the AGILE satellite in the MeV-GeV energy range of the remarkable long-duration gamma-ray burst GRB 221009A. The AGILE onboard detectors have good exposure to GRB 221009A during its initial crucial phases. Hard X-ray/MeV emission in the prompt phase lasted hundreds of seconds, with the brightest radiation being emitted between 200 and 300 seconds after the initial trigger. Very intense GeV gamma-ray emission is detected by AGILE in the prompt and early afterglow phase up to 10,000 seconds. Time-resolved spectral analysis shows time-variable MeV-peaked emission simultaneous with intense power-law GeV radiation that persists in the afterglow phase. The coexistence during the prompt phase of very intense MeV emission together with highly nonthermal and hardening GeV radiation is a remarkable feature of GRB 221009A. During the prompt phase, the event shows spectrally different MeV and GeV emissions that are most likely generated by physical mechanisms occurring in different locations. AGILE observations provide crucial flux and spectral gamma-ray information regarding the early phases of GRB 221009A during which emission in the TeV range was reported., Comment: Accepted for publication in ApJL on September 19, 2023. Published online on October 17, 2023. Revised Figure 5 (June 13, 2024)
- Published
- 2023
- Full Text
- View/download PDF
3. Titanium/FRP hybrid sandwich: in-plane flexural behaviour of short beam specimens
- Author
-
C. Bellini, V. Di Cocco, F. Iacoviello, L.P. Mocanu, L. Sorrentino, R. Borrelli, and S. Franchitti
- Subjects
fibre reinforced polymer ,titanium ,electron beam melting ,sandwich beam ,in-plane behaviour ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
Adopting novel sandwich structures with FRP (Fibre Reinforced Polymer) skins and a metallic lattice core, both of which have high specific strength and stiffness, is one way to achieve better mechanical performance while remaining lightweight. Flexural stress is a load pattern that frequently occurs in the structural frame components of automobiles; nonetheless, while the in-plane load scheme has scarcely been examined, the out-of-plane load one has. As a result, the former configuration received consideration in this work. Moreover, short beam specimens were taken into account. The mechanical response of specimens with three different kinds of composite materials as skin material was analysed. The skins were made of CFRP (Carbon Fiber Reinforced Polymer), with two different weaving styles, and AFRP (Aramid Fiber Reinforced Polymer). All-titanium specimens were studied, too. Similar maximum loads and maximum displacement at break were recorded for both CFRP and AFRP specimens, while the all-titanium one resulted stronger. In terms of the load-displacement curves, the first section featured an initial linear phase, followed by a minor load drop, likely attributed to the breakage of fibres. The CFRP specimens showed a sharp fracture of the skin fibres, while for the AFRP, a fraying was observed.
- Published
- 2024
- Full Text
- View/download PDF
4. Analyzing the Impact of CIT on the Largest Reported Cohort of Robotic Kidney Transplantation From the Deceased Donors
- Author
-
Egor Petrochenkov, MD, Giulia Bencini, MD, Alessandro Martinino, MD, Amy Lian, MD, Joanna Olazar, BS, Stepan Akshelyan, MD, Kentaro Yoshikawa, MD, Pierpaolo Di Cocco, MD, Jorge Almario-Alvarez, MD, Mario Spaggiari, MD, Enrico Benedetti, MD, and Ivo Tzvetanov, MD
- Subjects
Surgery ,RD1-811 - Abstract
Background. Robotic-assisted kidney transplant (RAKT) has proven to be a successful approach for patients with morbid obesity and more centers are encouraged to apply robotic approach also for deceased donor kidney transplantation. Prolonged cold ischemia time (CIT) is accompanied by delayed graft function (DGF) and early graft loss after traditional open kidney transplant (OKT). This study examines the impact of CIT after robotic kidney transplantation on settings of deceased donation. Methods. We present a single-center retrospective analysis of 115 cases of RAKT and 128 cases of OKT from deceased donors performed from deceased donor from 2009 to July 2022. Cohort was divided in 3 groups based on CIT (“high” CIT > 15 h, n = 43; “medium” CIT 11–15 h, n = 38; “low” CIT< 11 h, n = 40). The subgroup analysis of DGF and CIT was performed. Results. The median CIT in the cohort was 13.46 (7) h, and overall rate of DGF was 30.6%. The correlation between CIT and DGF was statistically significant (P = 0.008), and DGF negatively correlated with 1-y graft survival (P = 0.04). The rate of DGF was significantly different between the groups (P = 0.05). Conclusions. Results from our study demonstrate that the effect of CIT on DGF in settings of RAKT follows a similar pattern as in traditional OKT.
- Published
- 2024
- Full Text
- View/download PDF
5. Generational gap and post-ideological politics in Italy (POSTGEN). A generation-aware analysis of ideological destructuring and political change in the Italian case
- Author
-
Lorenzo De Sio, Guido Legnante, Dario Tuorto, Cristiano Vezzoni, Davide Angelucci, Matteo Boldrini, Margherita Bordignon, Luigi Curini, Andrea De Angelis, Jessica Di Cocco, Asia Leofreddi, Nicola Maggini, Elisabetta Mannoni, Francesco Marolla, Giovanni Pagano, Nicolò Pennucci, Arianna Piacentini, and Francesco Piacentini
- Subjects
De-ideologization ,Generations ,Influencer ,Mixed-methods research ,Social media ,Political science (General) ,JA1-92 ,Political theory ,JC11-607 - Abstract
Recent political upheavals, such as Brexit, Trump's election, the rise of challenger parties in Europe, and Italy’s first "populist" government in 2018, challenge traditional theories of voting behaviour and party competition. Conventional explanations often point to populism and voter irrationality. However, recent research highlights that challenger parties leverage issue opportunities that transcend traditional ideological boundaries, suggesting a de-ideologized context where voters are drawn to post-ideological platforms. Despite these insights, a possible de-ideologization process remains insufficiently understood. The POSTGEN project seeks to fill this gap by analysing de-ideologization mechanisms and dynamics, particularly in Italy—a key case of contemporary political transformation. It adopts a generation-focused approach, emphasizing the role of younger generations in the evolving political landscape. The project examines how political attitudes develop and impact individuals, generations, and society over time. It investigates whether political issues integrate into coherent ideological structures or remain fragmented, and how non-political influencers affect these dynamics amid the crisis of traditional epistemic authorities. The project employs a mixed-method, multi-method, longitudinal strategy that features multiple components: from mass surveys, to social media content (also analysed through automated methods), to dedicated surveys aimed at secondary-school students, to qualitative in-depth interviews to young adults. By integrating these methods within a robust theoretical framework, POSTGEN aims to provide insights into the evolution of the Italian political systems, also to help understand broader changes in democratic representation in Western political systems.
- Published
- 2024
6. Impact of parental status on US medical student specialty selection
- Author
-
Morrison, Georgia Mae, Di Cocco, Bianca L., Goldberg, Rebecca, Calderwood, Audrey H., Schulman, Allison R., Enestvedt, Brintha, and Yu, Jessica X.
- Published
- 2023
- Full Text
- View/download PDF
7. Material choice to optimise the performance index of isogrid structures
- Author
-
C. Bellini, V. Di Cocco, F. Iacoviello, L. P. Mocanu, and F. Berto
- Subjects
carbon fibre ,titanium ,performance index ,finite element analysis ,isogrid ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
Three key qualities should define the structures used in the aviation industry: they should be light, rigid, and strong. These goals can be met by selecting lightweight, high-performance materials like titanium alloy or composites, but careful structural design is also crucial to improve mechanical performance. The structures known as isogrids, which consist of a skin reinforced by a lattice frame, offer an effective way to meet the aforementioned specifications. The structural performances of isogrid-stiffened cylinders composed of various materials were compared in the current work. The structures under investigation were composed of titanium alloy, carbon fibre composite material, or a combination of both. A FEM model was proposed and validated by comparison with experimental results obtained from a composite material structure, and then it was used to simulate the behaviour of all the other structures. While there was some variation in the strength of the parts, it was discovered that the stiffness was almost uniform throughout all of the structures that were examined. But when the weight of the various constructions was taken into account, some very intriguing findings emerged: the composite material-only structure proved to be the most effective because it had the highest specific performances
- Published
- 2024
- Full Text
- View/download PDF
8. Timing Considerations for Sleeve Gastrectomy in Kidney Transplant Patients: A Single Center Evaluation
- Author
-
Mario Spaggiari, Alessandro Martinino, Giulia Bencini, Mario A. Masrur, Egor Petrochenkov, Amy Lian, Joanna Olazar, Pierpaolo Di Cocco, Jorge Almario-Alvarez, Enrico Benedetti, and Ivo Tzvetanov
- Subjects
kidney transplant ,sleeve gastrectomy ,timing ,weight loss ,robotic ,Specialties of internal medicine ,RC581-951 - Abstract
Current scientific literature is deficient in detailing the optimal timing for conducting bariatric surgery in relation to kidney transplantation. In this study, we performed a retrospective evaluation of kidney transplant recipients with BMI >35 kg/m2. It aimed to provide data on those who received both sleeve gastrectomy (SG) and kidney transplantation (KT) simultaneously, as well as on patients who underwent SG and KT at different times, either before or after. In addition, the acceptance levels of the bariatric surgery among different scenarios were assessed. Our findings demonstrated that combined KT and SG led to successful weight loss, in contrast to undergoing kidney transplant alone, while maintaining comparable rates of graft and patient survival. Weight loss was similar between recipients who had a combined operation and those who underwent SG following the transplant. Additionally, over a median time frame of 1.7 years, patients who underwent SG before KT exhibited a statistically significant reduction in BMI at the time of the transplant. Notably, our study highlights that patients offered the combined procedure were significantly more likely to undergo SG compared to those for whom SG was presented at a different operative time than the transplant.
- Published
- 2024
- Full Text
- View/download PDF
9. Titanium/FRP hybrid sandwich: in-plane flexural behaviour of short beam specimens
- Author
-
Costanzo Bellini, Rosario Borrelli, Vittorio Di Cocco, Stefania Franchitti, Francesco Iacoviello, Larisa Patricia Mocanu, and Luca Sorrentino
- Subjects
Fibre reinforced polymer ,Titanium ,Electron Beam Melting ,Sandwich beam ,In-plane behaviour ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
Adopting novel sandwich structures with FRP (Fibre Reinforced Polymer) skins and a metallic lattice core, both of which have high specific strength and stiffness, is one way to achieve better mechanical performance while remaining lightweight. Flexural stress is a load pattern that frequently occurs in the structural frame components of automobiles; nonetheless, while the in-plane load scheme has scarcely been examined, the out-of-plane load one has. As a result, the former configuration received consideration in this work. Moreover, short beam specimens were taken into account. The mechanical response of specimens with three different kinds of composite materials as skin material was analysed. The skins were made of CFRP (Carbon Fiber Reinforced Polymer), with two different weaving styles, and AFRP (Aramid Fiber Reinforced Polymer). All-titanium specimens were studied, too. Similar maximum loads and maximum displacement at break were recorded for both CFRP and AFRP specimens, while the all-titanium one resulted stronger. In terms of the load-displacement curves, the first section featured an initial linear phase, followed by a minor load drop, likely attributed to the breakage of fibres. The CFRP specimens showed a sharp fracture of the skin fibres, while for the AFRP, a fraying was observed.
- Published
- 2024
10. Corrigendum and addendum to: How Populist are Parties? Measuring Degrees of Populism in Party Manifestos Using Supervised Machine Learning
- Author
-
Di Cocco, Jessica and Monechi, Bernardo
- Subjects
Physics - Physics and Society ,Computer Science - Machine Learning - Abstract
This paper is a corrigendum and addendum to the previously published article: 'How Populist are Parties? Measuring Degrees of Populism in Party Manifestos Using Supervised Machine Learning' (Political Analysis, 1-17. doi:10.1017/pan.2021.29). These corrigendum and addendum were prepared to correct errors in data labelling and show some extra insights not included in the previously published paper. Here, we report these corrections and point to some additional conclusions by focusing on the effects of the label reshuffling per parties and years and presenting new figures wherever appropriate. We show that although the simplified labelling method proposed in the previously-published article can induce biases in the correlations with expert scores, random labelling reduces correlations significantly. We show that this is also true for correlations based on a manually-coded data set. These modifications are based on other evidence and results reported in detail in a future publication., Comment: 6 pages, 4 figures
- Published
- 2022
11. The Role of Colon in Isolated Intestinal Transplantation: Description of 4 Cases
- Author
-
Pierpaolo Di Cocco, Giulia Bencini, Alessandro Martinino, Egor Petrochenkov, Stepan Akshelyan, Kentaro Yoshikawa, Mario Spaggiari, Jorge Almario-Alvarez, Ivo Tzvetanov, and Enrico Benedetti
- Subjects
Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Intra-abdominal desmoid tumors are a rare and complex clinical problem. These tumors are locally invasive, and surgical ablation represents the mainstay of treatment. When localized at the root of the mesentery, their resection may require extensive excision of the intestine resulting in intestinal failure and life-long total parenteral nutrition. Intestinal transplantation, either autotransplantation or allotransplantation, has been used as a viable option to treat this group of patients. Herein, we describe a series of 4 patients with unresectable intra-abdominal desmoid tumor who underwent cadaveric isolated intestinal and ascending colon transplantation.
- Published
- 2024
- Full Text
- View/download PDF
12. An X-Ray Burst from a Magnetar Enlightening the Mechanism of Fast Radio Bursts
- Author
-
Tavani, M., Casentini, C., Ursi, A., Verrecchia, F., Addis, A., Antonelli, L. A., Argan, A., Barbiellini, G., Baroncelli, L., Bernardi, G., Bianchi, G., Bulgarelli, A., Caraveo, P., Cardillo, M., Cattaneo, P. W., Chen, A. W., Costa, E., Del Monte, E., Di Cocco, G., Di Persio, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fioretti, V., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lazzarotto, F., Lipari, P., Longo, F., Lucarelli, F., Magro, A., Marisaldi, M., Mereghetti, S., Morelli, E., Morselli, A., Naldi, G., Pacciani, L., Parmiggiani, N., Paoletti, F., Pellizzoni, A., Perri, M., Perotti, F., Piano, G., Picozza, P., Pilia, M., Pittori, C., Puccetti, S., Pupillo, G., Rapisarda, M., Rappoldi, A., Rubini, A., Setti, G., Soffitta, P., Trifoglio, M., Trois, A., Vercellone, S., Vittorini, V., Giommi, P., and Amico, F. D'
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Fast radio bursts (FRBs) are short (millisecond) radio pulses originating from enigmatic sources at extragalactic distances so far lacking a detection in other energy bands. Magnetized neutron stars (magnetars) have been considered as the sources powering the FRBs, but the connection is controversial because of differing energetics and the lack of radio and X-ray detections with similar characteristics in the two classes. We report here the detection by the AGILE satellite on April 28, 2020 of an X-ray burst in coincidence with the very bright radio burst from the Galactic magnetar SGR 1935+2154. The burst detected by AGILE in the hard X-ray band (18-60 keV) lasts about 0.5 seconds, it is spectrally cutoff above 80 keV, and implies an isotropically emitted energy ~ $10^{40}$ erg. This event is remarkable in many ways: it shows for the first time that a magnetar can produce X-ray bursts in coincidence with FRB-like radio bursts; it also suggests that FRBs associated with magnetars may emit X-ray bursts of both magnetospheric and radio-pulse types that may be discovered in nearby sources. Guided by this detection, we discuss SGR 1935+2154 in the context of FRBs, and especially focus on the class of repeating-FRBs. Based on energetics, magnetars with fields B ~ $10^{15}$ G may power the majority of repeating-FRBs. Nearby repeating-FRBs offer a unique occasion to consolidate the FRB-magnetar connection, and we present new data on the X-ray monitoring of nearby FRBs. Our detection enlightens and constrains the physical process leading to FRBs: contrary to previous expectations, high-brightness temperature radio emission coexists with spectrally-cutoff X-ray radiation., Comment: Submitted to Nature Astronomy, May 18, 2020
- Published
- 2020
13. The First Collective Examination of Immunosuppressive Practices Among American Intestinal Transplant Centers
- Author
-
Joshua Weiner, MD, Nathaly Llore, MD, Dylan Ormsby, Masato Fujiki, MD, Maria Cristina Segovia, MD, Mark Obri, MD, Syed-Mohammed Jafri, MD, Jedson Liggett, MD, Alexander H.K. Kroemer, MD, PhD, Cal Matsumoto, MD, Jang Moon, MD, Pierpaolo Di Cocco, MD, Gennaro Selvaggi, MD, Jennifer Garcia, MD, Armando Ganoza, MD, Ajai Khanna, MD, George Mazariegos, MD, Danielle Wendel, MD, Jorge Reyes, MD, and for The American Intestinal Transplantation Working Group
- Subjects
Surgery ,RD1-811 - Abstract
Background. Unlike other solid organs, no standardized treatment algorithms exist for intestinal transplantation (ITx). We established a consortium of American ITx centers to evaluate current practices. Methods. All American centers performing ITx during the past 3 y were invited to participate. As a consortium, we generated questions to evaluate and collect data from each institution. The data were compiled and analyzed. Results. Ten centers participated, performing 211 ITx during the past 3 y (range, 3–46; mean 21.1). Induction regimens varied widely. Thymoglobulin was the most common, used in the plurality of patients (85/211; 40.3%), but there was no consensus regimen. Similarly, regimens for the treatment of acute cellular rejection, antibody-mediated rejection, and graft-versus-host disease varied significantly between centers. We also evaluated differences in maintenance immunosuppression protocols, desensitization regimens, mammalian target of rapamycin use, antimetabolite use, and posttransplantation surveillance practices. Maintenance tacrolimus levels, stoma presence, and scoping frequency were not associated with differences in rejection events. Definitive association between treatments and outcomes, including graft and patient survival, was not the intention of this initial collaboration and is prevented by the lack of patient-level data and the presence of confounders. However, we identified trends regarding rejection episodes after various induction strategies that require further investigation in our subsequent collaborations. Conclusions. This initial collaboration reveals the extreme heterogeneity of practices among American ITx centers. Future collaboration will explore patient-level data, stratified by age and transplant type (isolated intestine versus multivisceral), to explore the association between treatment regimens and outcomes.
- Published
- 2023
- Full Text
- View/download PDF
14. AGILE detection of gamma-ray sources coincident with cosmic neutrino events
- Author
-
Lucarelli, F., Tavani, M., Piano, G., Bulgarelli, A., Donnarumma, I., Verrecchia, F., Pittori, C., Antonelli, L. A., Argan, A., Barbiellini, G., Caraveo, P., Cardillo, M., Cattaneo, P. W., Chen, A., Colafrancesco, S., Costa, E., Del Monte, E., Di Cocco, G., Ferrari, A., Fioretti, V., Galli, M., Giommi, P., Giuliani, A., Lipari, P., Longo, F., Mereghetti, S., Morselli, A., Paoletti, F., Parmiggiani, N., Pellizzoni, A., Picozza, P., Pilia, M., Rappoldi, A., Trois, A., Ursi, A., Vercellone, S., and Vittorini, V.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
The origin of cosmic neutrinos is still largely unknown. Using data obtained by the gamma-ray imager on board of the AGILE satellite, we systematically searched for transient gamma-ray sources above 100 MeV that are temporally and spatially coincident with ten recent high-energy neutrino IceCube events. We find three AGILE candidate sources that can be considered possible counterparts to neutrino events. Detecting 3 gamma-ray/neutrino associations out of 10 IceCube events is shown to be unlikely due to a chance coincidence. One of the sources is related to the BL Lac source TXS 0506+056. For the other two AGILE gamma-ray sources there are no obvious known counterparts, and both Galactic and extragalactic origin should be considered., Comment: 21 pages, 15 figures, 4 tables. Accepted for publication in ApJ
- Published
- 2018
- Full Text
- View/download PDF
15. Fracture micrographic analysis of a carbon FML under three-point bending load
- Author
-
Costanzo Bellini, Vittorio Di Cocco, and Francesco Iacoviello
- Subjects
fibre metal laminates ,fracture features ,flexural behaviour ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
The core of the present work concerns the analysis of the failure mode and the fracture process induced by the flexural load in Fibre Metal Laminates (FMLs). The influence of the connection layer placed between the composite ones and the metal sheets on the fracture mode was analysed. The considered FML was made of aluminium sheets interposed with carbon fibre reinforced polymer (CFRP) layers, joined with two different types of interface: by using a structural adhesive, or by relying on the bonding capacity of the prepreg resin. Then, the mechanical performances of the produced laminates were determined through the three-point bending test procedure, and the support span was varied to investigate different loading conditions. Finally, the fracture surface morphology was analysed by using both optical and scanning electron microscopes. The type of interface was found to influence the strength of the studied FML, and different fracture modes were observed, depending on the loading condition
- Published
- 2022
- Full Text
- View/download PDF
16. Temperature Influence on Brake Pad Friction Coefficient Modelisation
- Author
-
Costanzo Bellini, Vittorio Di Cocco, Daniela Iacoviello, and Francesco Iacoviello
- Subjects
brake pads ,friction coefficient ,tribological behaviour ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Brake pad linings are an essential part of the correct functioning of braking systems based on the use of pads and discs. Generally, the compounds used to make the gaskets are characterised by the use of over 20 sintered components, which allow friction coefficients that vary between 0.2 and 0.6 at temperatures up to 200 °C. In this work, a traditional compound was investigated under close-to-real conditions in order to evaluate the tribological behaviour at different temperatures. Finally, a model based on the proportionality between temperature increase and relative variation of the friction coefficient was proposed. From the experimental test, it was evident that the friction coefficient increased with the temperature, passing from 0.4 to 0.6 in the temperature range of 100 °C to 180 °C; however, a further temperature increment until 350 °C caused a reduction in the friction coefficient to 0.2. The proposed model was able to anticipate the abovementioned trend, especially at high temperatures.
- Published
- 2023
- Full Text
- View/download PDF
17. Successful minimally invasive management of adverse events following EUS-guided gallbladder drainage in a suboptimal surgical patient
- Author
-
Bianca L. Di Cocco, MD, Donevan R. Westerveld, MD, Kaveh Hajifathalian, MD, MPH, SriHari Mahadev, MD, MBBS, Reem Z. Sharaiha, MD, MSc, and Kartik Sampath, MD
- Subjects
Diseases of the digestive system. Gastroenterology ,RC799-869 - Published
- 2022
- Full Text
- View/download PDF
18. AGILE Gamma-Ray Detection of the Exceptional GRB 221009A
- Author
-
Marco Tavani, Giovanni Piano, Andrea Bulgarelli, Luca Foffano, Alessandro Ursi, Francesco Verrecchia, Carlotta Pittori, Claudio Casentini, Andrea Giuliani, Francesco Longo, Gabriele Panebianco, Ambra Di Piano, Leonardo Baroncelli, Valentina Fioretti, Nicolò Parmiggiani, Andrea Argan, Alessio Trois, Stefano Vercellone, Martina Cardillo, Lucio Angelo Antonelli, Guido Barbiellini, Patrizia Caraveo, Paolo W. Cattaneo, Andrew W. Chen, Enrico Costa, Ettore Del Monte, Guido Di Cocco, Immacolata Donnarumma, Yuri Evangelista, Marco Feroci, Fulvio Gianotti, Claudio Labanti, Francesco Lazzarotto, Paolo Lipari, Fabrizio Lucarelli, Martino Marisaldi, Sandro Mereghetti, Aldo Morselli, Luigi Pacciani, Alberto Pellizzoni, Francesco Perotti, Piergiorgio Picozza, Maura Pilia, Massimo Rapisarda, Andrea Rappoldi, Alda Rubini, Paolo Soffitta, Massimo Trifoglio, Valerio Vittorini, and Fabio D’Amico
- Subjects
Gamma-ray bursts ,Gamma-ray astronomy ,Gamma-ray observatories ,Astrophysics ,QB460-466 - Abstract
Gamma-ray emission in the MeV–GeV range from explosive cosmic events is of invaluable relevance to understanding physical processes related to the formation of neutron stars and black holes. Here we report on the detection by the AGILE satellite in the MeV–GeV energy range of the remarkable long-duration gamma-ray burst GRB 221009A. The AGILE onboard detectors have good exposure to GRB 221009A during its initial crucial phases. Hard X-ray/MeV emission in the prompt phase lasted hundreds of seconds, with the brightest radiation being emitted between 200 and 300 s after the initial trigger. Very intense GeV gamma-ray emission is detected by AGILE in the prompt and early afterglow phase up to 10,000 s. Time-resolved spectral analysis shows time-variable MeV-peaked emission simultaneous with intense power-law GeV radiation that persists in the afterglow phase. The coexistence during the prompt phase of very intense MeV emission together with highly nonthermal and hardening GeV radiation is a remarkable feature of GRB 221009A. During the prompt phase, the event shows spectrally different MeV and GeV emissions that are most likely generated by physical mechanisms occurring in different locations. AGILE observations provide crucial flux and spectral gamma-ray information regarding the early phases of GRB 221009A during which emission in the TeV range was reported.
- Published
- 2023
- Full Text
- View/download PDF
19. Geometrical Accuracy Analysis of Ti-6Al-4V Trusses Manufactured by Electron Beam Melting Process
- Author
-
Costanzo Bellini, Rosario Borrelli, Francesco Di Caprio, Vittorio Di Cocco, Stefania Franchitti, Francesco Iacoviello, Carmine Pirozzi, and Luca Sorrentino
- Subjects
electron beam melting ,titanium ,thin structure ,geometrical accuracy ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Lattice structures made of metal materials are very interesting since their structural efficiency is elevated, thanks to their good mechanical properties and light weight. Additive manufacturing processes are appropriate to produce those structures. However, the peculiar geometry of lattice structures causes the manufacturing process to create rather significant unconformities, affecting the structures’ mechanical properties. In this article, small trusses with different diameters were produced through electron beam melting (EBM) by varying the process parameters, like the orientation and the position in the build chamber. Then, their diameter was evaluated and compared with the nominal one. It was found that the orientation in the chamber was very influential on the geometrical error, as well as the nominal diameter, while the position in the building chamber was uninfluential. In particular, the highest deviation was found for the specimens oriented at 0° and those with a diameter of 1 mm. Moreover, a similar result was detected for the ovalisation of the truss section too.
- Published
- 2023
- Full Text
- View/download PDF
20. Fiber Bragg Grating Bonding Characterization under Long-Period Cyclic Loading
- Author
-
Angela Brindisi, Cristian Vendittozzi, Costanzo Bellini, Vittorio Di Cocco, Lidia Travascio, Luigi Di Palma, Marika Belardo, and Antonio Concilio
- Subjects
landing gear ,fiber optic sensors ,Fiber Bragg Gratings ,smart devices ,structural health monitoring ,fatigue-like test ,Applied optics. Photonics ,TA1501-1820 - Abstract
The Smart Landing Gear system to be developed in the framework of the ANGELA project provides the strain measurements on landing gear structure at landings, and this system should be maintained efficiently under operational conditions. It is intended to assess the relevance of Fiber Bragg Gratings for in-flight testing. To assess the capabilities of the FBG bonding and to analyze the strain transmission conditions from the host structure to the FBG through the bonding layer during the operational phases of landing gears, a long-period cyclic loading test campaign on the bonding layer itself was performed. The primary objective of this fatigue-like test was to prove the ability of FBG sensors to withstand the operational life-cycle of landing gear while providing the same strain transfer function throughout the entire cycle; the secondary objective was to select the most suitable fiber-coating and bonding agents for this application. This document describes the execution and results of the fatigue-like test, intended as a preparatory test campaign to support the preliminary design activities of the Smart Landing System.
- Published
- 2023
- Full Text
- View/download PDF
21. Time Domain NMR Approach in the Chemical and Physical Characterization of Hazelnuts (Corylus avellana L.)
- Author
-
Raffaella Gianferri, Fabio Sciubba, Alessandra Durazzo, Paolo Gabrielli, Ginevra Lombardi-Boccia, Francesca Giorgi, Antonello Santini, Petra Engel, Maria Enrica Di Cocco, Maurizio Delfini, and Massimo Lucarini
- Subjects
Tonda Gentile Romana ,Tonda di Giffoni ,hazelnut ,NMR relaxometry ,Chemical technology ,TP1-1185 - Abstract
‘Tonda Gentile Romana’ and ‘Tonda di Giffoni’ (Corylus avellana L.) are two Italian hazelnut cultivars, recognized under the quality labels “Protected Designation of Origin” (PDO) and “Protected Geographical Indication” (PGI), respectively. Hazelnut seeds are characterized by a complex microstructure and the presence of different physical compartments. This peculiarity has been studied and evidenced by Time Domain (TD) Nuclear Magnetic Resonance (NMR) experiments. This technique allowed the assessment of the presence of different diffusion compartments, or domains, by evaluating the distribution of the spin–spin relaxation time (T2).The aim of this research was to develop a method based on 1H NMR relaxometry to study the mobility in fresh hazelnut seeds (‘Tonda di Giffoni’ and ‘Tonda Gentile Romana’), in order to determine differences in seed structure and matrix mobility between the two cultivars. TD-NMR measurements were performed from 8 to 55 °C in order to mimic post-harvest processing as well the microscopic textural properties of hazelnut. The Carr–Purcell–Meiboom–Gill (CPMG) experiments showed five components for ‘Tonda Gentile Romana’ and four components for ‘Tonda di Giffoni’ relaxation times. The two slowest components of relaxation (T2,a about 30–40% of the NMR signal, and T2,b about 50% of the NMR signal) were attributed to the protons of the lipid molecules organized in the organelles (oleosomes), both for the ‘Tonda Gentile Romana’ and for the ‘Tonda di Giffoni’ samples. The component of relaxation T2,c was assigned to cytoplasmic water molecules, and showed a T2 value dominated by diffusive exchange with a reduced value compared to that of pure water at the same temperature. This can be attributed to the water molecules affected by the relaxation effect of the cell walls. The experiments carried out as a function of temperature showed, for ‘Tonda Gentile Romana’, an unexpected trend between 30 and 45 °C, indicating a phase transition in its oil component. This study provides information that could be used to strengthen the specifications underlying the definitions of “Protected Designation of Origin” (PDO) and “Protected Geographical Indication” (PGI).
- Published
- 2023
- Full Text
- View/download PDF
22. An X-ray burst from a magnetar enlightening the mechanism of fast radio bursts
- Author
-
Tavani, M., Casentini, C., Ursi, A., Verrecchia, F., Addis, A., Antonelli, L. A., Argan, A., Barbiellini, G., Baroncelli, L., Bernardi, G., Bianchi, G., Bulgarelli, A., Caraveo, P., Cardillo, M., Cattaneo, P. W., Chen, A. W., Costa, E., Del Monte, E., Di Cocco, G., Di Persio, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fioretti, V., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lazzarotto, F., Lipari, P., Longo, F., Lucarelli, F., Magro, A., Marisaldi, M., Mereghetti, S., Morelli, E., Morselli, A., Naldi, G., Pacciani, L., Parmiggiani, N., Paoletti, F., Pellizzoni, A., Perri, M., Perotti, F., Piano, G., Picozza, P., Pilia, M., Pittori, C., Puccetti, S., Pupillo, G., Rapisarda, M., Rappoldi, A., Rubini, A., Setti, G., Soffitta, P., Trifoglio, M., Trois, A., Vercellone, S., Vittorini, V., Giommi, P., and D’Amico, F.
- Published
- 2021
- Full Text
- View/download PDF
23. An Innovative Method to Analyse the Geometrical Accuracy of Ti6Al4V Octet-Truss Lattice Structures
- Author
-
Costanzo Bellini, Rosario Borrelli, Francesco Di Caprio, Vittorio Di Cocco, Stefania Franchitti, Francesco Iacoviello, and Luca Sorrentino
- Subjects
electron beam melting ,titanium ,thin structure ,geometrical accuracy ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Metal lattice structures manufactured utilising additive techniques are attracting increasing attention thanks to the high structural efficiency they can offer. Although many studies exist on the characterisation of massive parts in Ti6Al4V processed by Electron Beam Melting (EBM), several investigations are necessary to characterise the Ti6Al4V lattice structures made by the EBM process. The objective of this paper is to develop a measurement method to assess the dimensional accuracy of Ti6Al4V octet truss lattice structures manufactured by EBM technology. Beam specimens with a 2 mm diameter and different growth orientations with respect to the build direction were analysed. The geometry differences between the designed and the manufactured beam specimens were highlighted. Two effects were identified: (i) The EBM-manufactured beams are generally thinner than the designed ones, and (ii) the shape of the section was found to be almost circular for the beam specimens oriented at 45° and 90°; on the contrary, the section of the horizontal beam (0°) cannot be considered circular.
- Published
- 2023
- Full Text
- View/download PDF
24. An updated list of AGILE bright gamma-ray sources and their variability in pointing mode
- Author
-
Verrecchia, F., Pittori, C., Chen, A. W., Bulgarelli, A., Tavani, M., Lucarelli, F., Giommi, P., Vercellone, S., Pellizzoni, A., Giuliani, A., Longo, F., Barbiellini, G., Trifoglio, M., Gianotti, F., Argan, A., Antonelli, L. A., Caraveo, P., Cardillo, M., Cattaneo, P. W., Cocco, V., Colafrancesco, S., Contessi, T., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Di Persio, G., Donnarumma, I., Evangelista, Y., Fanari, G., Feroci, M., Ferrari, A., Fiorini, M., Fornari, F., Fuschino, F., Froysland, T., Frutti, M., Galli, M., Labanti, C., Lapshov, I., Lazzarotto, F., Liello, F., Lipari, P., Mattaini, E., Marisaldi, M., Mastropietro, M., Mauri, A., Mauri, F., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Pilia, M., Pontoni, C., Porrovecchio, G., Prest, M., Primavera, R., Pucella, G., Rapisarda, M., Rappoldi, A., Rossi, E., Rubini, A., Sabatini, S., Santolamazza, P., Soffitta, P., Stellato, S., Striani, E., Tamburelli, F., Traci, A., Trois, A., Vallazza, E., Vittorini, V., Zanello, D., Salotti, L., and Valentini, G.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present a variability study of a sample of bright gamma-ray (30 MeV -- 50 GeV) sources. This sample is an extension of the first AGILE catalogue of gamma-ray sources (1AGL), obtained using the complete set of AGILE observations in pointing mode performed during a 2.3 year period from July 9, 2007 until October 30, 2009. The dataset of AGILE pointed observations covers a long time interval and its gamma-ray data archive is useful for monitoring studies of medium-to-high brightness gamma-ray sources. In the analysis reported here, we used data obtained with an improved event filter that covers a wider field of view, on a much larger (about 27.5 months) dataset, integrating data on observation block time scales, which mostly range from a few days to thirty days. The data processing resulted in a better characterized source list than 1AGL was, and includes 54 sources, 7 of which are new high galactic latitude (|BII| >= 5) sources, 8 are new sources on the galactic plane, and 20 sources from the previous catalogue with revised positions. Eight 1AGL sources (2 high-latitude and 6 on the galactic plane) were not detected in the final processing either because of low OB exposure and/or due to their position in complex galactic regions. We report the results in a catalogue of all the detections obtained in each single OB, including the variability results for each of these sources. In particular, we found that 12 sources out of 42 or 11 out of 53 are variable, depending on the variability index used, where 42 and 53 are the number of sources for which these indices could be calculated. Seven of the 11 variable sources are blazars, the others are Crab pulsar+nebula, LS I +61{\deg}303, Cyg X-3, and 1AGLR J2021+4030., Comment: 30 pages, 12 figures
- Published
- 2013
- Full Text
- View/download PDF
25. Calibration of AGILE-GRID with In-Flight Data and Monte Carlo Simulations
- Author
-
Chen, Andrew W., Argan, A., Bulgarelli, A., Cattaneo, P. W., Contessi, T., Giuliani, A., Pittori, C., Pucella, G., Tavani, M., Trois, A., Verrecchia, F., Barbiellini, G., Caraveo, P., Colafrancesco, S., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Ferrari, A., Feroci, M., Fioretti, V., Fiorini, M., Fuschino, F., Galli, M., Gianotti, F., Giommi, P., Giusti, M., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Lucarelli, F., Marisaldi, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Santolamazza, P., Soffitta, P., Striani, E., Trifoglio, M., Valentini, G., Vallazza, E., Vercellone, S., Vittorini, V., and Zanello, D.
- Subjects
Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
Context: AGILE is a gamma-ray astrophysics mission which has been in orbit since 23 April 2007 and continues to operate reliably. The gamma-ray detector, AGILE-GRID, has observed Galactic and extragalactic sources, many of which were collected in the first AGILE Catalog. Aims: We present the calibration of the AGILE-GRID using in-flight data and Monte Carlo simulations, producing Instrument Response Functions (IRFs) for the effective area A_eff), Energy Dispersion Probability (EDP), and Point Spread Function (PSF), each as a function of incident direction in instrument coordinates and energy. Methods: We performed Monte Carlo simulations at different gamma-ray energies and incident angles, including background rejection filters and Kalman filter-based gamma-ray reconstruction. Long integrations of in-flight observations of the Vela, Crab and Geminga sources in broad and narrow energy bands were used to validate and improve the accuracy of the instrument response functions. Results: The weighted average PSFs as a function of spectra correspond well to the data for all sources and energy bands. Conclusions: Changes in the interpolation of the PSF from Monte Carlo data and in the procedure for construction of the energy-weighted effective areas have improved the correspondence between predicted and observed fluxes and spectra of celestial calibration sources, reducing false positives and obviating the need for post-hoc energy-dependent scaling factors. The new IRFs have been publicly available from the Agile Science Data Centre since November 25, 2011, while the changes in the analysis software will be distributed in an upcoming release.
- Published
- 2013
- Full Text
- View/download PDF
26. Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron
- Author
-
Diego Omar Fernandino, Vittorio Di Cocco, Nicolas Tenaglia, Costanzo Bellini, Francesco Iacoviello, and Roberto Enrique Boeri
- Subjects
spheroidal graphite cast iron ,fracture mechanisms ,intercritical adi ,tensile test ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
The goal of this work is to improve the understanding of the relation between the microstructural characteristics of Intercritical Austempered Ductile Cast Iron (IADI) and the damage micromechanisms observed during its tensile loading. The experimental methodology involves heat treatments to obtain IADI and the assessment of the damage mechanisms (sequence and occurrence) during step by step tensile testing. The damage evaluation was carried out by observing the surface of the tensile test specimen with optical and scanning electron microscopy. The results show that small cracks start forming soon after the yield stress is surpassed. The crack initiation is preferentially located at matrix-nodule interface. As loading increases, cracks also develop at the ferritic grain boundaries and the ausferritic/ferritic interfaces. Consequently, at higher strain values, a competition between the plastic deformation on internodular zones and crack propagation along ausferritic phase is observed. Finally, the final fracture is produced by the propagation of cracks across the internodular ligaments and through the ausferritic/ferritic interface that later coalesce into a single dominant crack leading to the material failure.
- Published
- 2020
- Full Text
- View/download PDF
27. Interlaminar shear strength study on CFRP/Al hybrid laminates with different properties
- Author
-
Costanzo Bellini, Vittorio Di Cocco, and Luca Sorrentino
- Subjects
carall ,short beam flexural test ,bonding strength ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
FML (Fibre Metal Laminate) is a hybrid material that presents outstanding structural properties, such as resistance to cyclic and dynamic loads, together with low specific weight. This material consists of metal sheets alternating to composite material layers. In the present work, the ILSS (Interlaminar Shear Strength) was evaluated for different types of carbon fibre/aluminium FML, produced varying the layer thickness and the bonding solution of layers. In fact, FMLs consisting of one or two metal sheets (a parameter strictly connected to the layer thickness, as the metal/composite volume fraction was kept at constant value) and bonded with structural adhesive or prepreg resin were considered for this study. The ILSS was determined according to the three-point bending method with short beam specimens. The experimental tests evidenced an effect of the adhesion methodology on the ILSS value, while the layer thickness did not influence the interlaminar strength. The mechanical behaviour after the maximum load point was investigated too, evaluating the trend of the shear stress as a function of the loading nose displacement.
- Published
- 2020
- Full Text
- View/download PDF
28. Longitudinal Multi-Omics Study of a Mother-Infant Dyad from Breastfeeding to Weaning: An Individualized Approach to Understand the Interactions Among Diet, Fecal Metabolome and Microbiota Composition
- Author
-
Giorgia Conta, Federica Del Chierico, Sofia Reddel, Federico Marini, Fabio Sciubba, Giorgio Capuani, Alberta Tomassini, Maria Enrica Di Cocco, Nicola Laforgia, Maria Elisabetta Baldassarre, Lorenza Putignani, and Alfredo Miccheli
- Subjects
gut microbiota ,NMR-based metabolomics ,metabolic profiling ,breast milk ,targeted metagenomics ,HMOs ,Biology (General) ,QH301-705.5 - Abstract
The development of the human gut microbiota is characterized by a dynamic sequence of events from birth to adulthood, which make the gut microbiota unique for everyone. Its composition and metabolism may play a critical role in the intestinal homeostasis and health. We propose a study on a single mother-infant dyad to follow the dynamics of an infant fecal microbiota and metabolome changes in relation to breast milk composition during the lactation period and evaluate the changes induced by introduction of complementary food during the weaning period. Nuclear Magnetic Resonance (NMR)-based metabolomics was performed on breast milk and, together with 16S RNA targeted-metagenomics analysis, also on infant stool samples of a mother-infant dyad collected over a period running from the exclusive breastfeeding diet to weaning. Breast milk samples and neonatal stool samples were collected from the 4th to the 10th month of life. Both specimens were collected from day 103 to day 175, while from day 219–268 only stool samples were examined. An exploratory and a predictive analysis were carried out by means of Common component and specific weight analysis and multi-block partial least squares discriminant analysis, respectively. Stools collected during breastfeeding and during a mixed fruit/breastfeeding diet were characterized by high levels of fucosyl-oligosaccharides and glycolysis intermediates, including succinate and formate. The transition to a semi-solid food diet was characterized by several changes in fecal parameters: increase in short-chain fatty acids (SCFAs) levels, including acetate, propionate and butyrate, dissapearance of HMOs and the shift in the community composition, mainly occurring within the Firmicutes phylum. The variations in the fecal metabolome reflected the infant’s diet transition, while the composition of the microbiota followed a more complex and still unstable behavior.
- Published
- 2021
- Full Text
- View/download PDF
29. Impact of Copper, Tin and Titanium Addition on Bending-Induced Damage of Intermetallic Phases in Hot Dip Galvanizing
- Author
-
Costanzo Bellini, Vittorio Di Cocco, Francesco Iacoviello, and Larisa Patricia Mocanu
- Subjects
damage ,hot dip galvanizing ,bath chemical composition ,intermetallic phases ,four-points bending test ,microstructure ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Hot dip galvanizing is among the cheapest methods for protecting ferrous alloys against corrosion. The success is due to both the low cost of the process and the high degree of protection in many corrosive environments, where the coatings serve as sacrificial protection. The purpose of this analysis is to study the mechanical characteristics of steel plates, that have been hot dip coated with five different zinc alloy molten bath for different time periods. The mechanical tests performed is a non-standardized four-point bending test considering three distinct bending angles. Results are examined in terms of both mechanical behaviour and coating phase damage. The development of intermetallic phases and their damage are both influenced by the chemical compositions of the zinc bath, demonstrating that fractures arise mostly at the substrate-coating interface. All the coatings showed the arising of micro-cracks except for the Aluminium, which demonstrated its ductility. In addition, Zn-Ti coatings showed the arising of a new compact phase rich in iron, characterized by a great hardness. More research is needed to explore the aluminium impact on the zinc bath, the lack of tiny fractures in the phase, and the lesser thickness compared to the other coatings tested.
- Published
- 2022
- Full Text
- View/download PDF
30. IPN localizations of Konus short gamma-ray bursts
- Author
-
Pal'shin, V. D., Hurley, K., Svinkin, D. S., Aptekar, R. L., Golenetskii, S. V., Frederiks, D. D., Mazets, E. P., Oleynik, P. P., Ulanov, M. V., Cline, T., Mitrofanov, I. G., Golovin, D. V., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., Trombka, J., McClanahan, T., Starr, R., Goldsten, J., Gold, R., Rau, A., von Kienlin, A., Savchenko, V., Smith, D. M., Hajdas, W., Barthelmy, S. D., Cummings, J., Gehrels, N., Krimm, H., Palmer, D., Yamaoka, K., Ohno, M., Fukazawa, Y., Hanabata, Y., Takahashi, T., Tashiro, M., Terada, Y., Murakami, T., Makishima, K., Briggs, M. S., Kippen, R. M., Kouveliotou, C., Meegan, C., Fishman, G., Connaughton, V., Boer, M., Guidorzi, C., Frontera, F., Montanari, E., Rossi, F., Feroci, M., Amati, L., Nicastro, L., Orlandini, M., Del Monte, E., Costa, E., Donnarumma, I., Evangelista, Y., Lapshov, I., Lazzarotto, F., Pacciani, L., Rapisarda, M., Soffitta, P., Di Cocco, G., Fuschino, F., Galli, M., Labanti, C., Marisaldi, M., Atteia, J. -L., Vanderspek, R., and Ricker, G.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Between the launch of the \textit{GGS Wind} spacecraft in 1994 November and the end of 2010, the Konus-\textit{Wind} experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the IPN consisted of up to eleven spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, $\sim$18 per year, exceeds that of many individual experiments., Comment: Published version
- Published
- 2013
- Full Text
- View/download PDF
31. Numerical model development to predict the process-induced residual stresses in fibre metal laminates
- Author
-
Costanzo Bellini, Vittorio Di Cocco, Francesco Iacoviello, and Luca Sorrentino
- Subjects
Fibre metal laminate ,Cure induced deformation ,Residual stresses ,Finite element analysis ,Mechanics of engineering. Applied mechanics ,TA349-359 ,Technology - Abstract
The thermomechanical interactions between the different materials constituting a hybrid laminate make residual stresses arise during the manufacturing process of such laminate. In turn, the residual stresses make the laminate deform as it is extracted from the mould. Cure induced deformation represent a problem for the assembly step, since additional operations are required for allowing the joining of the different components. Therefore, a tool suitable for the calculation of residual stresses and deformation is needed in order to predict them and to implement the necessary remedies. In the present work, a numerical model for the determination of residual stresses is presented and validated through experimental tests. The case study was a notched laminate, in order to emphasize the deformation without altering the thermal cycle experienced in the material. Both numerical and experimental runs highlighted a higher deformation near the vertex of the laminate.
- Published
- 2021
- Full Text
- View/download PDF
32. The characterization of the distant blazar GB6 J1239+0443 from flaring and low activity periods
- Author
-
Pacciani, L., Donnarumma, I., Denney, K. D., Assef, R. J., Ikejiri, Y., Yamanaka, M., Uemura, M., Domingo, A., Giommi, P., Tarchi, A., Verrecchia, F., Longo, F., Rainó, S., Giusti, M., Vercellone, S., Chen, A. W., Striani, E., Vittorini, V., Tavani, M., Bulgarelli, A., Giuliani, A., Pucella, G., Argan, A., Barbiellini, G., Caraveo, P., Cattaneo, P. W., Colafrancesco, S., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Evangelista, Y., Ferrari, A., Feroci, M., Fiorini, M., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Marisaldi, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Zanello, D., Pittori, C., Santolamazza, P., Lucarelli, F., Salotti, L., and Valentini, G.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
In 2008 AGILE and Fermi detected gamma-ray flaring activity from the unidentified EGRET source 3EG J1236+0457, recently associated with a flat spectrum radio quasar GB6 J1239+0443 at z=1.762. The optical counterpart of the gamma-ray source underwent a flux enhancement of a factor 15-30 in 6 years, and of ~10 in six months. We interpret this flare-up in terms of a transition from an accretion-disk dominated emission to a synchrotron-jet dominated one. We analysed a Sloan Digital Sky Survey (SDSS) archival optical spectrum taken during a period of low radio and optical activity of the source. We estimated the mass of the central black hole using the width of the CIV emission line. In our work, we have also investigated SDSS archival optical photometric data and UV GALEX observations to estimate the thermal-disk emission contribution of GB6 J1239+0443. Our analysis of the gamma-ray data taken during the flaring episodes indicates a flat gamma-ray spectrum, with an extension of up to 15 GeV, with no statistically-relevant sign of absorption from the broad line region, suggesting that the blazar-zone is located beyond the broad line region. This result is confirmed by the modeling of the broad-band spectral energy distribution (well constrained by the available multiwavelength data) of the flaring activity periods and by the accretion disk luminosity and black hole mass estimated by us using archival data., Comment: 30 pages, 7 figures, 4 tables MNRAS Accepted on 2012 June 18
- Published
- 2012
- Full Text
- View/download PDF
33. Galactic Sources Science With Agile: The Case Of The Carina Region
- Author
-
Sabatini, S., Tavani, M., Pian, E., Bulgarelli, A., Caraveo, P., Viotti, R., Corcoran, M. F., Giuliani, A., Pittori, C., Verrecchia, F., Vercellone, S., Mereghetti, S., Argan, A., Barbiellini, G., Boffelli, F., Cattaneo, P. W., Chen, A. W., Cocco, V., D'Ammando, F., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Ferrari, A., Feroci, M., Fiorini, M., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mastropietro, M., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Pucella, G., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Vittorini, V., Zambra, A., Zanello, D., Santolamazza, P., Giommi, P., Colafrancesco, S., Antonelli, L. A., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
During its first 2 years of operation, the gamma-ray AGILE satellite accumulated an extensive dataset for the Galactic plane. The data have been monitored for transient sources and several gamma-ray sources were detected. Their variability and possible association were studied. In this talk we will focus on the results of extensive observations of the Carina Region during the time period 2007 July - 2009 January, for a total livetime of ~130 days. The region is extremely complex, hosting massive star formation, with the remarkable colliding wind binary Eta Carinae, massive star clusters and HII regions (e.g. NGC 3324, RCW49, Westerlund II) and a giant molecular cloud extending over 150 pc (between l=284.7 and l=289). The Carina Nebula itself is the largest and IR highest surface brightness nebula of the Southern emisphere. We monitored several gamma ray sources in the Carina Region. In particular we detect a gamma ray source (1AGL J1043-5931) consistent with the position of Eta Carinae and report a remarkable 2-days gamma-ray flaring episode from this source on 2008 Oct 11-13. If 1AGL J1043-5931 is associated with the Eta Car system, our data provides the long sought first detection above 100 MeV of a colliding wind binary., Comment: 5 pages, 5 figures, proceedings of RICAP 2009
- Published
- 2012
- Full Text
- View/download PDF
34. The flaring blazars of the first 1.5 years of the AGILE mission
- Author
-
Pacciani, L., Bulgarelli, A., Chen, A. W., D'Ammando, F., Donnarumma, I., Giuliani, A., Longo, F., Pucella, G., Tavani, M., Vercellone, S., Vittorini, V., Argan, A., Barbiellini, G., Boffelli, F., Caraveo, P., Cattaneo, P. W., Cocco, V., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Evangelista, Y., Ferrari, A., Feroci, M., Fiorini, M., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Marisaldi, M., Mastropietro, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Antonelli, L. A., Colafrancesco, S., Giommi, P., Pittori, C., Verrecchia, F., Santolamazza, P., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report the AGILE gamma-ray observations and the results of the multiwavelength campaigns on seven flaring blazars detected by the mission: During two multiwavelength campaigns, we observed gamma-ray activity from two Flat Spectrum Radio Quasars of the Virgo region, e.g. 3C 279 and 3C 273 (the latter being the first extragalactic source simultaneously observed with the gamma-ray telescope and the hard X ray imager of the mission). Due to the large FOV of the AGILE/GRID instrument, we achieved an almost continuous coverage of the FSRQ 3C 454.3. The source showed flux above 10E-6 photons/cm2/s (E > 100 MeV) and showed day by day variability during all the AGILE observing periods. In the EGRET era, the source was found in high gamma-ray activity only once. An other blazar, PKS 1510-089 was frequently found in high gamma-ray activity. S5 0716+71, an intermediate BL Lac object, exhibited a very high gamma-ray activity and fast gamma-ray variability during a period of intense optical activity. We observed high gamma-ray activity from W Comae, a BL Lac object, and Mrk 421, an high energy peaked BL Lac object. For this source, a multiwavelength campaign from optical to TeV has been performed.
- Published
- 2011
- Full Text
- View/download PDF
35. The observation of Gamma Ray Bursts and Terrestrial Gamma-ray Flashes with AGILE
- Author
-
Del Monte, E., Barbiellini, G., Fuschino, F., Giuliani, A., Longo, F., Marisaldi, M., Mereghetti, S., Moretti, E., Trifoglio, M., Vianello, G., Costa, E., Donnarumma, I., Evangelista, Y., Feroci, M., Galli, M., Lapshov, I., Lazzarotto, F., Lipari, P., Pacciani, L., Rapisarda, M., Soffitta, P., Tavani, M., Vercellone, S., Cutini, S., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A., Di Cocco, G., Gianotti, F., Labanti, C., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Pucella, G., Rappoldi, A., Sabatini, S., Striani, E., Trois, A., Vallazza, E., Vittorini, V., Antonelli, L. A., Pittori, C., Preger, B., Santolamazza, P., Verrecchia, F., Giommi, P., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Since its early phases of operation, the AGILE mission is successfully observing Gamma Ray Bursts (GRBs) in the hard X-ray band with the SuperAGILE imager and in the MeV range with the Mini-Calorimeter. Up to now, three firm GRB detections were obtained above 25 MeV and some bursts were detected with lower statistical confidence in the same energy band. When a GRB is localized, either by SuperAGILE or Swift/BAT or INTEGRAL/IBIS or Fermi/GBM or IPN, inside the field of view of the Gamma Ray Imager of AGILE, a detection is searched for in the gamma ray band or an upper limit is provided. A promising result of AGILE is the detection of very short gamma ray transients, a few ms in duration and possibly identified with Terrestrial Gamma-ray Flashes. In this paper we show the current status of the observation of Gamma Ray Bursts and Terrestrial Gamma-ray Flashes with AGILE., Comment: Four pages and four figures
- Published
- 2011
- Full Text
- View/download PDF
36. First results about on-ground calibration of the Silicon Tracker for the AGILE satellite
- Author
-
AGILE Collaboration, Cattaneo, P. W., Argan, A., Boffelli, F., Bulgarelli, A., Buonomo, B., Chen, A. W., D'Ammando, F., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Longo, F., Marisaldi, M., Mazzitelli, G., Pellizzoni, A., Prest, M., Pucella, G., Quintieri, L., Rappoldi, A., Tavani, M., Trifoglio, M., Trois, A., Valente, P., Vallazza, E., Vercellone, S., Zambra, A., Barbiellini, G., Caraveo, P., Cocco, V., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Mastropietro, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Rapisarda, M., Rubini, A., Sabatini, S., Soffitta, P., Striani, E., Vittorini, V., Zanello, D., Colafrancesco, S., Giommi, P., Pittori, C., Santolamazza, P., Verrecchia, F., and Salotti, L.
- Subjects
Astrophysics - Instrumentation and Methods for Astrophysics ,Physics - Instrumentation and Detectors - Abstract
The AGILE scientific instrument has been calibrated with a tagged $\gamma$-ray beam at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali di Frascati (LNF). The goal of the calibration was the measure of the Point Spread Function (PSF) as a function of the photon energy and incident angle and the validation of the Monte Carlo (MC) simulation of the silicon tracker operation. The calibration setup is described and some preliminary results are presented., Comment: Presented at the 2nd Roma International Conference on Astroparticle Physics 2009, Villa Mondragone, Rome, Italy, May 13-15 2009. Pages 6, Figures 10
- Published
- 2011
- Full Text
- View/download PDF
37. Characterization of a tagged $\gamma$-ray beam line at the DA$\Phi$NE Beam Test Facility
- Author
-
Cattaneo, P. W., Argan, A., Boffelli, F., Bulgarelli, A., Buonomo, B., Chen, A. W., D'Ammando, F., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Longo, F., Marisaldi, M., Mazzitelli, G., Pellizzoni, A., Prest, M., Pucella, G., Quintieri, L., Rappoldi, A., Tavani, M., Trifoglio, M., Trois, A., Valente, P., Vallazza, E., Vercellone, S., Zambra, A., Barbiellini, G., Caraveo, P., Cocco, V., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Mastropietro, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Rapisarda, M., Rubini, A., Sabatini, S., Soffitta, P., Striani, E., Vittorini, V., Zanello, D., Colafrancesco, S., Giommi, P., Pittori, C., Santolamazza, P., Verrecchia, F., and Salotti, L.
- Subjects
Physics - Instrumentation and Detectors ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
At the core of the AGILE scientific instrument, designed to operate on a satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs an on-ground calibration with a $\gamma$-ray beam to validate the simulation used to calculate the energy response function and the effective area versus the energy and the direction of the $\gamma$ rays. A tagged $\gamma$-ray beam line was designed at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali of Frascati (LNF), based on an electron beam generating $\gamma$ rays through bremsstrahlung in a position-sensitive target. The $\gamma$-ray energy is deduced by difference with the post-bremsstrahlung electron energy \cite{prest}-\cite{hasan}. The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). The use of the combined BTF-PTS system as tagged photon beam requires understanding the efficiency of $\gamma$-ray tagging, the probability of fake tagging, the energy resolution and the relation of the PTS hit position versus the $\gamma$-ray energy. This paper describes this study comparing data taken during the AGILE calibration occurred in 2005 with simulation., Comment: 23 pages; 17 figures. Second and final version accepted by Nucl. Instr. & Meth. A
- Published
- 2011
- Full Text
- View/download PDF
38. AGILE detection of Cygnus X-3 {\gamma}-ray active states during the period mid-2009/mid-2010
- Author
-
Bulgarelli, A., Tavani, M., Chen, A. W., Evangelista, Y., Trifoglio, M., Gianotti, F., Piano, G., Sabatini, S., Striani, E., Pooley, G., Trushkin, S., Nizhelskij, N. A., McCollough, M., Koljonen, K. I. I., Hannikainen, D., Lähteenmäki, A., Tammi, J., Lavonen, N., Steeghs, D., Aboudan, A., Argan, A., Barbiellini, G., Campana, R., Caraveo, P., Cattaneo, P. W., Cocco, V., Contessi, T., Costa, E., D'Ammando, F., Del Monte, E., De Paris, G., Di Cocco, G., Donnarumma, I., Feroci, M., Fiorini, M., Fuschino, F., Galli, M., Giuliani, A., Giusti, M., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Pilia, M., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Rubini, A., Soffitta, P., Trois, A., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Giommi, P., Pittori, C., Verrecchia, F., Santolamazza, P., Lucarelli, F., Colafrancesco, S., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Cygnus X-3 (Cyg X-3) is a well-known microquasar producing variable emission at all wavelengths. Cyg X-3 is a prominent X-ray binary producing relativistic jets, and studying its high energy emission is crucial for the understanding of the fundamental acceleration processes in accreting compact objects. Aims. Our goal is to study extreme particle acceleration and {\gamma}-ray production above 100 MeV during special spectral states of Cyg X- 3 usually characterized by a low hard X-ray flux and enhanced soft X-ray states. We observed Cyg X-3 with the AGILE satellite in extended time intervals from 2009 Jun.-Jul., and 2009 Nov.-2010 Jul. We report here the results of the AGILE {\gamma}-ray monitoring of Cyg X-3 as well as the results from extensive multiwavelength campaigns involving radio (RATAN-600, AMI-LA and Mets\"{a}hovi Radio Observatories) and X-ray monitoring data (XTE and Swift). We detect a series of repeated {\gamma}-ray flaring activity from Cyg X-3 that correlate with the soft X-ray states and episodes of decreasing or non-detectable hard X-ray emission. Furthermore, we detect {\gamma}-ray enhanced emission that tends to be associated with radio flares greater than 1 Jy at 15 GHz, confirming a trend already detected in previous observations. The source remained active above 100 MeV for an extended period of time (almost 1.5 months in 2009 Jun.-Jul. and 1 month in 2010 May). We study in detail the short timescale {\gamma}-ray flares that occurred before or near the radio peaks. Our results confirm the transient nature of the extreme particle acceleration from the microquasar Cyg X-3. A series of repeated {\gamma}-ray flares shows correlations with radio and X-ray emission confirming a well established trend of emission. We compare our results with Fermi-LAT and MAGIC TeV observations of Cyg X-3., Comment: 16 pages, 8 figures, 7 tables; A&A (2011)
- Published
- 2011
- Full Text
- View/download PDF
39. The first GRB survey of the IBIS/PICsIT archive
- Author
-
Bianchin, V., Mereghetti, S., Guidorzi, C., Foschini, L., Vianello, G., Malaguti, G., Di Cocco, G., Gianotti, F., and Schiavone, F.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
The multi-purpose INTEGRAL mission is continuously contributing to Gamma Ray Burst (GRB) science, thanks to the performances of its two main instruments, IBIS and SPI, operating in the hard X-ray/soft gamma-ray domain. We investigate the possibilities offered to the study of GRBs by PICsIT, the high-energy detector of the IBIS instrument. We searched for transient episodes in the PICsIT light curves archive from May 2006 to August 2009, using stringent criteria optimized for the detection of long events. In the time interval under examination PICsIT provides an energy coverage from 208 to 2600 keV, resolved in eight energy channels, combined with a fine time resolution of 16 ms. PICsIT successfully observes GRBs in the 260-2600 keV energy range with an incoming direction spread over half the sky for the brightest events. We compiled a list of 39 bursts, most of which are confirmed GRBs or simultaneous to triggers from other satellites/instruments. We produced light curves with a time sampling down to 0.25 s in three energy intervals for all events. Because an adequate response matrix is not yet available for the PICsIT burst sample, we obtained a calibration coefficient in three selected energy bands by comparing instrumental counts with physical fluences inferred from observations with different satellites. The good time resolution provided by the PICsIT data allows a spectral variability study of our sample through the hardness ratio., Comment: 20 pages, 48 figures. Accepted for publication in A&A
- Published
- 2011
- Full Text
- View/download PDF
40. The AGILE observations of the hard and bright GRB 100724B
- Author
-
Del Monte, E., Barbiellini, G., Donnarumma, I., Fuschino, F., Giuliani, A., Longo, F., Marisaldi, M., Pucella, G., Tavani, M., Trifoglio, M., Trois, A., Argan, A., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A., Costa, E., D'Ammando, F., Di Cocco, G., Evangelista, Y., Feroci, M., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Mereghetti, S., Moretti, E., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Striani, E., Vallazza, E., Vercellone, S., Vittorini, V., Antonelli, L. A., Cutini, S., Pittori, C., Santolamazza, P., Verrecchia, F., Giommi, P., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
The observation of Gamma Ray Bursts (GRBs) in the gamma-ray band has been advanced by the AGILE and Fermi satellites after the era of the Compton Gamma-Ray Observatory. AGILE and Fermi are showing that the GeV-bright GRBs share a set of common features, particularly the high fluence from the keV up to the GeV energy bands, the high value of the minimum Lorentz factor, the presence of an extended emission of gamma-rays, often delayed with respect to lower energies, and finally the possible presence of multiple spectral components. GRB 100724B, localised in a joint effort by Fermi and the InterPlanetary Newtork, is the brightest burst detected in gamma-rays so far by AGILE. Characteristic features of GRB 100724B are the simultaneous emissions at MeV and GeV, without delayed onset nor time lag as shown by the analysis of the cross correlation function, and the significant spectral evolution in hard X-rays over the event duration. In this paper we show the analysis of the AGILE data of GRB 100724B and we discuss its features in the context of the bursts observed so far in gamma-rays and the recently proposed models., Comment: 8 pages, 5 figures. Accepted for publication by A&A. Final version after the correction by the language editor
- Published
- 2011
- Full Text
- View/download PDF
41. The Crab Nebula super-flare in April 2011: extremely fast particle acceleration and gamma-ray emission
- Author
-
Striani, E., Tavani, M., Piano, G., Donnarumma, I., Pucella, G., Vittorini, V., Bulgarelli, A., Trois, A., Pittori, C., Verrecchia, F., Costa, E., Weisskopf, M., Tennant, A., Argan, A., Barbiellini, G., Caraveo, P., Cardillo, M, Cattaneo, P. W., Chen, A. W., De Paris, G., Del Monte, E., Di Cocco, G., Evangelista, Y., Ferrari, A., Feroci, M., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lapshov, I., Lazzarotto, F., Longo, F., Marisaldi, M., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Pilia, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Trifoglio, M., Vercellone, S., Lucarelli, F., Santolamazza, P., and Giommi, P.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on the extremely intense and fast gamma-ray are above 100 MeV detected by AGILE from the Crab Nebula in mid-April 2011. This event is the fourth of a sequence of reported major gamma-ray flares produced by the Crab Nebula in the period 2007/mid-2011. These events are attributed to strong radiative and plasma instabilities in the inner Crab Nebula, and their properties are crucial for theoretical studies of fast and efficient particle acceleration up to 10^15 eV. Here we study the very rapid flux and spectral evolution of the event that reached on April 16, 2011 the record-high peak flux of F = (26 +/- 5) x 10^-6 ph cm^-2 s^-1 with a risetime timescale that we determine to be in the range 6-10 hrs. The peak flaring gamma-ray spectrum reaches a distinct maximum near 500 MeV with no substantial emission above 1 GeV. The very rapid risetime and overall evolution of the Crab Nebula are strongly constrain the acceleration mechanisms and challenge MHD models. We briefly discuss the theoretical implications of our observations., Comment: 4 pages, 2 figures. Accepted for pubblication in ApJL
- Published
- 2011
- Full Text
- View/download PDF
42. AGILE detection of extreme gamma-ray activity from the blazar PKS 1510-089 during March 2009. Multifrequency analysis
- Author
-
D'Ammando, F., Raiteri, C. M., Villata, M., Romano, P., Pucella, G., Krimm, H. A., Covino, S., Orienti, M., Giovannini, G., Vercellone, S., Pian, E., Donnarumma, I., Vittorini, V., Tavani, M., Argan, A., Barbiellini, G., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A. W., Cocco, V., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Froysland, T., Frutti, M., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Striani, E., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Benitez, E., Berdyugin, A., Blinov, D. A., Buemi, C. S., Chen, W. P., Di Paola, A., Dolci, M., Forne, E., Fuhrmann, L., Gomez, J. L., Gurwell, M. A., Jordan, B., Jorstad, S. G., Heidt, J., Hiriart, D., Hovatta, T., Hsiao, H. Y., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O. M., Kurtanidze, S. O., Larionov, V. M., Lahteenmaki, A., Leto, P., Lindfors, E., Marscher, A. P., McBreen, B., McHardy, I. M., Morozova, D. A., Nilsson, K., Pasanen, M., Roca-Sogorb, M., Sillanpaa, A., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., Umana, G., Antonelli, L. A., Colafrancesco, S., Pittori, C., Santolamazza, P., Verrecchia, F., Giommi, P., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on the extreme gamma-ray activity from the FSRQ PKS 1510-089 observed by AGILE in March 2009. In the same period a radio-to-optical monitoring of the source was provided by the GASP-WEBT and REM. Moreover, several Swift ToO observations were triggered, adding important information on the source behaviour from optical/UV to hard X-rays. We paid particular attention to the calibration of the Swift/UVOT data to make it suitable to the blazars spectra. Simultaneous observations from radio to gamma rays allowed us to study in detail the correlation among the emission variability at different frequencies and to investigate the mechanisms at work. In the period 9-30 March 2009, AGILE detected an average gamma-ray flux of (311+/-21)x10^-8 ph cm^-2 s^-1 for E>100 MeV, and a peak level of (702+/-131)x10^-8 ph cm^-2 s^-1 on daily integration. The gamma-ray activity occurred during a period of increasing activity from near-IR to UV, with a flaring episode detected on 26-27 March 2009, suggesting that a single mechanism is responsible for the flux enhancement observed from near-IR to UV. By contrast, Swift/XRT observations seem to show no clear correlation of the X-ray fluxes with the optical and gamma-ray ones. However, the X-ray observations show a harder photon index (1.3-1.6) with respect to most FSRQs and a hint of harder-when-brighter behaviour, indicating the possible presence of a second emission component at soft X-ray energies. Moreover, the broad band spectrum from radio-to-UV confirmed the evidence of thermal features in the optical/UV spectrum of PKS 1510-089 also during high gamma-ray state. On the other hand, during 25-26 March 2009 a flat spectrum in the optical/UV energy band was observed, suggesting an important contribution of the synchrotron emission in this part of the spectrum during the brightest gamma-ray flare, therefore a significant shift of the synchrotron peak., Comment: 13 pages, 7 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics
- Published
- 2011
- Full Text
- View/download PDF
43. Discovery of Powerful Gamma-Ray Flares from the Crab Nebula
- Author
-
Tavani, M., Bulgarelli, A., Vittorini, V., Pellizzoni, A., Striani, E., Caraveo, P., Weisskopf, M. C., Tennant, A., Pucella, G., Trois, A., Costa, E., Evangelista, Y., Pittori, C., Verrecchia, F., Del Monte, E., Campana, R., Pilia, M., De Luca, A., Donnarumma, I., Horns, D., Ferrigno, C., Heinke, C. O., Trifoglio, M., Gianotti, F., Vercellone, S., Argan, A., Barbiellini, G., Cattaneo, P. W., Chen, A. W., Contessi, T., D'Ammando, F., DeParis, G., Di Cocco, G., Di Persio, G., Feroci, M., Ferrari, A., Galli, M., Giuliani, A., Giusti, M., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Fuschino, F., Marisaldi, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Vallazza, E., Zambra, A., Zanello, D., Lucarelli, F., Santolamazza, P., Giommi, P., Salotti, L., and Bignami, G. F.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
The well known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally-powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar and nebula have been considered to be essentially stable. Here we report the detection of strong gamma-ray (100 MeV-10 GeV) flares observed by the AGILE satellite in September, 2010 and October, 2007. In both cases, the unpulsed flux increased by a factor of 3 compared to the non-flaring flux. The flare luminosity and short timescale favor an origin near the pulsar, and we discuss Chandra Observatory X-ray and HST optical follow-up observations of the nebula. Our observations challenge standard models of nebular emission and require power-law acceleration by shock-driven plasma wave turbulence within a ~1-day timescale., Comment: 23 pages (including Supporting On-line Material), 8 figures, 1 table. Version published in Science Express on January 6, 2011 (available at http://www.sciencemag.org/content/early/2011/01/05/science.1200083)
- Published
- 2011
- Full Text
- View/download PDF
44. 7-Docosahexaenoyl-Quercetin
- Author
-
Sarah Mazzotta, Gabriele Carullo, Fabio Sciubba, Maria Enrica Di Cocco, and Francesca Aiello
- Subjects
quercetin ,DHA ,lipase ,regioselective ,polyphenols ,Inorganic chemistry ,QD146-197 - Abstract
Fatty acids and polyphenols represent different classes of pharmacologically active molecules. Hybrid derivatives of these compounds are interesting therapeutic tools. They could be obtained using enzymatic approaches, which allow regioselective derivatizations. In this short note, the pancreatic porcine lipase was employed to mediate the regioselective synthesis of 7-docosahexaenoyl-quercetin was described. The C-7 regioisomer formation was confirmed by 1H-NMR experiment. Generally, in this approach the alcoholic OH- was preferred when present. Nevertheless, in this case, it was demonstrated that the hindrance of the acyl group is a variable to obtain a good regioselectivity in C-7 position, employing only one-step reaction.
- Published
- 2021
- Full Text
- View/download PDF
45. Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes
- Author
-
Marisaldi, M., Argan, A., Trois, A., Giuliani, A., Tavani, M., Labanti, C., Fuschino, F., Bulgarelli, A., Longo, F., Barbiellini, G., Del Monte, E., Moretti, E., Trifoglio, M., Costa, E., Caraveo, P., Cattaneo, P. W., Chen, A., D'Ammando, F., De Paris, G., Di Cocco, G., Di Persio, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Froysland, T., Galli, M., Gianotti, F., Lapshov, I., Lazzarotto, F., Lipari, P., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Piano, G., Pilia, M., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Striani, E., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Antonelli, L. A., Colafrancesco, S., Cutini, S., Giommi, P., Lucarelli, F., Pittori, C., Santolamazza, P., Verrecchia, F., and Salotti, L.
- Subjects
Physics - Atmospheric and Oceanic Physics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Terrestrial Gamma-Ray Flashes (TGFs) are very short bursts of high energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of 5-10 degrees at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the sub-satellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space., Comment: 5 pages, 4 figures, 1 table, available at http://prl.aps.org/abstract/PRL/v105/i12/e128501
- Published
- 2010
- Full Text
- View/download PDF
46. Study of the gamma-ray source 1AGL J2022+4032 in the Cygnus Region
- Author
-
Chen, A. W., Piano, G., Tavani, M., Trois, A., Dubner, G., Giacani, E., Argan, A., Barbiellini, G., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Costa, E., D'Ammando, F., De Paris, G., Del Monte, E., Di Cocco, G., Donnarumma, I., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Giusti, M., Labanti, C., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mereghetti, S., Moretti, E., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Pilia, M., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Sabatini, S., Scalise, E., Soffitta, P., Striani, E., Trifoglio, M., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Pittori, C., Giommi, P., Verrecchia, F., Lucarelli, F., Santolamazza, P., Colafrancesco, S., Antonelli, L. A., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Identification of gamma-ray-emitting Galactic sources is a long-standing problem in astrophysics. One such source, 1AGL J2022+4032, coincident with the interior of the radio shell of the supernova remnant Gamma Cygni (SNR G78.2+2.1) in the Cygnus Region, has recently been identified by Fermi as a gamma-ray pulsar, LAT PSR J2021+4026. We present long-term observations of 1AGL J2022+4032 with the AGILE gamma-ray telescope, measuring its flux and light curve. We compare the light curve of 1AGL J2022+4032 with that of 1AGL J2021+3652 (PSR J2021+3651), showing that the flux variability of 1AGL J2022+4032 appears to be greater than the level predicted from statistical and systematic effects and producing detailed simulations to estimate the probability of the apparent observed variability. We evaluate the possibility that the gamma-ray emission may be due to the superposition of two or more point sources, some of which may be variable, considering a number of possible counterparts. We consider the possibility of a nearby X-ray quiet microquasar contributing to the flux of 1AGL J2022+4032 to be more likely than the hypotheses of a background blazar or intrinsic gamma-ray variabilty of LAT PSR J2021+4026., Comment: 7 pages, 7 figures, accepted for publication in Astronomy & Astrophysics
- Published
- 2010
- Full Text
- View/download PDF
47. Agile Observations of the 'Soft' Gamma-Ray Pulsar PSR B1509-58
- Author
-
Pilia, M., Pellizzoni, A., Trois, A., Verrecchia, F., Esposito, P., Weltevrede, P., Johnston, S., Burgay, M., Possenti, A., Del Monte, E., Fuschino, F., Santolamazza, P., Chen, A., Giuliani, A., Caraveo, P., Mereghetti, S., Tavani, M., Argan, A., Costa, E., D'Amico, N., De Luca, A., Evangelista, Y., Feroci, M., Longo, F., Marisaldi, M., Barbiellini, G., Bulgarelli, A., Cattaneo, P. W., Cocco, V., D'Ammando, F., De Paris, G., Di Cocco, G., Donnarumma, I., Fiorini, M., Froysland, T., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Morselli, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Trifoglio, M., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Pittori, C., Lucarelli, F., Giommi, P., Salotti, L., and Bignami, G. F.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present the results of new Agile observations of PSR B1509-58 performed over a period of 2.5 years following the detection obtained with a subset of the present data. The modulation significance of the lightcurve above 30 MeV is at a 5$\sigma$ confidence level and the lightcurve is similar to those found earlier by Comptel up to 30 MeV: a broad asymmetric first peak reaching its maximum 0.39 +/- 0.02 cycles after the radio peak plus a second peak at 0.94 +/- 0.03. The gamma-ray spectral energy distribution of the pulsed flux detected by Comptel and Agile is well described by a power-law (photon index alpha=1.87+/-0.09) with a remarkable cutoff at E_c=81 +/- 20 MeV, representing the softest spectrum observed among gamma-ray pulsars so far. The pulsar luminosity at E > 1 MeV is $L_{\gamma}=4.2^{+0.5}_{-0.2} \times10^{35}$ erg/s, assuming a distance of 5.2 kpc, which implies a spin-down conversion efficiency to gamma-rays of $\sim 0.03$. The unusual soft break in the spectrum of PSR B1509-58 has been interpreted in the framework of polar cap models as a signature of the exotic photon splitting process in the strong magnetic field of this pulsar. In this interpretation our spectrum constrains the magnetic altitude of the emission point(s) at 3 km above the neutron star surface, implying that the attenuation may not be as strong as formerly suggested because pair production can substitute photon splitting in regions of the magnetosphere where the magnetic field becomes too low to sustain photon splitting. In the case of an outer-gap scenario, or the two pole caustic model, better constraints on the geometry of the emission would be needed from the radio band in order to establish whether the conditions required by the models to reproduce Agile lightcurves and spectra match the polarization measurements., Comment: 17 pages, 2 figures, accepted for publication in ApJ
- Published
- 2010
- Full Text
- View/download PDF
48. The extraordinary gamma-ray flare of the blazar 3C 454.3
- Author
-
Striani, E., Vercellone, S., Tavani, M., Vittorini, V., D'Ammando, F., Donnarumma, I., Pacciani, L., Pucella, G., Bulgarelli, A., Trifoglio, M., Gianotti, F., Giommi, P., Argan, A., Barbiellini, G., Caraveo, P., Cattaneo, P. W., Chen, A. W., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Fuschino, F., Galli, M., Giuliani, A., Giusti, M., Labanti, C., Lazzarotto, F., Lipari, P., Longo, F., Marisaldi, M., Mereghetti, S., Moretti, E., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Scalise, E., Soffitta, P., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Pittori, C., Verrecchia, F., Santolamazza, P., Lucarelli, F., Colafrancesco, S., Antonelli, L. A., and Salotti, L.
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present the gamma-ray data of the extraordinary flaring activity above 100 MeV from the flat spectrum radio quasar 3C 454.3 detected by AGILE during the month of December 2009. 3C 454.3, that has been among the most active blazars of the FSRQ type since 2007, was detected in the gamma-ray range with a progressively rising flux since November 10, 2009. The gamma-ray flux reached a value comparable with that of the Vela pulsar on December 2, 2009. Remarkably, between December 2 and 3, 2009 the source more than doubled its gamma-ray emission and became the brightest gamma-ray source in the sky with a peak flux of F_{\gamma,p} = (2000 \pm 400) x 10^-8 ph cm^-2 s^-1 for a 1-day integration above 100 MeV. The gamma-ray intensity decreased in the following days with the source flux remaining at large values near F \simeq (1000 \pm 200) x 10^-8 ph cm^-2 s^-1 for more than a week. This exceptional gamma-ray flare dissipated among the largest ever detected intrinsic radiated power in gamma-rays above 100 MeV (L_{\gamma, source, peak} \simeq 3 x 10^46 erg s^-1, for a relativistic Doppler factor of {\delta} \simeq 30). The total isotropic irradiated energy of the month-long episode in the range 100 MeV - 3 GeV is E_{\gamma,iso} \simeq 10^56 erg. We report the intensity and spectral evolution of the gamma-ray emission across the flaring episode. We briefly discuss the important theoretical implications of our detection., Comment: 17 pages, 3 figures, ApJ accepted
- Published
- 2010
- Full Text
- View/download PDF
49. The December 2009 gamma-ray flare of 3C 454.3: the multifrequency campaign
- Author
-
Pacciani, L., Vittorini, V., Tavani, M., Fiocchi, M. T., Vercellone, S., D'Ammando, F., Sakamoto, T., Pian, E., Raiteri, C. M., Villata, M., Sasada, M., Itoh, R., Yamanaka, M., Uemura, M., Striani, E., Fugazza, D., Tiengo, A., Krimm, H. A., Stroh, M. C., Falcone, A. D., Curran, P. A., Sadun, A. C., Lahteenmaki, A., Tornikoski, M., Aller, H. D., Aller, M. F., Lin, C. S., Larionov, V. M., Leto, P., Takalo, L. O., Berdyugin, A., Gurwell, M. A., Bulgarelli, A., Chen, A. W., Donnarumma, I., Giuliani, A., Longo, F., Pucella, G., Argan, A., Caraveo, G. Barbiellini P., Cattaneo, P. W., Cocco, V., Costa, E., De Paris, G., Del Monte, E., Di Cocco, G., Evangelista, Y., Ferrari, A., Feroci, M., Fiorini, M., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Marisaldi, M., Mereghetti, S., Morelli, E., Moretti, E., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Sabatini, S., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Zanello, D., Colafrancesco, S., Pittori, C., Verrecchia, F., Santolamazza, P., Lucarelli, F., Giommi, P., and Salotti, L.
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
During the month of December, 2009 the blazar 3C 454.3 became the brightest gamma-ray source in the sky, reaching a peak flux F ~2000E-8 ph/cm2/s for E > 100 MeV. Starting in November, 2009 intensive multifrequency campaigns monitored the 3C 454 gamma-ray outburst. Here we report the results of a 2-month campaign involving AGILE, INTEGRAL, Swift/XRT, Swift/BAT, RossiXTE for the high-energy observations, and Swift/UVOT, KANATA, GRT, REM for the near-IR/optical/UV data. The GASP/WEBT provided radio and additional optical data. We detected a long-term active emission phase lasting ~1 month at all wavelengths: in the gamma-ray band, peak emission was reached on December 2-3, 2009. Remarkably, this gamma-ray super-flare was not accompanied by correspondingly intense emission in the optical/UV band that reached a level substantially lower than the previous observations in 2007-2008. The lack of strong simultaneous optical brightening during the super-flare and the determination of the broad-band spectral evolution severely constrain the theoretical modelling. We find that the pre- and post-flare broad-band behavior can be explained by a one-zone model involving SSC plus external Compton emission from an accretion disk and a broad-line region. However, the spectra of the Dec. 2-3, 2009 super-flare and of the secondary peak emission on Dec. 9, 2009 cannot be satisfactorily modelled by a simple one-zone model. An additional particle component is most likely active during these states., Comment: 21 pages, 2 figures, ApJL accepted
- Published
- 2010
- Full Text
- View/download PDF
50. AGILE detection of GeV gamma-ray emission from the SNR W28
- Author
-
Giuliani, A., Tavani, M., Bulgarelli, A., Striani, E., Sabatini, S., Cardillo, M., Fukui, Y., Kawamura, A., Ohama, A., Furukawa, N., Torii, K., Aharonian, F. A., Verrecchia, F., Argan, A., Barbiellini, G., Caraveo, P. A., Cattaneo, P. W., Chen, A. W., Cocco, V., Costa, E., D'Ammando, F., Del Monte, E., De Paris, G., Di Cocco, G., Donnarumma, I., Evangelista, Y., Feroci, M., Fiorini, M., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, Y., Lazzarotto, F., Lipari, P., Longo, F., Mereghetti, M. Marisaldi., Morselli, A., Moretti, E., Pacciani, L., Pellizzoni, A., Perotti, F., Picozza, P., Pilia, M., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Pittori, C., Santolamazza, P., Giommi, P., Colafrancesco, S., and Salotti, L.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Supernova remnants (SNRs) are believed to be the main sources of Galactic cosmic rays. Molecular clouds associated with SNRs can produce gamma-ray emission through the interaction of accelerated particles with the concentrated gas. The middle aged SNR W28, for its associated system of dense molecular clouds, provides an excellent opportunity to test this hypothesis. We present the AGILE/GRID observations of SNR W28, and compare them with observations at other wavelengths (TeV and 12CO J=1-->0 molecular line emission). The gamma-ray flux detected by AGILE from the dominant source associated with W28 is (14 +- 5) 10^-8 ph cm^-2 s^-1 for E > 400 MeV. This source is positionally well correlated with the TeV emission observed by the HESS telescope. The local variations of the GeV to TeV flux ratio suggest a difference between the CR spectra of the north-west and south molecular cloud complexes. A model based on a hadronic-induced interaction and diffusion with two molecular clouds at different distances from the W28 shell can explain both the morphological and spectral features observed by AGILE in the MeV-GeV energy range and by the HESS telescope in the TeV energy range. The combined set of AGILE and H.E.S.S. data strongly support a hadronic model for the gamma-ray production in W28., Comment: Accepted for publication in Astronomy & Astrophysics Letters
- Published
- 2010
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.