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51. Magic Constraints on γ-ray Emission from Cygnus X-3

Author

Aleksic, J, Antonelli, La, Antoranz, P, Backes, M, Baixeras, C, Barrio, Ja, Bastieri, Denis, Gonzalez, Jb, Bednarek, W, Berdyugin, A, Berger, K, Bernardini, E, Biland, A, Blanch, O, Bock, Rk, Boller, A, Bonnoli, G, Bordas, P, Tridon, Db, BOSCH RAMON, V, Bose, D, Braun, I, Bretz, T, Britzger, D, Camara, M, Carmona, E, Carosi, A, Colin, P, Contreras, Jl, Cortina, J, Costado, Mt, Covino, S, Dazzi, F, DE ANGELIS, A, DEL POZO EDC, DE LOTTO, B, DE MARIA, M, DE SABATA, F, Mendez, Cd, Doert, M, Dominguez, A, Prester, Dd, Dorner, D, Doro, Michele, Elsaesser, D, Errando, M, Ferenc, D, Fonseca, Mv, Font, L, Lopez, Rjg, Garczarczyk, M, Gaug, M, Godinovic, N, Goebel, F, Hadasch, D, Herrero, A, Hildebrand, D, HOHNE MONCH, D, Hose, J, Hrupec, D, Hsu, Cc, Jogler, T, Klepser, S, Krahenbuhl, T, Kranich, D, LA BARBERA, A, Laille, A, Leonardo, E, Lindfors, E, Lombardi, S, Longo, F, Lopez, M, Lorenz, E, Majumdar, P, Maneva, G, Mankuzhiyil, N, Mannheim, K, Maraschi, L, Mariotti, Mose', Martinez, M, Mazin, D, Meucci, M, Miranda, Jm, Mirzoyan, R, Miyamoto, H, Moldon, J, Moles, M, Moralejo, A, Nieto, D, Nilsson, K, Ninkovic, J, Orito, R, Oya, I, Paiano, S, Paoletti, R, Paredes, Jm, Partini, S, Pasanen, M, Pascoli, Donatella, Pauss, F, Pegna, Rg, PEREZ TORRES MA, Persic, M, Peruzzo, L, Prada, F, Prandini, Elisa, Puchades, N, Puljak, I, Reichardt, I, Rhode, W, Ribo, M, Rico, J, Rissi, M, Rugamer, S, Saggion, Antonio, Saito, K, Saito, Ty, Salvati, M, SANCHEZ CONDE, M, Satalecka, K, Scalzotto, VILLI MARIO, Scapin, V, Schultz, C, Schweizer, T, Shayduk, M, Shore, Sn, SIERPOWSKA BARTOSIK, A, Sillanpaa, A, Sitarek, J, Sobczynska, D, Spanier, F, Spiro, S, Stamerra, A, Steinke, B, Struebig, Jc, Suric, T, Takalo, L, Tavecchio, F, Temnikov, P, Terzic, T, Tescaro, D, Teshima, M, Torres, Df, Vankov, H, Wagner, Rm, Weitzel, Q, Zabalza, V, Zandanel, F, Zanin, R, Bulgarelli, A, MAX MOERBECK, W, Piano, G, Pooley, G, Readhead, Acs, Richards, Jl, Sabatini, S, Striani, E, Tavani, M, Trushkin, S., J., Aleksic, L. A., Antonelli, P., Antoranz, M., Backe, C., Baixera, J. A., Barrio, D., Bastieri, J. B., Gonzalez, W., Bednarek, A., Berdyugin, K., Berger, E., Bernardini, A., Biland, O., Blanch, R. K., Bock, A., Boller, G., Bonnoli, P., Borda, D. B., Tridon, V., Bosch Ramon, D., Bose, I., Braun, T., Bretz, D., Britzger, M., Camara, E., Carmona, A., Carosi, P., Colin, J. L., Contrera, J., Cortina, M. T., Costado, S., Covino, F., Dazzi, A. D., Angeli, E. D. C., Del Pozo, B. D., Lotto, M. D., Maria, F. D., Sabata, C. D., Mendez, M., Doert, A., Dominguez, D. D., Prester, D., Dorner, M., Doro, D., Elsaesser, M., Errando, D., Ferenc, M. V., Fonseca, L., Font, R. J. G., Lopez, M., Garczarczyk, M., Gaug, N., Godinovic, F., Goebel, D., Hadasch, A., Herrero, D., Hildebrand, D., Hohne Monch, J., Hose, D., Hrupec, C. C., Hsu, T., Jogler, S., Klepser, T., Krahenbuhl, D., Kranich, A. L., Barbera, A., Laille, E., Leonardo, E., Lindfor, S., Lombardi, Longo, Francesco, M., Lopez, E., Lorenz, P., Majumdar, G., Maneva, N., Mankuzhiyil, K., Mannheim, L., Maraschi, M., Mariotti, M., Martinez, D., Mazin, M., Meucci, J. M., Miranda, R., Mirzoyan, H., Miyamoto, J., Moldon, M., Mole, A., Moralejo, D., Nieto, K., Nilsson, J., Ninkovic, R., Orito, I., Oya, S., Paiano, R., Paoletti, J. M., Parede, S., Partini, M., Pasanen, D., Pascoli, F., Pau, R. G., Pegna, M. A., Perez Torre, M., Persic, L., Peruzzo, F., Prada, E., Prandini, N., Puchade, I., Puljak, I., Reichardt, W., Rhode, M., Ribo, J., Rico, M., Rissi, S., Rugamer, A., Saggion, K., Saito, T. Y., Saito, M., Salvati, M., Sanchez Conde, K., Satalecka, V., Scalzotto, V., Scapin, C., Schultz, T., Schweizer, M., Shayduk, S. N., Shore, A., Sierpowska Bartosik, A., Sillanpaa, J., Sitarek, D., Sobczynska, F., Spanier, S., Spiro, A., Stamerra, B., Steinke, J. C., Struebig, T., Suric, L., Takalo, F., Tavecchio, P., Temnikov, T., Terzic, D., Tescaro, M., Teshima, D. F., Torre, H., Vankov, R. M., Wagner, Q., Weitzel, V., Zabalza, F., Zandanel, R., Zanin, A., Bulgarelli, W., Max Moerbeck, G., Piano, G., Pooley, A. C. S., Readhead, J. L., Richard, S., Sabatini, E., Striani, M., Tavani, and S., Trushkin

Subjects
Photon, HIGH-ENERGY EMISSION, MICROQUASAR GRS 1915+105, X-RAY, RELATIVISTIC JET, CYG X-3, RADIO OUTBURST, CRAB-NEBULA, BINARY, TELESCOPE, PULSAR, Astrophysics, 01 natural sciences, law.invention, Raigs gamma, law, Observacions astronòmiques, 010303 astronomy & astrophysics, Estels binaris de raigs X, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Very High Energy Gamma-ray Astronomy, MAGIC telescope, Black Holes, Gamma ray, X-ray binaries, Electrónica, Física nuclear, Radio frequency, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, Astronomical observations, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, Radiation, gamma ray astronomy, Cosmic rays, IMAGING CHERENKOV DETECTOR, Telescope, 0103 physical sciences, acceleration of particles, binaries: general, gamma rays: observations, X-rays: bina- ries — X-rays: individual (Cygnus X-3), Cherenkov radiation, Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, Gamma rays, Magic (programming), Astronomy, Astronomy and Astrophysics, Space and Planetary Science
Abstract

Cygnus X-3 is a microquasar consisting of an accreting compact object orbiting around a Wolf-Rayet star. It has been detected at radio frequencies and up to high-energy gamma rays (above 100 MeV). However, many models also predict a very high energy (VHE) emission (above hundreds of GeV) when the source displays relativistic persistent jets or transient ejections. Therefore, detecting such emission would improve the understanding of the jet physics. The imaging atmospheric Cherenkov telescope MAGIC observed Cygnus X-3 for about 70 hours between 2006 March and 2009 August in different X-ray/radio spectral states and also during a period of enhanced gamma-ray emission. MAGIC found no evidence for a VHE signal from the direction of the microquasar. An upper limit to the integral flux for energies higher than 250 GeV has been set to 2.2 x 10-12 photons cm-2 s-1 (95% confidence level). This is the best limit so far to the VHE emission from this source. The non-detection of a VHE signal during the period of activity in the high-energy band sheds light on the location of the possible VHE radiation favoring the emission from the innermost region of the jets, where absorption is significant. The current and future generations of Cherenkov telescopes may detect a signal under precise spectral conditions., 14 pages, 11 figures, This manuscript has been accepted by ApJ (2010)

Published
2010
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52. Detection of terrestrial gamma ray flashes up to 40 MeV by the AGILE satellite

Author

Marisaldi, M., Fuschino, F., Labanti, C., Galli, M., Longo, Francesco, Monte, E. D., Barbiellini, G., Tavani, M., Giuliani, A., Moretti, E., Vercellone, S., Costa, E., Cutini, S., Donnarumma, I., Evangelista, Y., Feroci, M., Lapshov, I., Lazzarotto, F., Lipari, P., Mereghetti, S., Pacciani, L., Rapisarda, M., Soffitta, P., Trifoglio, M., Argan, A., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A., Cocco, V., D'Ammando, F., Paris, G. D., Cocco, G. D., Persio, G. D., Ferrari, A., Fiorini, M., Froysland, T., Gianotti, F., Morselli, A., Pellizzoni, A., Perotti, F., Picozza, P., Piano, G., Pilia, M., Prest, M., Pucella, G., Rappoldi, A., Rubini, A., Sabatini, S., Striani, E., Trois, A., Vallazza, E., Vittorini, V., Zambra, A., Zanello, D., Antonelli, L. A., Colafrancesco, S., Gasparrini, D., Giommi, P., Pittori, C., Preger, B., Santolamazza, P., Verrecchia, F., Salotti, L., Marisaldi M, Fuschino F, Labanti C, Galli M, Longo F, Del Monte E, Barbiellini G, Tavani M, Giuliani A, Moretti E, Vercellone S, Costa E, Cutini S, Donnarumma I, Evangelista Y, Feroci M, Lapshov I, Lazzarotto F, Lipari P, Mereghetti S, Pacciani L, Rapisarda M, Soffitta P, Trifoglio M, Argan A, Boffelli F, Bulgarelli A, Caraveo P, Cattaneo PW, Chen A, Cocco V, DAmmando F, De Paris G, Di Cocco G, Di Persio G, Ferrari A, Fiorini M, Froysland T, Gianotti F, Morselli A, Pellizzoni A, Perotti F, Picozza P, Piano G, Pilia M, Prest M, Pucella G, Rappoldi A, Rubini A, Sabatini S, Striani E, Trois A, Vallazza E, Vittorini V, Zambra A, Zanello D, Antonelli LA, Colafrancesco S, Gasparrini D, Giommi P, Pittori C, Preger B, Santolamazza P, Verrecchia F, Salotti L, M., Marisaldi, F., Fuschino, C., Labanti, M., Galli, Longo, Francesco, E. D., Monte, G., Barbiellini, M., Tavani, A., Giuliani, E., Moretti, S., Vercellone, E., Costa, S., Cutini, I., Donnarumma, Y., Evangelista, M., Feroci, I., Lapshov, F., Lazzarotto, P., Lipari, S., Mereghetti, L., Pacciani, M., Rapisarda, P., Soffitta, M., Trifoglio, A., Argan, F., Boffelli, A., Bulgarelli, P., Caraveo, P. W., Cattaneo, A., Chen, V., Cocco, F., D'Ammando, G. D., Pari, G. D., Cocco, G. D., Persio, A., Ferrari, M., Fiorini, T., Froysland, F., Gianotti, A., Morselli, A., Pellizzoni, F., Perotti, P., Picozza, G., Piano, M., Pilia, M., Prest, G., Pucella, A., Rappoldi, A., Rubini, S., Sabatini, E., Striani, A., Troi, E., Vallazza, V., Vittorini, A., Zambra, D., Zanello, L. A., Antonelli, S., Colafrancesco, D., Gasparrini, P., Giommi, C., Pittori, B., Preger, P., Santolamazza, F., Verrecchia, and L., Salotti

Subjects
Agile, terrestrial gamma ray flashes, minicalorimeter, High Energy Gamma-ray Astronomy, AGILE satellite, Terrestrial Gamma-ray Flashes, terrestrial gamma ray flashes, AGILE satellite
Abstract

We report the detection by the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite of terrestrial gamma ray flashes (TGFs) obtained with the minicalorimeter (MCAL) detector operating in the energy range 0.3-100 MeV. We select events typically lasting a few milliseconds with spectral and directional selections consistent with the TGF characteristics previously reported by other space missions. During the period 1 June 2008 to 31 March 2009 we detect 34 high-confidence events showing millisecond durations and a geographical distribution peaked over continental Africa and Southeast Asia. For the first time, AGILE-MCAL detects photons associated with TGF events up to 40 MeV. We determine the cumulative spectral properties of the spectrum in the range 0.5-40 MeV, which can be effectively described by a Bremsstrahlung spectrum. We find that both the TGF cumulative spectral properties and their geographical distribution are in good agreement with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) results.

Published
2010

53. Discovery of powerful gamma-ray flares from the Crab Nebula.

Author

Tavani M, Bulgarelli A, Vittorini V, Pellizzoni A, Striani E, Caraveo P, Weisskopf MC, 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 CO, Trifoglio M, Gianotti F, Vercellone S, Argan A, Barbiellini G, Cattaneo PW, Chen AW, Contessi T, D'Ammando F, DePris 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 GF

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 mega-electron volts to 10 giga-electron volts) flares observed by the AGILE satellite in September 2010 and October 2007. In both cases, the total gamma-ray flux increased by a factor of three compared with the non-flaring flux. The flare luminosity and short time scale favor an origin near the pulsar, and we discuss Chandra Observatory x-ray and Hubble Space Telescope 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 an approximately 1-day time scale.

Published
2011
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54. Terrestrial gamma-ray flashes as powerful particle accelerators.

Author

Tavani M, Marisaldi M, Labanti C, Fuschino F, Argan A, Trois A, Giommi P, Colafrancesco S, Pittori C, Palma F, Trifoglio M, Gianotti F, Bulgarelli A, Vittorini V, Verrecchia F, Salotti L, Barbiellini G, Caraveo P, Cattaneo PW, Chen A, Contessi T, Costa E, D'Ammando F, Del Monte E, De Paris G, Di Cocco G, Di Persio G, Donnarumma I, Evangelista Y, Feroci M, Ferrari A, Galli M, Giuliani A, Giusti M, Lapshov I, Lazzarotto F, Lipari P, Longo F, Mereghetti S, Morelli E, Moretti E, Morselli A, Pacciani L, Pellizzoni A, Perotti F, Piano G, Picozza P, Pilia M, Pucella G, Prest M, Rapisarda M, Rappoldi A, Rossi E, Rubini A, Sabatini S, Scalise E, Soffitta P, Striani E, Vallazza E, Vercellone S, Zambra A, and Zanello D

Abstract

Strong electric discharges associated with thunderstorms can produce terrestrial gamma-ray flashes (TGFs), i.e., intense bursts of x rays and γ rays lasting a few milliseconds or less. We present in this Letter new TGF timing and spectral data based on the observations of the Italian Space Agency AGILE satellite. We determine that the TGF emission above 10 MeV has a significant power-law spectral component reaching energies up to 100 MeV. These results challenge TGF theoretical models based on runaway electron acceleration. The TGF discharge electric field accelerates particles over the large distances for which maximal voltages of hundreds of megavolts can be established. The combination of huge potentials and large electric fields in TGFs can efficiently accelerate particles in large numbers, and we reconsider here the photon spectrum and the neutron production by photonuclear reactions in the atmosphere.

Published
2011
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55. 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 PW, 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 LA, Colafrancesco S, Cutini S, Giommi P, Lucarelli F, Pittori C, Santolamazza P, Verrecchia F, and Salotti L

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° at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite 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.

Published
2010
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56. Detection of gamma-ray emission from the Vela pulsar wind nebula with AGILE.

Author

Pellizzoni A, Trois A, Tavani M, Pilia M, Giuliani A, Pucella G, Esposito P, Sabatini S, Piano G, Argan A, Barbiellini G, Bulgarelli A, Burgay M, Caraveo P, Cattaneo PW, Chen AW, Cocco V, Contessi T, Costa E, D'Ammando F, Del Monte E, De Paris G, Di Cocco G, Di Persio G, Donnarumma I, Evangelista Y, Feroci M, Ferrari A, Fiorini M, Fuschino F, Galli M, Gianotti F, Hotan A, Labanti C, Lapshov I, Lazzarotto F, Lipari P, Longo F, Marisaldi M, Mastropietro M, Mereghetti S, Moretti E, Morselli A, Pacciani L, Palfreyman J, Perotti F, Picozza P, Pittori C, Possenti A, Prest M, Rapisarda M, Rappoldi A, Rossi E, Rubini A, Santolamazza P, Scalise E, Soffitta P, Striani E, Trifoglio M, Vallazza E, Vercellone S, Verrecchia F, Vittorini V, Zambra A, Zanello D, Giommi P, Colafrancesco S, Antonelli A, Salotti L, D'Amico N, and Bignami GF

Abstract

Pulsars are known to power winds of relativistic particles that can produce bright nebulae by interacting with the surrounding medium. These pulsar wind nebulae are observed by their radio, optical, and x-ray emissions, and in some cases also at TeV (teraelectron volt) energies, but the lack of information in the gamma-ray band precludes drawing a comprehensive multiwavelength picture of their phenomenology and emission mechanisms. Using data from the AGILE satellite, we detected the Vela pulsar wind nebula in the energy range from 100 MeV to 3 GeV. This result constrains the particle population responsible for the GeV emission and establishes a class of gamma-ray emitters that could account for a fraction of the unidentified galactic gamma-ray sources.

Published
2010
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57. Fermi large area telescope measurements of the diffuse gamma-ray emission at intermediate galactic latitudes.

Author

Abdo AA, Ackermann M, Ajello M, Anderson B, Atwood WB, Axelsson M, Baldini L, Ballet J, Barbiellini G, Bastieri D, Baughman BM, Bechtol K, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bregeon J, Brez A, Brigida M, Bruel P, Burnett TH, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Dereli H, Dermer CD, de Angelis A, de Palma F, Digel SW, Di Bernardo G, Dormody M, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Edmonds Y, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Frailis M, Fukazawa Y, Funk S, Fusco P, Gaggero D, Gargano F, Gehrels N, Germani S, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hayashida M, Hays E, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knödlseder J, Kocian ML, Kuehn F, Kuss M, Lande J, Latronico L, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Mazziotta MN, McConville W, McEnery JE, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nolan PL, Nuss E, Ohsugi T, Okumura A, Omodei N, Orlando E, Ormes JF, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Porter TA, Rainò S, Rando R, Razzano M, Reimer A, Reimer O, Reposeur T, Ritz S, Rodriguez AY, Roth M, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Sellerholm A, Sgrò C, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Stecker FW, Striani E, Strickman MS, Strong AW, Suson DJ, Tajima H, Takahashi H, Tanaka T, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Vasileiou V, Vilchez N, Vitale V, Waite AP, Wang P, Winer BL, Wood KS, Ylinen T, and Ziegler M

Abstract

The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

Published
2009
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58. Extreme particle acceleration in the microquasar Cygnus X-3.

Author

Tavani M, Bulgarelli A, Piano G, Sabatini S, Striani E, Evangelista Y, Trois A, Pooley G, Trushkin S, Nizhelskij NA, McCollough M, Koljonen KI, Pucella G, Giuliani A, Chen AW, Costa E, Vittorini V, Trifoglio M, Gianotti F, Argan A, Barbiellini G, Caraveo P, Cattaneo PW, Cocco V, Contessi T, D'Ammando F, Del Monte E, De Paris G, Di Cocco G, Di Persio G, Donnarumma I, Feroci M, Ferrari A, Fuschino F, Galli M, Labanti C, Lapshov I, Lazzarotto F, Lipari P, Longo F, Mattaini E, Marisaldi M, Mastropietro M, Mauri A, Mereghetti S, Morelli E, Morselli A, Pacciani L, Pellizzoni A, Perotti F, Picozza P, Pilia M, Prest M, Rapisarda M, Rappoldi A, Rossi E, Rubini A, Scalise E, Soffitta P, Vallazza E, Vercellone S, Zambra A, Zanello D, Pittori C, Verrecchia F, Giommi P, Colafrancesco S, Santolamazza P, Antonelli A, and Salotti L

Abstract

Super-massive black holes in active galaxies can accelerate particles to relativistic energies, producing jets with associated gamma-ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares. Apart from an isolated event detected in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four gamma-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary that sporadically produces radio jets). There is a clear pattern of temporal correlations between the gamma-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

Published
2009
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59. A population of gamma-ray millisecond pulsars seen with the Fermi Large Area Telescope.

Author

Abdo AA, Ackermann M, Ajello M, Atwood WB, Axelsson M, Baldini L, Ballet J, Barbiellini G, Baring MG, Bastieri D, Baughman BM, Bechtol K, Bellazzini R, Berenji B, Bignami GF, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bregeon J, Brez A, Brigida M, Bruel P, Burnett TH, Caliandro GA, Cameron RA, Camilo F, Caraveo PA, Carlson P, Casandjian J, Cecchi C, Celik O, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cognard I, Cohen-Tanugi J, Cominsky LR, Conrad J, Corbet R, Cutini S, Dermer CD, Desvignes G, de Angelis A, de Luca A, de Palma F, Digel SW, Dormody M, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Edmonds Y, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Frailis M, Freire PC, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hayashida M, Hays E, Hobbs G, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson TJ, Johnson WN, Johnston S, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knödlseder J, Kocian ML, Kramer M, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Manchester RN, Marelli M, Mazziotta MN, McConville W, McEnery JE, McLaughlin MA, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nolan PL, Norris JP, Nuss E, Ohsugi T, Omodei N, Orlando E, Ormes JF, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Porter TA, Rainò S, Rando R, Ransom SM, Ray PS, Razzano M, Rea N, Reimer A, Reimer O, Reposeur T, Ritz S, Rochester LS, Rodriguez AY, Romani RW, Roth M, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Schalk TL, Sgrò C, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Stappers BW, Starck JL, Striani E, Strickman MS, Suson DJ, Tajima H, Takahashi H, Tanaka T, Thayer JB, Thayer JG, Theureau G, Thompson DJ, Thorsett SE, Tibaldo L, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Van Etten A, Vasileiou V, Venter C, Vilchez N, Vitale V, Waite AP, Wallace E, Wang P, Watters K, Webb N, Weltevrede P, Winer BL, Wood KS, Ylinen T, and Ziegler M

Abstract

Pulsars are born with subsecond spin periods and slow by electromagnetic braking for several tens of millions of years, when detectable radiation ceases. A second life can occur for neutron stars in binary systems. They can acquire mass and angular momentum from their companions, to be spun up to millisecond periods and begin radiating again. We searched Fermi Large Area Telescope data for pulsations from all known millisecond pulsars (MSPs) outside of globular clusters, using rotation parameters from radio telescopes. Strong gamma-ray pulsations were detected for eight MSPs. The gamma-ray pulse profiles and spectral properties resemble those of young gamma-ray pulsars. The basic emission mechanism seems to be the same for MSPs and young pulsars, with the emission originating in regions far from the neutron star surface.

Published
2009
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