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1. Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

Author

Abdo, AA, Abeysekara, AU, Alfaro, R, Allen, BT, Alvarez, C, Álvarez, JD, Arceo, R, Arteaga-Velázquez, JC, Aune, T, Ayala Solares, HA, Barber, AS, Baughman, BM, Bautista-Elivar, N, Becerra Gonzalez, J, Belmont, E, Benzvi, SY, Berley, D, Bonilla Rosales, M, Braun, J, Caballero-Lopez, RA, Caballero-Mora, KS, Carramiñana, A, Castillo, M, Christopher, GE, Cotti, U, Cotzomi, J, De La Fuente, E, De León, C, Deyoung, T, Diaz Hernandez, R, Diaz-Cruz, L, Díaz-Vélez, JC, Dingus, BL, Duvernois, MA, Ellsworth, RW, Fiorino, DW, Fraija, N, Galindo, A, Garfias, F, González, MM, Goodman, JA, Grabski, V, Gussert, M, Hampel-Arias, Z, Harding, JP, Hays, E, Hoffman, CM, Hui, CM, Hüntemeyer, P, Imran, A, Iriarte, A, Karn, P, Kieda, D, Kolterman, BE, Kunde, GJ, Lara, A, Lauer, RJ, Lee, WH, Lennarz, D, León Vargas, H, Linares, EC, Linnemann, JT, Longo, M, Luna-Garcia, R, Macgibbon, JH, Marinelli, A, Marinelli, SS, Martinez, H, Martinez, O, Martínez-Castro, J, Matthews, JAJ, McEnery, J, Mendoza Torres, E, Mincer, AI, Miranda-Romagnoli, P, Moreno, E, Morgan, T, Mostafá, M, Nellen, L, Nemethy, P, Newbold, M, Noriega-Papaqui, R, Oceguera-Becerra, T, Patricelli, B, Pelayo, R, Pérez-Pérez, EG, Pretz, J, Rivière, C, Rosa-González, D, Ruiz-Velasco, E, Ryan, J, Salazar, H, Salesa, F, Sandoval, A, Saz Parkinson, PM, Schneider, M, Silich, S, Sinnis, G, Smith, AJ, and Stump, D

Subjects
Primordial Black Holes, HAWC, Milagro, Very High Energy Bursts, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract

Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

Published
2015

2. The study of TeV variability and the duty cycle of Mrk 421 from 3 Yr of observations with the Milagro observatory

Author

Abdo, AA, Abeysekara, AU, Allen, BT, Aune, T, Barber, AS, Berley, D, Braun, J, Chen, C, Christopher, GE, Delay, RS, Deyoung, T, Dingus, BL, Ellsworth, RW, Fraija, N, González, MM, Goodman, JA, Hays, E, Hoffman, CM, Hüntemeyer, PH, Imran, A, Kolterman, BE, Linnemann, JT, Marinelli, A, McEnery, JE, Morgan, T, Mincer, AI, Nemethy, P, Patricelli, B, Pretz, J, Ryan, JM, Saz Parkinson, PM, Schneider, M, Shoup, A, Sinnis, G, Smith, AJ, Vasileiou, V, Walker, GP, Williams, DA, and Yodh, GB

Subjects
BL Lacertae objects: individual, gamma rays: general, astro-ph.HE, astro-ph.CO, Astronomy & Astrophysics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural)
Abstract

TeV-flaring activity with timescales as short as tens of minutes and an orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421). The TeV emission from Mrk 421 is believed to be produced by leptonic synchrotron self-Compton (SSC) emission. In this scenario, correlations between the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly explained, and the activity (measured as duty cycle) of the source at TeV energies is expected to be equal to or less than that observed in X-rays if only SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish limits on its variability at different timescales, we continuously observed Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a statistical significance of 7.1 standard deviations between 2005 September 21 and 2008 March 15. The observed spectrum is consistent with previous observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies above 1 TeV for different hypotheses of the baseline flux and for different flare selections and we compared our results with the X-ray duty cycle estimated by Resconi et al. The robustness of the results is discussed. © 2014. The American Astronomical Society. All rights reserved..

Published
2014

3. Milagro observations of potential TeV emitters

Author

Abdo, AA, Abeysekara, AU, Allen, BT, Aune, T, Barber, AS, Berley, D, Braun, J, Chen, C, Christopher, GE, Deyoung, T, Dingus, BL, Ellsworth, RW, Gonzalez, MM, Goodman, JA, Hays, E, Hoffman, CM, Hüntemeyer, PH, Imran, A, Kolterman, BE, Linnemann, JT, McEnery, JE, Morgan, T, Mincer, AI, Nemethy, P, Pretz, J, Ryan, JM, Saz Parkinson, PM, Schneider, M, Shoup, A, Sinnis, G, Smith, AJ, Vasileiou, V, Walker, GP, Williams, DA, and Yodh, GB

Subjects
Astroparticle physics, Pulsars, Galaxies, Active galactic nuclei, Gamma-rays, astro-ph.HE, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

This paper reports the results from three targeted searches of Milagro TeV sky maps: two extragalactic point source lists and one pulsar source list. The first extragalactic candidate list consists of 709 candidates selected from the Fermi-LAT 2FGL catalog. The second extragalactic candidate list contains 31 candidates selected from the TeVCat source catalog that have been detected by imaging atmospheric Cherenkov telescopes (IACTs). In both extragalactic candidate lists Mkn 421 was the only source detected by Milagro. This paper presents the Milagro TeV flux for Mkn 421 and flux limits for the brighter Fermi-LAT extragalactic sources and for all TeVCat candidates. The pulsar list extends a previously published Milagro targeted search for Galactic sources. With the 32 new gamma-ray pulsars identified in 2FGL, the number of pulsars that are studied by both Fermi-LAT and Milagro is increased to 52. In this sample, we find that the probability of Milagro detecting a TeV emission coincident with a pulsar increases with the GeV flux observed by the Fermi-LAT in the energy range from 0.1 GeV to 100 GeV. © 2014 Elsevier B.V. All rights reserved.

Published
2014

4. ERRATUM: THE FIRST FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS (vol 187, pg 460, 2010)

Author

Abdo, Aa, Ackermann, M, Ajello, M, Atwood, Wb, Axelsson, M, Baldini, L, Ballet, J, Barbiellini, G, Baring, Mg, Bastieri, Denis, 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, Buson, Sara, Caliandro, Ga, Cameron, Ra, Camilo, F, Caraveo, Pa, Casandjian, Jm, 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, DEN HARTOG PR, Dermer, Cd, DE ANGELIS, A, DE LUCA, A, DE PALMA, F, Digel, Sw, Dormody, M, SILVA E, DOCOUTO E., Drell, Ps, Dubois, R, Dumora, D, Espinoza, C, Farnier, C, Favuzzi, C, Fegan, Sj, Ferrara, Ec, Focke, Wb, Fortin, P, Frailis, M, Freire, Pcc, Fukazawa, Y, Funk, S, Fusco, P, Gargano, F, Gasparrini, D, Gehrels, N, Germani, S, Giavitto, G, Giebels, B, Giglietto, N, Giommi, P, Giordano, F, Glanzman, T, Godfrey, G, Gotthelf, Ev, Grenier, Ia, Grondin, Mh, Grove, Je, Guillemot, L, Guiriec, S, Gwon, C, Hanabata, Y, Harding, Ak, Hayashida, M, Hays, E, Hughes, Re, Jackson, Ms, Johannesson, G, Johnson, As, Johnson, Rp, Johnson, Tj, Johnson, Wn, Johnston, S, Kamae, T, Kanbach, G, Kaspi, Vm, Katagiri, H, Kataoka, J, Kawai, N, Kerr, M, Knoedlseder, J, Kocian, Ml, Kramer, M, Kuss, M, Lande, J, Latronico, L, LEMOINE GOUMARD, M, Livingstone, M, Longo, F, Loparco, F, Lott, B, Lovellette, Mn, Lubrano, P, Lyne, Ag, Madejski, Gm, Makeev, A, Manchester, Rn, Marelli, M, Mazziotta, Mn, Mcconville, W, Mcenery, Je, Mcglynn, S, Meurer, C, Michelson, Pf, Mineo, T, Mitthumsiri, W, Mizuno, T, Moiseev, Aa, Monte, C, Monzani, Me, Morselli, A, Moskalenko, Iv, Murgia, S, Nakamori, T, Nolan, Pl, Norris, Jp, Noutsos, A, Nuss, E, Ohsugi, T, Omodei, N, Orlando, E, Ormes, Jf, Ozaki, M, Paneque, D, Panetta, Jh, Parent, D, Pelassa, V, Pepe, M, PESCE ROLLINS, M, Piron, F, Porter, Ta, Raino, S, Rando, Riccardo, Ransom, Sm, Ray, Ps, Razzano, M, Rea, N, Reimer, A, Reimer, O, Reposeur, T, Ritz, S, Rodriguez, Ay, Romani, Rw, Roth, M, Ryde, F, Sadrozinski, Hfw, Sanchez, D, Sander, A, SAZ PARKINSON PM, Scargle, Jd, Schalk, Tl, Sellerholm, A, Sgro, C, Siskind, Ej, Smith, Da, Smith, Pd, Spandre, G, Spinelli, P, Stappers, Bw, Starck, Jl, Striani, E, Strickman, Ms, Strong, Aw, Suson, Dj, Tajima, H, Takahashi, H, Takahashi, T, Tanaka, T, Thayer, Jb, Thayer, Jg, Theureau, G, Thompson, Dj, Thorsett, Se, Tibaldo, Luigi, Tibolla, O, Torres, Df, Tosti, G, Tramacere, A, Uchiyama, Y, Usher, Tl, VAN ETTEN, A, Vasileiou, V, Venter, C, Vilchez, N, Vitale, V, Waite, Ap, Wang, P, Wang, N, Watters, K, Weltevrede, P, Winer, Bl, Wood, Ks, Ylinen, T, and Ziegler, M.

Published
2011

5. Measurement of the Cosmic Ray e(+)+e(-) Spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope

Author

Abdo, Aa, Ackermann, M, Ajello, M, Atwood, Wb, Axelsson, M, Baldini, L, Ballet, J, Barbiellini, G, Bastieri, Denis, Battelino, M, Baughman, Bm, Bechtol, K, Bellazzini, R, Berenji, B, Blandford, Rd, Bloom, Ed, Bogaert, G, Bonamente, E, Borgland, Aw, Bregeon, J, Brez, A, Brigida, M, Bruel, P, Burnett, Th, Caliandro, Ga, Cameron, Ra, Caraveo, Pa, Carlson, P, Casandjian, Jm, Cecchi, C, Charles, E, Chekhtman, A, Cheung, Cc, Chiang, J, Ciprini, S, Claus, R, COHEN TANUGI, J, Cominsky, Lr, Conrad, J, Cutini, S, Dermer, Cd, DE ANGELIS, A, DE PALMA, F, Digel, Sw, DI BERNARDO, G, Silva, Ede, Drell, Ps, Dubois, R, Dumora, D, Edmonds, Y, Farnier, C, Favuzzi, C, Focke, Wb, Frailis, M, Fukazawa, Y, Funk, S, Fusco, P, Gaggero, D, Gargano, F, Gasparrini, D, Gehrels, N, Germani, S, Giebels, B, Giglietto, N, Giordano, F, Glanzman, T, Godfrey, G, Grasso, D, Grenier, Ia, Grondin, Mh, Grove, Je, Guillemot, L, Guiriec, S, Hanabata, Y, Harding, Ak, Hartman, Rc, Hayashida, M, Hays, E, Hughes, Re, Johannesson, G, Johnson, As, Johnson, Rp, Johnson, Wn, Kamae, T, Katagiri, H, Kataoka, J, Kawai, N, Kerr, M, Knodlseder, J, Kocevski, D, Kuehn, F, Kuss, M, Lande, J, Latronico, L, LEMOINE GOUMARD, M, Longo, F, Loparco, F, Lott, B, Lovellette, Mn, Lubrano, P, Madejski, Gm, Makeev, A, Massai, Mm, Mazziotta, Mn, Mcconville, W, Mcenery, Je, Meurer, C, Michelson, Pf, Mitthumsiri, W, Mizuno, T, Moiseev, Aa, Monte, C, Monzani, Me, Moretti, E, Morselli, A, Moskalenko, Iv, Murgia, S, Nolan, Pl, Norris, Jp, Nuss, E, Ohsugi, T, Omodei, N, Orlando, E, Ormes, Jf, Ozaki, M, Paneque, D, Panetta, Jh, Parent, D, Pelassa, V, Pepe, M, PESCE ROLLINS, M, Piron, F, Pohl, M, Porter, Ta, Profumo, S, Raino, S, Rando, Riccardo, Razzano, M, Reimer, A, Reimer, O, Reposeur, T, Ritz, S, Rochester, Ls, Rodriguez, Ay, Romani, Rw, Roth, M, Ryde, F, Sadrozinski, Hfw, Sanchez, D, Sander, A, SAZ PARKINSON PM, Scargle, Jd, Schalk, Tl, Sellerholm, A, Sgro, C, Smith, Da, Smith, Pd, Spandre, G, Spinelli, P, Starck, Jl, Stephens, Te, Strickman, Ms, Strong, Aw, Suson, Dj, Tajima, H, Takahashi, H, Takahashi, T, Tanaka, T, Thayer, Jb, Thayer, Jg, Thompson, Dj, Tibaldo, Luigi, Tibolla, O, Torres, Df, Tosti, G, Tramacere, A, Uchiyama, Y, Usher, Tl, VAN ETTEN, A, Vasileiou, V, Vilchez, N, Vitale, V, Waite, Ap, Wallace, E, Wang, P, Winer, Bl, Wood, Ks, Ylinen, T, and Ziegler, M.

Abstract

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m;{2} sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E-3.0 and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.

Published
2009

6. Einstein@Home discovers a radio-quiet gamma-ray millisecond pulsar.

Author

Clark CJ, Pletsch HJ, Wu J, Guillemot L, Kerr M, Johnson TJ, Camilo F, Salvetti D, Allen B, Anderson D, Aulbert C, Beer C, Bock O, Cuéllar A, Eggenstein HB, Fehrmann H, Kramer M, Kwang SA, Machenschalk B, Nieder L, Ackermann M, Ajello M, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bellazzini R, Bissaldi E, Blandford RD, Bloom ED, Bonino R, Bottacini E, Brandt TJ, Bregeon J, Bruel P, Buehler R, Burnett TH, Buson S, Cameron RA, Caputo R, Caraveo PA, Cavazzuti E, Cecchi C, Charles E, Chekhtman A, Ciprini S, Cominsky LR, Costantin D, Cutini S, D'Ammando F, De Luca A, Desiante R, Di Venere L, Di Mauro M, Di Lalla N, Digel SW, Favuzzi C, Ferrara EC, Franckowiak A, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Giglietto N, Giordano F, Giroletti M, Gomez-Vargas GA, Green D, Grenier IA, Guiriec S, Harding AK, Hewitt JW, Horan D, Jóhannesson G, Kensei S, Kuss M, La Mura G, Larsson S, Latronico L, Li J, Longo F, Loparco F, Lovellette MN, Lubrano P, Magill JD, Maldera S, Manfreda A, Mazziotta MN, McEnery JE, Michelson PF, Mirabal N, Mitthumsiri W, Mizuno T, Monzani ME, Morselli A, Moskalenko IV, Nuss E, Ohsugi T, Omodei N, Orienti M, Orlando E, Palatiello M, Paliya VS, de Palma F, Paneque D, Perkins JS, Persic M, Pesce-Rollins M, Porter TA, Principe G, Rainò S, Rando R, Ray PS, Razzano M, Reimer A, Reimer O, Romani RW, Saz Parkinson PM, Sgrò C, Siskind EJ, Smith DA, Spada F, Spandre G, Spinelli P, Thayer JB, Thompson DJ, Torres DF, Troja E, Vianello G, Wood K, and Wood M

Abstract

Millisecond pulsars (MSPs) are old neutron stars that spin hundreds of times per second and appear to pulsate as their emission beams cross our line of sight. To date, radio pulsations have been detected from all rotation-powered MSPs. In an attempt to discover radio-quiet gamma-ray MSPs, we used the aggregated power from the computers of tens of thousands of volunteers participating in the Einstein@Home distributed computing project to search for pulsations from unidentified gamma-ray sources in Fermi Large Area Telescope data. This survey discovered two isolated MSPs, one of which is the only known rotation-powered MSP to remain undetected in radio observations. These gamma-ray MSPs were discovered in completely blind searches without prior constraints from other observations, raising hopes for detecting MSPs from a predicted Galactic bulge population.

Published
2018
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7. Binary millisecond pulsar discovery via gamma-ray pulsations.

Author

Pletsch HJ, Guillemot L, Fehrmann H, Allen B, Kramer M, Aulbert C, Ackermann M, Ajello M, de Angelis A, Atwood WB, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Borgland AW, Bottacini E, Brandt TJ, Bregeon J, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Çelik Ö, Charles E, Chaves RC, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Cutini S, D'Ammando F, Dermer CD, Digel SW, Drell PS, Drlica-Wagner A, Dubois R, Dumora D, Favuzzi C, Ferrara EC, Franckowiak A, Fukazawa Y, Fusco P, Gargano F, Gehrels N, Germani S, Giglietto N, Giordano F, Giroletti M, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guiriec S, Hadasch D, Hanabata Y, Harding AK, den Hartog PR, Hayashida M, Hays E, Hill AB, Hou X, Hughes RE, Jóhannesson G, Jackson MS, Jogler T, Johnson AS, Johnson WN, Kataoka J, Kerr M, Knödlseder J, Kuss M, Lande J, Larsson S, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lovellette MN, Lubrano P, Massaro F, Mayer M, Mazziotta MN, McEnery JE, Mehault J, Michelson PF, Mitthumsiri W, Mizuno T, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Nemmen R, Nuss E, Ohno M, Ohsugi T, Omodei N, Orienti M, Orlando E, de Palma F, Paneque D, Perkins JS, Piron F, Pivato G, Porter TA, Rainò S, Rando R, Ray PS, Razzano M, Reimer A, Reimer O, Reposeur T, Ritz S, Romani RW, Romoli C, Sanchez DA, Saz Parkinson PM, Schulz A, Sgrò C, do Couto e Silva E, Siskind EJ, Smith DA, Spandre G, Spinelli P, Suson DJ, Takahashi H, Tanaka T, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Tinivella M, Troja E, Usher TL, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, Waite AP, Winer BL, Wood KS, Wood M, Yang Z, and Zimmer S

Abstract

Millisecond pulsars, old neutron stars spun up by accreting matter from a companion star, can reach high rotation rates of hundreds of revolutions per second. Until now, all such "recycled" rotation-powered pulsars have been detected by their spin-modulated radio emission. In a computing-intensive blind search of gamma-ray data from the Fermi Large Area Telescope (with partial constraints from optical data), we detected a 2.5-millisecond pulsar, PSR J1311-3430. This unambiguously explains a formerly unidentified gamma-ray source that had been a decade-long enigma, confirming previous conjectures. The pulsar is in a circular orbit with an orbital period of only 93 minutes, the shortest of any spin-powered pulsar binary ever found.

Published
2012
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8. Periodic emission from the gamma-ray binary 1FGL J1018.6-5856.

Author

Fermi LAT Collaboration, Ackermann M, Ajello M, Ballet J, Barbiellini G, Bastieri D, Belfiore A, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bregeon J, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Cavazzuti E, Cecchi C, Çelik Ö, Charles E, Chaty S, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Corbel S, Corbet RH, Cutini S, de Luca A, den Hartog PR, de Palma F, Dermer CD, Digel SW, do Couto e Silva E, Donato D, Drell PS, Drlica-Wagner A, Dubois R, Dubus G, Favuzzi C, Fegan SJ, Ferrara EC, Focke WB, Fortin P, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grove JE, Guiriec S, Hadasch D, Hanabata Y, Harding AK, Hayashida M, Hays E, Hill AB, Hughes RE, Jóhannesson G, Johnson AS, Johnson TJ, Kamae T, Katagiri H, Kataoka J, Kerr M, Knödlseder J, Kuss M, Lande J, Longo F, Loparco F, Lovellette MN, Lubrano P, Mazziotta MN, McEnery JE, Michelson PF, Mitthumsiri W, Mizuno T, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Naumann-Godo M, Norris JP, Nuss E, Ohno M, Ohsugi T, Okumura A, Omodei N, Orlando E, Ozaki M, Paneque D, Parent D, Pesce-Rollins M, Pierbattista M, Piron F, Pivato G, Porter TA, Rainò S, Rando R, Razzano M, Reimer A, Reimer O, Ritz S, Romani RW, Roth M, Saz Parkinson PM, Sgrò C, Siskind EJ, Spandre G, Spinelli P, Suson DJ, Takahashi H, Tanaka T, Thayer JG, Thayer JB, Thompson DJ, Tibaldo L, Tinivella M, Torres DF, Tosti G, Troja E, Uchiyama Y, Usher TL, Vandenbroucke J, Vianello G, Vitale V, Waite AP, Winer BL, Wood KS, Wood M, Yang Z, Zimmer S, Coe MJ, Di Mille F, Edwards PG, Filipović MD, Payne JL, Stevens J, and Torres MA

Abstract

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

Published
2012
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9. Gamma-ray flares from the Crab Nebula.

Author

Abdo AA, Ackermann M, Ajello M, Allafort A, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bouvier A, Brandt TJ, Bregeon J, Brez A, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Cannon A, Caraveo PA, Casandjian JM, Çelik Ö, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Costamante L, Cutini S, D'Ammando F, Dermer CD, de Angelis A, de Luca A, de Palma F, Digel SW, do Couto e Silva E, Drell PS, Drlica-Wagner A, Dubois R, Dumora D, Favuzzi C, Fegan SJ, Ferrara EC, Focke WB, Fortin P, Frailis M, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guiriec S, Hadasch D, Hanabata Y, Harding AK, Hayashi K, Hayashida M, Hays E, Horan D, Itoh R, Jóhannesson G, Johnson AS, Johnson TJ, Khangulyan D, Kamae T, Katagiri H, Kataoka J, Kerr M, Knödlseder J, Kuss M, Lande J, Latronico L, Lee SH, Lemoine-Goumard M, Longo F, Loparco F, Lubrano P, Madejski GM, Makeev A, Marelli M, Mazziotta MN, McEnery JE, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Naumann-Godo M, Nolan PL, Norris JP, Nuss E, Ohsugi T, Okumura A, Omodei N, Ormes JF, Ozaki M, Paneque D, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Pierbattista M, Piron F, Porter TA, Rainò S, Rando R, Ray PS, Razzano M, Reimer A, Reimer O, Reposeur T, Ritz S, Romani RW, Sadrozinski HF, Sanchez D, Saz Parkinson PM, Scargle JD, Schalk TL, Sgrò C, Siskind EJ, Smith PD, Spandre G, Spinelli P, Strickman MS, Suson DJ, Takahashi H, Takahashi T, Tanaka T, Thayer JB, Thompson DJ, Tibaldo L, Torres DF, Tosti G, Tramacere A, Troja E, Uchiyama Y, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, Wang P, Wood KS, Yang Z, and Ziegler M

Abstract

A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.

Published
2011
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10. Fermi gamma-ray imaging of a radio galaxy.

Author

Abdo AA, Ackermann M, Ajello M, Atwood WB, 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, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cavazzuti E, Cecchi C, Celik O, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Colafrancesco S, Cominsky LR, Conrad J, Costamante L, Cutini S, Davis DS, Dermer CD, de Angelis A, de Palma F, Digel SW, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Finke J, Focke WB, Fortin P, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Georganopoulos M, Germani S, Giebels B, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grove JE, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hayashida M, Hays E, Hughes RE, Jackson MS, Jóhannesson G, Johnson AS, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knödlseder J, Kocian ML, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, 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, Norris JP, Nuss E, Ohsugi T, Omodei N, Orlando E, Ormes JF, Paneque D, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Porter TA, Rainò S, Rando R, Razzano M, Razzaque S, Reimer A, Reimer O, Reposeur T, Ritz S, Rochester LS, Rodriguez AY, Romani RW, Roth M, Ryde F, Sadrozinski HF, Sambruna R, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Sgrò C, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Stawarz Ł, Strickman MS, Suson DJ, Tajima H, Takahashi H, Takahashi T, 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, Wallace E, Wang P, Winer BL, Wood KS, Ylinen T, Ziegler M, Hardcastle MJ, and Kazanas D

Abstract

The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton-scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields.

Published
2010
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11. Spectrum of the isotropic diffuse gamma-ray emission derived from first-year Fermi Large Area Telescope data.

Author

Abdo AA, Ackermann M, Ajello M, Atwood WB, 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, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cavazzuti E, Cecchi C, Celik O, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Conrad J, Cutini S, Dermer CD, de Angelis A, de Palma F, Digel SW, Di Bernardo G, do Couto e Silva E, Drell PS, Drlica-Wagner A, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Fortin P, Frailis M, Fukazawa Y, Funk S, Fusco P, Gaggero D, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giommi P, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Gustafsson M, Hanabata Y, Harding AK, Hayashida M, Hughes RE, Itoh R, Jackson MS, 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, Lemoine-Goumard M, 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, 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, Razzano M, Reimer A, Reimer O, Reposeur T, Ritz S, Rochester LS, Rodriguez AY, Roth M, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Sellerholm A, Sgrò C, Shaw MS, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Strickman MS, Strong AW, Suson DJ, Tajima H, Takahashi H, Takahashi T, 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

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extragalactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic gamma-ray emission, the detected LAT sources, and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index gamma = 2.41 +/- 0.05 and intensity I(>100 MeV) = (1.03 +/- 0.17) x 10(-5) cm(-2) s(-1) sr(-1), where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

Published
2010
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12. Gamma-ray emission from the shell of supernova remnant W44 revealed by the Fermi LAT.

Author

Abdo AA, Ackermann M, Ajello M, Baldini L, Ballet J, Barbiellini G, Baring MG, 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, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Celik O, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cognard I, Cohen-Tanugi J, Cominsky LR, Conrad J, Cutini S, Dermer CD, de Angelis A, de Palma F, Digel SW, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Espinoza C, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Fortin P, Frailis M, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giavitto G, 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, Jackson MS, Jóhannesson G, Johnson AS, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kataoka J, Katsuta 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, Lyne AG, Madejski GM, Makeev A, Mazziotta MN, McEnery JE, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Nolan PL, Norris JP, Noutsos A, Nuss E, Ohsugi T, Omodei N, Orlando E, Ormes JF, Paneque D, 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, Rochester LS, Rodriguez AY, Romani RW, Roth M, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Sgrò C, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Stappers BW, Stecker FW, Strickman MS, Suson DJ, Tajima H, Takahashi H, Takahashi T, Tanaka T, Thayer JB, Thayer JG, Theureau G, Thompson DJ, Tibaldo L, Tibolla O, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Vasileiou V, Venter C, Vilchez N, Vitale V, Waite AP, Wang P, Winer BL, Wood KS, Yamazaki R, Ylinen T, and Ziegler M

Abstract

Recent observations of supernova remnants (SNRs) hint that they accelerate cosmic rays to energies close to ~10(15) electron volts. However, the nature of the particles that produce the emission remains ambiguous. We report observations of SNR W44 with the Fermi Large Area Telescope at energies between 2 x 10(8) electron volts and 3 x10(11) electron volts. The detection of a source with a morphology corresponding to the SNR shell implies that the emission is produced by particles accelerated there. The gamma-ray spectrum is well modeled with emission from protons and nuclei. Its steepening above approximately 10(9) electron volts provides a probe with which to study how particle acceleration responds to environmental effects such as shock propagation in dense clouds and how accelerated particles are released into interstellar space.

Published
2010
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13. 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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14. Modulated high-energy gamma-ray emission from the microquasar Cygnus X-3.

Author

Abdo AA, Ackermann M, Ajello M, 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, Brez A, Brigida M, Bruel P, Burnett TH, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Celik O, Chaty S, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Conrad J, Corbel S, Corbet R, Dermer CD, de Palma F, Digel SW, do Couto e Silva E, Drell PS, Dubois R, Dubus G, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Fortin P, Frailis M, Fusco P, Gargano F, Gehrels N, Germani S, Giavitto G, 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, Hill AB, Hjalmarsdotter L, Horan D, Hughes RE, Jackson MS, Jóhannesson G, Johnson AS, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kawai N, Kerr M, Knödlseder J, Kocian ML, Koerding E, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Marchand L, Marelli M, Max-Moerbeck W, Mazziotta MN, McColl N, McEnery JE, Meurer C, Michelson PF, Migliari S, Mitthumsiri W, Mizuno T, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nolan PL, Norris JP, Nuss E, Ohsugi T, Omodei N, Ong RA, Ormes JF, Paneque D, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Pooley G, Porter TA, Pottschmidt K, Rainò S, Rando R, Ray PS, Razzano M, Rea N, Readhead A, Reimer A, Reimer O, Richards JL, Rochester LS, Rodriguez J, Rodriguez AY, Romani RW, Ryde F, Sadrozinski HF, Sander A, Saz Parkinson PM, Sgrò C, Siskind EJ, Smith DA, Smith PD, Spinelli P, Starck JL, Stevenson M, Strickman MS, Suson DJ, Takahashi H, Tanaka T, Thayer JB, Thompson DJ, Tibaldo L, Tomsick JA, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Vasileiou V, Vilchez N, Vitale V, Waite AP, Wang P, Wilms J, Winer BL, Wood KS, Ylinen T, and Ziegler M

Abstract

Microquasars are accreting black holes or neutron stars in binary systems with associated relativistic jets. Despite their frequent outburst activity, they have never been unambiguously detected emitting high-energy gamma rays. The Fermi Large Area Telescope (LAT) has detected a variable high-energy source coinciding with the position of the x-ray binary and microquasar Cygnus X-3. Its identification with Cygnus X-3 is secured by the detection of its orbital period in gamma rays, as well as the correlation of the LAT flux with radio emission from the relativistic jets of Cygnus X-3. The gamma-ray emission probably originates from within the binary system, opening new areas in which to study the formation of relativistic jets.

Published
2009
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15. A limit on the variation of the speed of light arising from quantum gravity effects.

Author

Abdo AA, Ackermann M, Ajello M, Asano K, Atwood WB, Axelsson M, Baldini L, Ballet J, Barbiellini G, Baring MG, Bastieri D, Bechtol K, Bellazzini R, Berenji B, Bhat PN, Bissaldi E, Bloom ED, Bonamente E, Bonnell J, Borgland AW, Bouvier A, Bregeon J, Brez A, Briggs MS, Brigida M, Bruel P, Burgess JM, Burnett TH, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Celik O, Chaplin V, Charles E, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Connaughton V, Conrad J, Cutini S, Dermer CD, de Angelis A, de Palma F, Digel SW, Dingus BL, do Couto E Silva E, Drell PS, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Finke J, Fishman G, Focke WB, Foschini L, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Gibby L, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Granot J, Greiner J, Grenier IA, Grondin MH, Grove JE, Grupe D, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hayashida M, Hays E, Hoversten EA, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Kippen RM, Knödlseder J, Kocevski D, Kouveliotou C, Kuehn F, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Mazziotta MN, McBreen S, McEnery JE, McGlynn S, Mészáros P, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Moretti E, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Nolan PL, Norris JP, Nuss E, Ohno M, Ohsugi T, Omodei N, Orlando E, Ormes JF, Ozaki M, Paciesas WS, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Petrosian V, Piron F, Porter TA, Preece R, Rainò S, Ramirez-Ruiz E, Rando R, Razzano M, Razzaque S, Reimer A, Reimer O, Reposeur T, Ritz S, Rochester LS, Rodriguez AY, 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, Stamatikos M, Stecker FW, Strickman MS, Suson DJ, Tajima H, Takahashi H, Takahashi T, Tanaka T, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Toma K, Torres DF, Tosti G, Troja E, Uchiyama Y, Uehara T, Usher TL, van der Horst AJ, Vasileiou V, Vilchez N, Vitale V, von Kienlin A, Waite AP, Wang P, Wilson-Hodge C, Winer BL, Wood KS, Wu XF, Yamazaki R, Ylinen T, and Ziegler M

Abstract

A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximately 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximately 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves. Here we report the detection of emission up to approximately 31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space-time on a very small scale linearly alters the speed of light.

Published
2009
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16. Detection of 16 gamma-ray pulsars through blind frequency searches using the Fermi LAT.

Author

Abdo AA, Ackermann M, Ajello M, Anderson B, 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, Caraveo PA, Casandjian JM, Cecchi C, Celik O, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Cutini S, Dermer CD, de Angelis A, de Luca A, de Palma F, Digel SW, Dormody M, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giommi P, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Gwon C, Hanabata Y, Harding AK, Hayashida M, Hays E, Hughes RE, Jóhannesson G, Johnson RP, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knödlseder J, Kocian ML, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Marelli M, Mazziotta MN, McConville W, McEnery JE, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, 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, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Pierbattista M, Piron F, Porter TA, Primack JR, Rainò S, Rando R, Ray PS, Razzano M, Rea N, Reimer A, Reimer O, Reposeur T, Ritz S, Rochester LS, Rodriguez AY, Romani RW, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Sgrò C, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Strickman MS, Suson DJ, Tajima H, Takahashi H, Takahashi T, Tanaka T, Thayer JG, Thompson DJ, Tibaldo L, Tibolla O, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Van Etten A, Vasileiou V, Vilchez N, Vitale V, Waite AP, Wang P, Watters K, Winer BL, Wolff MT, Wood KS, Ylinen T, and Ziegler M

Abstract

Pulsars are rapidly rotating, highly magnetized neutron stars emitting radiation across the electromagnetic spectrum. Although there are more than 1800 known radio pulsars, until recently only seven were observed to pulse in gamma rays, and these were all discovered at other wavelengths. The Fermi Large Area Telescope (LAT) makes it possible to pinpoint neutron stars through their gamma-ray pulsations. We report the detection of 16 gamma-ray pulsars in blind frequency searches using the LAT. Most of these pulsars are coincident with previously unidentified gamma-ray sources, and many are associated with supernova remnants. Direct detection of gamma-ray pulsars enables studies of emission mechanisms, population statistics, and the energetics of pulsar wind nebulae and supernova remnants.

Published
2009
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17. Detection of high-energy gamma-ray emission from the globular cluster 47 Tucanae with Fermi.

Author

Abdo AA, Ackermann M, Ajello M, 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, Celik O, Charles E, Chaty S, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Cutini S, Dermer CD, de Palma F, Digel SW, Dormody M, do Couto e Silva E, Drell PS, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Frailis M, Fukazawa Y, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grove JE, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hayashida M, Hays E, Horan D, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kawai N, Kerr M, Knödlseder J, Kuehn F, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, 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, Norris JP, Nuss E, Ohsugi T, Omodei N, Orlando E, Ormes JF, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Pierbattista M, Piron F, Porter TA, Rainò S, Rando R, 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, Sgrò C, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Strickman MS, 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, Wang P, Webb N, Winer BL, Wood KS, Ylinen T, and Ziegler M

Abstract

We report the detection of gamma-ray emissions above 200 megaelectron volts at a significance level of 17sigma from the globular cluster 47 Tucanae, using data obtained with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. Globular clusters are expected to emit gamma rays because of the large populations of millisecond pulsars that they contain. The spectral shape of 47 Tucanae is consistent with gamma-ray emission from a population of millisecond pulsars. The observed gamma-ray luminosity implies an upper limit of 60 millisecond pulsars present in 47 Tucanae.

Published
2009
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18. 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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19. Measurement of the cosmic ray e+ +e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope.

Author

Abdo AA, Ackermann M, Ajello M, Atwood WB, Axelsson M, Baldini L, Ballet J, Barbiellini G, Bastieri D, Battelino M, Baughman BM, Bechtol K, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bogaert G, Bonamente E, Borgland AW, Bregeon J, Brez A, Brigida M, Bruel P, Burnett TH, Caliandro GA, Cameron RA, Caraveo PA, Carlson P, Casandjian JM, Cecchi C, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Conrad J, Cutini S, Dermer CD, de Angelis A, de Palma F, Digel SW, Di Bernardo G, do Couto E Silva E, Drell PS, Dubois R, Dumora D, Edmonds Y, Farnier C, Favuzzi C, Focke WB, Frailis M, Fukazawa Y, Funk S, Fusco P, Gaggero D, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Grasso D, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Hanabata Y, Harding AK, Hartman RC, Hayashida M, Hays E, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knödlseder J, Kocevski D, Kuehn F, Kuss M, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Massai MM, Mazziotta MN, McConville W, McEnery JE, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Moretti E, Morselli A, Moskalenko IV, Murgia S, Nolan PL, Norris JP, Nuss E, Ohsugi T, Omodei N, Orlando E, Ormes JF, Ozaki M, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Pohl M, Porter TA, Profumo S, Rainò S, Rando R, Razzano M, 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, Sellerholm A, Sgrò C, Smith DA, Smith PD, Spandre G, Spinelli P, Starck JL, Stephens TE, Strickman MS, Strong AW, Suson DJ, Tajima H, Takahashi H, Takahashi T, Tanaka T, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Tibolla O, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Van Etten A, Vasileiou V, Vilchez N, Vitale V, Waite AP, Wallace E, Wang P, Winer BL, Wood KS, Ylinen T, and Ziegler M

Abstract

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 m;{2} sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply falling electron spectrum up to 1 TeV. Our high precision data show that the electron spectrum falls with energy as E-3.0 and does not exhibit prominent spectral features. Interpretations in terms of a conventional diffusive model as well as a potential local extra component are briefly discussed.

Published
2009
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20. Fermi observations of high-energy gamma-ray emission from GRB 080916C.

Author

Abdo AA, Ackermann M, Arimoto M, Asano K, Atwood WB, Axelsson M, Baldini L, Ballet J, Band DL, Barbiellini G, Baring MG, Bastieri D, Battelino M, Baughman BM, Bechtol K, Bellardi F, Bellazzini R, Berenji B, Bhat PN, Bissaldi E, Blandford RD, Bloom ED, Bogaert G, Bogart JR, Bonamente E, Bonnell J, Borgland AW, Bouvier A, Bregeon J, Brez A, Briggs MS, Brigida M, Bruel P, Burnett TH, Burrows D, Busetto G, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Ceccanti M, Cecchi C, Celotti A, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Connaughton V, Conrad J, Costamante L, Cutini S, Deklotz M, Dermer CD, de Angelis A, de Palma F, Digel SW, Dingus BL, do Couto E Silva E, Drell PS, Dubois R, Dumora D, Edmonds Y, Evans PA, Fabiani D, Farnier C, Favuzzi C, Finke J, Fishman G, Focke WB, Frailis M, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Gehrels N, Germani S, Giebels B, Giglietto N, Giommi P, Giordano F, Glanzman T, Godfrey G, Goldstein A, Granot J, Greiner J, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Haller G, Hanabata Y, Harding AK, Hayashida M, Hays E, Hernando Morat JA, Hoover A, Hughes RE, Jóhannesson G, Johnson AS, Johnson RP, Johnson TJ, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kavelaars A, Kawai N, Kelly H, Kennea J, Kerr M, Kippen RM, Knödlseder J, Kocevski D, Kocian ML, Komin N, Kouveliotou C, Kuehn F, Kuss M, Lande J, Landriu D, Larsson S, Latronico L, Lavalley C, Lee B, Lee SH, Lemoine-Goumard M, Lichti GG, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Madejski GM, Makeev A, Marangelli B, Mazziotta MN, McBreen S, McEnery JE, McGlynn S, Meegan C, Mészáros P, Meurer C, Michelson PF, Minuti M, Mirizzi N, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Moretti E, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Nelson D, Nolan PL, Norris JP, Nuss E, Ohno M, Ohsugi T, Okumura A, Omodei N, Orlando E, Ormes JF, Ozaki M, Paciesas WS, Paneque D, Panetta JH, Parent D, Pelassa V, Pepe M, Perri M, Pesce-Rollins M, Petrosian V, Pinchera M, Piron F, Porter TA, Preece R, Rainò S, Ramirez-Ruiz E, Rando R, Rapposelli E, Razzano M, Razzaque S, Rea N, Reimer A, Reimer O, Reposeur T, Reyes LC, Ritz S, Rochester LS, Rodriguez AY, Roth M, Ryde F, Sadrozinski HF, Sanchez D, Sander A, Saz Parkinson PM, Scargle JD, Schalk TL, Segal KN, Sgrò C, Shimokawabe T, Siskind EJ, Smith DA, Smith PD, Spandre G, Spinelli P, Stamatikos M, Starck JL, Stecker FW, Steinle H, Stephens TE, Strickman MS, Suson DJ, Tagliaferri G, Tajima H, Takahashi H, Takahashi T, Tanaka T, Tenze A, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Torres DF, Tosti G, Tramacere A, Turri M, Tuvi S, Usher TL, van der Horst AJ, Vigiani L, Vilchez N, Vitale V, von Kienlin A, Waite AP, Williams DA, Wilson-Hodge C, Winer BL, Wood KS, Wu XF, Yamazaki R, Ylinen T, and Ziegler M

Abstract

Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

Published
2009
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