Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT

A. A. Abdo, M. Ackermann, M. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, A. Bouvier, T. J. Brandt, J. Bregeon, A. Brez, M. Brigida, P. BruelR. Buehler, S. Buson, G. A. Caliandro, R. A. Cameron, P. A. Caraveo, S. Carrigan, J. M. Casandjian, C. Cecchi, Ö Çelik, E. Charles, A. Chekhtman, C. C. Cheung, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, C. D. Dermer, F. De Palma, S. W. Digel, E. Do Couto E Silva, P. S. Drell, R. Dubois, D. Dumora, C. Favuzzi, S. J. Fegan, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, M. H. Grondin, J. E. Grove, S. Guiriec, D. Hadasch, A. K. Harding, M. Hayashida, E. Hays, D. Horan, R. E. Hughes, P. Jean, G. Jóhannesson, A. S. Johnson, W. N. Johnson, T. Kamae, H. Katagiri, Jun Kataoka, M. Kerr, J. Knödlseder, M. Kuss, J. Lande, L. Latronico, S. H. Lee, M. Lemoine-Goumard, M. Llena Garde, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, A. Makeev, P. Martin, M. N. Mazziotta, J. E. McEnery, P. F. Michelson, W. Mitthumsiri, T. Mizuno, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, T. Nakamori, M. Naumann-Godo, P. L. Nolan, J. P. Norris, E. Nuss, T. Ohsugi, A. Okumura, N. Omodei, E. Orlando, J. F. Ormes, J. H. Panetta, D. Parent, V. Pelassa, M. Pepe, M. Pesce-Rollins, F. Piron, T. A. Porter, S. Rainò, R. Rando, M. Razzano, A. Reimer, O. Reimer, T. Reposeur, J. Ripken, S. Ritz, R. W. Romani, H. F W Sadrozinski, A. Sander, P. M. Saz Parkinson, J. D. Scargle, C. Sgrò, E. J. Siskind, D. A. Smith, P. D. Smith, G. Spandre, P. Spinelli, M. S. Strickman, A. W. Strong, D. J. Suson, H. Takahashi, T. Takahashi, T. Tanaka, J. B. Thayer, J. G. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, G. Tosti, A. Tramacere, Y. Uchiyama, T. L. Usher, J. Vandenbroucke, V. Vasileiou, N. Vilchez, V. Vitale, A. P. Waite, P. Wang, B. L. Winer, K. S. Wood, Z. Yang, T. Ylinen, M. Ziegler

    Research output: Contribution to journalArticle

    67 Citations (Scopus)

    Abstract

    Context. The flux of gamma rays with energies greater than 100 MeV is dominated by diffuse emission coming from cosmic-rays (CRs) illuminating the interstellar medium (ISM) of our Galaxy through the processes of Bremsstrahlung, pion production and decay, and inverse-Compton scattering. The study of this diffuse emission provides insight into the origin and transport of cosmic rays. Aims.We searched for gamma-ray emission from the Small Magellanic Cloud (SMC) in order to derive constraints on the cosmic-ray population and transport in an external system with properties different from the Milky Way. Methods.We analysed the first 17 months of continuous all-sky observations by the Large Area Telescope (LAT) of the Fermi mission to determine the spatial distribution, flux and spectrum of the gamma-ray emission from the SMC. We also used past radio synchrotron observations of the SMC to study the population of CR electrons specifically. Results.We obtained the first detection of the SMC in high-energy gamma rays, with an integrated >100MeV flux of (3.7±0.7)×10-8 ph cm-2 s-1, with additional systematic uncertainty of ≤16%. The emission is steady and from an extended source ∼3. in size. It is not clearly correlated with the distribution of massive stars or neutral gas, nor with known pulsars or supernova remnants, but a certain correlation with supergiant shells is observed. Conclusions.The observed flux implies an upper limit on the average CR nuclei density in the SMC of ∼15% of the value measured locally in the Milky Way. The population of high-energy pulsars of the SMC may account for a substantial fraction of the gamma-ray flux, which would make the inferred CR nuclei density even lower. The average density of CR electrons derived from radio synchrotron observations is consistent with the same reduction factor but the uncertainties are large. From our current knowledge of the SMC, such a low CR density does not seem to be due to a lower rate of CR injection and rather indicates a smaller CR confinement volume characteristic size.

    Original languageEnglish
    Article numberA46
    JournalAstronomy and Astrophysics
    Volume523
    Issue number3
    DOIs
    Publication statusPublished - 2010 Nov 16

    Fingerprint

    Magellanic clouds
    cosmic ray
    cosmic rays
    gamma rays
    telescopes
    pulsars
    synchrotrons
    detection
    radio
    energy
    electron
    nuclei
    neutral gases
    supernova remnants
    massive stars
    bremsstrahlung
    illuminating
    sky
    spatial distribution
    pions

    Keywords

    • acceleration of particles
    • cosmic rays
    • gamma rays: general
    • Magellanic Clouds

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., ... Ziegler, M. (2010). Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT. Astronomy and Astrophysics, 523(3), [A46]. https://doi.org/10.1051/0004-6361/201014855

    Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT. / Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Dermer, C. D.; De Palma, F.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Dubois, R.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; 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, I. A.; Grondin, M. H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jean, P.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, Jun; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. H.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Martin, P.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Romani, R. W.; Sadrozinski, H. F W; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    In: Astronomy and Astrophysics, Vol. 523, No. 3, A46, 16.11.2010.

    Research output: Contribution to journalArticle

    Abdo, AA, Ackermann, M, Ajello, M, 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, Caraveo, PA, Carrigan, S, Casandjian, JM, Cecchi, C, Çelik, Ö, Charles, E, Chekhtman, A, Cheung, CC, Chiang, J, Ciprini, S, Claus, R, Cohen-Tanugi, J, Conrad, J, Dermer, CD, De Palma, F, Digel, SW, Do Couto E Silva, E, Drell, PS, Dubois, R, Dumora, D, Favuzzi, C, Fegan, SJ, 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, Harding, AK, Hayashida, M, Hays, E, Horan, D, Hughes, RE, Jean, P, Jóhannesson, G, Johnson, AS, Johnson, WN, Kamae, T, Katagiri, H, Kataoka, J, Kerr, M, Knödlseder, J, Kuss, M, Lande, J, Latronico, L, Lee, SH, Lemoine-Goumard, M, Llena Garde, M, Longo, F, Loparco, F, Lovellette, MN, Lubrano, P, Makeev, A, Martin, 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, Nolan, PL, Norris, JP, Nuss, E, Ohsugi, T, Okumura, A, Omodei, N, Orlando, E, Ormes, JF, 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, Ripken, J, Ritz, S, Romani, RW, Sadrozinski, HFW, Sander, A, Saz Parkinson, PM, Scargle, JD, Sgrò, C, Siskind, EJ, Smith, DA, Smith, PD, Spandre, G, Spinelli, P, Strickman, MS, Strong, AW, Suson, DJ, Takahashi, H, Takahashi, T, Tanaka, T, Thayer, JB, Thayer, JG, Thompson, DJ, Tibaldo, L, Torres, DF, Tosti, G, Tramacere, A, Uchiyama, Y, Usher, TL, Vandenbroucke, J, Vasileiou, V, Vilchez, N, Vitale, V, Waite, AP, Wang, P, Winer, BL, Wood, KS, Yang, Z, Ylinen, T & Ziegler, M 2010, 'Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT', Astronomy and Astrophysics, vol. 523, no. 3, A46. https://doi.org/10.1051/0004-6361/201014855
    Abdo AA, Ackermann M, Ajello M, Baldini L, Ballet J, Barbiellini G et al. Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT. Astronomy and Astrophysics. 2010 Nov 16;523(3). A46. https://doi.org/10.1051/0004-6361/201014855
    Abdo, A. A. ; Ackermann, M. ; Ajello, M. ; Baldini, L. ; Ballet, J. ; Barbiellini, G. ; Bastieri, D. ; Bechtol, K. ; Bellazzini, R. ; Berenji, B. ; Blandford, R. D. ; Bloom, E. D. ; Bonamente, E. ; Borgland, A. W. ; Bouvier, A. ; Brandt, T. J. ; Bregeon, J. ; Brez, A. ; Brigida, M. ; Bruel, P. ; Buehler, R. ; Buson, S. ; Caliandro, G. A. ; Cameron, R. A. ; Caraveo, P. A. ; Carrigan, S. ; Casandjian, J. M. ; Cecchi, C. ; Çelik, Ö ; Charles, E. ; Chekhtman, A. ; Cheung, C. C. ; Chiang, J. ; Ciprini, S. ; Claus, R. ; Cohen-Tanugi, J. ; Conrad, J. ; Dermer, C. D. ; De Palma, F. ; Digel, S. W. ; Do Couto E Silva, E. ; Drell, P. S. ; Dubois, R. ; Dumora, D. ; Favuzzi, C. ; Fegan, S. J. ; 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, I. A. ; Grondin, M. H. ; Grove, J. E. ; Guiriec, S. ; Hadasch, D. ; Harding, A. K. ; Hayashida, M. ; Hays, E. ; Horan, D. ; Hughes, R. E. ; Jean, P. ; Jóhannesson, G. ; Johnson, A. S. ; Johnson, W. N. ; Kamae, T. ; Katagiri, H. ; Kataoka, Jun ; Kerr, M. ; Knödlseder, J. ; Kuss, M. ; Lande, J. ; Latronico, L. ; Lee, S. H. ; Lemoine-Goumard, M. ; Llena Garde, M. ; Longo, F. ; Loparco, F. ; Lovellette, M. N. ; Lubrano, P. ; Makeev, A. ; Martin, P. ; Mazziotta, M. N. ; McEnery, J. E. ; Michelson, P. F. ; Mitthumsiri, W. ; Mizuno, T. ; Monte, C. ; Monzani, M. E. ; Morselli, A. ; Moskalenko, I. V. ; Murgia, S. ; Nakamori, T. ; Naumann-Godo, M. ; Nolan, P. L. ; Norris, J. P. ; Nuss, E. ; Ohsugi, T. ; Okumura, A. ; Omodei, N. ; Orlando, E. ; Ormes, J. F. ; Panetta, J. H. ; Parent, D. ; Pelassa, V. ; Pepe, M. ; Pesce-Rollins, M. ; Piron, F. ; Porter, T. A. ; Rainò, S. ; Rando, R. ; Razzano, M. ; Reimer, A. ; Reimer, O. ; Reposeur, T. ; Ripken, J. ; Ritz, S. ; Romani, R. W. ; Sadrozinski, H. F W ; Sander, A. ; Saz Parkinson, P. M. ; Scargle, J. D. ; Sgrò, C. ; Siskind, E. J. ; Smith, D. A. ; Smith, P. D. ; Spandre, G. ; Spinelli, P. ; Strickman, M. S. ; Strong, A. W. ; Suson, D. J. ; Takahashi, H. ; Takahashi, T. ; Tanaka, T. ; Thayer, J. B. ; Thayer, J. G. ; Thompson, D. J. ; Tibaldo, L. ; Torres, D. F. ; Tosti, G. ; Tramacere, A. ; Uchiyama, Y. ; Usher, T. L. ; Vandenbroucke, J. ; Vasileiou, V. ; Vilchez, N. ; Vitale, V. ; Waite, A. P. ; Wang, P. ; Winer, B. L. ; Wood, K. S. ; Yang, Z. ; Ylinen, T. ; Ziegler, M. / Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT. In: Astronomy and Astrophysics. 2010 ; Vol. 523, No. 3.
    @article{a10ece949b964b1484136b2d1e0d6cda,
    title = "Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT",
    abstract = "Context. The flux of gamma rays with energies greater than 100 MeV is dominated by diffuse emission coming from cosmic-rays (CRs) illuminating the interstellar medium (ISM) of our Galaxy through the processes of Bremsstrahlung, pion production and decay, and inverse-Compton scattering. The study of this diffuse emission provides insight into the origin and transport of cosmic rays. Aims.We searched for gamma-ray emission from the Small Magellanic Cloud (SMC) in order to derive constraints on the cosmic-ray population and transport in an external system with properties different from the Milky Way. Methods.We analysed the first 17 months of continuous all-sky observations by the Large Area Telescope (LAT) of the Fermi mission to determine the spatial distribution, flux and spectrum of the gamma-ray emission from the SMC. We also used past radio synchrotron observations of the SMC to study the population of CR electrons specifically. Results.We obtained the first detection of the SMC in high-energy gamma rays, with an integrated >100MeV flux of (3.7±0.7)×10-8 ph cm-2 s-1, with additional systematic uncertainty of ≤16{\%}. The emission is steady and from an extended source ∼3. in size. It is not clearly correlated with the distribution of massive stars or neutral gas, nor with known pulsars or supernova remnants, but a certain correlation with supergiant shells is observed. Conclusions.The observed flux implies an upper limit on the average CR nuclei density in the SMC of ∼15{\%} of the value measured locally in the Milky Way. The population of high-energy pulsars of the SMC may account for a substantial fraction of the gamma-ray flux, which would make the inferred CR nuclei density even lower. The average density of CR electrons derived from radio synchrotron observations is consistent with the same reduction factor but the uncertainties are large. From our current knowledge of the SMC, such a low CR density does not seem to be due to a lower rate of CR injection and rather indicates a smaller CR confinement volume characteristic size.",
    keywords = "acceleration of particles, cosmic rays, gamma rays: general, Magellanic Clouds",
    author = "Abdo, {A. A.} and M. Ackermann and M. Ajello and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and K. Bechtol and R. Bellazzini and B. Berenji and Blandford, {R. D.} and Bloom, {E. D.} and E. Bonamente and Borgland, {A. W.} and A. Bouvier and Brandt, {T. J.} and J. Bregeon and A. Brez and M. Brigida and P. Bruel and R. Buehler and S. Buson and Caliandro, {G. A.} and Cameron, {R. A.} and Caraveo, {P. A.} and S. Carrigan and Casandjian, {J. M.} and C. Cecchi and {\"O} {\cC}elik and E. Charles and A. Chekhtman and Cheung, {C. C.} and J. Chiang and S. Ciprini and R. Claus and J. Cohen-Tanugi and J. Conrad and Dermer, {C. D.} and {De Palma}, F. and Digel, {S. W.} and {Do Couto E Silva}, E. and Drell, {P. S.} and R. Dubois and D. Dumora and C. Favuzzi and Fegan, {S. J.} and Y. Fukazawa and S. Funk and P. Fusco and F. Gargano and D. Gasparrini and N. Gehrels and S. Germani and N. Giglietto and F. Giordano and M. Giroletti and T. Glanzman and G. Godfrey and Grenier, {I. A.} and Grondin, {M. H.} and Grove, {J. E.} and S. Guiriec and D. Hadasch and Harding, {A. K.} and M. Hayashida and E. Hays and D. Horan and Hughes, {R. E.} and P. Jean and G. J{\'o}hannesson and Johnson, {A. S.} and Johnson, {W. N.} and T. Kamae and H. Katagiri and Jun Kataoka and M. Kerr and J. Kn{\"o}dlseder and M. Kuss and J. Lande and L. Latronico and Lee, {S. H.} and M. Lemoine-Goumard and {Llena Garde}, M. and F. Longo and F. Loparco and Lovellette, {M. N.} and P. Lubrano and A. Makeev and P. Martin and Mazziotta, {M. N.} and McEnery, {J. E.} and Michelson, {P. F.} and W. Mitthumsiri and T. Mizuno and C. Monte and Monzani, {M. E.} and A. Morselli and Moskalenko, {I. V.} and S. Murgia and T. Nakamori and M. Naumann-Godo and Nolan, {P. L.} and Norris, {J. P.} and E. Nuss and T. Ohsugi and A. Okumura and N. Omodei and E. Orlando and Ormes, {J. F.} and Panetta, {J. H.} and D. Parent and V. Pelassa and M. Pepe and M. Pesce-Rollins and F. Piron and Porter, {T. A.} and S. Rain{\`o} and R. Rando and M. Razzano and A. Reimer and O. Reimer and T. Reposeur and J. Ripken and S. Ritz and Romani, {R. W.} and Sadrozinski, {H. F W} and A. Sander and {Saz Parkinson}, {P. M.} and Scargle, {J. D.} and C. Sgr{\`o} and Siskind, {E. J.} and Smith, {D. A.} and Smith, {P. D.} and G. Spandre and P. Spinelli and Strickman, {M. S.} and Strong, {A. W.} and Suson, {D. J.} and H. Takahashi and T. Takahashi and T. Tanaka and Thayer, {J. B.} and Thayer, {J. G.} and Thompson, {D. J.} and L. Tibaldo and Torres, {D. F.} and G. Tosti and A. Tramacere and Y. Uchiyama and Usher, {T. L.} and J. Vandenbroucke and V. Vasileiou and N. Vilchez and V. Vitale and Waite, {A. P.} and P. Wang and Winer, {B. L.} and Wood, {K. S.} and Z. Yang and T. Ylinen and M. Ziegler",
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    month = "11",
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    doi = "10.1051/0004-6361/201014855",
    language = "English",
    volume = "523",
    journal = "Astronomy and Astrophysics",
    issn = "0004-6361",
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    TY - JOUR

    T1 - Detection of the Small Magellanic Cloud in gamma-rays with Fermi /LAT

    AU - Abdo, A. A.

    AU - Ackermann, M.

    AU - Ajello, M.

    AU - Baldini, L.

    AU - Ballet, J.

    AU - Barbiellini, G.

    AU - Bastieri, D.

    AU - Bechtol, K.

    AU - Bellazzini, R.

    AU - Berenji, B.

    AU - Blandford, R. D.

    AU - Bloom, E. D.

    AU - Bonamente, E.

    AU - Borgland, A. W.

    AU - Bouvier, A.

    AU - Brandt, T. J.

    AU - Bregeon, J.

    AU - Brez, A.

    AU - Brigida, M.

    AU - Bruel, P.

    AU - Buehler, R.

    AU - Buson, S.

    AU - Caliandro, G. A.

    AU - Cameron, R. A.

    AU - Caraveo, P. A.

    AU - Carrigan, S.

    AU - Casandjian, J. M.

    AU - Cecchi, C.

    AU - Çelik, Ö

    AU - Charles, E.

    AU - Chekhtman, A.

    AU - Cheung, C. C.

    AU - Chiang, J.

    AU - Ciprini, S.

    AU - Claus, R.

    AU - Cohen-Tanugi, J.

    AU - Conrad, J.

    AU - Dermer, C. D.

    AU - De Palma, F.

    AU - Digel, S. W.

    AU - Do Couto E Silva, E.

    AU - Drell, P. S.

    AU - Dubois, R.

    AU - Dumora, D.

    AU - Favuzzi, C.

    AU - Fegan, S. J.

    AU - Fukazawa, Y.

    AU - Funk, S.

    AU - Fusco, P.

    AU - Gargano, F.

    AU - Gasparrini, D.

    AU - Gehrels, N.

    AU - Germani, S.

    AU - Giglietto, N.

    AU - Giordano, F.

    AU - Giroletti, M.

    AU - Glanzman, T.

    AU - Godfrey, G.

    AU - Grenier, I. A.

    AU - Grondin, M. H.

    AU - Grove, J. E.

    AU - Guiriec, S.

    AU - Hadasch, D.

    AU - Harding, A. K.

    AU - Hayashida, M.

    AU - Hays, E.

    AU - Horan, D.

    AU - Hughes, R. E.

    AU - Jean, P.

    AU - Jóhannesson, G.

    AU - Johnson, A. S.

    AU - Johnson, W. N.

    AU - Kamae, T.

    AU - Katagiri, H.

    AU - Kataoka, Jun

    AU - Kerr, M.

    AU - Knödlseder, J.

    AU - Kuss, M.

    AU - Lande, J.

    AU - Latronico, L.

    AU - Lee, S. H.

    AU - Lemoine-Goumard, M.

    AU - Llena Garde, M.

    AU - Longo, F.

    AU - Loparco, F.

    AU - Lovellette, M. N.

    AU - Lubrano, P.

    AU - Makeev, A.

    AU - Martin, P.

    AU - Mazziotta, M. N.

    AU - McEnery, J. E.

    AU - Michelson, P. F.

    AU - Mitthumsiri, W.

    AU - Mizuno, T.

    AU - Monte, C.

    AU - Monzani, M. E.

    AU - Morselli, A.

    AU - Moskalenko, I. V.

    AU - Murgia, S.

    AU - Nakamori, T.

    AU - Naumann-Godo, M.

    AU - Nolan, P. L.

    AU - Norris, J. P.

    AU - Nuss, E.

    AU - Ohsugi, T.

    AU - Okumura, A.

    AU - Omodei, N.

    AU - Orlando, E.

    AU - Ormes, J. F.

    AU - Panetta, J. H.

    AU - Parent, D.

    AU - Pelassa, V.

    AU - Pepe, M.

    AU - Pesce-Rollins, M.

    AU - Piron, F.

    AU - Porter, T. A.

    AU - Rainò, S.

    AU - Rando, R.

    AU - Razzano, M.

    AU - Reimer, A.

    AU - Reimer, O.

    AU - Reposeur, T.

    AU - Ripken, J.

    AU - Ritz, S.

    AU - Romani, R. W.

    AU - Sadrozinski, H. F W

    AU - Sander, A.

    AU - Saz Parkinson, P. M.

    AU - Scargle, J. D.

    AU - Sgrò, C.

    AU - Siskind, E. J.

    AU - Smith, D. A.

    AU - Smith, P. D.

    AU - Spandre, G.

    AU - Spinelli, P.

    AU - Strickman, M. S.

    AU - Strong, A. W.

    AU - Suson, D. J.

    AU - Takahashi, H.

    AU - Takahashi, T.

    AU - Tanaka, T.

    AU - Thayer, J. B.

    AU - Thayer, J. G.

    AU - Thompson, D. J.

    AU - Tibaldo, L.

    AU - Torres, D. F.

    AU - Tosti, G.

    AU - Tramacere, A.

    AU - Uchiyama, Y.

    AU - Usher, T. L.

    AU - Vandenbroucke, J.

    AU - Vasileiou, V.

    AU - Vilchez, N.

    AU - Vitale, V.

    AU - Waite, A. P.

    AU - Wang, P.

    AU - Winer, B. L.

    AU - Wood, K. S.

    AU - Yang, Z.

    AU - Ylinen, T.

    AU - Ziegler, M.

    PY - 2010/11/16

    Y1 - 2010/11/16

    N2 - Context. The flux of gamma rays with energies greater than 100 MeV is dominated by diffuse emission coming from cosmic-rays (CRs) illuminating the interstellar medium (ISM) of our Galaxy through the processes of Bremsstrahlung, pion production and decay, and inverse-Compton scattering. The study of this diffuse emission provides insight into the origin and transport of cosmic rays. Aims.We searched for gamma-ray emission from the Small Magellanic Cloud (SMC) in order to derive constraints on the cosmic-ray population and transport in an external system with properties different from the Milky Way. Methods.We analysed the first 17 months of continuous all-sky observations by the Large Area Telescope (LAT) of the Fermi mission to determine the spatial distribution, flux and spectrum of the gamma-ray emission from the SMC. We also used past radio synchrotron observations of the SMC to study the population of CR electrons specifically. Results.We obtained the first detection of the SMC in high-energy gamma rays, with an integrated >100MeV flux of (3.7±0.7)×10-8 ph cm-2 s-1, with additional systematic uncertainty of ≤16%. The emission is steady and from an extended source ∼3. in size. It is not clearly correlated with the distribution of massive stars or neutral gas, nor with known pulsars or supernova remnants, but a certain correlation with supergiant shells is observed. Conclusions.The observed flux implies an upper limit on the average CR nuclei density in the SMC of ∼15% of the value measured locally in the Milky Way. The population of high-energy pulsars of the SMC may account for a substantial fraction of the gamma-ray flux, which would make the inferred CR nuclei density even lower. The average density of CR electrons derived from radio synchrotron observations is consistent with the same reduction factor but the uncertainties are large. From our current knowledge of the SMC, such a low CR density does not seem to be due to a lower rate of CR injection and rather indicates a smaller CR confinement volume characteristic size.

    AB - Context. The flux of gamma rays with energies greater than 100 MeV is dominated by diffuse emission coming from cosmic-rays (CRs) illuminating the interstellar medium (ISM) of our Galaxy through the processes of Bremsstrahlung, pion production and decay, and inverse-Compton scattering. The study of this diffuse emission provides insight into the origin and transport of cosmic rays. Aims.We searched for gamma-ray emission from the Small Magellanic Cloud (SMC) in order to derive constraints on the cosmic-ray population and transport in an external system with properties different from the Milky Way. Methods.We analysed the first 17 months of continuous all-sky observations by the Large Area Telescope (LAT) of the Fermi mission to determine the spatial distribution, flux and spectrum of the gamma-ray emission from the SMC. We also used past radio synchrotron observations of the SMC to study the population of CR electrons specifically. Results.We obtained the first detection of the SMC in high-energy gamma rays, with an integrated >100MeV flux of (3.7±0.7)×10-8 ph cm-2 s-1, with additional systematic uncertainty of ≤16%. The emission is steady and from an extended source ∼3. in size. It is not clearly correlated with the distribution of massive stars or neutral gas, nor with known pulsars or supernova remnants, but a certain correlation with supergiant shells is observed. Conclusions.The observed flux implies an upper limit on the average CR nuclei density in the SMC of ∼15% of the value measured locally in the Milky Way. The population of high-energy pulsars of the SMC may account for a substantial fraction of the gamma-ray flux, which would make the inferred CR nuclei density even lower. The average density of CR electrons derived from radio synchrotron observations is consistent with the same reduction factor but the uncertainties are large. From our current knowledge of the SMC, such a low CR density does not seem to be due to a lower rate of CR injection and rather indicates a smaller CR confinement volume characteristic size.

    KW - acceleration of particles

    KW - cosmic rays

    KW - gamma rays: general

    KW - Magellanic Clouds

    UR - http://www.scopus.com/inward/record.url?scp=78449261568&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=78449261568&partnerID=8YFLogxK

    U2 - 10.1051/0004-6361/201014855

    DO - 10.1051/0004-6361/201014855

    M3 - Article

    AN - SCOPUS:78449261568

    VL - 523

    JO - Astronomy and Astrophysics

    JF - Astronomy and Astrophysics

    SN - 0004-6361

    IS - 3

    M1 - A46

    ER -