Fermi/lat observations of LS 5039

A. A. Abdo; M. Ackermann; M. Ajello; W. B. Atwood; M. Axelsson; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; B. M. Baughman; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; P. Bruel; T. H. Burnett; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; Ö Çelik; S. Chaty; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; S. Corbel; R. Corbet; S. Cutini; C. D. Dermer; A. De Angelis; F. De Palma; S. W. Digel; E. Docouto E Silva; P. S. Drell; R. Dubois; G. Dubus; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; P. Fortin; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M. H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; M. Hayashida; E. Hays; A. B. Hill; D. Horan; R. E. Hughes; M. S. Jackson; G. Jóhannesson; A. S. Johnson; T. J. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; J. Knödlseder; M. L. Kocian; F. Kuehn; M. Kuss; J. Lande; S. Larsson; L. Latronico; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; M. Marelli; M. N. Mazziotta; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; A. A. Moiseev; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; P. S. Ray; M. Razzano; N. Rea; A. Reimer; O. Reimer; T. Reposeur; S. Ritz; L. S. Rochester; A. Y. Rodriguez; R. W. Romani; M. Roth; F. Ryde; H. F.W. Sadrozinski; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; C. Sgrò; A. Sierpowska-Bartosik; E. J. Siskind; D. A. Smith; P. D. Smith; G. Spandre; P. Spinelli; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; Y. Tanaka; J. B. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; V. Vasileiou; C. Venter; N. Vilchez; V. Vitale; A. P. Waite; E. Wallace; P. Wang; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

doi:10.1088/0004-637X/706/1/L56

Fermi/lat observations of LS 5039

A. A. Abdo, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, B. M. Baughman, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, J. Bregeon, A. Brez, M. BrigidaP. Bruel, T. H. Burnett, S. Buson, G. A. Caliandro, R. A. Cameron, P. A. Caraveo, J. M. Casandjian, E. Cavazzuti, C. Cecchi, Ö Çelik, S. Chaty, A. Chekhtman, C. C. Cheung, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, L. R. Cominsky, J. Conrad, S. Corbel, R. Corbet, S. Cutini, C. D. Dermer, A. De Angelis, F. De Palma, S. W. Digel, E. Docouto E Silva, P. S. Drell, R. Dubois, G. Dubus, D. Dumora, C. Farnier, C. Favuzzi, S. J. Fegan, W. B. Focke, P. Fortin, M. Frailis, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, B. Giebels, N. Giglietto, F. Giordano, T. Glanzman, G. Godfrey, I. A. Grenier, M. H. Grondin, J. E. Grove, L. Guillemot, S. Guiriec, Y. Hanabata, A. K. Harding, M. Hayashida, E. Hays, A. B. Hill, D. Horan, R. E. Hughes, M. S. Jackson, G. Jóhannesson, A. S. Johnson, T. J. Johnson, W. N. Johnson, T. Kamae, H. Katagiri, J. Kataoka, N. Kawai, M. Kerr, J. Knödlseder, M. L. Kocian, F. Kuehn, M. Kuss, J. Lande, S. Larsson, L. Latronico, M. Lemoine-Goumard, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, A. Makeev, M. Marelli, M. N. Mazziotta, J. E. McEnery, C. Meurer, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, P. L. Nolan, J. P. Norris, E. Nuss, T. Ohsugi, N. Omodei, E. Orlando, J. F. Ormes, M. Ozaki, D. Paneque, J. H. Panetta, D. Parent, V. Pelassa, M. Pepe, M. Pesce-Rollins, F. Piron, T. A. Porter, S. Rainò, R. Rando, P. S. Ray, M. Razzano, N. Rea, A. Reimer, O. Reimer, T. Reposeur, S. Ritz, L. S. Rochester, A. Y. Rodriguez, R. W. Romani, M. Roth, F. Ryde, H. F.W. Sadrozinski, D. Sanchez, A. Sander, P. M. Saz Parkinson, J. D. Scargle, C. Sgrò, A. Sierpowska-Bartosik, E. J. Siskind, D. A. Smith, P. D. Smith, G. Spandre, P. Spinelli, M. S. Strickman, D. J. Suson, H. Tajima, H. Takahashi, T. Takahashi, T. Tanaka, Y. Tanaka, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, G. Tosti, A. Tramacere, Y. Uchiyama, T. L. Usher, V. Vasileiou, C. Venter, N. Vilchez, V. Vitale, A. P. Waite, E. Wallace, P. Wang, B. L. Winer, K. S. Wood, T. Ylinen, M. Ziegler

School of Advanced Science and Engineering

Research output: Contribution to journal › Article › peer-review

139 Citations (Scopus)

Abstract

The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) 1.8(syst) ×10^-7 photon cm^-2 s^-1, with a cutoff at 2.1 ± 0.3(stat) 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.

Original language	English
Pages (from-to)	L56-L61
Journal	Astrophysical Journal
Volume	706
Issue number	1 PART 2
DOIs	https://doi.org/10.1088/0004-637X/706/1/L56
Publication status	Published - 2009

Keywords

Binaries: close
Gamma rays: observations
Stars: variables: other
X-rays: binaries
X-rays: individual (LS 5039)

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1088/0004-637X/706/1/L56

Cite this

Abdo, A. A., Ackermann, M., Ajello, M., Atwood, W. B., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Baughman, B. M., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bregeon, J., Brez, A., ... Ziegler, M. (2009). Fermi/lat observations of LS 5039. Astrophysical Journal, 706(1 PART 2), L56-L61. https://doi.org/10.1088/0004-637X/706/1/L56

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, Buson, S, Caliandro, GA, Cameron, RA, Caraveo, PA, Casandjian, JM, Cavazzuti, E, Cecchi, C, Çelik, Ö, Chaty, S, Chekhtman, A, Cheung, CC, Chiang, J, Ciprini, S, Claus, R, Cohen-Tanugi, J, Cominsky, LR, Conrad, J, Corbel, S, Corbet, R, Cutini, S, Dermer, CD, De Angelis, A, De Palma, F, Digel, SW, Docouto E Silva, E, Drell, PS, Dubois, R, Dubus, G, Dumora, D, 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, 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, Horan, D, 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, Kuehn, F, Kuss, M, Lande, J, Larsson, S, Latronico, L, Lemoine-Goumard, M, Longo, F, Loparco, F, Lott, B, Lovellette, MN, Lubrano, P, Madejski, GM, Makeev, A, Marelli, M, Mazziotta, MN, 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, Ozaki, M, Paneque, D, Panetta, JH, Parent, D, Pelassa, V, Pepe, M, Pesce-Rollins, M, Piron, F, Porter, TA, Rainò, S, Rando, R, 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, HFW, Sanchez, D, Sander, A, Saz Parkinson, PM, Scargle, JD, Sgrò, C, Sierpowska-Bartosik, A, Siskind, EJ, Smith, DA, Smith, PD, Spandre, G, Spinelli, P, Strickman, MS, Suson, DJ, Tajima, H, Takahashi, H, Takahashi, T, Tanaka, T, Tanaka, Y, Thayer, JB, Thompson, DJ, Tibaldo, L, Torres, DF, Tosti, G, Tramacere, A, Uchiyama, Y, Usher, TL, Vasileiou, V, Venter, C, Vilchez, N, Vitale, V, Waite, AP, Wallace, E, Wang, P, Winer, BL, Wood, KS, Ylinen, T & Ziegler, M 2009, 'Fermi/lat observations of LS 5039', Astrophysical Journal, vol. 706, no. 1 PART 2, pp. L56-L61. https://doi.org/10.1088/0004-637X/706/1/L56

@article{48274b347f654123a9abd543eda34e37,

title = "Fermi/lat observations of LS 5039",

abstract = "The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) 1.8(syst) ×10-7 photon cm-2 s-1, with a cutoff at 2.1 ± 0.3(stat) 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.",

keywords = "Binaries: close, Gamma rays: observations, Stars: variables: other, X-rays: binaries, X-rays: individual (LS 5039)",

author = "Abdo, {A. A.} and M. Ackermann and M. Ajello and Atwood, {W. B.} and M. Axelsson and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and Baughman, {B. M.} 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 J. Bregeon and A. Brez and M. Brigida and P. Bruel and Burnett, {T. H.} and S. Buson and Caliandro, {G. A.} and Cameron, {R. A.} and Caraveo, {P. A.} and Casandjian, {J. M.} and E. Cavazzuti and C. Cecchi and {\"O} {\c C}elik and S. Chaty and A. Chekhtman and Cheung, {C. C.} and J. Chiang and S. Ciprini and R. Claus and J. Cohen-Tanugi and Cominsky, {L. R.} and J. Conrad and S. Corbel and R. Corbet and S. Cutini and Dermer, {C. D.} and {De Angelis}, A. and {De Palma}, F. and Digel, {S. W.} and {Docouto E Silva}, E. and Drell, {P. S.} and R. Dubois and G. Dubus and D. Dumora and C. Farnier and C. Favuzzi and Fegan, {S. J.} and Focke, {W. B.} and P. Fortin and M. Frailis and Y. Fukazawa and S. Funk and P. Fusco and F. Gargano and D. Gasparrini and N. Gehrels and S. Germani and B. Giebels and N. Giglietto and F. Giordano and T. Glanzman and G. Godfrey and Grenier, {I. A.} and Grondin, {M. H.} and Grove, {J. E.} and L. Guillemot and S. Guiriec and Y. Hanabata and Harding, {A. K.} and M. Hayashida and E. Hays and Hill, {A. B.} and D. Horan and Hughes, {R. E.} and Jackson, {M. S.} and G. J{\'o}hannesson and Johnson, {A. S.} and Johnson, {T. J.} and Johnson, {W. N.} and T. Kamae and H. Katagiri and J. Kataoka and N. Kawai and M. Kerr and J. Kn{\"o}dlseder and Kocian, {M. L.} and F. Kuehn and M. Kuss and J. Lande and S. Larsson and L. Latronico and M. Lemoine-Goumard and F. Longo and F. Loparco and B. Lott and Lovellette, {M. N.} and P. Lubrano and Madejski, {G. M.} and A. Makeev and M. Marelli and Mazziotta, {M. N.} and McEnery, {J. E.} and C. Meurer and Michelson, {P. F.} and W. Mitthumsiri and T. Mizuno and Moiseev, {A. A.} and C. Monte and Monzani, {M. E.} and A. Morselli and Moskalenko, {I. V.} and S. Murgia and Nolan, {P. L.} and Norris, {J. P.} and E. Nuss and T. Ohsugi and N. Omodei and E. Orlando and Ormes, {J. F.} and M. Ozaki and D. Paneque 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 Ray, {P. S.} and M. Razzano and N. Rea and A. Reimer and O. Reimer and T. Reposeur and S. Ritz and Rochester, {L. S.} and Rodriguez, {A. Y.} and Romani, {R. W.} and M. Roth and F. Ryde and Sadrozinski, {H. F.W.} and D. Sanchez and A. Sander and {Saz Parkinson}, {P. M.} and Scargle, {J. D.} and C. Sgr{\`o} and A. Sierpowska-Bartosik and Siskind, {E. J.} and Smith, {D. A.} and Smith, {P. D.} and G. Spandre and P. Spinelli and Strickman, {M. S.} and Suson, {D. J.} and H. Tajima and H. Takahashi and T. Takahashi and T. Tanaka and Y. Tanaka and Thayer, {J. B.} 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 V. Vasileiou and C. Venter and N. Vilchez and V. Vitale and Waite, {A. P.} and E. Wallace and P. Wang and Winer, {B. L.} and Wood, {K. S.} and T. Ylinen and M. Ziegler",

year = "2009",

doi = "10.1088/0004-637X/706/1/L56",

language = "English",

volume = "706",

pages = "L56--L61",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1 PART 2",

}

TY - JOUR

T1 - Fermi/lat observations of LS 5039

AU - Abdo, A. A.

AU - Ackermann, M.

AU - Ajello, M.

AU - Atwood, W. B.

AU - Axelsson, M.

AU - Baldini, L.

AU - Ballet, J.

AU - Barbiellini, G.

AU - Bastieri, D.

AU - Baughman, B. M.

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 - Bregeon, J.

AU - Brez, A.

AU - Brigida, M.

AU - Bruel, P.

AU - Burnett, T. H.

AU - Buson, S.

AU - Caliandro, G. A.

AU - Cameron, R. A.

AU - Caraveo, P. A.

AU - Casandjian, J. M.

AU - Cavazzuti, E.

AU - Cecchi, C.

AU - Çelik, Ö

AU - Chaty, S.

AU - Chekhtman, A.

AU - Cheung, C. C.

AU - Chiang, J.

AU - Ciprini, S.

AU - Claus, R.

AU - Cohen-Tanugi, J.

AU - Cominsky, L. R.

AU - Conrad, J.

AU - Corbel, S.

AU - Corbet, R.

AU - Cutini, S.

AU - Dermer, C. D.

AU - De Angelis, A.

AU - De Palma, F.

AU - Digel, S. W.

AU - Docouto E Silva, E.

AU - Drell, P. S.

AU - Dubois, R.

AU - Dubus, G.

AU - Dumora, D.

AU - Farnier, C.

AU - Favuzzi, C.

AU - Fegan, S. J.

AU - Focke, W. B.

AU - Fortin, P.

AU - Frailis, M.

AU - Fukazawa, Y.

AU - Funk, S.

AU - Fusco, P.

AU - Gargano, F.

AU - Gasparrini, D.

AU - Gehrels, N.

AU - Germani, S.

AU - Giebels, B.

AU - Giglietto, N.

AU - Giordano, F.

AU - Glanzman, T.

AU - Godfrey, G.

AU - Grenier, I. A.

AU - Grondin, M. H.

AU - Grove, J. E.

AU - Guillemot, L.

AU - Guiriec, S.

AU - Hanabata, Y.

AU - Harding, A. K.

AU - Hayashida, M.

AU - Hays, E.

AU - Hill, A. B.

AU - Horan, D.

AU - Hughes, R. E.

AU - Jackson, M. S.

AU - Jóhannesson, G.

AU - Johnson, A. S.

AU - Johnson, T. J.

AU - Johnson, W. N.

AU - Kamae, T.

AU - Katagiri, H.

AU - Kataoka, J.

AU - Kawai, N.

AU - Kerr, M.

AU - Knödlseder, J.

AU - Kocian, M. L.

AU - Kuehn, F.

AU - Kuss, M.

AU - Lande, J.

AU - Larsson, S.

AU - Latronico, L.

AU - Lemoine-Goumard, M.

AU - Longo, F.

AU - Loparco, F.

AU - Lott, B.

AU - Lovellette, M. N.

AU - Lubrano, P.

AU - Madejski, G. M.

AU - Makeev, A.

AU - Marelli, M.

AU - Mazziotta, M. N.

AU - McEnery, J. E.

AU - Meurer, C.

AU - Michelson, P. F.

AU - Mitthumsiri, W.

AU - Mizuno, T.

AU - Moiseev, A. A.

AU - Monte, C.

AU - Monzani, M. E.

AU - Morselli, A.

AU - Moskalenko, I. V.

AU - Murgia, S.

AU - Nolan, P. L.

AU - Norris, J. P.

AU - Nuss, E.

AU - Ohsugi, T.

AU - Omodei, N.

AU - Orlando, E.

AU - Ormes, J. F.

AU - Ozaki, M.

AU - Paneque, D.

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 - Ray, P. S.

AU - Razzano, M.

AU - Rea, N.

AU - Reimer, A.

AU - Reimer, O.

AU - Reposeur, T.

AU - Ritz, S.

AU - Rochester, L. S.

AU - Rodriguez, A. Y.

AU - Romani, R. W.

AU - Roth, M.

AU - Ryde, F.

AU - Sadrozinski, H. F.W.

AU - Sanchez, D.

AU - Sander, A.

AU - Saz Parkinson, P. M.

AU - Scargle, J. D.

AU - Sgrò, C.

AU - Sierpowska-Bartosik, A.

AU - Siskind, E. J.

AU - Smith, D. A.

AU - Smith, P. D.

AU - Spandre, G.

AU - Spinelli, P.

AU - Strickman, M. S.

AU - Suson, D. J.

AU - Tajima, H.

AU - Takahashi, H.

AU - Takahashi, T.

AU - Tanaka, T.

AU - Tanaka, Y.

AU - Thayer, J. B.

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 - Vasileiou, V.

AU - Venter, C.

AU - Vilchez, N.

AU - Vitale, V.

AU - Waite, A. P.

AU - Wallace, E.

AU - Wang, P.

AU - Winer, B. L.

AU - Wood, K. S.

AU - Ylinen, T.

AU - Ziegler, M.

PY - 2009

Y1 - 2009

N2 - The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) 1.8(syst) ×10-7 photon cm-2 s-1, with a cutoff at 2.1 ± 0.3(stat) 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.

AB - The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 ± 0.5(stat) 1.8(syst) ×10-7 photon cm-2 s-1, with a cutoff at 2.1 ± 0.3(stat) 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.

KW - Binaries: close

KW - Gamma rays: observations

KW - Stars: variables: other

KW - X-rays: binaries

KW - X-rays: individual (LS 5039)

UR - http://www.scopus.com/inward/record.url?scp=77949528567&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77949528567&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/706/1/L56

DO - 10.1088/0004-637X/706/1/L56

M3 - Article

AN - SCOPUS:77949528567

SN - 0004-637X

VL - 706

SP - L56-L61

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 PART 2

ER -

Fermi/lat observations of LS 5039

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