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) x 10(-7) photon cm(-2) s(-1), with a cutoff at 2.1 +/- 0.3(stat) +/- 1.1(syst) GeV and photon index G = 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.

Fermi/lat observations of LS 5039 / 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., Brigida, M., et al.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 706:1(2009), pp. L56-L61. [10.1088/0004-637X/706/1/L56]

Fermi/lat observations of LS 5039

Favuzzi C.;GIGLIETTO, Nicola;
2009

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) x 10(-7) photon cm(-2) s(-1), with a cutoff at 2.1 +/- 0.3(stat) +/- 1.1(syst) GeV and photon index G = 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.
2009
http://iopscience.iop.org/article/10.1088/0004-637X/706/1/L56/meta
Fermi/lat observations of LS 5039 / 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., Brigida, M., et al.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 706:1(2009), pp. L56-L61. [10.1088/0004-637X/706/1/L56]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/5137
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