The ARGO-YBJ air shower detector monitored the Crab Nebula gamma-ray emission from 2007 November to 2013 February. The integrated signal, consisting of similar to 3.3 x 10(5) events, reached the statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I-0 (E/2TeV)(-alpha), with a flux normalization I-0 = (5.2 +/- 0.2) x 10(-12) photons cm(-2) s(-1) TeV (1) and alpha = 2.63 +/- 0.05, corresponding to an integrated flux above 1 TeV of 1.97 x 10(-11) photons cm(-2) s(-1). The systematic error is estimated to be less than 30% for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I-0 (E/2 TeV)(-alpha) exp (-E/E-cut), the lower limit of the cutoff energy E-cut is 12 TeV, at 90% confidence level. Our extended data set allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 x 10(-2). A correlated analysis with Fermi-LAT data over similar to 4.5 yr using the light curves of the two experiments gives a Pearson correlation coefficient r = 0.56 +/- 0.22. Concerning flux variations on timescales of days, a "blind" search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 +/- 91 photons day(-1), consistent with the average value of 137 +/- 10 day(-1).
Bartoli, B., Bernardini, P., Bi, X., Branchini, P., Budano, A., CAMARRI, P., et al. (2015). CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ. THE ASTROPHYSICAL JOURNAL, 798(2) [10.1088/0004-637X/798/2/119].
Tipologia: | Articolo su rivista | |
Citazione: | Bartoli, B., Bernardini, P., Bi, X., Branchini, P., Budano, A., CAMARRI, P., et al. (2015). CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ. THE ASTROPHYSICAL JOURNAL, 798(2) [10.1088/0004-637X/798/2/119]. | |
IF: | Con Impact Factor ISI | |
Lingua: | English | |
Settore Scientifico Disciplinare: | Settore FIS/01 - Fisica Sperimentale | |
Revisione (peer review): | Esperti anonimi | |
Tipo: | Articolo | |
Rilevanza: | Rilevanza internazionale | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1088/0004-637X/798/2/119 | |
Stato di pubblicazione: | Pubblicato | |
Data di pubblicazione: | 2015 | |
Titolo: | CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ | |
Autori: | ||
Autori: | Bartoli, B; Bernardini, P; Bi, X; Branchini, P; Budano, A; CAMARRI, P; Cao, Z; Cardarelli, R; Catalanotti, S; Chen, S; Chen, T; Creti, P; Cui, S; Dai, B; D'Amone, A; Danzengluobu, ; De Mitri, I; Piazzoli, B; Di Girolamo, T; Di Sciascio, G; Feng, C; Feng, Z; Feng, Z; Gou, Q; Guo, Y; He, H; Hu, H; Hu, H; Iacovacci, M; Iuppa, R; Jia, H; Labaciren, ; Li, H; Liguori, G; Liu, C; Liu, J; Liu, M; Lu, H; Ma, L; Ma, X; Mancarella, G; Mari, S; Marsella, G; Martello, D; Mastroianni, S; Montini, P; Ning, C; Panareo, M; Perrone, L; Pistilli, P; Ruggieri, F; Salvini, P; Santonico, R; Shen, P; Sheng, X; Shi, F; Surdo, A; Tan, Y; Vallania, P; Vernetto, S; Vigorito, C; Wang, H; Wu, C; Wu, H; Xue, L; Yang, Q; Yang, X; Yao, Z; Yuan, A; Zha, M; Zhang, H; Zhang, L; Zhang, X; Zhang, Y; Zhao, J; Zhaxiciren, ; Zhaxisangzhu, ; Zhou, X; Zhu, F; Zhu, Q; Zizzi, G; Striani, E | |
Appare nelle tipologie: | 01 - Articolo su rivista |
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