SPECTRAL EVOLUTION OF THE 2010 SEPTEMBER GAMMA-RAY FLARE FROM THE CRAB NEBULA

Journal Article · Tue May 10 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/732/2/L22· OSTI ID:21562696

Vittorini, V; Tavani, M; Donnarumma, I; Trois, A; Del Monte, E; Evangelista, Y; Lazzarotto, F; Pacciani, L ^[1]; Pucella, G ^[2]; Striani, E ^[3]; Caraveo, P; Giuliani, A; Mereghetti, S ^[4]; Pellizzoni, A ^[5]; Ferrari, A ^[6]; Barbiellini, G ^[7]; Bulgarelli, A ^[8]; Cattaneo, P W ^[9]; Colafrancesco, S ^[10]; Pilia, M ^[11]

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1. INAF/IASF-Roma, I-00133 Roma (Italy)
2. ENEA Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy)
3. Dipartimento di Fisica, Universita Tor Vergata, I-00133 Roma (Italy)
4. INAF/IASF-Milano, I-20133 Milano (Italy)
5. INAF-Osservatorio Astronomico di Cagliari, localita' Poggio dei Pini, strada 54, I-09012 Capoterra (Italy)
6. Dipartimento Fisica, Universita di Torino, Turin (Italy)
7. Dipartimento Fisica and INFN Trieste, I-34127 Trieste (Italy)
8. INAF/IASF-Bologna, I-40129 Bologna (Italy)
9. INFN-Pavia, I-27100 Pavia (Italy)
10. ASI Science Data Center, I-00044 Frascati (Roma) (Italy)
11. Dipartimento di Fisica, Universita dell'Insubria, Via Valleggio 11, I-22100 Como (Italy)

Strong gamma-ray flares from the Crab Nebula have been recently discovered by AGILE and confirmed by Fermi-LAT. We study here the spectral evolution in the gamma-ray energy range above 50 MeV of the 2010 September flare that was simultaneously detected by AGILE and Fermi-LAT. We revisit the AGILE spectral data and present an emission model based on rapid (within 1 day) acceleration followed by synchrotron cooling. We show that this model successfully explains both the published AGILE and Fermi-LAT spectral data showing a rapid rise and a decay within 2 and 3 days. Our analysis constrains the acceleration timescale and mechanism, the properties of the particle distribution function, and the local magnetic field. The combination of very rapid acceleration, emission well above 100 MeV, and the spectral evolution consistent with synchrotron cooling contradicts the idealized scenario predicting an exponential cutoff at photon energies above 100 MeV. We also consider a variation of our model based on even shorter acceleration and decay timescales, which can be consistent with the published averaged properties.

• OSTI ID: 21562696
• Journal Information: Astrophysical Journal Letters, Vol. 732, Issue 2; Other Information: DOI: 10.1088/2041-8205/732/2/L22; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCELERATION
CRAB NEBULA
DISTRIBUTION FUNCTIONS
EMISSION
EVOLUTION
GAMMA RADIATION
GAMMA SPECTRA
MAGNETIC FIELDS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
FUNCTIONS
IONIZING RADIATIONS
NEBULAE
RADIATIONS
SPECTRA
SUPERNOVA REMNANTS