Free Access

Table 4.

60 MeV–10 GeV spectral properties of the Crab Nebula measured in different flux states.

Component State (b) PL Γ PLEC Γ PLEC Ec TSPLEC − TSPL(c) Integrated flux (d)
(GeV) (10−9 cm−2 s−1)
IC (a) Average 1.415 ± 0.023 107 ± 5

High 2.830 ± 0.015 2.497 ± 0.041 0.77 ± 0.10 114.1 8432 ± 92
Synchrotron Average 3.278 ± 0.011 3.250, ± 0.026 6.6 ± 5.7 1.7 2534 ± 15
Low 370 ± 130

Syn+IC Low 1.653 ± 0.048 221 ± 22



The parameters of the IC component are determined from the complete ten-year data set, and are assumed to remain constant.


The high and low states are defined based on the 60 MeV–600 MeV light curve of the Crab Nebula (Fig. 2).


Γ is the photon index. Ec is the energy of the exponential cutoff. TSPLEC − TSPL is the difference in test-statistic (TS) between PLEC and PL.


For the high state and the average, the integral fluxes of the synchrotron component are based on PLEC and PL models respectively. For the low state, it is the sum over the binned spectrum subtracting the IC component.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.