**Table 1:** Some characteristics of several composite GRB spectra.
GRB	$\epsilon_{\rm p}$ (MeV)	$\Gamma[\gamma_{\min}^2B]_{12}$	$\Gamma[\gamma_{\min}^3/\rho]_{8}$	$\Gamma[\gamma_{\min}^3/\bar{\rho}]_{8}$	n
930131	$\sim$ 0.2	4.91	12.2	10.7	$\sim$ 5.3
910503	$\sim$ 1	17.8	8.9	8.14	$\sim$ 4.3
910601	$\sim$ 0.5	12.8	6.4	5.81	$\sim$ 6.1
910814	$\sim$ 2	44.7	50.0	45.0	$\sim$ 5.2

$\epsilon_{\rm p}$ is the peak photon energy of the $\nu F_\nu$ spectral distribution.
$[\gamma_{\min}^2 B]_{12} = \gamma_{\min}^2 B/10^{12}$ .
$[\gamma_{\min}^3/\rho]_{8} = \gamma_{\min}^3/\rho/10^8$ .
$\bar{\rho}$ is the expected value of $\rho$ with variance $\sigma=\frac{1}{5}\bar{\rho}$ for Gaussian distribution of the radius of curvature.
n is the index of the distribution of electrons.
References: 930131: Bromm & Schaefer (1999); Meegan et al. (1996); Ryan et al. (1994); Kouveliotou (1994).
910503: Tavani (1996a); Schaefer et al. (1994a); Schaefer et al. (1998).
910601: Tavani (1996a); Schaefer et al. (1994b); Hanlon et al. (1994); Shaefer et al. (1998).
910814: Tavani (1996a); Schaefer et al. (1994b); Hanlon et al. (1994); Shaefer et al. (1998).

Source LaTeX | All tables | In the text

	1 Introduction
	2 The synchro-curvature mechanism
	3 New explanations for GRB spectra
	4 Discussion
	5 Conclusions
	References