这是我GARCH（1,1）拟合后的结果，还有arch效应，而且残差不成正态啊，怎么办？

Call:
garch(x = dcad, order = c(1, 1))

Model:
GARCH(1,1)

Residuals:
     Min       1Q   Median       3Q      Max
-4.51159 -0.66779  0.02183  0.65037  2.90558

Coefficient(s):
    Estimate  Std. Error  t value Pr(>|t|)   
a0 2.009e-05   4.710e-06    4.266 1.99e-05 ***
a1 2.019e-01   4.492e-02    4.494 6.98e-06 ***
b1 1.329e-14   1.893e-01    0.000        1   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Diagnostic Tests:
        Jarque Bera Test

data:  Residuals
X-squared = 8.0657, df = 2, p-value = 0.01772


        Box-Ljung test

data:  Squared.Residuals
X-squared = 9.5897, df = 1, p-value = 0.001957