THE LOGNORMAL PROPERTIES OF THE SOFT GAMMA-RAY REPEATER SGR 1806-20 AND THE VELA PULSAR

The time intervals between the bursts from the soft gamma ray repeatin g source, SGR 1806-20, are consistent with a lognormal distribution. T he intensity of the bursts is compatible with a truncated lognormal lu minosity distribution but there is no correlation between the intensit y and the time interval between bursts. The large range in the time in tervals between the bursts from the other two known sources, SGR 190014 and SGR 0526-66, may be compatible with a lognormal distribution. T he time intervals between the microjumps in the Vela pulsar and the si ze of the microjumps are compatible with lognormal distributions and t here is no correlation between the time interval and the size of the m icrojump. The statistical properties of the bursts from SGR 1806-20 ar e very similar to the microjumps observed from the Vela pulsar and thi s association favours models of adjustments within a neutron star for the soft repeaters. There may be a large number of soft gamma ray repe ating sources to be discovered with mean time intervals between bursts much longer than SGR 1806-20. New experiments are required to search for this population.