Context : We investigate the possible theoretical properties of the putative pulsar associated with the pulsar wind nebula IGR J18135 - 1751/HESS J1813 - 178 based upon recent \gamma -ray observations and archival multi-wavelength observations .

Aims : We show that when using the standard equations for magnetic dipole radiation with recent soft \gamma -ray observations leads to deriving an extreme set of parameters ( magnetic field , period and spin down rate ) for the putative pulsar .
Alternative scenarios that generate more typical parameter values are explored .

Methods : The properties of the putative pulsar are calculated assuming that the 20–100 keV luminosity corresponds to 1 % of \dot { E } , that the source is 4.5 kpc away , and that the pulsar age is 300 yrs .
This gives P = 0.55 s , \dot { P } = 3 \times 10 ^ { -11 } ss ^ { -1 } , and B = 1.28 \times 10 ^ { 14 } G. This is a very extreme set compared to the population of known pulsars in PWN systems .
Using the equations for magnetic dipole losses makes it possible to adjust the initial assumptions to see what is required for a more reasonable set of pulsar parameters .

Results : The current measured properties for IGR J18135 - 1751/HESS J1813 - 178 ( i.e .
luminosity , distance , and age ) result in extreme properties of the unseen pulsar within the PWN .
The simplest method for achieving more reasonable properties for the pulsar is to decouple the spin-down age of the pulsar from the actual age for the system .

Conclusions :