EDP Sciences
Free access
Volume 485, Number 1, July I 2008
Page(s) 195 - 198
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:200809356
Published online 22 April 2008

A&A 485, 195-198 (2008)
DOI: 10.1051/0004-6361:200809356

Research Note

The properties of the putative pulsar associated with IGR J18135-1751/HESS J1813-178

A. J. Dean and A. B. Hill

School of Physics & Astronomy, University of Southampton, UK
    e-mail: ajd@astro.soton.ac.uk

Received 7 January 2008 / Accepted 2 April 2008

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, $\dot{P} = 3 \times 10 ^{-11}$ s s-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.

Key words: X-rays: individual: IGR J18135-1751 (HESS J1813-178) -- stars: neutron -- pulsars: general -- gamma rays: observations

© ESO 2008