their observational manifestations. The general TTFT tool we have developed can also be used for studying radiation from other magnetic NSs.'
author:
- Natalia Shabaltas1 and Dong Lai1
title: The Hidden Magnetic Field of The Young Neutron Star in Kesteven 79
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1[Center for Space Research, Department of Astronomy, Cornell University, Ithaca, NY 14853, USA]{}

Introduction
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Magnetic field is perhaps the single most important quantity that determines the observational manifestations of isolated neutron stars (NSs; see, e.g., Turolla 2009; Kaspi 2010). Most of our knowledge of NS magnetic fields is based on the measurement of the rotation period $P$ and period derivative $\dot{P}$, which, assuming that NS spin-down is due to angular momentum loss through magnetic dipole radiation or magnetic wind, yields estimates for the dipolar magnetic field strength of many NSs. Several NSs are observed to have spectral lines which, when interpreted as electron/ion cyclotron lines or atomic lines, yield a value for the *surface* magnetic field strength (e.g., Ho & Lai 2004; van Kerkwijk & Kaplan 2007; Suleimanov et al. 2010). Neither of these measurements sheds any light on the internal magnetic field configuration. Several recent observations suggest that the internal NS magnetic field must be more 