AAS Meeting #193 - Austin, Texas, January 1999
Session 41. Pulsars
Display, Thursday, January 7, 1999, 9:20am-6:30pm, Exhibits Hall 1

## [41.02] New Analysis of the Extreme 12-s pulsar in the SNR Kes~73

G. Vasisht (JPL/Caltech), E. V. Gotthelf (Columbia U.), T. Dotani (ISAS-Japan)

We present the spin-down history of the recently discovered 12-s pulsar in Kes 73, 1E~1841-045 using new ASCA observations and archival GINGA and ROSAT measurements. We confirm the remarkably rapid but steady spin-down rate for this pulsar of 4.1 \times 10-11 s/s, orders of magnitude faster than the Crab-like pulsars. Most importantly, the characteristic pulsar age is consistent with the age derived for the host SNR (~2,000 yrs). The ASCA flux has remained steady and consistent with the Rosat flux measurement. The ASCA spectrum also remains unchanged, described by a steep power-law of photon index ~3.4, most unlike a typical Crab-like or recycled pulsar.

The unusual spectral and temporal properties of 1E~1841-045 are similar to the other seemingly isolated, young anomalous X-ray pulsars; and these objects appear related to the SGRs. As an isolated'' NS, this pulsar is the one having the longest spin period ever observed. If these and other NS candidates like them were indeed born as fast rotators, then a mechanism must be found to slow them down to their currently observed rates. The rapid but steady spin-down of the Kes~73 pulsar suggests a possibility. The equivalent magnetic field for a rotating dipole is Bdipole ~q 3.2\times1019~(P\dot P)1/2 \approx 8\times 1014 G, one of the highest magnetic fields observed in nature. We suggest that the pulsar in Kes~73 was born as such a magnetar'' ~2,000 yrs ago and has since spun down to a long period due to rapid dipole radiation losses; 1E~1841-045 provides the first direct evidence of a magnetar and suggests an alternative evolutionary path for young pulsars.