The Spin-Down Rate of the Anomalous X-ray Pulsar CXO J164710.2-455216
ATel #929; P. M. Woods (Dynetics), V. M. Kaspi (McGill U.), F. P. Gavriil (NPP Fellow; GSFC)
on 2 Nov 2006; 16:02 UT
Credential Certification: Victoria Kaspi (vkaspi@physics.mcgill.ca)
Subjects: X-ray, Soft Gamma-ray Repeater, Transient, Pulsar
Referred to by ATel #: 932, 989
We obtained a 15 ks Director's Discretionary observation of the anomalous
X-ray pulsar (AXP) CXO J164710.2-455216 with the ACIS-S detector aboard
the Chandra X-ray Observatory beginning October 28, 2006 (07:06 UT).
The data were obtained in continuous clocking mode. We detected
the source clearly and measure a pulse frequency f=0.094244883(4) Hz
(1 sigma uncertainty). Using a phase coherent timing analysis which
incorporates three previous Target-of-Opportunity CXO observations of
this source (see e.g. ATEL #901) we have obtained a significant (5 sigma)
measurement of a secular spin-down rate of (fdot = -1.38+/-0.28)e-14
Hz/s, valid since the first CXO ToO observation on September 27, 2006.
This value is consistent with the upper limits placed in ATELs #901 and #902
and implies a surface dipolar magnetic field of 1.3e14 G, as estimated
using the standard vacuum dipole formula, B=3.2e19*sqrt(P Pdot) G.
This result provides additional confirmation that this source is an AXP.
