We report the detection of a sudden spin-up of the 11 s anomalous X-ray pulsar 1RXS J170849.0−4000910 in regular timing observations made with the Rossi X-ray Timing Explorer. The event, which occurred between MJD 51446 (1999 September 25) and 51472 (1999 October 21), is well characterized by an increase in the rotational frequency of magnitude |∆ν/ν| = (6.2 ±0.3) ×10 −7 and an increase in the rate of spin down |∆ν/ν| = (1.38 ± 0.25) × 10 −2 . These values are very similar to those of glitches observed in the Vela radio pulsar and other young radio pulsars. The event therefore suggests that the internal structure of this anomalous X-ray pulsar is similar to those of the radio pulsars. In particular, it implies that the fractional moment of inertia in neutron superfluid that is not corotating with the crust is ≥1%. The detection of a glitch in this anomalous X-ray pulsar constrains models for the origin of glitches in neutron stars. Most notably, it challenges models that preclude glitches in long-period pulsars, and, under the magnetar hypothesis, suggests that large glitches can occur in hot neutron stars. The glitch is consistent with the predictions of the magnetar model for anomalous X-ray pulsars, but accretion-powered scenarios cannot be excluded using our observations alone.

No abstract

We present results of Compton Gamma-Ray Observatory/EGRET observations of the unidentified high-energy γ-ray sources 2EG J1049−5847 (GEV J1047−5840, 3EG J1048−5840) and 2EG J1103−6106 (3EG J1102−6103). These sources are spatially coincident with the young, energetic radio pulsars PSRs B1046−58 and J1105−6107, respectively. We find evidence for an association between PSR B1046−58 and 2EG J1049−5847. The γ-ray pulse profile, obtained by folding time-tagged photons having energies above 400 MeV using contemporaneous radio ephemerides, has probability of arising by chance of 1.2 × 10 −4 according to the binning-independent H-test. A spatial analysis of the on-pulse 1 Alfred P. Sloan Research Fellow; vicky@space.mit.edu 2 jes@space.mit.edu 3 mattox@bu.edu 4 rmanches@atnf.csiro.au 5 mbailes@swin.edu.au -2photons reveals a point source of equivalent significance 10.2σ. Off-pulse, the significance drops to 5.8σ. Archival ASCA data show that the only hard X-ray point source in the 95% confidence error box of the γ-ray source is spatially coincident with the pulsar within the 1 ′ uncertainty (Pivovaroff, Kaspi, & Gotthelf 1999). The double peaked γ-ray pulse morphology and leading radio pulse are similar to those seen for other γ-ray pulsars and are well-explained in models in which the γ-ray emission is produced in charge-depleted gaps in the outer magnetosphere. The inferred pulsed γ-ray flux above 400 MeV, (2.5 ± 0.6) × 10 −10 erg cm −2 s −1 , represents 0.011±0.003 of the pulsar's spin-down luminosity, for a distance of 3 kpc and 1 sr beaming. For PSR J1105−6107, light curves obtained by folding EGRET photons using contemporaneous radio ephemerides show no significant features. We conclude that this pulsar converts less than 0.014 of its spin-down luminosity into E > 100 MeV γ-rays beaming in our direction (99% confidence), assuming a distance of 7 kpc, 1 sr beaming and a duty cycle of 0.5.