Margaret A. Livingstone

Magnetar-like Emission from the Young Pulsar in Kes 75

We report the detection of magnetar-like x-ray bursts from the young pulsar PSR J1846–0258, at the center of the supernova remnant Kes 75. This pulsar, long thought to be exclusively rotation-powered, has an inferred surface dipolar magnetic field of 4.9 × 1013 gauss, which is higher than those of the vast majority of rotation-powered pulsars, but lower than those of the approximately 12 previously identified magnetars. The bursts were accompanied by a sudden flux increase and an unprecedented change in timing behavior. These phenomena lower the magnetic and rotational thresholds associated with magnetar-like behavior and suggest that in neutron stars there exists a continuum of magnetic activity that increases with inferred magnetic field strength.

A Braking Index for the Young, High Magnetic Field, Rotation-Powered Pulsar in Kesteven 75

We present the first phase-coherent measurement of a braking index for the young, energetic rotation-powered pulsar PSR J1846-0258. This 324 ms pulsar is located at the center of the supernova remnant Kesteven 75 and has a characteristic age of τc = 723 yr, a spin-down energy of Ė = 8.3 × 1036 ergs s-1, and an inferred magnetic field of 4.9 × 1013 G. Two independent phase-coherent timing solutions are derived, which together span 5.5 yr of data obtained with the Rossi X-Ray Timing Explorer. In addition, a partially phase-coherent timing analysis confirms the fully phase-coherent result. The measured value of the braking index, n = 2.65 ± 0.01, is significantly less than 3, the value expected from magnetic dipole radiation, implying another physical process must contribute to the pulsars rotational evolution. Assuming the braking index has been constant since birth, we place an upper limit on the spin-down age of PSR J1846-0258 of 884 yr, the smallest age estimate of any rotation-powered pulsar.

Pulsed Gamma Rays from the Original Millisecond and Black Widow Pulsars: A Case for Caustic Radio Emission?

We report the detection of pulsed gamma-ray emission from the fast millisecond pulsars (MSPs) B1937+21 (also known as J1939+2134) and B1957+20 (J1959+2048) using 18 months of survey data recorded by the \emph{Fermi} Large Area Telescope (LAT) and timing solutions based on radio observations conducted at the Westerbork and Nancay radio telescopes. In addition, we analyzed archival \emph{RXTE} and \emph{XMM-Newton} X-ray data for the two MSPs, confirming the X-ray emission properties of PSR B1937+21 and finding evidence (

POST-OUTBURST OBSERVATIONS OF THE MAGNETICALLY ACTIVE PULSAR J1846-0258. A NEW BRAKING INDEX, INCREASED TIMING NOISE, AND RADIATIVE RECOVERY

\sim 4\sigma

Timing Behavior of the Magnetically Active Rotation-Powered Pulsar in the Supernova Remnant Kesteven 75

) for pulsed emission from PSR B1957+20 for the first time. In both cases the gamma-ray emission profile is characterized by two peaks separated by half a rotation and are in close alignment with components observed in radio and X-rays. These two pulsars join PSRs J0034-0534 and J2214+3000 to form an emerging class of gamma-ray MSPs with phase-aligned peaks in different energy bands. The modeling of the radio and gamma-ray emission profiles suggests co-located emission regions in the outer magnetosphere.

21 Years of Timing PSR B1509–58

The ~800 year old pulsar J1846–0258 is a unique transition object between rotation-powered pulsars and magnetars: though behaving like a rotation-powered pulsar most of the time, in 2006 it exhibited a distinctly magnetar-like outburst accompanied by a large glitch. Here, we present X-ray timing observations taken with the Rossi X-ray Timing Explorer over a 2.2 year period after the X-ray outburst and glitch had recovered. We observe that the braking index of the pulsar, previously measured to be n = 2.65 ± 0.01, is now n = 2.16 ± 0.13, a decrease of 18% ± 5%. We also note a persistent increase in the timing noise relative to the pre-outburst level. Despite the timing changes, a 2009 Chandra X-ray Observatory observation shows that the X-ray flux and spectrum of the pulsar and its wind nebula are consistent with the quiescent levels observed in 2000.

LONG-TERM PHASE-COHERENT X-RAY TIMING OF PSR B0540-69

We report a large spin-up glitch in PSR J1846–0258 which coincided with the onset of magnetar-like behavior on 2006 May 31. We show that the pulsar experienced an unusually large glitch recovery, with a recovery fraction of Q = 8.7 ± 2.5, resulting in a net decrease of the pulse frequency. Such a glitch recovery has never before been observed in a rotation-powered pulsar (RPP); however, similar but smaller glitch over-recovery has been recently reported in the magnetar AXP 4U 0142+61 and may have occurred in SGR 1900+14. We also report a large increase in the timing noise of the source. We discuss the implications of the unusual timing behavior in PSR J1846–0258 on its status as the first identified magnetically active RPP.

OBSERVATIONS OF ENERGETIC HIGH MAGNETIC FIELD PULSARS WITH THE FERMI LARGE AREA TELESCOPE

We present an updated timing solution for the young, energetic pulsar PSR B1509-58 based on 21.3 yr of radio timing data and 7.6 yr of X-ray timing data. No glitches have occurred in this time span, in contrast to other well-studied young pulsars, which show frequent glitches. We report a measurement of the third frequency derivative of = (-1.28 ± 0.21) × 10-31 s-4. This value is 1.65 σ from (i.e., consistent with) that predicted by the simple constant magnetic dipole model of pulsar spin-down. We measured the braking index to be n = 2.839 ± 0.003 and show that it varies by 1.5% over 21.3 yr owing to contamination from timing noise. Results of a low-resolution power spectral analysis of the significant noise apparent in the data yield a spectral index of α = -4.6 ± 1.0 for the red-noise component.

A Survey of 56 Midlatitude EGRET Error Boxes for Radio Pulsars

We present a new phase-coherent timing analysis for the young, energetic pulsar PSR B0540-69 using 7.6 yr of data from the Rossi X-Ray Timing Explorer. We measure the braking index, n = 2.140 ± 0.009, and discuss our measurement in the context of other discordant values reported in the literature. We present an improved source position from the phase-coherent timing of the pulsar, to our knowledge, the first of its kind from X-ray pulsar timing. In addition, we detect evidence for a glitch that had been previously reported but later disputed. The glitch occurred at MJD 51,335 ± 12 with Δν/ν = (1.4 ± 0.2) × 10-9 and Δ/ = (1.33 ± 0.02) × 10-4. We calculate that the glitch activity parameter for PSR B0540-69 is 2 orders of magnitude smaller than that of the Crab pulsar, which otherwise has very similar properties. This suggests that neutron stars of similar apparent ages, rotation properties, and inferred dipolar B fields can have significantly different internal properties.

NO DETECTABLE RADIO EMISSION FROM THE MAGNETAR-LIKE PULSAR IN Kes 75

We report the detection of γ-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119 6127 using data from the Fermi Large Area Telescope. The γ-ray light curve of PSR J1119 6127 shows a single, wide peak offset from the radio peak by 0.43±0.02 in phase. Spectral analysis suggests a power law of index 1.0 ± 0.3 +0.4 −0.2 with an energy cut-off at 0.8 ± 0.2 +2.0 −0.5 GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119 6127 and demonstrate that despite the object’s high surface magnetic field—near that of magnetars—the field strength and structure in the γ-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the γ-ray pulsed emission for the magnetically active PSR J1846 0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718 3718 and J1734 3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry. Subject headings: gamma rays: stars — pulsars: general — pulsars: individual (PSR J1119 6127, PSR J1718 3718, PSR J1734 3333, PSR J1846 0258)