Finding (or not) New Gamma-ray Pulsars with GLAST

Young energetic pulsars will likely be the largest class of Galactic sources observed by GLAST, with many hundreds detected. Many will be unknown as radio pulsars, making pulsation detection dependent on radio and/or x-ray observations or on blind periodicity searches of the gamma-rays. Estimates for the number of pulsars GLAST will detect in blind searches have ranged from tens to many hundreds. I argue that the number will be near the low end of this range, partly due to observations being made in a scanning as opposed to a pointing mode. This paper briefly reviews how blind pulsar searches will be conducted using GLAST, what limits these searches, and how the computations and statistics scale with various parameters.Comment: 3 pages, 2 figures, for the Proceedings of the First GLAST Symposium (5-8 Feb 2007

A compact steep spectrum radio source in NGC1977

A compact steep spectrum radio source (J0535-0452) is located in the sky coincident with a bright optical rim in the HII region NGC1977. J0535-0452 is observed to be $\leq 100$ mas in angular size at 8.44 GHz. The spectrum for the radio source is steep and straight with a spectral index of -1.3 between 330 and 8440 MHz. No 2 \mu m IR counter part for the source is detected. These characteristics indicate that the source may be either a rare high redshift radio galaxy or a millisecond pulsar (MSP). Here we investigate whether the steep spectrum source is a millisecond pulsar.The optical rim is believed to be the interface between the HII region and the adjacent molecular cloud. If the compact source is a millisecond pulsar, it would have eluded detection in previous pulsar surveys because of the extreme scattering due to the HII region--molecular cloud interface. The limits obtained on the angular broadening along with the distance to the scattering screen are used to estimate the pulse broadening. The pulse broadening is shown to be less than a few msec at frequencies \gtsim 5 GHz. We therefore searched for pulsed emission from J0535-0452 at 14.8 and 4.8 GHz with the Green Bank Telescope (GBT). No pulsed emission is detected to 55 and 30 \mu Jy level at 4.8 and 14.8 GHz. Based on the parameter space explored by our pulsar search algorithm, we conclude that, if J0535-0452 is a pulsar, then it could only be a binary MSP of orbital period \ltsim 5 hrs.Comment: Accepted for publication in A&A (3pages, 1 fig

STICAP: A linear circuit analysis program with stiff systems capability. Volume 3: Systems

For abstract, see N76-13798

Twenty Years of Searching for (and Finding) Globular Cluster Pulsars

Globular clusters produce orders of magnitude more millisecond pulsars per unit mass than the Galactic disk. Since the first cluster pulsar was uncovered twenty years ago, at least 138 have been identified - most of which are binary millisecond pulsars. Because of their origins involving stellar encounters, many of these systems are exotic objects that would never be observed in the Galactic disk. Examples include pulsar-main sequence binaries, extremely rapid rotators (including the current record holder), and millisecond pulsars in highly eccentric orbits. These systems are allowing new probes of the interstellar medium, the equation of state of material at supra-nuclear density, the mass distribution of neutron stars, and the dynamics of globular clusters.Comment: 9 pages, 6 figures. Submitted review for the "40 Years of Pulsars" conference in Montreal, Aug 2007. To be published by the AI

X-Ray Timing, Spectroscopy and Photometry of the Anomalous X-Ray Pulsar Candidate CXOU J010043.1-721134

We present new X-ray timing and spectral results on the 8.0-second X-ray pulsar CXOU J010043.1-721134 from a series of observations using the Chandra X-ray Observatory. We find a spin period in 2004 January of 8.020392pm0.000009 seconds. Comparison of this to 2001 Chandra observations implies a period derivative dot{P} = (1.88 pm 0.08) times 10^{-11} s s^{-1}, leading to an inferred dipole surface magnetic field of 3.9 times 10^{14} G. The spectrum is well fit to an absorbed blackbody of temperature kT = 0.38pm0.02 keV with a power law tail of photon index Gamma = 2.0pm0.6. We find that the source has an unabsorbed X-ray flux (0.5-10 keV) of 4(+2-1) times 10^{-13} erg cm^{-2} s^{-1} and a corresponding X-ray luminosity of ~2 times 10^{35} erg s^{-1} for a distance of 60 kpc. These properties support classification of CXOU J010043.1-721134 as the seventh confirmed anomalous X-ray pulsar,the eleventh confirmed magnetar, and the first magnetar to be identified in the Small Magellanic Cloud.Comment: 5 pages, plus 1 embedded eps figure. Refined coordinates of source, including typo in declination. ApJ Letters, in pres