arXiv subjects

A. Possenti

Publications and source records attributed to A. Possenti.

294 records · Page 17Linked to original sources

arXiv2000

Discovery of a Young Radio Pulsar in a Relativistic Binary Orbit

We report on the discovery of PSR J1141-6545, a radio pulsar in an eccentric, relativistic 5-hr binary orbit. The pulsar shows no evidence for being recycled, having pulse period P = 394 ms, characteristic age tau_c = 1.4 x 10^6 yr, and inferred surface magnetic dipole field strength B = 1.3 x 10^12 G. From the mass function and measured rate of periastron advance, we determine the total mass in the system to be (2.300 +/- 0.012) solar masses, assuming that the periastron advance is purely relativistic. Under the same assumption, we constrain the pulsar's mass to be M_p < 1.348 solar masses and the companion's mass to be M_c > 0.968 solar masses (both 99% confidence). Given the total system mass and the distribution of measured neutron star masses, the companion is probably a massive white dwarf which formed prior to the birth of the pulsar. Optical observations can test this hypothesis.

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arXiv1999

The Parkes Multibeam Pulsar Survey: preliminary results

A high-frequency survey of the Galactic plane for radio pulsars is in progress, using the multibeam receiver on the 64-m Parkes radiotelescope. We describe the survey motivations, the observing plan and the inital results. The survey is discovering many pulsars, more than 500 so far. Eight of the new pulsars are binary, one with a massive companion. At least eight are young, with characteristic ages of less than 100 kyr. Two of these (Kaspi et al, this Conference) have surface dipole magnetic field strengths greater than any other known radio pulsar.

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arXiv1999

The Parkes Multibeam Pulsar Survey Data Release

The Parkes multibeam pulsar survey began in 1997 and is now about 50% complete. It has discovered more than 400 new pulsars so far, including a number of young, high magnetic field, and relativistic binary pulsars. Early results, descriptions of the survey and follow up timing programs can be found in papers by Lyne et al. (1999 MNRAS in press, astro-ph/9911313), Camilo et al. (astro-ph/9911185), and Manchester et al. (astro-ph/9911319). This paper describes the data release policy and how you can gain access to the raw data and details on the pulsars discovered.

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arXiv1999

The Parkes Multibeam Pulsar Survey

The Parkes multibeam pulsar survey uses a 13-element receiver operating at a wavelength of 20 cm to survey the inner Galactic plane with remarkable sensitivity. To date we have collected and analyzed data from 45% of the survey region (|b| < 5 deg.; 260 deg. < l < 50 deg.), and have discovered 440 pulsars, in addition to re-detecting 190 previously known ones. Most of the newly discovered pulsars are at great distances, as inferred from a median dispersion measure (DM) of 400 pc/cm^3.

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arXiv1998

Population synthesis of millisecond and submillisecond pulsars

Known millisecond pulsars have periods longer than 1.558 ms. Recycled in binary systems, neutron stars can attain very short spin periods. In this paper we investigate the expected properties of the millisecond pulsar distribution by simulating synthetic populations under different assumptions for the neutron star equation of state and decay of the magnetic field. We find evidence that a tail in the distribution of millisecond pulsars may exist at periods shorter than those observed.

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arXiv1996

The Pulsed Soft X-Ray Emission from PSR 0656+14

We present the results of a spectral and timing analysis of PSR 0656+14 based on the complete set of ROSAT observations carried out with the PSPC instrument in 1991 and 1992. The present analysis confirms the thermal origin of the bulk of the emission in the soft X-ray band (Finley et al. 1992). In addition, we find strong evidence of a harder component, described equally well with a blackbody at T about 2x10^6 K, or with a steep power law with photon index Gamma about 4.5. This bimodal emission is also supported by an analysis of the light curve shape as a function of the energy. The 0.1--2.4 keV light curve of PSR 0656+14, with a pulsed fraction of about 9%, is interpreted with a simple model for the temperature distribution on the neutron star surface, coupled with the geometrical information derived from radio data. In this model, which includes the effects of relativistic light bending and gravitational redshift, the X--rays originate from two thermal components resulting from neutron star cooling and blackbody emission released in the hotter polar cap regions. The observed modulation can be reproduced only if PSR 0656+14 has a relatively high dipole inclination (about 30 deg) and (1+z) is less than about 1.15. The overall pulsed fraction cannot be significantly increased by including the polar cap contribution, if its temperature and intensity are to be consistent with the observed spectra.

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