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Using observations of millisecond pulsars (MSPs) can construct a time scale that is independent of terrestrial time standards. We investigate the 5-year rotation stability of PSR B1937 + 21 (PSR J1939 + 2134) using the Neutron Star Interior Composition Explorer (NICER) observations and compare it with that of the radio data from North American Nanohertz Observatory for Gravitational Waves (NANOGrav). We implement a data screening method to improve the accuracy of X-ray pulse times of arrival (TOAs), and develop a data-analysis framework based on an iterative least square technique for the X-ray timing parameter fitting. Finally, we carefully consider the main factors affecting the pulsar rotation stability. We find that the root mean square error (RMS) of the timing residuals of PSR B1937 + 21 based on NICER observations is 4.7 μs (1σ), and the 5-year rotation stability is 1.7 × 10−14 the accuracy of which is comparable to that of NANOGrav data. In order to ensure less than 10−14 of the main factors influencing the rotation stability on 5-year time scale, the errors of R.A. and Dec shall be no more than 2 mas and 6 mas respectively, while the amplitudes of the white noise and red noise must be less than 5 μs and 1 μs, respectively. • We adopted χ 2 -test technique to implement energy and flux filtering to improve the accuracy of X-ray pulse TOAs. • We gave the 5-year timing model of PSR B1937+21 by developing a data-analysis framework based on iterative least square method. • We reported that the 5-year rotation stability is 1.7 × 10 − 14 , whose accuracy is comparable to that of NANOGrav data. • We analyzed the main factors of the pulsar rotation stability including planetary ephemeris, R.A., Dec, etc. [ABSTRACT FROM AUTHOR]

The Fermi -LAT Collaboration recently presented a new catalog of gamma-ray sources located within the 40 ° × 40 ° region around the Galactic Center Ajello et al. (2017) — the Second Fermi Inner Galaxy (2FIG) catalog. Utilizing this catalog, they analyzed models for the spatial distribution and luminosity function of sources with a pulsar-like gamma-ray spectrum. Ajello et al. (2017) v1 also claimed to detect, in addition to a disk-like population of pulsar-like sources, an approximately 7 σ preference for an additional centrally concentrated population of pulsar-like sources, which they referred to as a “Galactic Bulge” population. Such a population would be of great interest, as it would support a pulsar interpretation of the gamma-ray excess that has long been observed in this region. In an effort to further explore the implications of this new source catalog, we attempted to reproduce the results presented by the Fermi -LAT Collaboration, but failed to do so. Mimicking as closely as possible the analysis techniques undertaken in Ajello et al. (2017), we instead find that our likelihood analysis favors a very different spatial distribution and luminosity function for these sources. Most notably, our results do not exhibit a strong preference for a “Galactic Bulge” population of pulsars. Furthermore, we find that masking the regions immediately surrounding each of the 2FIG pulsar candidates does not significantly impact the spectrum or intensity of the Galactic Center gamma-ray excess. Although these results refute the claim of strong evidence for a centrally concentrated pulsar population presented in Ajello et al. (2017), they neither rule out nor provide support for the possibility that the Galactic Center excess is generated by a population of low-luminosity and currently largely unobserved pulsars. In a spirit of maximal openness and transparency, we have made our analysis code available at https://github.com/bsafdi/GCE-2FIG . [ABSTRACT FROM AUTHOR]

Based on over 10-year timing data for 12 millisecond pulsars from the Parks telescope at Australia Telescope National Facility, TOAs(time of arrival) for these millisecond pulsars and their errors were solved using the cross-correlation technique. The corresponding timing residuals in Barycentric Coordinate Time were analyzed and then the Ensemble Pulsar Timescale model was constructed using Fourier series in order to realize Terrestrial Time. The stability of the timescale was evaluated with sz method. The results show that the stability of the ensemble Pulsar Timescale reached 10-15 over 10 years, presenting a linear increasing trend with an a upward tendency over time. The stability could rise with a longer observation time. White noise is the primary noise source and its impact on stability of the timescale decreased over time. Ensemble Pulsar Timescale could be considered as a realization of Terrestrial Time since the stability of the timescale is comparable to that of BIPM(2013). [ABSTRACT FROM AUTHOR]

Abstract: PSR J0437-4715 is one of the closest millisecond pulsars (MSPs) to Earth, lying at a distance of ∼140pc. This pulsar has a characteristic age of 4.9Gyr and a relatively low spindown power of ∼1034 ergs/s. During its rather long lifetime, a large fraction of the energy output has been in the form of multi-TeV electrons. In this paper, we investigate the possible contribution of this nearby MSP to the local interstellar electron spectrum (LIS). The old age of the system justifies a steady-state evaluation of the contribution from this pulsar to the LIS. We calculate the electron spectrum at the light cylinder in the framework of a General Relativistic polar cap (PC) model, and use this as an injection spectrum in a diffusion model. The younger Geminga pulsar is also very close to Earth and warrants investigation. A steady-state approach is however no longer justified, so we use an impulsive injection model. We will present results of a study of the contribution from these pulsars to the cosmic ray (CR) LIS. Our calculations show that pulsars like Geminga can make a non-negligible contribution to the LIS. [Copyright &y& Elsevier]

The gravitational wave radiation will release the energy momentum, which will dissipate the rotation of neutron star while in the accretion process. If the deformation of star is known, then we can estimate the maximum spin frequency of pulsar, based on which we can interpret why the spin periods of all millisecond pulsars cannot be less than one millisecond. [ABSTRACT FROM PUBLISHER]

186 binary pulsars are shown in the magnetic field versus spin period (B-P) diagram, and their relations to the millisecond pulsars can be clearly seen. We declaim a minimum accretion rate for the millisecond pulsar formation both from the observation and theory. If the accretion rate is lower than the minimum accretion rate, the pulsar in binary system will not become a millisecond pulsar after the evolution. [ABSTRACT FROM PUBLISHER]