We use the Jodrell Bank Observatory glitch database containing 472 glitches from 165 pulsars to investigate the angular momentum transfer during rotational glitches in pulsars. Our emphasis is on pulsars with at least five glitches, of which there are 26 that exhibit 261 glitches in total. This paper identifies four pulsars in which the angular momentum transfer, after many glitches, is almost linear with time. The Lilliefore test on the cumulative distribution of glitch spin-up sizes in these glitching pulsars shows that glitch sizes in 12 pulsars are normally distributed, suggesting that their glitches originate from the same momentum reservoir. In addition, the distribution of the fractional moment of inertia (i.e., the ratio of the moment of inertia of neutron star components that are involved in the glitch process) have a single mode, unlike the distribution of fractional glitch size (Δν/ν), which is usually bimodal. The mean fractional moment of inertia in the glitching pulsars we sampled has a very weak correlation with the pulsar spin properties, thereby supporting a neutron star interior mechanism for the glitch phenomenon.

The glitch size, ∆ν/ν, inter-glitch time interval, t i and frequency of glitches in pulsars are key parameters in discussing glitch phenomena. In this paper, the glitch sizes and inter-glitch time intervals were statistically analysed in a sample of 168 pulsars with a total of 483 glitches. The glitches were broadly divided into two groups. Those with ∆ν/ν < 10 −7 are regarded as small size glitches, while those with ∆ν/ν ≥ 10 −7 are regarded as relatively large size glitches. In the ensemble of glitches, the distribution of ∆ν/ν is seen to be bimodal as usual. The distribution of inter-glitch time intervals is unimodal and the inter-glitch time intervals between small and large size glitches are not significantly different from each other. This observation shows that inter-glitch time intervals are size independent. In addition, the distribution of the ratio ∆ν/ν : t i in both small and large size glitches has the same pattern. This observation suggests that a parameter which depends on time, which could be the spin-down rate of a pulsar plays a similar role in the processes that regulate both small and large size glitches. Equally this could be an indication that a single physical mechanism, which could produce varying glitch sizes at similar time-intervals could be responsible for both classes of glitch sizes.

Strange Nuggets are believed to be among the relics of the early universe. They appear as dark matter due to their low charge-to-mass ratio. Their distribution is believed to be the same as that of dark matter. As such, they could be accreted by high magnetic field objects and their collisions with pulsars are inevitable. Pulsar glitches are commonly seen as sudden spin-ups in pulsar frequency. It is still an open debate with regard to mechanisms giving rise to such a phenomenon. However, there is a class of sudden changes in pulsar spin frequency known as microglitches. These event are characterized by sudden small change in pulsar spin frequency (δν/ν ≈ ±10 −9). Clearly, the negative signature seen in some of the events is inconsistent with the known glitch mechanisms. In this analysis, we suggest that accretion of strange nuggets with pulsars could readily give rise to microglitch events. The signature of the events depends on the energy of the strange nuggets and line of interaction.

Neutron star glitches; spanning a period of 42 years of pulsar timing were studied. These glitches are from Radio, X-ray, Anomalous X-ray and Milliseconds Pulsars. Radio Pulsars dominates the glitch events, contributing 87% of the glitches. Pulsars of characteristic age bracket 10 3 to 10 5 yrs dominated the glitch events, at a rate of 5.2 glitches per year per pulsar. Pulsar of the above age bracket exhibits large size glitches compared to others. A large frequency spin-up (△v) is generally associated with large frequency derivative jump (△). The distribution of the glitch magnitude (△v/v) is bimodal reaffirming dual glitch mechanism, but that of spin-up (△v) is tending towards multi-modal. Moreover, glitches in Vela pulsar and PSR J0537-6910 showed strong elasticity of the objects, suggesting that the interiors of these objects are in thermal equilibrium. Glitches from PSR J1740-3015 and PSR J1341-6220 appeared to occur in groups, suggesting that their interior fluid is switching between two phases. We discussed the glitch activity of young pulsars in terms of vortex creep model.

No abstract

RESUMENFavor de proporcionar un resumen en español. If you are unable to translate your abstract into Spanish, the editors will do it for you. ABSTRACTThe superfluid in the inner crust of neutron star is assumed to be the reservoir of momentum released in pulsar glitch. Recently, due to crustal entrainment, it is debatable whether the magnitude of the inner crust is sufficient to contain superfluid responsible for large glitches. This paper calculates the fractional moment of inertia (FMI)(i.e. the ratio of the inner crust superfluid moment of inertia to that of the coupled components) associated with individual glitches. It is shown that the effective moment of inertia associated with the transferred momentum is that of the entrained neutrons. The FMI for glitches in three pulsars, which exhibit the signature of exhausting their momentum reservoir were calculated and scaled with entrainment factor. Some of the glitches require inner crust superfluid with moment of inertia larger than the current suggested values of 7-10% of the stellar moment of inertia.

Statistical analyses are invaluable methods used to understand intrinsic emission processes and the unification of extragalactic radio sources. In this paper, we collected radio, X-ray, and γ-ray data of blazars from the Fermi Large Area Telescope (Fermi-LAT) and Seyfert galaxies from the INTEGRAL/IBIS survey and investigated the relationship between the emission properties of Seyfert galaxies and blazar subclasses of flat-spectrum radio quasars (FSRQs) and BL Lac objects (BL Lacs). The results show from the average values that these objects follow a sequence that is indicative of probable Seyfert galaxies-BL Lacs-FSRQs unification. We discovered that Seyfert galaxies, BL Lacs, and FSRQs share similar emission characteristics in X-ray luminosity (L X-ray ), suggestive of fundamental connection while the γ-ray (L γ-ray ) and radio (L radio ) luminosities of Seyfert galaxies are the least powerful, signifying an evolving structure. From the two-dimensional Kolmogorov-Smirnov (K − S) test, we found that Seyfert galaxies differ from the blazar subclasses in L radio while there is no significant difference between them in L X-ray and L γ-ray which implies that high-energy emissions in Seyfert galaxies and blazar subclasses may come from the same emission mechanism. Significant positive correlations (with coefficient r > 0.60) exist between the high-energy luminosities (X-ray and γ-ray) and the low-energy components (radio) within the whole sample of blazars and Seyfert galaxies implying a form of connection between them. These results are not only consistent with the prediction of the unified scheme for blazars but also show that Seyfert galaxies have an evolutionary link with blazar subclasses.

The unified scheme of Seyfert galaxies hypothesizes that the observed differences between the two categories of Seyfert galaxies, type 1 (Sy1) and type 2 (Sy2) are merely due to the difference in the orientation of the toroidal shape of the obscuring material in the active galactic nuclei. We used in this paper, a sample consisting of 120 Seyfert galaxies at 1.40 × 109 Hz in radio, 2.52 × 1017 Hz in X-ray and 2.52 × 1023 Hz in γ-ray luminosities observed by the Fermi Large Area Telescope (Fermi- LAT) in order to test the unified scheme of radio-quiet Seyfert galaxies. Our main results are as follows: (i) We found that the distributions of multiwave luminosities (Lradio, LX-ray, and Lγ-ray) of Sy1 and Sy2 are completely overlapped with up to a factor of 4. The principal component analysis result reveals that Sy1 and Sy2 also occupy the same parameter spaces, which agrees with the notion that Sy1 and Sy2 are the same class objects. A Kolmogorov-Smirnov test performed on the sub-samples indicates that the null hypothesis (both are from the same population) cannot be rejected with chance probability p ~ 0 and separation distance K = 0.013. This result supports the fact that there is no statistical difference between the properties of Sy1 and Sy2 (ii) We found that the coefficient of the best-fit linear regression equation between the common properties of Sy1 and Sy2 is significant (r > 0.50) which plausibly implies that Sy1 and Sy2 are the same type of objects observed at different viewing angle.