Are the magnetic fields of millisecond pulsars ∼108 G?

It is generally assumed that the magnetic fields of millisecond pulsars (MSPs) are ～10⁸ G. We argue that this may not be true and the fields may be appreciably greater. We present six evidences for this: (1) The ～10⁸G field estimate is based on magnetic dipole emission losses which is shown to be questionable; (2) The MSPs in low mass X-ray binaries (LMXBs) are claimed to have <10¹¹ G on the basis of a Rayleygh-Taylor instability accretion argument. We show that the accretion argument is questionable and the upper limit 10¹¹ G may be much higher; (3) Low magnetic field neutron stars have difficulty being produced in LMXBs; (4) MSPs may still be accreting indicating a much higher magnetic field; (5) The data that predict ～10⁸ G for MSPs also predict ages on the order of, and greater than, ten billion years, which is much greater than normal pulsars. If the predicted ages are wrong, most likely the predicted ～10⁸ G fields of MSPs are wrong; (6) When magnetic fields are measured directly with cyclotron lines in X-ray binaries, fields ?10⁸ G are indicated. Other scenarios should be investigated. One such scenario is the following. Over 85% of MSPs are confirmed members of a binary. It is possible that all MSPs are in large separation binaries having magnetic fields >10⁸ G with their magnetic dipole emission being balanced by low level accretion from their companions.     

Identification of candidate millisecond pulsars from Fermi LAT observations Ⅱ

On the basis of the properties of known γ-ray millisecond pulsars(MSPs), we have selected 77un-associated sources from the Fermi Large Area Telescope(LAT) third source catalog for the purpose of finding likely candidate MSPs. Previously, detailed LAT data analysis for 39 of them was reported,and here we report the analysis for the remaining 38 sources. We identify that among the 38 sources, 28 of them are single point-like sources with clean background and their spectra show significant curvature.We also conduct an analysis of archival X-ray data available for 24 of the 28 sources. In the fields of10 sources, there is at least one X-ray object, and in those of the other 14 sources, no X-ray object is detected but this is probably due to the X-ray observations being short. We discuss the possible MSP nature for these sources. Six of them(J0514.6-4406, J1035.7-6720, J1624.2-4041, J1744.1-7619,J1946.4-5403 and J2039.6-5618) are most likely associated with pulsars because of multi-wavelength identifications including direct radio or γ-ray detection of pulsations. To firmly establish the associations or verify the MSP nature for other sources, deep X-ray and/or optical observations are needed.     

Where do 'red and dead' early-type void galaxies come from?

Void regions of the Universe offer a special environment for studying cosmology and galaxy formation, which may expose weaknesses in our understanding of these phenomena. Although galaxies in voids are observed to be predominately gas rich, star forming and blue, a subpopulation of bright-red void galaxies can also be found, whose star formation was shutdown long ago. Are the same processes that quench star formation in denser regions of the Universe also at work in voids?
We compare the luminosity function of void galaxies in the 2dF Galaxy Redshift Survey, to those from a galaxy formation model built on the Millennium simulation. We show that a global star formation suppression mechanism in the form of low-luminosity 'radio-mode' active galactic nuclei (AGN) heating is sufficient to reproduce the observed population of void early types. Radio-mode heating is environment independent other than its dependence on dark matter halo mass, where, above a critical mass threshold of approximately   M _vir∼ 10^12.5 M_⊙  , gas cooling on to the galaxy is suppressed and star formation subsequently fades. In the Millennium simulation, the void halo mass function is shifted with respect to denser environments, but still maintains a high-mass tail above this critical threshold. In such void haloes, radio-mode heating remains efficient and red galaxies are found; collectively these galaxies match the observed space density without any modification to the model. Consequently, galaxies living in vastly different large-scale environments but hosted by haloes of similar mass are predicted to have similar properties, consistent with observations.     

Can the known millisecond pulsars help in the detection of intermediate-mass black holes at the centers of globular clusters?

We consider the possibility of detecting intermediate-mass (10³–10⁴ M _⊙) black holes, whose existence at the centers of globular clusters is expected from optical and infrared observations, using precise pulse arrival timing for the millisecond pulsars in globular clusters known to date. For some of these pulsars closest to the cluster centers, we have calculated the expected delay times of pulses as they pass in the gravitational field of the central black hole. The detection of such a time delay by currently available instruments for the known pulsars is shown to be impossible at a black hole mass of 10³ M _⊙ and very problematic at a black hole mass of 10⁴ M _⊙. In addition, the signal delay will have a negligible effect on the pulsar periods and their first derivatives compared to the current accuracy of their measurements.     

Can the inner gap sparking take place in millisecond pulsars？

The inner vacuum gap model has become the foundation stone of most theories on pulsar radio emission. The fundamental picture of this model is the sparking, which was conjectured to be induced by magnetic absorption of background gamma photons. However, a question is, can the sparking be triggered in the millisecond pulsars (MSPs) with magnetic fields (B) only about 108 G? We investigate this problem by including the pair production above the inner gap. Under the assumption that the magnetic field is dipolar, our results show the background gamma-ray emission can not be the key factor that triggers the sparking, at least not in MSPs with B - 108 G, if the temperature in the polar cap region is only so high as is observed (< 4 × 106 K). Some other mechanisms are required.     

Bimodality of anomalous pulsars?

At present, it is widely believed that anomalous X-ray pulsars (AXPs), soft gamma-ray repeaters (SGRs), rotational radio transients (RRATs), compact central objects (CCOs) in supernova remnants, and X-ray dim isolated neutron stars (XDINSs) belong to different classes of anomalous objects in which the central bodies are isolated neutron stars. Previously, we have shown that AXPs and SGRs can be described in terms of the drift model for parameters of the central neutron star typical of radio pulsars (rotation periods P ～ 0.1–1 s and surface magnetic fields B ～ 10¹¹–10¹³ G). Here, we show that some of the peculiarities of the sources under consideration can be explained by their geometry (in particular, by the angle β between the rotation axis and the magnetic moment). If β ? 10° (an aligned rotator), the drift waves in the outer layers of the neutron star magnetosphere can account for the observed periodicity in the radiation. For large β (a nearly orthogonal rotator), the observed modulation of the radiation and its short bursts can be explained by mass accretion from the ambient medium (e.g., a relic disk).     

Where are the rings of Neptune?

Stable rings can exist at inclinations of 0–15°, 165°–180°, or ～90° to Neptune's equator, but perturbations due to the massive satellite Triton would produce a severe “warping” of the ring plane. If Neptune possesses rings, they may not lie in the plane of its equator.     

Do stony meteorites come from comets?

The place of origin of stony meteorites can be determined from their trapped solar-wind gases. “Gas-rich” meteorites have only 10^?3?10^?4 the solar noble gas content and ?10^?2?10^?4 the surface exposure age of lunar soils. These differences suggest that the gas implantation took place between 1 and 8 AU from the Sun, in a region where the cratering rate was 10²?10³ times higher than at 1 AU. Both characteristics point to the asteroid belt. The predicted Ne²⁰ content a gas-rich meteorite formed at 2.5 AU is 1.2 × 10^?5 cc STP g^?1, compared to an observed mean for H-chondrites of 0.5 × 10^?5 cc STP g^?1. The observed prevalence of gas-rich meteorites (40–100% among carbonaceous chondrites, 2–33% among other classes) requires that the parent body remained long enough in the asteroid belt to develop a substantial regolith. This condition can be met by asteroids (～ 10% of mass converted to regolith.in 4.5 × 10⁹ yr), but not by short period comets (～0.04% converted in 10⁷ yr). It appears that a cometary origin can be ruled out for all stony meteorite clases that have gas-rich members. This includes carbonaceous chondrites.     

Where are the prompt emitting regions of long GRBs?

We have used a simple method to estimate the prompt emission radii of 27 Swift and 37 pre-Swift long gamma-ray bursts with known redshift and jet break time. The prompt γ-rays are found to emit mainly from a beamed jet with dynamic open angle narrower than its geometric open angle, suggesting an obviously dynamic evolution from prompt to follow-up phases for the jetted outflow. Under condition of the external shock scenario, we confirm that long gamma-ray bursts are produced at a larger radius of ∼10¹⁶ cm, which puts a strict constraint on the currently theoretical models.     

Will the lunar renaissance come forth?

The article gives a brief review of the scientific program of the unmanned studies of the Moon performed in the USSR in 1960s–1970s, most notably by the “Luna” Spacecraft. The main results obtained during this period are considered, in particular photographing of the far side of the Moon, mapping of the far side of the Moon, soft landing, remote (from the orbit of an artificial lunar satellite) and in situ (on the surface) studies of the lunar surface composition and circumlunar space, automated soil sampling, and delivery of surface samples to the Earth. Various institutes of the Russian Academy of Sciences played important role in the studies, including the Vernadskii Institute of Geochemistry and Analytical Chemistry and the Space Research Institute, established in 1965, where the Moon and Planets Department was established under the leadership of K.P. Florenskii. In the conclusion, the article considers some further issues of lunar studies and possibilities for lunar exploration. The challenging Moon exploration mission “Luna-Glob”, currently under development in Russia, is a potentially important step in the beginning of the process.     

Where are the halo stars?

In the usual and most widespread textbook picture of the Milky Way Galaxy, disk stars like the Sun are referred to as Population I, the spheroidal or halo component in turn as Population II. The latter is thought of as the pressure-supported, metal-poor relic of the early Galaxy, with renewed interest in recent years in the search for dark matter via microlensing. Modelling the putative massive compact halo objects however, faces the problem that the stellar halo is generally considered to consist of only a few billion solar masses. Here we present observational evidence that even this low budget may be a factor ten too high. If so, this immediately implies that the classical population II of halo stars is fairly irrelevant, not only in the dark matter context, but, in particular, in models of the formation and evolution of the Milky Way Galaxy.     

Where are the Uranus Trojans?

The area of stable motion for fictitious Trojan asteroids around Uranus’ equilateral equilibrium points is investigated with respect to the inclination of the asteroid’s orbit to determine the size of the regions and their shape. For this task we used the results of extensive numerical integrations of orbits for a grid of initial conditions around the points L ₄ and L ₅, and analyzed the stability of the individual orbits. Our basic dynamical model was the Outer Solar System (Jupiter, Saturn, Uranus and Neptune). We integrated the equations of motion of fictitious Trojans in the vicinity of the stable equilibrium points for selected orbits up to the age of the Solar system of 5 × 10⁹ years. One experiment has been undertaken for cuts through the Lagrange points for fixed values of the inclinations, while the semimajor axes were varied. The extension of the stable region with respect to the initial semimajor axis lies between 19.05 ≤ a ≤ 19.3 AU but depends on the initial inclination. In another run the inclination of the asteroids’ orbit was varied in the range 0° < i < 60° and the semimajor axes were fixed. It turned out that only four ‘windows’ of stable orbits survive: these are the orbits for the initial inclinations 0° < i < 7°, 9° < i < 13°, 31° < i < 36° and 38° < i < 50°. We postulate the existence of at least some Trojans around the Uranus Lagrange points for the stability window at small and also high inclinations.     

Leonids 2006 observations of the tail of trails: Where is the comet fluff?

In 2006, Earth encountered a trail of dust left by Comet 55P/Tempel-Tuttle two revolutions ago, in A.D. 1932. The resulting Leonid shower outburst was observed by low light level cameras from locations in Spain. The outburst peaked on 2006 Nov. 19d 04h39m ± 3m UT (predicted: 19d 04h50m ± 15m UT), with a FWHM of 43 ± 10 min (predicted: 38 min), at a peak rate of ZHR=80±10/h (predicted: 50-200 per hour). A low level background of older and brighter Filament Leonids (χ∼2.1) was also present, which dominated rates for Leonids brighter than magnitude +4. The 1932-dust outburst was detected among Leonids of +0 magnitude and brighter. These outburst Leonids were much brighter than expected, with a magnitude distribution index χ=2.60±0.15 (predicted: χ=3.47 and up). Trajectories and orbits of 24 meteors were calculated, most of which are part of the Filament component. Those that were identified as 1932-dust grains penetrated just as deep as Leonids in past encounters. We conclude that larger meteoroids than expected were present in the tail of the 1932-dust trail and meteoroids did not end up there because of low density. We also find that the radiant position of meteors in the Filament component scatter in a circle with radius 0.39°, which is wider than in 1998, when the diameter was 0.09°. This supports the hypothesis that the Filament component consists of meteoroids in mean-motion resonances.     

The existence of a ‘gap’ in the evolutionary sequence of pulsars

A replot of period derivative against period is done for about 300 pulsars, and the main features of the plot are discussed. The significance of a gap in this plot is reexamined and the existence of pulsars with nulling and subpulse drifting behaviour below this gap is pointed out. The implications of this for pulsar evolution are also discussed.     

The many faces of pulsars – the case of PSR B0833-45

A review of observational properties of the Vela pulsar across a wide energy spectrum is given. Then current approaches to the modelling of pulsars and their wind zones are briefly presented. The challenges posed to the models by the diversity of Vela’s light curves in different energy ranges are discussed.     

Higher-order corrections to the relativistic perihelion advance and the mass of binary pulsars

We study the general relativistic orbital equation and using a straightforward perturbation method and a mathematical device first introduced by d’Alembert, we work out approximate expressions of a bound planetary orbit in the form of trigonometrical polynomials and the first three terms of the power series development of the perihelion advance. The results are applied to a more precise determination of the total mass of the double pulsar J0737-3039.     

Gravitomagnetism: a novel explanation of the precession of planets and binary pulsars

We continue former work on the modeling of potential effects of Gamma Ray Bursts on Phanerozoic Earth. We focus on global biospheric effects of ozone depletion and model the spectral reduction of light by NO₂ formed in the stratosphere. We also illustrate the current complexities involved in the prediction of how terrestrial ecosystems would respond to this kind of burst. We conclude that more biological field and laboratory data are needed to reach even moderate accuracy in this modeling.     

Possible modulated γ-ray emission from the transitional millisecond pulsar binary PSR J1023+0038

We report the results from our analysis of Fermi Large Area Telescope(LAT) data for the transitional millisecond pulsar binary PSR J1023+0038. The time period of the data is nearly 9 yr, and that after the source's transition, in June 2013 from the disk-free state to the active state of having an accretion disk, is approximately 4 yr. We identify a high-energy 5.5 GeV component in the source's spectrum in the active state, and find this component is only significantly detected in half of the orbital phase centered at the descending node(when the pulsar is moving towards the Earth). Considering the pulsar scenario proposed for multi-frequency emission from the source, in which the pulsar is still active and a cold-relativistic pulsar wind inverse-Compton scatters the photons from the accretion disk, we discuss the origin of the high-energy component. In order to explain the observed spectrum, a power-law distribution of particles, with an index of ～3, in the pulsar wind is required, while the orbital variations are possibly due to changes in power-law index as a function of orbital phase.