Modeling the spatial distribution of neutron stars in the Galaxy

Taani, Ali; Naso, L.; Wei, Yanchang; Zhang, Chengmin; Zhao, Yi

doi:10.1007/s10509-012-1121-7

Cited by 13 publications

(21 citation statements)

References 31 publications

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“…This method is similar with others reported in Tanaka and Takahara (2010), Martín et al (2012). The time dependent model by Zhang et al (2008) describes both particle and photon injection spectra from the nebula.…”

Section: Electron and Positron Spectra At The Sourcesupporting

confidence: 72%

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Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Torre

Gervasi

Rancoita

et al. 2015

Journal of High Energy Astrophysics

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We investigate, in terms of production from pulsars and their nebulae, the cosmic ray positron and electron fluxes above ∼10 GeV, observed by the AMS-02 experiment up to 1 TeV. We concentrate on the Vela-X case. Starting from the gamma-ray photon spectrum of the source, generated via synchrotron and inverse Compton processes, we estimated the electron and positron injection spectra. Several features are fixed from observations of Vela-X and unknown parameters are borrowed from the Crab nebula. The particle spectra produced in the pulsar wind nebula are then propagated up to the Solar System, using a diffusion model. Differently from previous works, the omnidirectional intensity excess for electrons and positrons is obtained as a difference between the AMS-02 data and the corresponding local interstellar spectrum. An equal amount of electron and positron excess is observed and we interpreted this excess (above ∼100 GeV in the AMS-02 data) as a supply coming from Vela-X. The particle contribution is consistent with models predicting the gamma-ray emission at the source. The input of a few more young pulsars is also allowed, while below ∼100 GeV more aged pulsars could be the main contributors.

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Section: Electron and Positron Spectra At The Sourcesupporting

confidence: 72%

“…The diffusion equation for the differential electron density n e (E e , t) = dN(E e , t)/dE e can be approximated as (Zhang et al, 2008;Tanaka and Takahara, 2010;Martín et al, 2012):…”

Section: Electron and Positron Spectra At The Sourcementioning

confidence: 99%

Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Torre

Gervasi

Rancoita

et al. 2015

Journal of High Energy Astrophysics

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“…For ASts, we use (again) the NFW profile in eq. (12), while for neutron stars we use the phenomenological fit of [56]. The number density n N S ( , z) of neutron stars can be written in terms…”

Section: Collisions Of An Ast With a Neutron Starmentioning

confidence: 99%

Collisions of dark matter axion stars with astrophysical sources

Eby

Leembruggen

Leeney

et al. 2017

J. High Energ. Phys.

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If QCD axions form a large fraction of the total mass of dark matter, then axion stars could be very abundant in galaxies. As a result, collisions with each other, and with other astrophysical bodies, can occur. We calculate the rate and analyze the consequences of three classes of collisions, those occurring between a dilute axion star and: another dilute axion star, an ordinary star, or a neutron star. In all cases we attempt to quantify the most important astrophysical uncertainties; we also pay particular attention to scenarios in which collisions lead to collapse of otherwise stable axion stars, and possible subsequent decay through number changing interactions. Collisions between two axion stars can occur with a high total rate, but the low relative velocity required for collapse to occur leads to a very low total rate of collapses. On the other hand, collisions between an axion star and an ordinary star have a large rate, Γ ∼ 3000 collisions/year/galaxy, and for sufficiently heavy axion stars, it is plausible that most or all such collisions lead to collapse. We identify in this case a parameter space which has a stable region and a region in which collision triggers collapse, which depend on the axion number (N ) in the axion star, and a ratio of mass to radius cubed characterizing the ordinary star (M s /R 3 s ). Finally, we revisit the calculation of collision rates between axion stars and neutron stars, improving on previous estimates by taking cylindrical symmetry of the neutron star distribution into account. Collapse and subsequent decay through collision processes, if occurring with a significant rate, can affect dark matter phenomenology and the axion star mass distribution.

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“…influence of the Paczynski galactic gravitational potential, it has been shown in [56] that the distribution of the old neutron stars (age ~10 9 to 10 10 years, similar to that of the galaxy) follow a torus-like shape above the galactic plane. Such a picture is consistent to our model that pulsars are new-born stars, but are aging to become old neutron stars, with age about that of our galaxy.…”

Section: Neutron Stars Are the Very Old Starsmentioning

confidence: 99%

On the Origin of Mass and Angular Momentum of Stellar Objects

Fung¹,

Wong²

2015

JMP

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The consequence of the 5D projection theory [1] is extended beyond the Gell-Mann Standard Model for hadrons to cover astronomical objects and galaxies. The proof of Poincare conjecture by Perelman's differential geometrical techniques led us to the consequence that charged massless spinors reside in a 5D void of a galactic core, represented by either an open 5D core or a closed, time frozen, 3D × 1D space structure, embedded in massive structural stellar objects such as stars and planets. The open galactic core is obtained from Ricci Flow mapping. There exist in phase, in plane rotating massless spinors within these void cores, and are responsible for 1) the outward spiral motion of stars in the galaxy in the open core, and 2) self rotations of the massive stellar objects. It is noted that another set of eigen states pertaining to the massless charged spinor pairs rotating out of phase in 1D (out of the 5D manifold) also exist and will generate a relatively weak magnetic field out of the void core. For stars and planets, it forms the intrinsic dipole field. Due to the existence of a homogeneous 5D manifold from which we believe the universe evolves, the angular momentum arising from the rotation of the in-phase spinor pairs is proposed to be counter-balanced by the rotation of the matter in the surrounding Lorentz domain, so as to conserve net zero angular momentum. Explicit expression for this total angular momentum in terms of a number of convergent series is derived for the totally enclosed void case/core, forming in general the structure of a star or a planet. It is shown that the variables/parameters in the Lorentz spacetime domain for these stellar objects involve the object's mass M, the object's Radius R, period of rotation P, and the 5D void radius Ro, together with the Fermi energy E f and temperature T of the massless charged spinors residing in the void. We discovered three laws governing the relationships between R o /R, T, E f and the angular momentum Iω of such astronomical object of interest, from which we established two distinct regions, which we define as the First and Second Laws for the evolution of the stellar object. The Fermi energy E f was found to be that of the electron mass, as it is the lightest massive elementary particle that could be created from pure energy in the core. In fact the mid-temperature of the transition region between the First and Second Law regions for this E f value is 5.3 × 10 9 K, just about that of the Bethe fusion temperature. We then apply our P. C. W. Fung, K. W. Wong 2304 theory to analyse observed data of magnetars, pulsars, pre-main-sequence stars, the NGC 6819 group, a number of low-to-mid mass main sequence stars, the M35 members, the NGC 2516 group, brown dwarfs, white dwarfs, magnetic white dwarfs, and members of the solar system. The ρ = (R o /R) versus T, and ρ versus P relations for each representative object are analysed, with reference to the general process of stellar evolution. Our analysis leads us to the following age sequence of stell...

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Modeling the spatial distribution of neutron stars in the Galaxy

Cited by 13 publications

References 31 publications

Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Collisions of dark matter axion stars with astrophysical sources

On the Origin of Mass and Angular Momentum of Stellar Objects

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