arXiv subjects

Awni Khasawneh

Publications and source records attributed to Awni Khasawneh.

5 recordsLinked to original sources

arXiv2020

Probability Distribution of Magnetic Field Strengths through the Cyclotron Lines in High-Mass X-ray Binaries

The study of variation of measured cyclotron lines is of fundamental importance to understand the physics of the accretion process in magnetized neutron star systems. We investigate the magnetic field formation, evolution and distribution for several High- Mass X-ray Binaries (HMXBs). We focus our attention on the cyclotron lines that have been detected in HMXB classes in their X-ray spectra. As has been correctly pointed out, several sources show variation in cyclotron lines, this can result due to the effect of accretion dynamics, and hence that would reflect the magnetic field characteristics. Besides, the difference in time scales of variation of accretion rate and different type of companion can be used to distinguish between magnetized neutron stars.

astro-ph.HE↗

arXiv2019

The Nucleosynthesis and Reaction Rates of Fluorine 19 ($^{19}F$) in the Sun

We investigate the abundance of $^{19}F$ in the Sun through the nucleosynthesis scenario. In addition, we calculate the rate equations and reaction rates of the nucleosynthesis of $^{19}F$ at different temperature scale. Other important functions of this nucleosynthesis (nuclear partition function and statistical equilibrium conditions) are also obtained. The resulting stability of $^{19}F$ occurs at nucleus with A = 19 and Mass Excess= -1.4874 MeV. As a result, this will tend to a series of neutron captures and beta-decay until $^{19}F$ is produced. The reaction rate of $^{15}N$ ($α$, $γ$) $^{19}F$ was dominated by the contribution of three low-energy resonances, which enhanced the final $^{19}F$ abundance in the envelope.

astro-ph.SR↗

arXiv2019

Evolution of Accreting Binary Systems on the Spin-up Line

The measured characteristics of binary pulsars provide valuable insights into the evolution of these systems. We study the aspects of binary evolution particularly relevant to binary Millisecond Pulsars (MSPs), and the formation of close binaries involving degenerate stars through a spin-evolution diagram (spin-up line). For this task, we use a wide variety of binaries, including those with compact components that observed in different energy bands, which we analyze them according to the spin-up line. Their formation and evolution over timescales of binary evolution models are investigated in order to grab any constraint on their evolution, and to estimate the masses of neutron stars with different mass-transfer histories.

astro-ph.HE↗

arXiv2019

Probing the Accretion Induced Collapse of White Dwarfs in Millisecond Pulsars

This paper investigates the progenitors of Millisecond Pulsars (MSPs) with a distribution of long orbital periods (P_orb > 2 d), to show the link between white dwarf (WD) binaries and long orbits for some binary MSPs through the Accretion Induced Collapse (AIC) of a WD. For this purpose, a model is presented to turn binary MSPs into wide binaries and highly circular orbits (e < 0.1) through the asymmetric kick imparted to the pulsar during the AIC process, which may indicate a sizeable kick velocity along the rotation of the proto-neutron star. The results show the effects of shock wave, binding energy, and mass loss (0.2M_sun). The model shows the pulsar systems are relevant to AIC-candidates.

astro-ph.HE↗

arXiv2018

On the possibility of disk-fed formation in supergiant high-mass X-ray binaries

We have considered the existence of neutron star magnetic field given by the cyclotron lines. We collected the data of 9 sources of high-mass X-ray binaries with supergiant companions as a case of testing our model, to demonstrate their distribution and evolution. The wind velocity, spin period and magnetic field strength are studied under different mass loss rate. In our model, correlations between mass-loss rate and wind velocity are found and can be tested in further observations. We examined the parameter space where wind accretion is allowed, avoiding barrier of rotating magnetic fields, with robust data of magnetic field of neutron stars. Our model shows that most of sources (6 of 9 systems) can be fed by the wind with relatively slow velocity, and this result is consistent with previous predictions. In a few sources, our model cannot fit under the standard wind accretion scenario. In these peculiar cases, other scenarios (disk formation, partial Roche lobe overflow) should be considered. This would provide information about the evolutionary tracks of various types of binaries, and thus show a clear dichotomy behavior in wind-fed X-ray binary systems.

astro-ph.HE↗