Probing the accretion disc structure by the twin kHz QPOs and spins of neutron stars in LMXBs
| Autor: | Qi-Jun Zhi, J. L. Qu, Cheng-Min Zhang, Ya-Juan Lei, De-Hua Wang, Li Chen |
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| Rok vydání: | 2016 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Physics Solar mass Spins 010308 nuclear & particles physics FOS: Physical sciences Astronomy Astronomy and Astrophysics Astrophysics Radius Critical ionization velocity 01 natural sciences Accretion (astrophysics) Magnetic field Neutron star Space and Planetary Science 0103 physical sciences Astrophysics - High Energy Astrophysical Phenomena Low Mass 010303 astronomy & astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 466:1111-1117 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stw3134 |
| Popis: | We analyze the relation between the emission radii of twin kilohertz quasi-periodic oscillations (kHz QPOs) and the co-rotation radii of the 12 neutron star low mass X-ray binaries (NS-LMXBs) which are simultaneously detected with the twin kHz QPOs and NS spins. We find that the average co-rotation radius of these sources is r_co about 32 km, and all the emission positions of twin kHz QPOs lie inside the corotation radii, indicating that the twin kHz QPOs are formed in the spin-up process. It is noticed that the upper frequency of twin kHz QPOs is higher than NS spin frequency by > 10%, which may account for a critical velocity difference between the Keplerian motion of accretion matter and NS spin that is corresponding to the production of twin kHz QPOs. In addition, we also find that about 83% of twin kHz QPOs cluster around the radius range of 15-20 km, which may be affected by the hard surface or the local strong magnetic field of NS. As a special case, SAX J1808.4-3658 shows the larger emission radii of twin kHz QPOs of r about 21-24 km, which may be due to its low accretion rate or small measured NS mass (< 1.4 solar mass). 7 pages, 5 figures, 1 table |
| Databáze: | OpenAIRE |
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