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A systematic study of the advection-dominated accretion flow for the origin of the X-ray emission in weakly magnetized low-level accreting neutron stars
Qiao, Erlin1,2; Liu, B. F.1,2
2020-02-01
Source PublicationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN0035-8711
Volume492Issue:1Pages:615-627
AbstractObservationally, the X-ray spectrum (0.5-10 keV) of low-level accreting neutron stars (NSs) (L0.5-10 kev less than or similar to 10(36) erg s(-1)) can generally be well fitted by the model with two components, i.e., a thermal soft X-ray component plus a power-law component. Meanwhile, the fractional contribution of the power-law luminosity eta (eta = L-0.5-10 kev(power law)/L0.5-10 kev) varies with the X-ray luminosity L0.5-10 kev. In this paper, we systematically investigate the origin of such X-ray emission within the framework of the advection-dominated accretion flow (ADAF) around a weakly magnetized NS, in which the thermal soft X-ray component arises from the surface of the NS and the power-law component arises from the ADAF itself. We test the effects of the viscosity parameter alpha in the ADAF and thermalized parameter f(th) (describing the fraction of the ADAF energy released at the surface of the NS as thermal emission) on the relation of eta versus L0.5-10 kev. It is found that eta is nearly a constant (similar to zero) with L0.5-10 kev for different alpha with f(th) = 1, which is inconsistent with observations. Meanwhile, it is found that a change of f(th) can significantly change the relation of eta versus L0.5-10 kev. By comparing with a sample of non-pulsating NS-low mass X-ray binaries probably dominated by low-level accretion on to NSs, it is found that a small value of f(th) less than or similar to 0.1 is needed to match the observed range of eta greater than or similar to 10 per cent in the diagram of eta versus L0.5-10 kev. Finally, we argue that the small value of f(th) less than or similar to 0.1 implies that the radiative efficiency of NSs with an ADAF accretion may not be as high as the predicted result previously of epsilon similar to (M) over dot GM/R-not equal/(M) over dot c(2) similar to 0.2 despite the existence of the hard surface.
Keywordaccretion, accretion discs black hole physics stars: neutron X-rays: binaries
Funding OrganizationNational Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project
DOI10.1093/mnras/stz3510
WOS KeywordCEN X-4 ; BLACK-HOLES ; RADIATIVE EFFICIENCY ; SWIFT OBSERVATIONS ; THERMAL EMISSION ; SAX J1808.4-3658 ; DISK ACCRETION ; EXO 0748-676 ; AQL X-1 ; QUIESCENCE
Language英语
Funding ProjectNational Natural Science Foundation of China[11773037] ; National Natural Science Foundation of China[11673026] ; gravitational wave pilot B[XDB23040100] ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences[XDA15052100] ; National Program on Key Research and Development Project[2016YFA0400804]
Funding OrganizationNational Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; gravitational wave pilot B ; gravitational wave pilot B ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; Strategic Pioneer Program on Space Science, Chinese Academy of Sciences ; National Program on Key Research and Development Project ; National Program on Key Research and Development Project
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000512329900048
PublisherOXFORD UNIV PRESS
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/54187
Collection中国科学院国家天文台
Corresponding AuthorQiao, Erlin
Affiliation1.Chinese Acad Sci, Natl Astron Observ, Key Lab Space Astron & Technol, Beijing 100101, Peoples R China
2.Univ Chinese Acad Sci, Sch Astron & Space Sci, 19A Yuquan Rd, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
Qiao, Erlin,Liu, B. F.. A systematic study of the advection-dominated accretion flow for the origin of the X-ray emission in weakly magnetized low-level accreting neutron stars[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2020,492(1):615-627.
APA Qiao, Erlin,&Liu, B. F..(2020).A systematic study of the advection-dominated accretion flow for the origin of the X-ray emission in weakly magnetized low-level accreting neutron stars.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,492(1),615-627.
MLA Qiao, Erlin,et al."A systematic study of the advection-dominated accretion flow for the origin of the X-ray emission in weakly magnetized low-level accreting neutron stars".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 492.1(2020):615-627.
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