NAOC Open IR
Wind accretion in Cygnus X-1
Meyer-Hofmeister, E.1; Liu, B. F.2,3; Qiao, E.2,3; Taam, R. E.4
2020-05-15
Source PublicationASTRONOMY & ASTROPHYSICS
ISSN0004-6361
Volume637Pages:8
AbstractContext. Cygnus X-1 is a black hole X-ray binary system in which the black hole captures and accretes gas from the strong stellar wind emitted by its supergiant O9.7 companion star. The irradiation of the supergiant star essentially determines the flow properties of the stellar wind and the X-ray luminosity from the system. The results of three-dimensional hydrodynamical simulations of wind-fed X-ray binary systems reported in recent work reveal that the ionizing feedback of the X-ray irradiation leads to the existence of two stable states with either a soft or a hard spectrum. Aims. We discuss the observed radiation of Cygnus X-1 in the soft and hard state in the context of mass flow in the corona and disk, as predicted by the recent application of a condensation model. Methods. The rates of gas condensation from the corona to the disk for Cygnus X-1 are determined, and the spectra of the hard and soft radiation are computed. The theoretical results are compared with the MAXI observations of Cygnus X-1 from 2009 to 2018. In particular, we evaluate the hardness-intensity diagrams (HIDs) for its ten episodes of soft and hard states which show that Cygnus X-1 is distinct in its spectral changes as compared to those found in the HIDs of low-mass X-ray binaries. Results. The theoretically derived values of photon counts and hardness are in approximate agreement with the observed data in the HID. However, the scatter in the diagram is not reproduced. Improved agreement could result from variations in the viscosity associated with clumping in the stellar wind and corresponding changes of the magnetic fields in the disk. The observed dipping events in the hard state may also contribute to the scatter and to a harder spectrum than predicted by the model.
KeywordX-rays binaries binaries close stars individual Cygnus X-1 stars winds outflows
Funding OrganizationNational 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 ; 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 ; 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 ; 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
DOI10.1051/0004-6361/202037561
WOS KeywordRADIATION-DRIVEN WINDS ; INNER COOL DISKS ; STATE
Language英语
Funding ProjectNational Program on Key Research and Development Project[2016YFA0400804] ; National Natural Science Foundation of China[11673026] ; National Natural Science Foundation of China[11773037] ; gravitational wave pilot B[XDB23040100]
Funding OrganizationNational 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 ; 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 ; 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 ; 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
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000536554100005
PublisherEDP SCIENCES S A
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/54671
Collection中国科学院国家天文台
Corresponding AuthorMeyer-Hofmeister, E.
Affiliation1.Max Planck Inst Astrophys, Karl Schwarzschildstr 1, D-85740 Garching, Germany
2.Chinese Acad Sci, Natl Astron Observ, Key Lab Space Astron & Technol, Beijing 100012, Peoples R China
3.Univ Chinese Acad Sci, Sch Astron & Space Sci, 19A Yuquan Rd, Beijing 100049, Peoples R China
4.Northwestern Univ, Ctr Interdisciplinary Explorat & Res Astrophys CI, Dept Phys & Astron, 2145 Sheridan Rd, Evanston, IL 60208 USA
Recommended Citation
GB/T 7714
Meyer-Hofmeister, E.,Liu, B. F.,Qiao, E.,et al. Wind accretion in Cygnus X-1[J]. ASTRONOMY & ASTROPHYSICS,2020,637:8.
APA Meyer-Hofmeister, E.,Liu, B. F.,Qiao, E.,&Taam, R. E..(2020).Wind accretion in Cygnus X-1.ASTRONOMY & ASTROPHYSICS,637,8.
MLA Meyer-Hofmeister, E.,et al."Wind accretion in Cygnus X-1".ASTRONOMY & ASTROPHYSICS 637(2020):8.
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