{"title":"受双高频准周期振荡限制的超自旋夸克星","authors":"Z. Stuchlík, J. Schee, E. Šrámková, G. Török","doi":"10.32023/0001-5237/67.2.6","DOIUrl":null,"url":null,"abstract":"We study properties of Keplerian disks and their high-frequency\nquasi-periodic oscillations (HF QPOs) in the field of quark\nstars with dimensionless spin a breaking the black-hole spin\nlimit of a = 1 up to a approximate to 1.3. Using the external\ngeometry of the superspinning quark stars approximated by the\nKerr geometry, we show that the Keplerian disks have to touch\nthe surface of such quark stars and their accretion efficiency\neta approximate to 18% significantly exceeds the efficiency\nrelated to the Schwarzschild black holes. Using the geodesic\noscillation models, we test possible existence of the\nsuperspinning quark stars in atoll sources demonstrating the\ntwin HF QPOs with resonant frequency ratios 3:2, 4:3, 5:4. For\nexplanation of the twin HF QPOs we consider the standard\nrelativistic precession model and its modifications, the tidal\ndistortion model, the resonance epicyclic and the warped disk\nmodel. In a given model, we assume occurrence of the twin\noscillatory modes at a common resonant dimensionless radius x =\nr/M determined by the frequency ratio and the quark star spin\na. The theoretical limit R > 3M on the quark star surface\nradius puts strong restrictions on the relations between the\nresonant radii x and the quark star spin a. These restrictions\nimply that all the considered geodesic oscillation models can\nbe excluded, except for one variant of the relativistic\nprecession model, or alternatively the tidal distortion and\nwarped disk models, that allow for appearance of the twin HF\nQPOs with frequency ratio 3 : 2 at radii slightly above the\ntheoretical limit on the radius of the quark star surface, but\nexclude the smaller frequency ratios (4:3, 5:4).","PeriodicalId":44887,"journal":{"name":"Acta Astronomica","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":"{\"title\":\"Superspinning Quark Stars Limited by Twin High-FrequencyQuasiperiodic Oscillations\",\"authors\":\"Z. Stuchlík, J. Schee, E. Šrámková, G. Török\",\"doi\":\"10.32023/0001-5237/67.2.6\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We study properties of Keplerian disks and their high-frequency\\nquasi-periodic oscillations (HF QPOs) in the field of quark\\nstars with dimensionless spin a breaking the black-hole spin\\nlimit of a = 1 up to a approximate to 1.3. Using the external\\ngeometry of the superspinning quark stars approximated by the\\nKerr geometry, we show that the Keplerian disks have to touch\\nthe surface of such quark stars and their accretion efficiency\\neta approximate to 18% significantly exceeds the efficiency\\nrelated to the Schwarzschild black holes. Using the geodesic\\noscillation models, we test possible existence of the\\nsuperspinning quark stars in atoll sources demonstrating the\\ntwin HF QPOs with resonant frequency ratios 3:2, 4:3, 5:4. For\\nexplanation of the twin HF QPOs we consider the standard\\nrelativistic precession model and its modifications, the tidal\\ndistortion model, the resonance epicyclic and the warped disk\\nmodel. In a given model, we assume occurrence of the twin\\noscillatory modes at a common resonant dimensionless radius x =\\nr/M determined by the frequency ratio and the quark star spin\\na. The theoretical limit R > 3M on the quark star surface\\nradius puts strong restrictions on the relations between the\\nresonant radii x and the quark star spin a. These restrictions\\nimply that all the considered geodesic oscillation models can\\nbe excluded, except for one variant of the relativistic\\nprecession model, or alternatively the tidal distortion and\\nwarped disk models, that allow for appearance of the twin HF\\nQPOs with frequency ratio 3 : 2 at radii slightly above the\\ntheoretical limit on the radius of the quark star surface, but\\nexclude the smaller frequency ratios (4:3, 5:4).\",\"PeriodicalId\":44887,\"journal\":{\"name\":\"Acta Astronomica\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.0000,\"publicationDate\":\"2017-06-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Astronomica\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.32023/0001-5237/67.2.6\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Astronomica","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.32023/0001-5237/67.2.6","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Superspinning Quark Stars Limited by Twin High-FrequencyQuasiperiodic Oscillations
We study properties of Keplerian disks and their high-frequency
quasi-periodic oscillations (HF QPOs) in the field of quark
stars with dimensionless spin a breaking the black-hole spin
limit of a = 1 up to a approximate to 1.3. Using the external
geometry of the superspinning quark stars approximated by the
Kerr geometry, we show that the Keplerian disks have to touch
the surface of such quark stars and their accretion efficiency
eta approximate to 18% significantly exceeds the efficiency
related to the Schwarzschild black holes. Using the geodesic
oscillation models, we test possible existence of the
superspinning quark stars in atoll sources demonstrating the
twin HF QPOs with resonant frequency ratios 3:2, 4:3, 5:4. For
explanation of the twin HF QPOs we consider the standard
relativistic precession model and its modifications, the tidal
distortion model, the resonance epicyclic and the warped disk
model. In a given model, we assume occurrence of the twin
oscillatory modes at a common resonant dimensionless radius x =
r/M determined by the frequency ratio and the quark star spin
a. The theoretical limit R > 3M on the quark star surface
radius puts strong restrictions on the relations between the
resonant radii x and the quark star spin a. These restrictions
imply that all the considered geodesic oscillation models can
be excluded, except for one variant of the relativistic
precession model, or alternatively the tidal distortion and
warped disk models, that allow for appearance of the twin HF
QPOs with frequency ratio 3 : 2 at radii slightly above the
theoretical limit on the radius of the quark star surface, but
exclude the smaller frequency ratios (4:3, 5:4).