HST observations of the eclipsing dwarf nova OY Car after its 1992 April superoutburst are used to isolate ultraviolet spectra (1150–2500 A at 9.2 A FWHM resolution) of the white dwarf, the accretion disk, and the bright spot. The white dwarf spectra have a Stark‐broadened photospheric Lα absorption, but are veiled by a forest of blended Fe II features that we attribute to absorption by intervening disk material. Spectral fits give white dwarf temperatures changing from ∼19500 K just after outburst ∼17400 K around three months after outburst. The temperature of intervening disk material is ∼8600 K–9800 K; the velocity dispersion of the intervening disk material is ∼60–70 km/s. Fitting results also shows that the decay time of white dwarf temperature is ∼27 days, that is much shorter than ∼687 days in dwarf nova WZ Sge.
在1992年4月的超爆发后，HST观测了日食矮新星OY Car，用于分离白矮星，吸积盘和亮点的紫外光谱(1150-2500 A, 9.2 A FWHM分辨率)。白矮星光谱具有Stark‐拓宽的光球Lα吸收，但被混合的Fe II特征所掩盖，我们将其归因于中间盘物质的吸收。光谱拟合显示白矮星温度从爆发后的~ 19500 K到爆发后约三个月的17400 K变化。中间盘状物质的温度为~ 8600 K - 9800 K;中间盘状物质的速度色散为~ 60-70 km/s。拟合结果还表明，白矮星温度的衰减时间为~ 27天，远短于矮新星WZ Sge的~ 687天。
{"title":"The cooling of the white dwarf in OY Car after 1992 superoutburst","authors":"F. H. Cheng, T. Marsh, K. Horne, I. Hubeny","doi":"10.1063/1.46008","DOIUrl":"https://doi.org/10.1063/1.46008","url":null,"abstract":"HST observations of the eclipsing dwarf nova OY Car after its 1992 April superoutburst are used to isolate ultraviolet spectra (1150–2500 A at 9.2 A FWHM resolution) of the white dwarf, the accretion disk, and the bright spot. The white dwarf spectra have a Stark‐broadened photospheric Lα absorption, but are veiled by a forest of blended Fe II features that we attribute to absorption by intervening disk material. Spectral fits give white dwarf temperatures changing from ∼19500 K just after outburst ∼17400 K around three months after outburst. The temperature of intervening disk material is ∼8600 K–9800 K; the velocity dispersion of the intervening disk material is ∼60–70 km/s. Fitting results also shows that the decay time of white dwarf temperature is ∼27 days, that is much shorter than ∼687 days in dwarf nova WZ Sge.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115963410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The x‐ray spectra of accreting black holes in x‐ray binaries show an ultrasoft/ultrahard spectral combination that is distinct amongst the galactic population of x‐ray binaries. This spectral signature is used to identify new black hole candidates, BHC. A total of 23 BHC are listed (including six that have been well established from optical radial velocity measurements). In 20 BHC systems the binary companion star is late type, and of these 15 are transient systems. Only 3 BHC are associated with early type companions. The galactic distribution of these black hole candidates, BHC, is compared with that of the entire population of low mass and high mass x‐ray binaries. The transient BHC are not strongly clustered at the galactic center, nor have any been found in a globular cluster. This suggests the transient BHC systems are population I.
{"title":"The galactic distribution of black holes in x‐ray binaries","authors":"N. White","doi":"10.1063/1.45935","DOIUrl":"https://doi.org/10.1063/1.45935","url":null,"abstract":"The x‐ray spectra of accreting black holes in x‐ray binaries show an ultrasoft/ultrahard spectral combination that is distinct amongst the galactic population of x‐ray binaries. This spectral signature is used to identify new black hole candidates, BHC. A total of 23 BHC are listed (including six that have been well established from optical radial velocity measurements). In 20 BHC systems the binary companion star is late type, and of these 15 are transient systems. Only 3 BHC are associated with early type companions. The galactic distribution of these black hole candidates, BHC, is compared with that of the entire population of low mass and high mass x‐ray binaries. The transient BHC are not strongly clustered at the galactic center, nor have any been found in a globular cluster. This suggests the transient BHC systems are population I.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115702174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many of the recently‐discovered soft x‐ray transients are also black hole candidates; I explore the possibility that magnetic braking, a plausible driving mechanism of mass transfer in these systems, may naturally lead black hole systems to become transients. I show that, regardless of the details, magnetic braking leads to a lower accretion rate for black hole primary with masses substantially greater than 1.4 M⊙ than for neutron star binaries.
{"title":"Application of magnetic braking theories to black hole binaries","authors":"K. Mukai","doi":"10.1063/1.45992","DOIUrl":"https://doi.org/10.1063/1.45992","url":null,"abstract":"Many of the recently‐discovered soft x‐ray transients are also black hole candidates; I explore the possibility that magnetic braking, a plausible driving mechanism of mass transfer in these systems, may naturally lead black hole systems to become transients. I show that, regardless of the details, magnetic braking leads to a lower accretion rate for black hole primary with masses substantially greater than 1.4 M⊙ than for neutron star binaries.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125412307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report on the results of V, R, I photometry of BQ Cam—the optical counterpart of the transient x‐ray pulsar V0332+53, during the years 1985–91. Throughout this period we have detected a long‐term modulation correlated with the last observed x‐ray eruption. Similar long‐term modulation and correlation were observed in 4U0115+63—another Be‐star x‐ray source. We discussed briefly two scenarios for the optical modulation, with and without a possible large mediatory disc around the neutron star.
{"title":"Six‐year photometry of BQ Cameloparadalis—The optical counterpart of V0332+53","authors":"T. Mazeh, H. Mendelson","doi":"10.1063/1.46024","DOIUrl":"https://doi.org/10.1063/1.46024","url":null,"abstract":"We report on the results of V, R, I photometry of BQ Cam—the optical counterpart of the transient x‐ray pulsar V0332+53, during the years 1985–91. Throughout this period we have detected a long‐term modulation correlated with the last observed x‐ray eruption. Similar long‐term modulation and correlation were observed in 4U0115+63—another Be‐star x‐ray source. We discussed briefly two scenarios for the optical modulation, with and without a possible large mediatory disc around the neutron star.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122617278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Stella, S. Campana, M. Colpi, S. Mereghetti, M. Tavani
Soft x‐ray transients (SXRTs) in outburst show properties similar to those of persistent low mass x‐ray binaries (LMXRBs), and therefore likely contain an old weakly magnetic neutron star spun‐up by accretion torques. Available x‐ray observations can be used to constrain the spin period and magnetic field strength of the neutron stars in SXRTs. The conditions under which a detectable radio pulsar signal can be produced by the rapidly rotating neutron star in the quiescent phase of a SRXT are investigated.
{"title":"Do quiescent soft x‐ray transients contain millisecond radio pulsars?","authors":"L. Stella, S. Campana, M. Colpi, S. Mereghetti, M. Tavani","doi":"10.1063/1.45975","DOIUrl":"https://doi.org/10.1063/1.45975","url":null,"abstract":"Soft x‐ray transients (SXRTs) in outburst show properties similar to those of persistent low mass x‐ray binaries (LMXRBs), and therefore likely contain an old weakly magnetic neutron star spun‐up by accretion torques. Available x‐ray observations can be used to constrain the spin period and magnetic field strength of the neutron stars in SXRTs. The conditions under which a detectable radio pulsar signal can be produced by the rapidly rotating neutron star in the quiescent phase of a SRXT are investigated.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126492773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I will review major accretion disk spectral models which have been used to fit observed x‐ray spectral of black hole candidates and low mass x‐ray binaries. These spectral models are compared in the light of recent observations of luminosity/spectral variations of black hole candidates. Blackbody disk models can explain the observed luminosity/spectral variations in terms of variation of the mass accretion rate and constant mass of the central object, although the local emission of accretion disk will not be a blackbody. Because of the Comptonization, color temperature of the local emission will be significantly larger than the effective temperature, and success of the blackbody disk model suggests the color to the effective temperature ratio (Tcol/Teff) is constant along the disk and radius and disk luminosity variations. Precise calculation of accretion disk spectral models by Titarchuk (1993) taking account of Comptonization and radiative transfer reproduced the observed results successfully.
{"title":"X‐ray energy spectra from accretion disks in black hole candidates","authors":"K. Ebisawa","doi":"10.1063/1.46000","DOIUrl":"https://doi.org/10.1063/1.46000","url":null,"abstract":"I will review major accretion disk spectral models which have been used to fit observed x‐ray spectral of black hole candidates and low mass x‐ray binaries. These spectral models are compared in the light of recent observations of luminosity/spectral variations of black hole candidates. Blackbody disk models can explain the observed luminosity/spectral variations in terms of variation of the mass accretion rate and constant mass of the central object, although the local emission of accretion disk will not be a blackbody. Because of the Comptonization, color temperature of the local emission will be significantly larger than the effective temperature, and success of the blackbody disk model suggests the color to the effective temperature ratio (Tcol/Teff) is constant along the disk and radius and disk luminosity variations. Precise calculation of accretion disk spectral models by Titarchuk (1993) taking account of Comptonization and radiative transfer reproduced the observed results successfully.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"277 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133848403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Zhao, P. Callanan, Michael R. Garcia, J. McClintock, R. Remillard, A. Silber
We present the results of a photometric and spectroscopic study of the optical counterpart of the x‐ray nova J0422+32, a recently discovered black hole candidate. Its light curve shows a similar decay pattern to that of other novae black hole candidates, but with a slower decay rate. Its rapid decline started 240 days after the outburst. Its current magnitude is R∼19.4, which is still brighter than its quiescent value. Intensive photometry in January 1993 shows evidence of the 5.1 hour modulation reported by other groups. However, this modulation is not present in data taken in October 1992 and October 1993. Outburst spectra of J0422+32 are remarkably similar to those of Nova Muscae 1991 (a strong black‐hole candidate) including double peaked emission lines of Hα, Hβ, Hγ, He ii 4686 A, He i 5876 A and 6678 A.
我们介绍了最近发现的黑洞候选者——x射线新星J0422+32的光学对偶体的光度和光谱研究结果。它的光曲线显示出与其他新星黑洞候选者相似的衰减模式，但衰减速度较慢。在爆发后240天，它开始迅速下降。它目前的星等为R ~ 19.4，仍然比它的静止值亮。1993年1月进行的密集光度测定显示了其他小组报告的5.1小时调制的证据。但是，1992年10月和1993年10月的数据没有出现这种变化。J0422+32的爆发光谱与Nova Muscae 1991(强黑洞候选者)的爆发光谱非常相似，包括Hα、Hβ、Hγ、He ii 4686 a、He i 5876 a和6678 a的双峰发射线。
{"title":"Optical observations of the x‐ray nova J0422+32","authors":"P. Zhao, P. Callanan, Michael R. Garcia, J. McClintock, R. Remillard, A. Silber","doi":"10.1063/1.45997","DOIUrl":"https://doi.org/10.1063/1.45997","url":null,"abstract":"We present the results of a photometric and spectroscopic study of the optical counterpart of the x‐ray nova J0422+32, a recently discovered black hole candidate. Its light curve shows a similar decay pattern to that of other novae black hole candidates, but with a slower decay rate. Its rapid decline started 240 days after the outburst. Its current magnitude is R∼19.4, which is still brighter than its quiescent value. Intensive photometry in January 1993 shows evidence of the 5.1 hour modulation reported by other groups. However, this modulation is not present in data taken in October 1992 and October 1993. Outburst spectra of J0422+32 are remarkably similar to those of Nova Muscae 1991 (a strong black‐hole candidate) including double peaked emission lines of Hα, Hβ, Hγ, He ii 4686 A, He i 5876 A and 6678 A.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"2516 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131347033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The global nonlinear time dependent evolution of thermal and viscous instabilities in Keplerian accretion disks in x‐ray binary sources has been investigated to understand the low frequency (∼0.04 Hz) quasi‐periodic oscillations (QPOs) seen recently in some black hole candidates (Cyg X–1 and GRO J0422+32) and the Rapid Burster MXB 1730–335. Within the framework of the α‐viscosity model, we assume the viscous stress scales with gas pressure only but that the α parameter is formulated as a function of the local scale height, h. Specifically, α=min[α0(h/r)n, αmax], where r is the distance from the compact object, and n, α0, and αmax are constants. It is found that nonsteady behavior may arise for sufficiently large n (∼1.2). We show that, the low frequency QPOs may be explicable in terms of a thermal‐viscous instability in accretion disks, which results in periodic or quasi‐periodic oscillations in the mass accretion rate. These oscillations are globally coherent in the unstable regions of the disk and the d...
{"title":"Low frequency oscillations from accretion disks in x‐ray binaries","authors":"Xingming Chen, R. Taam","doi":"10.1063/1.46012","DOIUrl":"https://doi.org/10.1063/1.46012","url":null,"abstract":"The global nonlinear time dependent evolution of thermal and viscous instabilities in Keplerian accretion disks in x‐ray binary sources has been investigated to understand the low frequency (∼0.04 Hz) quasi‐periodic oscillations (QPOs) seen recently in some black hole candidates (Cyg X–1 and GRO J0422+32) and the Rapid Burster MXB 1730–335. Within the framework of the α‐viscosity model, we assume the viscous stress scales with gas pressure only but that the α parameter is formulated as a function of the local scale height, h. Specifically, α=min[α0(h/r)n, αmax], where r is the distance from the compact object, and n, α0, and αmax are constants. It is found that nonsteady behavior may arise for sufficiently large n (∼1.2). We show that, the low frequency QPOs may be explicable in terms of a thermal‐viscous instability in accretion disks, which results in periodic or quasi‐periodic oscillations in the mass accretion rate. These oscillations are globally coherent in the unstable regions of the disk and the d...","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121251886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have collected data from the literature of the past two decades, and are carrying out for the first time a systematic, statistical study of all the documented long‐term x‐ray and optical light curves of x‐ray nova outbursts. This study can yield information which is critical to our understanding of these systems, as well as provide us with the necessary empirical ingredients for detailed theoretical modeling efforts. In this paper we discuss the basic properties of the light curves. Some distinguished features not well known before are also identified and briefly discussed.
{"title":"A systematic and statistical study of the x‐ray and optical light curves of x‐ray novae","authors":"Wan Chen, C. Schrader, M. Livio","doi":"10.1063/1.45956","DOIUrl":"https://doi.org/10.1063/1.45956","url":null,"abstract":"We have collected data from the literature of the past two decades, and are carrying out for the first time a systematic, statistical study of all the documented long‐term x‐ray and optical light curves of x‐ray nova outbursts. This study can yield information which is critical to our understanding of these systems, as well as provide us with the necessary empirical ingredients for detailed theoretical modeling efforts. In this paper we discuss the basic properties of the light curves. Some distinguished features not well known before are also identified and briefly discussed.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"9 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132070444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using a 3‐dimensional hydrodynamic fluid code based on the Free Lagrange Method, we study the loss of specific angular momentum from a binary system due to an evaporative wind from the companion of a millisecond pulsar. We consider binaries of different mass ratios and winds of different initial velocities and in particular attempt to model the system PSR 1957+20. We are in the process of incorporating the effect of the radiation force from the pulsar and the magnetic field of the companion on the mass outflow. The latter effect would also enable us to study magnetic braking in Cataclysmic Variables and Low Mass X‐ray Binaries.
{"title":"A study of angular momentum loss in binaries using the free Lagrange method","authors":"A. Rajasekhar, J. Frank, R. Whitehurst","doi":"10.1063/1.45974","DOIUrl":"https://doi.org/10.1063/1.45974","url":null,"abstract":"Using a 3‐dimensional hydrodynamic fluid code based on the Free Lagrange Method, we study the loss of specific angular momentum from a binary system due to an evaporative wind from the companion of a millisecond pulsar. We consider binaries of different mass ratios and winds of different initial velocities and in particular attempt to model the system PSR 1957+20. We are in the process of incorporating the effect of the radiation force from the pulsar and the magnetic field of the companion on the mass outflow. The latter effect would also enable us to study magnetic braking in Cataclysmic Variables and Low Mass X‐ray Binaries.","PeriodicalId":101857,"journal":{"name":"The evolution of X‐ray binaries","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115838880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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