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Showing 1-10 of about 10 results.
A wide star-black-hole binary system from radial-velocity measurementsLiu, JifengZhang, HaotongHoward, Andrew W.Bai, ZhongruiLu, YoujunSoria, RobertoJustham, StephenLi, XiangdongZheng, ZhengWang, TingguiBelczynski, KrzysztofCasares, JorgeZhang, WeiYuan, HailongDong, YiqiaoLei, YajuanIsaacson, HowardWang, SongBai, YuShao, YongGao, QingWang, YilunNiu, ZexiCui, KaimingZheng, ChuanjieMu, XiaoyongZhang, LanWang, WeiHeger, AlexanderQi, ZhaoxiangLiao, ShilongLattanzi, MarioGu, Wei-MinWang, JunfengWu, JianfengShao, LijingShen, RongfengWang, XiaofengBregman, JoelDi Stefano, RosanneLiu, QingzhongHan, ZhanwenZhang, TianmengWang, HuijuanRen, JuanjuanZhang, JunboZhang, JujiaWang, XiaoliCabrera-Lavers, AntonioCorradi, RomanoRebolo, RafaelZhao, YonghengZhao, GangChu, YaoquanCui, XiangqunDOI: info:10.1038/s41586-019-1766-2v. 575618–621
Liu, Jifeng, Zhang, Haotong, Howard, Andrew W., Bai, Zhongrui, Lu, Youjun, Soria, Roberto, Justham, Stephen, Li, Xiangdong, Zheng, Zheng, Wang, Tinggui, Belczynski, Krzysztof, Casares, Jorge, Zhang, Wei, Yuan, Hailong, Dong, Yiqiao, Lei, Yajuan, Isaacson, Howard, Wang, Song, Bai, Yu, Shao, Yong, Gao, Qing, Wang, Yilun, Niu, Zexi, Cui, Kaiming, Zheng, Chuanjie et al. 2019. "A wide star-black-hole binary system from radial-velocity measurements." Nature 575:618– 621. https://doi.org/10.1038/s41586-019-1766-2
ID: 154614
Type: article
Authors: Liu, Jifeng; Zhang, Haotong; Howard, Andrew W.; Bai, Zhongrui; Lu, Youjun; Soria, Roberto; Justham, Stephen; Li, Xiangdong; Zheng, Zheng; Wang, Tinggui; Belczynski, Krzysztof; Casares, Jorge; Zhang, Wei; Yuan, Hailong; Dong, Yiqiao; Lei, Yajuan; Isaacson, Howard; Wang, Song; Bai, Yu; Shao, Yong; Gao, Qing; Wang, Yilun; Niu, Zexi; Cui, Kaiming; Zheng, Chuanjie; Mu, Xiaoyong; Zhang, Lan; Wang, Wei; Heger, Alexander; Qi, Zhaoxiang; Liao, Shilong; Lattanzi, Mario; Gu, Wei-Min; Wang, Junfeng; Wu, Jianfeng; Shao, Lijing; Shen, Rongfeng; Wang, Xiaofeng; Bregman, Joel; Di Stefano, Rosanne; Liu, Qingzhong; Han, Zhanwen; Zhang, Tianmeng; Wang, Huijuan; Ren, Juanjuan; Zhang, Junbo; Zhang, Jujia; Wang, Xiaoli; Cabrera-Lavers, Antonio; Corradi, Romano; Rebolo, Rafael; Zhao, Yongheng; Zhao, Gang; Chu, Yaoquan; Cui, Xiangqun
Abstract: All stellar-mass black holes have hitherto been identified by X-rays emitted from gas that is accreting onto the black hole from a companion star. These systems are all binaries with a black-hole mass that is less than 30 times that of the Sun1-4. Theory predicts, however, that X-ray-emitting systems form a minority of the total population of star-black-hole binaries5,6. When the black hole is not accreting gas, it can be found through radial-velocity measurements of the motion of the companion star. Here we report radial-velocity measurements taken over two years of the Galactic B-type star, LB-1. We find that the motion of the B star and an accompanying Hα emission line require the presence of a dark companion with a mass of 68-13+11 solar masses, which can only be a black hole. The long orbital period of 78.9 days shows that this is a wide binary system. Gravitational-wave experiments have detected black holes of similar mass, but the formation of such massive ones in a high- metallicity environment would be extremely challenging within current stellar evolution theories.
The Spin of The Black Hole in the X-ray Binary Nova Muscae 1991Chen, ZihanGou, LijunMcClintock, Jeffrey E.Steiner, James F.Wu, JianfengXu, WeiweiOrosz, Jerome A.Xiang, YanmeiDOI: info:10.3847/0004-637X/825/1/45v. 82545
Chen, Zihan, Gou, Lijun, McClintock, Jeffrey E., Steiner, James F., Wu, Jianfeng, Xu, Weiwei, Orosz, Jerome A., and Xiang, Yanmei. 2016. "The Spin of The Black Hole in the X-ray Binary Nova Muscae 1991." The Astrophysical Journal 825:45. https://doi.org/10.3847/0004-637X/825/1/45
ID: 139995
Type: article
Authors: Chen, Zihan; Gou, Lijun; McClintock, Jeffrey E.; Steiner, James F.; Wu, Jianfeng; Xu, Weiwei; Orosz, Jerome A.; Xiang, Yanmei
Abstract: The bright soft X-ray transient Nova Muscae 1991 was intensively observed during its entire eight-month outburst using the Large Area Counter on board the Ginga satellite. Recently, we obtained accurate estimates of the mass of the black hole primary, the orbital inclination angle of the system, and the distance. Using these crucial input data and Ginga X-ray spectra, we have measured the spin of the black hole using the continuum-fitting method. For four X-ray spectra of extraordinary quality we have determined the dimensionless spin parameter of the black hole to be {a}* ={0.63}-0.19+0.16 (1s confidence level), a result that we confirm using 11 additional spectra of lower quality. Our spin estimate challenges two published results: it is somewhat higher than the value predicted by a proposed relationship between jet power and spin; and we find that the spin of the black hole is decidedly prograde, not retrograde as has been claimed.
The Mass of the Black Hole in the X-ray Binary Nova Muscae 1991Wu, JianfengOrosz, Jerome A.McClintock, Jeffrey E.Hasan, ImranBailyn, Charles D.Gou, LijunChen, ZihanDOI: info:10.3847/0004-637X/825/1/46v. 82546
Wu, Jianfeng, Orosz, Jerome A., McClintock, Jeffrey E., Hasan, Imran, Bailyn, Charles D., Gou, Lijun, and Chen, Zihan. 2016. "The Mass of the Black Hole in the X-ray Binary Nova Muscae 1991." The Astrophysical Journal 825:46. https://doi.org/10.3847/0004-637X/825/1/46
ID: 139994
Type: article
Authors: Wu, Jianfeng; Orosz, Jerome A.; McClintock, Jeffrey E.; Hasan, Imran; Bailyn, Charles D.; Gou, Lijun; Chen, Zihan
Abstract: The optical counterpart of the black hole soft X-ray transient Nova Muscae 1991 has brightened by ?V ˜ 0.8 mag since its return to quiescence 23 yr ago. We present the first clear evidence that the brightening of soft X-ray transients in quiescence occurs at a nearly linear rate. This discovery, and our precise determination of the disk component of emission obtained using our simultaneous photometric and spectroscopic data, has allowed us to identify and accurately model archival ellipsoidal light curves of the highest quality. The simultaneity, and the strong constraint it provides on the component of disk emission, is a key element of our work. Based on our analysis of the light curves, and our earlier measurements of the mass function and mass ratio, we have obtained for Nova Muscae 1991 the first accurate estimates of its systemic inclination i = {43.2}-2.7+2.1 deg, and black hole mass M = {11.0}-1.4+2.1 {M}? . Based on our determination of the radius of the secondary, we estimate the distance to be D = {4.95}-0.65+0.69 kpc. We discuss the implications of our work for future dynamical studies of black hole soft X-ray transients.
X-ray Insights into the Nature of PHL 1811 Analogs and Weak Emission-line Quasars: Unification with a Geometrically Thick Accretion Disk?Luo, B.Brandt, W. N.Hall, P. B.Wu, JianfengAnderson, S. F.Garmire, G. P.Gibson, R. R.Plotkin, R. M.Richards, G. T.Schneider, D. P.Shemmer, O.Shen, YueDOI: info:10.1088/0004-637X/805/2/122v. 805122
Luo, B., Brandt, W. N., Hall, P. B., Wu, Jianfeng, Anderson, S. F., Garmire, G. P., Gibson, R. R., Plotkin, R. M., Richards, G. T., Schneider, D. P., Shemmer, O., and Shen, Yue. 2015. "X-ray Insights into the Nature of PHL 1811 Analogs and Weak Emission-line Quasars: Unification with a Geometrically Thick Accretion Disk?." The Astrophysical Journal 805:122. https://doi.org/10.1088/0004-637X/805/2/122
ID: 136597
Type: article
Authors: Luo, B.; Brandt, W. N.; Hall, P. B.; Wu, Jianfeng; Anderson, S. F.; Garmire, G. P.; Gibson, R. R.; Plotkin, R. M.; Richards, G. T.; Schneider, D. P.; Shemmer, O.; Shen, Yue
Abstract: We present an X-ray and multiwavelength study of 33 weak emission-line quasars (WLQs) and 18 quasars that are analogs of the extreme WLQ, PHL 1811, at z˜ 0.5–2.9. New Chandra 1.5–9.5 ks exploratory observations were obtained for 32 objects while the others have archival X-ray observations. Significant fractions of these luminous type 1 quasars are distinctly X-ray weak compared to typical quasars, including 16 (48%) of the WLQs and 17 (94%) of the PHL 1811 analogs with average X-ray weakness factors of 17 and 39, respectively. We measure a relatively hard ({G }=1.16-0.32+0.37) effective power-law photon index for a stack of the X-ray weak subsample, suggesting X-ray absorption, and spectral analysis of one PHL 1811 analog, J1521+5202, also indicates significant intrinsic X-ray absorption. We compare composite Sloan Digital Sky Survey spectra for the X-ray weak and X-ray normal populations and find several optical–UV tracers of X-ray weakness, e.g., Fe ii rest-frame equivalent width (REW) and relative color. We describe how orientation effects under our previously proposed “shielding-gas” scenario can likely unify the X-ray weak and X-ray normal populations. We suggest that the shielding gas may naturally be understood as a geometrically thick inner accretion disk that shields the broad line region from the ionizing continuum. If WLQs and PHL 1811 analogs have very high Eddington ratios, the inner disk could be significantly puffed up (e.g., a slim disk). Shielding of the broad emission-line region by a geometrically thick disk may have a significant role in setting the broad distributions of C iv REW and blueshift for quasars more generally.
Tomography of X-ray Nova Muscae 1991: evidence for ongoing mass transfer and stream-disc overflowPeris, Charith S.Vrtilek, Saeqa D.Steiner, James F.Vrtilek, Jan M.Wu, JianfengMcClintock, Jeffrey E.Longa-Peña, PenelopeSteeghs, DannyCallanan, PaulHo, Luis C.Orosz, Jerome A.Reynolds, Mark T.DOI: info:10.1093/mnras/stv407v. 4491584–1592
Peris, Charith S., Vrtilek, Saeqa D., Steiner, James F., Vrtilek, Jan M., Wu, Jianfeng, McClintock, Jeffrey E., Longa-Peña, Penelope, Steeghs, Danny, Callanan, Paul, Ho, Luis C., Orosz, Jerome A., and Reynolds, Mark T. 2015. "Tomography of X-ray Nova Muscae 1991: evidence for ongoing mass transfer and stream-disc overflow." Monthly Notices of the Royal Astronomical Society 449:1584– 1592. https://doi.org/10.1093/mnras/stv407
ID: 136402
Type: article
Authors: Peris, Charith S.; Vrtilek, Saeqa D.; Steiner, James F.; Vrtilek, Jan M.; Wu, Jianfeng; McClintock, Jeffrey E.; Longa-Peña, Penelope; Steeghs, Danny; Callanan, Paul; Ho, Luis C.; Orosz, Jerome A.; Reynolds, Mark T.
Abstract: We present a spectroscopic analysis of the black hole binary Nova Muscae 1991 in quiescence using data obtained in 2009 with Magellan Echelette on the Magellan Clay telescope and in 2010 with IMACS on the Magellan Baade telescope at the Las Campanas Observatory. Emission from the disc is observed in Ha, Hß and Ca II (?8662). A prominent hotspot is observed in the Doppler maps of all three emission lines. The existence of this spot establishes ongoing mass transfer from the donor star in 2009-2010 and, given its absence in the 1993-1995 observations, demonstrates the presence of a variable hotspot in the system. We find the radial distance to the hotspot from the black hole to be consistent with the circularization radius. Our tomograms are suggestive of stream-disc overflow in the system. We also detect possible Ca II (?8662) absorption from the donor star.
Detection of Rest-frame Optical Lines from X-shooter Spectroscopy of Weak Emission Line QuasarsPlotkin, Richard M.Shemmer, OhadTrakhtenbrot, BennyAnderson, Scott F.Brandt, W. N.Fan, XiaohuiGallo, ElenaLira, PaulinaLuo, BinRichards, Gordon T.Schneider, Donald P.Strauss, Michael A.Wu, JianfengDOI: info:10.1088/0004-637X/805/2/123v. 805123
Plotkin, Richard M., Shemmer, Ohad, Trakhtenbrot, Benny, Anderson, Scott F., Brandt, W. N., Fan, Xiaohui, Gallo, Elena, Lira, Paulina, Luo, Bin, Richards, Gordon T., Schneider, Donald P., Strauss, Michael A., and Wu, Jianfeng. 2015. "Detection of Rest-frame Optical Lines from X-shooter Spectroscopy of Weak Emission Line Quasars." The Astrophysical Journal 805:123. https://doi.org/10.1088/0004-637X/805/2/123
ID: 136596
Type: article
Authors: Plotkin, Richard M.; Shemmer, Ohad; Trakhtenbrot, Benny; Anderson, Scott F.; Brandt, W. N.; Fan, Xiaohui; Gallo, Elena; Lira, Paulina; Luo, Bin; Richards, Gordon T.; Schneider, Donald P.; Strauss, Michael A.; Wu, Jianfeng
Abstract: Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hß, Ha) in individual objects. We detect broad Hß and Ha emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hß has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hß FWHM ? 4000 km s-1, and significant C iv blueshifts (˜1000–5500 km s-1) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 088.B-0355 and 090.B-0438.
VLT spectroscopy of the black hole candidate Swift J1357.2-0933 in quiescenceTorres, M. A. P.Jonker, P. G.Miller-Jones, J. C. A.Steeghs, D.Repetto, S.Wu, JianfengDOI: info:10.1093/mnras/stv720v. 4504292–4300
Torres, M. A. P., Jonker, P. G., Miller-Jones, J. C. A., Steeghs, D., Repetto, S., and Wu, Jianfeng. 2015. "VLT spectroscopy of the black hole candidate Swift J1357.2-0933 in quiescence." Monthly Notices of the Royal Astronomical Society 450:4292– 4300. https://doi.org/10.1093/mnras/stv720
ID: 136951
Type: article
Authors: Torres, M. A. P.; Jonker, P. G.; Miller-Jones, J. C. A.; Steeghs, D.; Repetto, S.; Wu, Jianfeng
Abstract: We present time-resolved optical spectroscopy of the counterpart to the high-inclination black hole low-mass X-ray binary Swift J1357.2-0933 in quiescence. Absorption features from the mass donor star were not detected. Instead the spectra display prominent broad double-peaked H a emission and weaker He I emission lines. From the H a peak-to-peak separation, we constrain the radial velocity semi-amplitude of the donor star to K2 > 789 km s-1. Further analysis through radial velocity and equivalent width measurements indicates that the H a line is free of variability due to S-wave components or disc eclipses. From our data and previous observations during outburst, we conclude that long-term radial velocity changes ascribed to a precessing disc were of low amplitude or not present. This implies that the centroid position of the line should closely represent the systemic radial velocity, ?. Using the derived ? = -150 km s-1 and the best available limits on the source distance, we infer that the black hole is moving towards the plane in its current Galactic orbit unless the proper motion is substantial. Finally, the depth of the central absorption in the double-peaked profiles adds support for Swift J1357.2-0933 as a high-inclination system. On the other hand, we argue that the low hydrogen column density inferred from X-ray fitting suggests that the system is not seen edge-on.
Gemini spectroscopy of Galactic Bulge Sources: a population of hidden accreting binaries revealed?Wu, JianfengJonker, P. G.Torres, M. A. P.Britt, C. T.Johnson, C. B.Hynes, R. I.Greiss, S.Steeghs, D. T. H.Maccarone, T. J.Heinke, C. O.Wevers, T.DOI: info:10.1093/mnras/stv047v. 4481900–1915
Wu, Jianfeng, Jonker, P. G., Torres, M. A. P., Britt, C. T., Johnson, C. B., Hynes, R. I., Greiss, S., Steeghs, D. T. H., Maccarone, T. J., Heinke, C. O., and Wevers, T. 2015. "Gemini spectroscopy of Galactic Bulge Sources: a population of hidden accreting binaries revealed?." Monthly Notices of the Royal Astronomical Society 448:1900– 1915. https://doi.org/10.1093/mnras/stv047
ID: 135998
Type: article
Authors: Wu, Jianfeng; Jonker, P. G.; Torres, M. A. P.; Britt, C. T.; Johnson, C. B.; Hynes, R. I.; Greiss, S.; Steeghs, D. T. H.; Maccarone, T. J.; Heinke, C. O.; Wevers, T.
Abstract: We present Gemini spectroscopy for 21 candidate optical counterparts to X-ray sources discovered in the Galactic Bulge Survey (GBS). For the majority of the 21 sources, the optical spectroscopy establishes that they are indeed the likely counterparts. One of the criteria we used for the identification was the presence of an Ha emission line. The spectra of several sources revealed an Ha emission line only after careful subtraction of the F or G stellar spectral absorption lines. In a subclass of three of these sources, the residual Ha emission line is broad (? 400 km s-1) which suggests that it is formed in an accretion disc, whereas in other cases the line width is such that we currently cannot determine whether the line emission is formed in an active star/binary or in an accretion disc. GBS source CX377 shows this hidden-accretion behaviour most dramatically. The previously identified broad Ha emission of this source is not present in its Gemini spectra taken ˜1 yr later. However, broad emission is revealed after subtracting an F6 template star spectrum. The Gemini spectra of three sources (CX446, CX1004, and CXB2) as well as the presence of possible eclipses in light curves of these sources suggest that these sources are accreting binaries viewed under a high inclination.
A Dynamical Study of the Black Hole X-Ray Binary Nova Muscae 1991Wu, JianfengOrosz, Jerome A.McClintock, Jeffrey E.Steeghs, DannyLonga-Peña, PenélopeCallanan, Paul J.Gou, LijunHo, Luis C.Jonker, Peter G.Reynolds, Mark T.Torres, Manuel A. P.DOI: info:10.1088/0004-637X/806/1/92v. 80692
Wu, Jianfeng, Orosz, Jerome A., McClintock, Jeffrey E., Steeghs, Danny, Longa-Peña, Penélope, Callanan, Paul J., Gou, Lijun, Ho, Luis C., Jonker, Peter G., Reynolds, Mark T., and Torres, Manuel A. P. 2015. "A Dynamical Study of the Black Hole X-Ray Binary Nova Muscae 1991." The Astrophysical Journal 806:92. https://doi.org/10.1088/0004-637X/806/1/92
ID: 136577
Type: article
Authors: Wu, Jianfeng; Orosz, Jerome A.; McClintock, Jeffrey E.; Steeghs, Danny; Longa-Peña, Penélope; Callanan, Paul J.; Gou, Lijun; Ho, Luis C.; Jonker, Peter G.; Reynolds, Mark T.; Torres, Manuel A. P.
Abstract: We present a dynamical study of the Galactic black hole binary system Nova Muscae 1991 (GS/GRS 1124–683). We utilize 72 high-resolution Magellan Echellette spectra and 72 strictly simultaneous V-band photometric observations; the simultaneity is a unique and crucial feature of this dynamical study. The data were taken on two consecutive nights and cover the full 10.4 hr orbital cycle. The radial velocities of the secondary star are determined by cross-correlating the object spectra with the best-match template spectrum obtained using the same instrument configuration. Based on our independent analysis of five orders of the echellette spectrum, the semi-amplitude of the radial velocity of the secondary is measured to be {{K}2}=406.8+/- 2.7 km s-1, which is consistent with previous work, while the uncertainty is reduced by a factor of 3. The corresponding mass function is f(M)=3.02+/- 0.06 {{M}? }. We have also obtained an accurate measurement of the rotational broadening of the stellar absorption lines (vsin i=85.0+/- 2.6 km s-1), and hence the mass ratio of the system q=0.079+/- 0.007. Finally, we have measured the spectrum of the non-stellar component of emission that veils the spectrum of the secondary. In a future paper, we will use our veiling-corrected spectrum of the secondary and accurate values of K2 and q to model multi-color light curves and determine the systemic inclination and the mass of the black hole. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.
The Galactic Bulge Survey: Completion of the X-Ray Survey ObservationsJonker, Peter G.Torres, Manuel A. P.Hynes, Robert I.Maccarone, Thomas J.Steeghs, DannyGreiss, SandraBritt, Christopher T.Wu, JianfengJohnson, Christopher B.Nelemans, GijsHeinke, CraigDOI: info:10.1088/0067-0049/210/2/18v. 21018
Jonker, Peter G., Torres, Manuel A. P., Hynes, Robert I., Maccarone, Thomas J., Steeghs, Danny, Greiss, Sandra, Britt, Christopher T., Wu, Jianfeng, Johnson, Christopher B., Nelemans, Gijs, and Heinke, Craig. 2014. "The Galactic Bulge Survey: Completion of the X-Ray Survey Observations." The Astrophysical Journal Supplement Series 210:18. https://doi.org/10.1088/0067-0049/210/2/18
ID: 119076
Type: article
Authors: Jonker, Peter G.; Torres, Manuel A. P.; Hynes, Robert I.; Maccarone, Thomas J.; Steeghs, Danny; Greiss, Sandra; Britt, Christopher T.; Wu, Jianfeng; Johnson, Christopher B.; Nelemans, Gijs; Heinke, Craig
Abstract: We provide the Chandra source list for the last ~quarter of the area covered by the Galactic Bulge Survey (GBS). The GBS targets two strips of 6° × 1° (12 square degrees in total), one above (1° < b < 2°) and one below (–2° < b < –1°) the Galactic plane in the direction of the Galactic center at X-ray, optical, and near-infrared wavelengths. For the X-ray part of the survey we use 2 ks per Chandra pointing. We find 424 X-ray sources in the 63 Chandra observations on which we report here. These sources are in addition to the 1216 X-ray sources discovered in the first part of the GBS survey described previously. We discuss the characteristics and the X-ray variability of the brightest of the sources as well as the radio properties from existing radio surveys. We point out an interesting asymmetry in the number of X-ray sources as a function of their Galactic l and b coordinates which is probably caused by differences in average extinction toward the different parts of the GBS survey area.