The Trigonometric Parallax of Cygnus X-1 Reid, Mark J; McClintock, Jeffrey E; Narayan, Ramesh ...
The Astrophysical journal,
12/2011, Letnik:
742, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report a direct and accurate measurement of the distance to the X-ray binary Cygnus X-1, which contains the first black hole to be discovered. The distance of 1.86+0.12 -- 0.11 kpc was obtained ...from a trigonometric parallax measurement using the Very Long Baseline Array. The position measurements are also sensitive to the 5.6 day binary orbit and we determine the orbit to be clockwise on the sky. We also measured the proper motion of Cygnus X-1 which, when coupled to the distance and Doppler shift, gives the three-dimensional space motion of the system. When corrected for differential Galactic rotation, the non-circular (peculiar) motion of the binary is only about 21 km s--1, indicating that the binary did not experience a large 'kick' at formation.
The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and ...for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole's accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a * > 0.95 (3 Delta *s). For a less probable (synchronous) dynamical model, we find a * > 0.92 (3 Delta *s). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk's low luminosity.
The evolution of massive stars is influenced by the mass lost to stellar winds over their lifetimes. These winds limit the masses of the stellar remnants (such as black holes) that the stars ...ultimately produce. We used radio astrometry to refine the distance to the black hole x-ray binary Cygnus X-1, which we found to be Formula: see text kiloparsecs. When combined with archival optical data, this implies a black hole mass of 21.2 ± 2.2 solar masses, which is higher than previous measurements. The formation of such a high-mass black hole in a high-metallicity system (within the Milky Way) constrains wind mass loss from massive stars.
The Mass of the Black Hole in Cygnus X-1 Orosz, Jerome A; McClintock, Jeffrey E; Aufdenberg, Jason P ...
The Astrophysical journal,
12/2011, Letnik:
742, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Cygnus X-1 is a binary star system that is comprised of a black hole and a massive giant companion star in a tight orbit. Building on our accurate distance measurement reported in the preceding ...paper, we first determine the radius of the companion star, thereby constraining the scale of the binary system. To obtain a full dynamical model of the binary, we use an extensive collection of optical photometric and spectroscopic data taken from the literature. By using all of the available observational constraints, we show that the orbit is slightly eccentric (both the radial velocity and photometric data independently confirm this result) and that the companion star rotates roughly 1.4 times its pseudosynchronous value. We find a black hole mass of M = 14.8 ? 1.0 M , a companion mass of M opt = 19.2 ? 1.9 M , and the angle of inclination of the orbital plane to our line of sight of i = 27.1 ? 0.8 deg.
Cygnus X-1 is a well-studied persistent black hole X-ray binary. Recently, the three parameters needed to estimate the black hole spin of this system, namely the black hole mass M, the orbital ...inclination i, and the source distance D, have been updated. In this work we redetermine the spin parameter using the continuum-fitting technique for those updated parameter values. Based on the assumption that the spin axis of the black hole is aligned with the orbital plane, we fit the thermal disk component to a fully relativistic thin accretion disk model. The error in the spin estimate arising from the combined observational uncertainties is obtained via Monte Carlo simulations. We demonstrate that, without considering the counteracting torque effect, the new spin parameter is constrained to be a* > 0.9985 (3 ), which confirms that the spin of the black hole in Cygnus X-1 is extreme.
The black hole binary system LMC X-3 has been observed by virtually every X-ray mission since the inception of X-ray astronomy. Among the persistent sources, LMC X-3 is uniquely both habitually soft ...and highly variable. Using a fully relativistic accretion disk model, we analyze hundreds of spectra collected during eight X-ray missions that span 26 years. For a selected sample of 391 RXTE spectra, we find that to within {approx}2% the inner radius of the accretion disk is constant over time and unaffected by source variability. Even considering an ensemble of eight X-ray missions, we find consistent values of the radius to within {approx}4%-6%. Our results provide strong evidence for the existence of a fixed inner-disk radius. The only reasonable inference is that this radius is closely associated with the general relativistic innermost stable circular orbit. Our findings establish a firm foundation for the measurement of black hole spin.
Measuring the spins of accreting black holes McClintock, Jeffrey E; Narayan, Ramesh; Davis, Shane W ...
Classical and quantum gravity,
06/2011, Letnik:
28, Številka:
11
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
A typical galaxy is thought to contain tens of millions of stellar-mass black holes, the collapsed remnants of once massive stars, and a single nuclear supermassive black hole. Both classes of black ...holes accrete gas from their environments. The accreting gas forms a flattened orbiting structure known as an accretion disk. During the past several years, it has become possible to obtain measurements of the spins of the two classes of black holes by modeling the x-ray emission from their accretion disks. Two methods are employed, both of which depend upon identifying the inner radius of the accretion disk with the innermost stable circular orbit, whose radius depends only on the mass and spin of the black hole. In the Fe Kalpha method, which applies to both classes of black holes, one models the profile of the relativistically broadened iron line with a special focus on the gravitationally redshifted red wing of the line. In the continuum-fitting (CF) method, which has so far only been applied to stellar-mass black holes, one models the thermal x-ray continuum spectrum of the accretion disk. We discuss both methods, with a strong emphasis on the CF method and its application to stellar-mass black holes. Spin results for eight stellar-mass black holes are summarized. These data are used to argue that the high spins of at least some of these black holes are natal, and that the presence or absence of relativistic jets in accreting black holes is not entirely determined by the spin of the black hole.
ObjectiveTo analyze the monitoring result of iodine deficiency disorders (IDD) in Erqi District of Zhengzhou City from 2013 to 2020.MethodsSalt iodine monitoring was carried out in Erqi District of ...Zhengzhou City from 2013 to 2020 according to the national IDD monitoring program, at the same time, urine samples were collected from newly married women of childbearing age, pregnant women, lactating women, infants aged 0-2 and children aged 8-10, and the content of urinary iodine was determined.ResultsDuring 2013-2020, the median and mean value of salt iodine content of residents in Erqi District of Zhengzhou City were in the range of 21-39 mg/kg; the coverage rate of iodized salt was more than 90.00% except for 2017, the qualified rate of iodized salt was more than 90.00% except for 2013 and 2017, the consumption rate of qualified iodized salt was more than 90.00% except for 2013, and the non iodized salt rate in 2017 was more than 20.00%. The median of urine iodine concentration in 2016, 2017, 2019 and 2020 of
We measure the spin of XTE J1550−564 using the two leading methods: (i) modelling the thermal continuum spectrum of the accretion disc; and (ii) modelling the broad red wing of the reflection ...fluorescence Fe Kα line. We find that these two independent measurements of spin are in agreement. For the continuum-fitting analysis, we use a data sample consisting of several dozen Rossi X-ray Timing Explorer spectra, and for the Fe Kα analysis, we use a pair of ASCA spectra from a single epoch. Our spin estimate for the black hole primary using the continuum-fitting method is −0.11 < a
* < 0.71 (90 per cent confidence), with a most likely spin of a
*= 0.34. In obtaining this result, we have thoroughly explored the dependence of the spin value on a wide range of model-dependent systematic errors and observational errors; our precision is limited by uncertainties in the distance and orbital inclination of the system. For the Fe-line method, our estimate of spin is a
*= 0.55+0.15
− 0.22. Combining these results, we conclude that the spin of this black hole is moderate, a
*= 0.49+0.13
− 0.20, which suggests that the jet activity of this microquasar is powered largely by its accretion disc rather than by the spin energy of the black hole.
ObjectiveTo investigate the iodine nutrition status of children under 8-10 years old in Erqi District of Zhengzhou City from 2017 to 2020, and to analyze the correlation between iodine nutrition ...status and salt iodine.MethodsA total of 800 children under 8-10 years old were selected from 9 communities in Erqi District of Zhengzhou City by stratified sampling method, and their urine iodine, salt iodine and thyroid were detected. The salt iodine content, urine iodine content and qualified rate of salt iodine in different years were analyzed, and the correlation between urine iodine and salt iodine was analyzed by Spearman rank correlation.ResultsThe overall median of salt iodine concentration was 26.2 mg/kg, and the total qualified rate of salt iodine was 93.00% (744/800); there were significant differences in salt iodine content and qualified rate among different years (P<0.05); the median urinary iodine content of children was 170.9 μg/L, and the difference was statistically significant among different years
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