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NuSTAR Spectroscopy of GRS 1915+105: Disk Reflection, Spin, and Connections to Jets
High Energy Astrophysical Phenomena · Submitted 21 Aug 2013
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim A spin parameter of a = 0.98 +/- 0.01 (1-sigma statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence.
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The abstract, sentence by sentence
We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a "plateau" state. This state is of special interest because it is similar to the "low/hard" state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly-spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 +/- 0.01 (1-sigma statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a "plateau" state. | contribution 1.00 | 0.97 | 0.03 | asserted 0.96 |
| s1 | This state is of special interest because it is similar to the "low/hard" state seen in other black holes, especially in that compact, steady jets are launched in this phase. | background 1.00 | 0.06 | 0.03 | asserted 1.00 |
| s2 | The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. | method 0.59 | 0.08 | 0.02 | asserted 1.00 |
| s3 | In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. | method 0.75 | 0.91 | 0.02 | asserted 1.00 |
| s4 | Ionized reflection from a disk around a rapidly-spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. | result 1.00 | 0.91 | 0.24 | asserted 1.00 |
| s5 | A spin parameter of a = 0.98 +/- 0.01 (1-sigma statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. | result 1.00 | 0.96 | 0.66 | asserted 1.00 |
| s6 | This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. | interpretation 1.00 | 0.42 | 0.28 | hedged possibility 1.00 |
| s7 | A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. | result 0.98 | 0.94 | 0.05 | hedged possibility 0.68 |
| s8 | These results support an emerging association between the hard X-ray corona and the base of the relativistic jet. | interpretation 1.00 | 0.43 | 0.23 | hedged possibility 0.61 |
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The paper
Original abstract
We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a "plateau" state. This state is of special interest because it is similar to the "low/hard" state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly-spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 +/- 0.01 (1-sigma statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.
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References
How the literature uses it
9 arXiv papers cite this in 15 sentences
Papers citing it · 8 sentences without a confident label
Uses its data or values 3 papers
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Tab. [ref] shows the list of black holes in X-ray binary systems for which an estimate of the inclination angle from both dynamical/jet methods and analysis of the iron line are reported in the literature [ref] .
Constraining possible variations of the fine structure constant in strong gravitational fields with the K$\alpha$ iron line · Constraints · 0.94
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For the NuSTAR observation of 2012, the Eddington-scaled accretion luminosity of the source is $0.23 ±0.04$ [ref] , which is in the 0.05-0.30 range required to have thin disks [ref] .
About the Kerr nature of the stellar-mass black hole in GRS 1915+105 · Discussion and conclusions · 0.81
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For example, GRS 1915+105 involves a binary system with a black hole of mass $∼10 M_⊙$ and a spin parameter which has been measured to be around $0.98$ [ref] – making it very nearly extremal.
Jackiw-Teitelboim Gravity and Rotating Black Holes · Conclusions · 0.97
Compares with it 2 papers
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However, such a high value of the viewing angle is quite suspicious and previous studies have reported values ranging from $∼55^∘$ to $∼75^∘$ [ref] .
Testing the Keplerian disk hypothesis using X-ray reflection spectroscopy · Discussion and conclusions · 0.85
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Note also that our measurements of the model parameters for the Kerr case are consistent with those reported in [ref] even if there are some minor differences between the two models [ [ref] use reflionx as non-relativistic reflection model while here we use xillver].
About the Kerr nature of the stellar-mass black hole in GRS 1915+105 · Spectral analysis · 1.00
Cites it as support 1 paper
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[ref] showed that considering a realistic radial ionization profile can explain the very steep emissivity profiles often required by spectral fits that parameterize the radial dependence of illuminating flux [ref] , since the strength of the iron line increases with ionization and $ξ$ is expected to increase with proximity to the hole.
Exploring the radial disc ionization profile of the black hole X-ray binary GRS 1915+105 · Introduction · 0.99
Cites it as background 1 paper
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Relativistic reflection features are commonly observed in the X-ray spectra of black hole binaries and active galactic nuclei (AGNs) [ref] .
Modeling uncertainties in X-ray reflection spectroscopy measurements II: Impact of the radiation from the plunging region · Introduction · 0.96
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