The Experts below are selected from a list of 32562 Experts worldwide ranked by ideXlab platform
Christopher S Reynolds - One of the best experts on this subject based on the ideXlab platform.
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exploring the effects of disk thickness on the black hole Reflection Spectrum
The Astrophysical Journal, 2018Co-Authors: Corbin Taylor, Christopher S ReynoldsAbstract:The relativistically broadened Reflection Spectrum, observed in both AGN and X-ray binaries, has proven to be a powerful probe of the properties of black holes and the environments in which they reside. Emitted from the innermost regions of the accretion disk, this X-ray spectral component carries with it information not only about the plasma that resides in these extreme conditions, but also the black hole spin, a marker of the formation and accretion history of these objects. The models currently used to interpret the Reflection Spectrum are often simplistic, however, approximating the disk as an infinitely thin, optically thick plane of material orbiting in circular Keplerian orbits around the central object. Using a new relativistic ray-tracing suite (Fenrir) that allows for more complex disk approximations, we examine the effects that disk thickness may have on the Reflection Spectrum. Assuming a lamppost corona, we find that finite disk thickness can have a variety of effects on the Reflection Spectrum, including a truncation of the blue wing (from self-shadowing of the accretion disk) and an enhancement of the red wing (from the irradiation of the central "eye wall" of the inner disk). We deduce the systematic errors on black hole spin and height that may result from neglecting these effects.
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exploring the effects of disk thickness on the black hole Reflection Spectrum
arXiv: High Energy Astrophysical Phenomena, 2017Co-Authors: Corbin Taylor, Christopher S ReynoldsAbstract:The relativistically-broadened Reflection Spectrum, observed in both AGN and X-ray binaries, has proven to be a powerful probe of the properties of black holes and the environments in which they reside. Being emitted from the inner-most regions of the accretion disk, this X-ray spectral component carries with it information not only about the plasma that resides in these extreme conditions, but also the black hole spin, a marker of the formation and accretion history of these objects. The models currently used to interpret the Reflection Spectrum are often simplistic, however, approximating the disk as an infinitely thin, optically thick plane of material orbiting in circular Keplerian orbits around the central object. Using a new relativistic ray tracing suite (Fenrir) that allows for more complex disk approximations, we examine the effects that disk thickness may have on the Reflection Spectrum. Assuming a lamp post corona, we find that finite disk thickness can have a variety of effects on the Reflection Spectrum, including a truncation of the blue wing (from self-shadowing of the accretion disk) and an enhancement of the red wing (from the irradiation of the central 'eye wall' of the inner disk). We make a first estimate on the systematic errors on black hole spin and height that may result from neglecting these effects.
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evidence of black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
The Astrophysical Journal, 2004Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ks XMM-Newton/EPIC-pn and 10 ks Rossi X-Ray Timing Explorer observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe Kalpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe Kalpha emission-line profile and disk Reflection Spectrum rule out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of (2-3)rg suggests that GX 339-4 harbors a black hole with a>=0.8-0.9 (where rg=GM/c2 and a=cJ/GM2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule out a standard power-law disk emissivity in GX 339-4 a broken power-law form with enhanced emissivity inside ~6rg gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and the steep emissivity require a centrally concentrated source of hard X-rays that can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet-enhanced by gravitational light-bending effects-could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG -6-30-15, and of models for the inner accretion flow environment around black holes.
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evidence for black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
arXiv: Astrophysics, 2003Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ksec XMM-Newton/EPIC-pn and 10 ksec RXTE observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe K-alpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe K-alpha emission line profile and disk Reflection Spectrum rule-out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of 2-3 r_g suggests that GX 339-4 harbors a black hole with a ~ 0.8-0.9 (where r_g = GM/c^2 and a=cJ/GM^2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule-out a standard power-law disk emissivity in GX 339-4; a broken power-law form with enhanced emissivity inside ~6 r_{g} gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and steep emissivity require a centrally--concentrated source of hard X-rays which can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet - enhanced by gravitational light bending effects - could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG-6-30-15, and models for the inner accretion flow environment around black holes.
Kazuo Hotate - One of the best experts on this subject based on the ideXlab platform.
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Distributed measurement of Brillouin dynamic grating Spectrum localized by an intensity- modulated correlation-domain technique.
Optics express, 2020Co-Authors: Youhei Okawa, Masato Kishi, Rodrigo Kendy Yamashita, Kazuo HotateAbstract:Higher spatial resolution of the Reflection Spectrum measurement of Brillouin dynamic grating (BDG) was achieved by controlling phonon power distribution. We experimentally demonstrate the improvement effect of the light-source intensity-modulation method, proposed recently in a correlation-domain technique, and successfully detected an 8-cm cooled section in a 100-m-long polarization-maintaining fiber. Our method can improve the spatial resolution of BDG measurements, leading to high resolution discriminative and distributed fiber sensing of temperature and strain.
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Analysis of Brillouin dynamic grating localized by intensity-modulated correlation-domain technique for distributed fiber sensing.
Optics express, 2020Co-Authors: Youhei Okawa, Masato Kishi, Rodrigo Kendy Yamashita, Kazuo HotateAbstract:We numerically analyzed Reflection Spectrum of Brillouin dynamic grating localized by intensity-modulated correlation-domain technique. Furthermore, based on the results, we proposed a novel modulation technique achieving better spatial resolution for distributed fiber sensing along a polarization-maintaining fiber.
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spatial resolution improvement of discriminative and distributed measurement of temperature strain with pmf using intensity modulated correlation domain technique
Optical Sensors and Sensing Congress (ES FTS HISE Sensors) (2019) paper STh4A.3, 2019Co-Authors: Youhei Okawa, Masato Kishi, Rodrigo Kendy Yamashita, Kazuo HotateAbstract:We numerically analyzed Reflection Spectrum of Brillouin dynamic grating localized by intensity-modulated correlation-domain technique. Then, we proposed newly modulation technique achieving better spatial resolution for discriminative temperature/strain sensing along a PM-fiber.
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theoretical evaluation of brillouin dynamic grating length localized by optical correlation domain technique through Reflection Spectrum simulation
Applied Physics Express, 2017Co-Authors: Rodrigo Kendy Yamashita, Masato Kishi, Kazuo HotateAbstract:We derive formulae based on Fourier transformation to calculate the Reflection Spectrum of a Brillouin dynamic grating (BDG), which is localized along an optical fiber by an optical correlation domain technique. First, we calculate the typical Reflection spectra of the BDG localized by the technique and confirm the validity of the formulae by showing coincidence with previous theoretical or experimental works. Next, we evaluate theoretically the spatial resolution in the BDG distributed measurement by the technique, through simulations considering different strained fiber lengths. It is confirmed theoretically, for the first time, that the resolution in the BDG measurement is worse than that for the Brillouin gain Spectrum.
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a multiplexing technique for fibre bragg grating sensors with the same Reflection wavelength by the synthesis of optical coherence function
Measurement Science and Technology, 2004Co-Authors: Kazuo Hotate, Momoyo Enyama, Shinji Yamashita, Yusuke NasuAbstract:We propose a technique for multiplexing fibre Bragg grating (FBG) sensors with the same Bragg wavelength. We have already developed a technique for the synthesis of an optical coherence function, in which we can select one signal among various Reflections along an optical path in an interferometer. By applying the technique, the Reflection Spectrum of each FBG in arrayed FBGs can selectively be obtained, even if the array is composed of FBGs with the same Bragg wavelength. In this paper, we first describe the principle of the proposed system, and then show the experimental results.
J M Miller - One of the best experts on this subject based on the ideXlab platform.
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nustar and xmm newton observations of ngc 1365 extreme absorption variability and a constant inner accretion disk
The Astrophysical Journal, 2014Co-Authors: D J Walton, D R Ballantyne, S E Boggs, J M Miller, P Arevalo, A C Fabian, G Risaliti, F A Harrison, L W BrennemanAbstract:We present a spectral analysis of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365. These exhibit an extreme level of spectral variability, which is primarily due to variable line-of-sight absorption, revealing relatively unobscured states in this source for the first time. Despite the diverse range of absorption states, each of the observations displays the same characteristic signatures of relativistic Reflection from the inner accretion disk. Through time-resolved spectroscopy, we find that the strength of the relativistic iron line and the Compton Reflection hump relative to the intrinsic continuum are well correlated, which is expected if they are two aspects of the same broadband Reflection Spectrum. We apply self-consistent disk Reflection models to these time-resolved spectra in order to constrain the inner disk parameters, allowing for variable, partially covering absorption to account for the vastly different absorption states that were observed. Each of the four observations is treated independently to test the consistency of the results obtained for the black hole spin and the disk inclination, which should not vary on observable timescales. We find both the spin and the inclination determined from the Reflection Spectrum to be consistent, confirming that NGC 1365 hosts a rapidly rotating black hole; in all cases the dimensionless spin parameter is constrained to be a* > 0.97 (at 90% statistical confidence or better.
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nustar and xmm newton observations of ngc 1365 extreme absorption variability and a constant inner accretion disk
arXiv: High Energy Astrophysical Phenomena, 2014Co-Authors: D J Walton, D R Ballantyne, S E Boggs, J M Miller, P Arevalo, A C Fabian, G Risaliti, F A Harrison, L W BrennemanAbstract:We present a spectral analysis of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365. These exhibit an extreme level of spectral variability, which is primarily due to variable line-of-sight absorption, revealing relatively unobscured states in this source for the first time. Despite the diverse range of absorption states, each of the observations displays the same characteristic signatures of relativistic Reflection from the inner accretion disk. Through time-resolved spectroscopy we find that the strength of the relativistic iron line and the Compton Reflection hump relative to the intrinsic continuum are well correlated, as expected if they are two aspects of the same broadband Reflection Spectrum. We apply self-consistent disk Reflection models to these time-resolved spectra in order to constrain the inner disk parameters, allowing for variable, partially covering absorption to account for the vastly different absorption states observed. Each of the four observations is treated independently to test the consistency of the results obtained for the black hole spin and the disk inclination, which should not vary on observable timescales. We find both the spin and the inclination determined from the Reflection Spectrum to be consistent, confirming NGC 1365 hosts a rapidly rotating black hole; in all cases the dimensionless spin parameter is constrained to be a* > 0.97 (at 90% statistical confidence or better).
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evidence of black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
The Astrophysical Journal, 2004Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ks XMM-Newton/EPIC-pn and 10 ks Rossi X-Ray Timing Explorer observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe Kalpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe Kalpha emission-line profile and disk Reflection Spectrum rule out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of (2-3)rg suggests that GX 339-4 harbors a black hole with a>=0.8-0.9 (where rg=GM/c2 and a=cJ/GM2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule out a standard power-law disk emissivity in GX 339-4 a broken power-law form with enhanced emissivity inside ~6rg gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and the steep emissivity require a centrally concentrated source of hard X-rays that can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet-enhanced by gravitational light-bending effects-could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG -6-30-15, and of models for the inner accretion flow environment around black holes.
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evidence for black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
arXiv: Astrophysics, 2003Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ksec XMM-Newton/EPIC-pn and 10 ksec RXTE observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe K-alpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe K-alpha emission line profile and disk Reflection Spectrum rule-out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of 2-3 r_g suggests that GX 339-4 harbors a black hole with a ~ 0.8-0.9 (where r_g = GM/c^2 and a=cJ/GM^2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule-out a standard power-law disk emissivity in GX 339-4; a broken power-law form with enhanced emissivity inside ~6 r_{g} gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and steep emissivity require a centrally--concentrated source of hard X-rays which can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet - enhanced by gravitational light bending effects - could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG-6-30-15, and models for the inner accretion flow environment around black holes.
André D. Gomes - One of the best experts on this subject based on the ideXlab platform.
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multimode fabry perot interferometer probe based on vernier effect for enhanced temperature sensing
Sensors, 2019Co-Authors: André D. Gomes, Martin Becker, Jan Dellith, Mohammad I. Zibaii, Hamid Latifi, Manfred Rothhardt, Hartmut Bartelt, Orlando FrazãoAbstract:New miniaturized sensors for biological and medical applications must be adapted to the measuring environments and they should provide a high measurement resolution to sense small changes. The Vernier effect is an effective way of magnifying the sensitivity of a device, allowing for higher resolution sensing. We applied this concept to the development of a small-size optical fiber Fabry⁻Perot interferometer probe that presents more than 60-fold higher sensitivity to temperature than the normal Fabry⁻Perot interferometer without the Vernier effect. This enables the sensor to reach higher temperature resolutions. The silica Fabry⁻Perot interferometer is created by focused ion beam milling of the end of a tapered multimode fiber. Multiple Fabry⁻Perot interferometers with shifted frequencies are generated in the cavity due to the presence of multiple modes. The Reflection Spectrum shows two main components in the Fast Fourier transform that give rise to the Vernier effect. The superposition of these components presents an enhancement of sensitivity to temperature. The same effect is also obtained by monitoring the Reflection Spectrum node without any filtering. A temperature sensitivity of -654 pm/°C was obtained between 30 °C and 120 °C, with an experimental resolution of 0.14 °C. Stability measurements are also reported.
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Multimode Fabry–Perot Interferometer Probe Based on Vernier Effect for Enhanced Temperature Sensing
MDPI AG, 2019Co-Authors: André D. Gomes, Martin Becker, Jan Dellith, Mohammad I. Zibaii, Hamid Latifi, Manfred Rothhardt, Hartmut Bartelt, Orlando FrazãoAbstract:New miniaturized sensors for biological and medical applications must be adapted to the measuring environments and they should provide a high measurement resolution to sense small changes. The Vernier effect is an effective way of magnifying the sensitivity of a device, allowing for higher resolution sensing. We applied this concept to the development of a small-size optical fiber Fabry–Perot interferometer probe that presents more than 60-fold higher sensitivity to temperature than the normal Fabry–Perot interferometer without the Vernier effect. This enables the sensor to reach higher temperature resolutions. The silica Fabry–Perot interferometer is created by focused ion beam milling of the end of a tapered multimode fiber. Multiple Fabry–Perot interferometers with shifted frequencies are generated in the cavity due to the presence of multiple modes. The Reflection Spectrum shows two main components in the Fast Fourier transform that give rise to the Vernier effect. The superposition of these components presents an enhancement of sensitivity to temperature. The same effect is also obtained by monitoring the Reflection Spectrum node without any filtering. A temperature sensitivity of -654 pm/°C was obtained between 30 °C and 120 °C, with an experimental resolution of 0.14 °C. Stability measurements are also reported
M Van Der Klis - One of the best experts on this subject based on the ideXlab platform.
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evidence of black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
The Astrophysical Journal, 2004Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ks XMM-Newton/EPIC-pn and 10 ks Rossi X-Ray Timing Explorer observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe Kalpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe Kalpha emission-line profile and disk Reflection Spectrum rule out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of (2-3)rg suggests that GX 339-4 harbors a black hole with a>=0.8-0.9 (where rg=GM/c2 and a=cJ/GM2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule out a standard power-law disk emissivity in GX 339-4 a broken power-law form with enhanced emissivity inside ~6rg gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and the steep emissivity require a centrally concentrated source of hard X-rays that can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet-enhanced by gravitational light-bending effects-could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG -6-30-15, and of models for the inner accretion flow environment around black holes.
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evidence for black hole spin in gx 339 4 xmm newton epic pn and rxte spectroscopy of the very high state
arXiv: Astrophysics, 2003Co-Authors: J M Miller, A C Fabian, Christopher S Reynolds, Michael A Nowak, Jeroen Homan, M J Freyberg, M Ehle, T Belloni, R Wijnands, M Van Der KlisAbstract:We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ksec XMM-Newton/EPIC-pn and 10 ksec RXTE observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe K-alpha emission line and ionized disk Reflection Spectrum are revealed in these spectra. Self-consistent models for the Fe K-alpha emission line profile and disk Reflection Spectrum rule-out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of 2-3 r_g suggests that GX 339-4 harbors a black hole with a ~ 0.8-0.9 (where r_g = GM/c^2 and a=cJ/GM^2, and assuming that Reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra Spectrum obtained later in the outburst. The emission line and Reflection Spectrum also rule-out a standard power-law disk emissivity in GX 339-4; a broken power-law form with enhanced emissivity inside ~6 r_{g} gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and steep emissivity require a centrally--concentrated source of hard X-rays which can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet - enhanced by gravitational light bending effects - could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG-6-30-15, and models for the inner accretion flow environment around black holes.
