The Experts below are selected from a list of 5835 Experts worldwide ranked by ideXlab platform
Vladimir Osherovich - One of the best experts on this subject based on the ideXlab platform.
-
correlations between kilohertz quasi periodic oscillations and low frequency features attributed to radial oscillations and diffusive propagation in the viscous boundary layer around a neutron star
The Astrophysical Journal, 1999Co-Authors: Lev Titarchuk, Vladimir OsherovichAbstract:We present a dimensional analysis of two characteristic timescales in the boundary layer where the disk adjusts to the rotating neutron star (NS). The boundary layer is treated as a transition region between the NS surface and the first Keplerian Orbit. The radial transport of the angular momentum in this layer is controlled by a viscous force defined by the Reynolds number, which in turn is related to the mass accretion rate. We show that the observed low-Lorentzian frequency is associated with radial oscillations in the boundary layer, where the observed break frequency is determined by the characteristic diffusion time of the inward motion of the matter in the accretion flow. Predictions of our model regarding relations between those two frequencies and the frequencies of kilohertz quasi-periodic oscillations (kHz QPOs) compare favorably with recent observations of the source 4U 1728-34. This Letter contains a theoretical classification of kHz QPOs in NS binaries and the related low-frequency features. Thus, results concerning the relationship between the low-Lorentzian frequency of viscous oscillations and the break frequency are presented in the framework of our model of kHz QPOs viewed as Keplerian oscillations in a rotating frame of reference.
-
correlations between khz qpo and low frequency features attributed to radial oscillations and diffusive propagation in the viscous boundary layer around a neutron star
arXiv: Astrophysics, 1999Co-Authors: Lev Titarchuk, Vladimir OsherovichAbstract:We present a dimensional analysis of two characteristic time scales in the boundary layer where the disk adjusts to the rotating neutron star (NS). The boundary layer is treated as a transition region between the NS surface and the first Keplerian Orbit. The radial transport of the angular momentum in this layer is controlled by a viscous force defined by the Reynolds number, which in turn is related to the mass accretion rate. We show that the observed low-Lorentzian frequency is associated with radial oscillations in the boundary layer, where the observed break frequency is determined by the characteristic diffusion time of the inward motion of the matter in the accretion flow. Predictions of our model regarding relations between those two frequencies and frequencies of kHz QPO's compare favorably with recent observations for the source 4U 1728-34. This Letter contains a theoretical classification of kHz QPO's in NS binaries and the related low frequency features. Thus, results concerning the relationship of the low-Lorentzian frequency of viscous oscillations and the break frequency are presented in the framework of our model of kHz QPO's viewed as Keplerian oscillations in a rotating frame of reference.
Masato Tsuboi - One of the best experts on this subject based on the ideXlab platform.
-
the second galactic center black hole a possible detection of ionized gas Orbiting around an imbh embedded in the galactic center irs13e complex
The Astrophysical Journal, 2017Co-Authors: Masato Tsuboi, Yoshimi Kitamura, Takahiro Tsutsumi, Kenta Uehara, Makoto Miyoshi, Ryosuke Miyawaki, Atsushi MiyazakiAbstract:The Galactic Center is the nuclear region of the nearest spiral galaxy, the Milky Way, and contains the supermassive black hole with , Sagittarius A* (Sgr A*). One of the basic questions about the Galactic Center is whether or not Sgr A* is the only "massive" black hole in the region. The IRS13E complex is a very intriguing infrared (IR) object that contains a large dark mass comparable to the mass of an intermediate mass black hole (IMBH) from the proper motions of the main member stars. However, the existence of the IMBH remains controversial. There are some objections to accepting the existence of the IMBH. In this study, we detected ionized gas with a very large velocity width ( km s−1) and a very compact size ( au) in the complex using the Atacama Large Millimeter/submillimeter Array (ALMA). We also found an extended component connecting with the compact ionized gas. The properties suggest that this is an ionized gas flow on the Keplerian Orbit with high eccentricity. The enclosed mass is estimated to be by the analysis of the Orbit. The mass does not conflict with the upper limit mass of the IMBH around Sgr A*, which is derived by the long-term astrometry with the Very Long Baseline Array (VLBA). In addition, the object probably has an X-ray counterpart. Consequently, a very fascinating possibility is that the detected ionized gas is rotating around an IMBH embedded in the IRS13E complex.
-
the second galactic center black hole a possible detection of ionized gas Orbiting around an imbh embedded in the galactic center irs13e complex
arXiv: Astrophysics of Galaxies, 2017Co-Authors: Masato Tsuboi, Yoshimi Kitamura, Takahiro Tsutsumi, Kenta Uehara, Makoto Miyoshi, Ryosuke Miyawaki, Atsushi MiyazakiAbstract:The Galactic Center is the nuclear region of the nearest spiral galaxy, Milky Way, and contains the supermassive black hole with M~4x10^6 Msun, Sagittarius A* (Sgr A*). One of basic questions about the Galactic Center is whether Sgr A* alone exists as a "massive" black hole in the region or not. The IRS13E complex is a very intriguing IR object which contains a large dark mass comparable to the mass of an intermediate mass black hole (IMBH) from the proper motions of the main member stars. However, the existence of the IMBH remains controversial. There are some objections to accepting the existence of the IMBH. In this study, we detected ionized gas with a very large velocity width (Delta v_{FWZI} ~ 650 km/s) and a very compact size (~400 AU) in the complex using ALMA. We also found an extended component connecting with the compact ionized gas. The properties suggest that this would be an ionized gas flow on the Keplerian Orbit with high eccentricity. The enclosed mass is estimated to be 10^4 Msun by the analysis of the Orbit. The mass does not conflict with the upper limit mass of the IMBH around Sgr A* which is derived by the long-term astrometry with VLBA. In addition, the object probably has an X-ray counterpart. Consequently, a very fascinated possibility is that the detected ionized gas is rotating around an IMBH embedded in the IRS13E complex.
Subo Dong - One of the best experts on this subject based on the ideXlab platform.
-
moa 2010 blg 477lb constraining the mass of a microlensing planet from microlensing parallax Orbital motion and detection of blended light
The Astrophysical Journal, 2012Co-Authors: E Bachelet, I G Shin, C Han, P Fouque, A Gould, J Menzies, J P Beaulieu, D P Bennett, I A Bond, Subo DongAbstract:Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA 2010-BLG-477. The measured planet-star mass ratio is q = (2.181 {+-} 0.004) Multiplication-Sign 10{sup -3} and the projected separation is s = 1.1228 {+-} 0.0006 in units of the Einstein radius. The angular Einstein radius is unusually large {theta}{sub E} = 1.38 {+-} 0.11 mas. Combining this measurement with constraints on the 'microlens parallax' and the lens flux, we can only limit the host mass to the range 0.13 < M/M{sub Sun} < 1.0. In this particular case, the strong degeneracy between microlensing parallax and planet Orbital motion prevents us from measuring more accurate host and planet masses. However, we find that adding Bayesian priors from two effects (Galactic model and Keplerian Orbit) each independently favors the upper end of this mass range, yielding star and planet masses of M{sub *} = 0.67{supmore » +0.33}{sub -0.13} M{sub Sun} and m{sub p} = 1.5{sup +0.8}{sub -0.3} M{sub JUP} at a distance of D = 2.3 {+-} 0.6 kpc, and with a semi-major axis of a = 2{sup +3}{sub -1} AU. Finally, we show that the lens mass can be determined from future high-resolution near-IR adaptive optics observations independently from two effects, photometric and astrometric.« less
-
moa 2010 blg 477lb constraining the mass of a microlensing planet from microlensing parallax Orbital motion and detection of blended light
arXiv: Earth and Planetary Astrophysics, 2012Co-Authors: E Bachelet, I G Shin, C Han, P Fouque, A Gould, J Menzies, J P Beaulieu, D P Bennett, I A Bond, Subo DongAbstract:Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA-2010-BLG-477. The measured planet-star mass ratio is $q=(2.181\pm0.004)\times 10^{-3}$ and the projected separation is $s=1.1228\pm0.0006$ in units of the Einstein radius. The angular Einstein radius is unusually large $\theta_{\rm E}=1.38\pm 0.11$ mas. Combining this measurement with constraints on the "microlens parallax" and the lens flux, we can only limit the host mass to the range $0.13
Orbital motion prevents us from measuring more accurate host and planet masses. However, we find that adding Bayesian priors from two effects (Galactic model and Keplerian Orbit) each independently favors the upper end of this mass range, yielding star and planet masses of $M_*=0.67^{+0.33}_{-0.13}\ M_\odot$ and $m_p=1.5^{+0.8}_{-0.3}\ M_{\rm JUP}$ at a distance of $D=2.3\pm0.6$ kpc, and with a semi-major axis of $a=2^{+3}_{-1}$ AU. Finally, we show that the lens mass can be determined from future high-resolution near-IR adaptive optics observations independently from two effects, photometric and astrometric.
Atsushi Miyazaki - One of the best experts on this subject based on the ideXlab platform.
-
the second galactic center black hole a possible detection of ionized gas Orbiting around an imbh embedded in the galactic center irs13e complex
The Astrophysical Journal, 2017Co-Authors: Masato Tsuboi, Yoshimi Kitamura, Takahiro Tsutsumi, Kenta Uehara, Makoto Miyoshi, Ryosuke Miyawaki, Atsushi MiyazakiAbstract:The Galactic Center is the nuclear region of the nearest spiral galaxy, the Milky Way, and contains the supermassive black hole with , Sagittarius A* (Sgr A*). One of the basic questions about the Galactic Center is whether or not Sgr A* is the only "massive" black hole in the region. The IRS13E complex is a very intriguing infrared (IR) object that contains a large dark mass comparable to the mass of an intermediate mass black hole (IMBH) from the proper motions of the main member stars. However, the existence of the IMBH remains controversial. There are some objections to accepting the existence of the IMBH. In this study, we detected ionized gas with a very large velocity width ( km s−1) and a very compact size ( au) in the complex using the Atacama Large Millimeter/submillimeter Array (ALMA). We also found an extended component connecting with the compact ionized gas. The properties suggest that this is an ionized gas flow on the Keplerian Orbit with high eccentricity. The enclosed mass is estimated to be by the analysis of the Orbit. The mass does not conflict with the upper limit mass of the IMBH around Sgr A*, which is derived by the long-term astrometry with the Very Long Baseline Array (VLBA). In addition, the object probably has an X-ray counterpart. Consequently, a very fascinating possibility is that the detected ionized gas is rotating around an IMBH embedded in the IRS13E complex.
-
the second galactic center black hole a possible detection of ionized gas Orbiting around an imbh embedded in the galactic center irs13e complex
arXiv: Astrophysics of Galaxies, 2017Co-Authors: Masato Tsuboi, Yoshimi Kitamura, Takahiro Tsutsumi, Kenta Uehara, Makoto Miyoshi, Ryosuke Miyawaki, Atsushi MiyazakiAbstract:The Galactic Center is the nuclear region of the nearest spiral galaxy, Milky Way, and contains the supermassive black hole with M~4x10^6 Msun, Sagittarius A* (Sgr A*). One of basic questions about the Galactic Center is whether Sgr A* alone exists as a "massive" black hole in the region or not. The IRS13E complex is a very intriguing IR object which contains a large dark mass comparable to the mass of an intermediate mass black hole (IMBH) from the proper motions of the main member stars. However, the existence of the IMBH remains controversial. There are some objections to accepting the existence of the IMBH. In this study, we detected ionized gas with a very large velocity width (Delta v_{FWZI} ~ 650 km/s) and a very compact size (~400 AU) in the complex using ALMA. We also found an extended component connecting with the compact ionized gas. The properties suggest that this would be an ionized gas flow on the Keplerian Orbit with high eccentricity. The enclosed mass is estimated to be 10^4 Msun by the analysis of the Orbit. The mass does not conflict with the upper limit mass of the IMBH around Sgr A* which is derived by the long-term astrometry with VLBA. In addition, the object probably has an X-ray counterpart. Consequently, a very fascinated possibility is that the detected ionized gas is rotating around an IMBH embedded in the IRS13E complex.
Lev Titarchuk - One of the best experts on this subject based on the ideXlab platform.
-
correlations between kilohertz quasi periodic oscillations and low frequency features attributed to radial oscillations and diffusive propagation in the viscous boundary layer around a neutron star
The Astrophysical Journal, 1999Co-Authors: Lev Titarchuk, Vladimir OsherovichAbstract:We present a dimensional analysis of two characteristic timescales in the boundary layer where the disk adjusts to the rotating neutron star (NS). The boundary layer is treated as a transition region between the NS surface and the first Keplerian Orbit. The radial transport of the angular momentum in this layer is controlled by a viscous force defined by the Reynolds number, which in turn is related to the mass accretion rate. We show that the observed low-Lorentzian frequency is associated with radial oscillations in the boundary layer, where the observed break frequency is determined by the characteristic diffusion time of the inward motion of the matter in the accretion flow. Predictions of our model regarding relations between those two frequencies and the frequencies of kilohertz quasi-periodic oscillations (kHz QPOs) compare favorably with recent observations of the source 4U 1728-34. This Letter contains a theoretical classification of kHz QPOs in NS binaries and the related low-frequency features. Thus, results concerning the relationship between the low-Lorentzian frequency of viscous oscillations and the break frequency are presented in the framework of our model of kHz QPOs viewed as Keplerian oscillations in a rotating frame of reference.
-
correlations between khz qpo and low frequency features attributed to radial oscillations and diffusive propagation in the viscous boundary layer around a neutron star
arXiv: Astrophysics, 1999Co-Authors: Lev Titarchuk, Vladimir OsherovichAbstract:We present a dimensional analysis of two characteristic time scales in the boundary layer where the disk adjusts to the rotating neutron star (NS). The boundary layer is treated as a transition region between the NS surface and the first Keplerian Orbit. The radial transport of the angular momentum in this layer is controlled by a viscous force defined by the Reynolds number, which in turn is related to the mass accretion rate. We show that the observed low-Lorentzian frequency is associated with radial oscillations in the boundary layer, where the observed break frequency is determined by the characteristic diffusion time of the inward motion of the matter in the accretion flow. Predictions of our model regarding relations between those two frequencies and frequencies of kHz QPO's compare favorably with recent observations for the source 4U 1728-34. This Letter contains a theoretical classification of kHz QPO's in NS binaries and the related low frequency features. Thus, results concerning the relationship of the low-Lorentzian frequency of viscous oscillations and the break frequency are presented in the framework of our model of kHz QPO's viewed as Keplerian oscillations in a rotating frame of reference.
