The Experts below are selected from a list of 6021 Experts worldwide ranked by ideXlab platform
C Rodriguez - One of the best experts on this subject based on the ideXlab platform.
-
a compact supermassive binary black Hole System
The Astrophysical Journal, 2006Co-Authors: C Rodriguez, G B Taylor, R T Zavala, A B Peck, L K Pollack, Roger W RomaniAbstract:We report on the discovery of a supermassive binary black Hole System in the radio galaxy 0402+379, with a projected separation between the two black Holes of just 7.3 pc. This is the closest black Hole pair yet found by more than 2 orders of magnitude. These results are based on recent multifrequency observations using the Very Long Baseline Array (VLBA), which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the System. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity Systems with a combined mass of the two black Holes of ~1.5 × 108 M☉. The two nuclei appear stationary, while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this System has implications for the number of close binary black Holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting System are also presented.
Roger W Romani - One of the best experts on this subject based on the ideXlab platform.
-
a compact supermassive binary black Hole System
The Astrophysical Journal, 2006Co-Authors: C Rodriguez, G B Taylor, R T Zavala, A B Peck, L K Pollack, Roger W RomaniAbstract:We report on the discovery of a supermassive binary black Hole System in the radio galaxy 0402+379, with a projected separation between the two black Holes of just 7.3 pc. This is the closest black Hole pair yet found by more than 2 orders of magnitude. These results are based on recent multifrequency observations using the Very Long Baseline Array (VLBA), which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the System. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity Systems with a combined mass of the two black Holes of ~1.5 × 108 M☉. The two nuclei appear stationary, while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this System has implications for the number of close binary black Holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting System are also presented.
G B Taylor - One of the best experts on this subject based on the ideXlab platform.
-
a compact supermassive binary black Hole System
The Astrophysical Journal, 2006Co-Authors: C Rodriguez, G B Taylor, R T Zavala, A B Peck, L K Pollack, Roger W RomaniAbstract:We report on the discovery of a supermassive binary black Hole System in the radio galaxy 0402+379, with a projected separation between the two black Holes of just 7.3 pc. This is the closest black Hole pair yet found by more than 2 orders of magnitude. These results are based on recent multifrequency observations using the Very Long Baseline Array (VLBA), which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the System. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity Systems with a combined mass of the two black Holes of ~1.5 × 108 M☉. The two nuclei appear stationary, while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this System has implications for the number of close binary black Holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting System are also presented.
J. C. Portal - One of the best experts on this subject based on the ideXlab platform.
-
quantum hall effect near the charge neutrality point in a two dimensional electron Hole System
Physical Review Letters, 2010Co-Authors: G M Gusev, Z. D. Kvon, E. B. Olshanetsky, N. N. Mikhailov, S A Dvoretsky, J. C. PortalAbstract:We study the transport properties of HgTe-based quantum wells containing simultaneously electrons and Holes in a magnetic field B. At the charge neutrality point (CNP) with nearly equal electron and Hole densities, the resistance is found to increase very strongly with B while the Hall resistivity turns to zero.
-
Breakdown of the quantum Hall effect in an electron–Hole System
Physica B-condensed Matter, 2001Co-Authors: Kei Takashina, Robin J. Nicholas, Beata Kardynal, N.j. Mason, D. K. Maude, J. C. PortalAbstract:Abstract We examine the edge states picture as applied to the electron–Hole System, and show that compensated quantum Hall states are fundamentally different to quantum Hall states of single carrier type Systems. Measurements of their current driven breakdown are described, and we show that these states have very small breakdown currents.
-
Edge effects in an insulating state of an electron–Hole System in magnetic field
Physica B-condensed Matter, 2001Co-Authors: Kei Takashina, Robin J. Nicholas, N.j. Mason, D. K. Maude, B. Kardynal, J. C. PortalAbstract:Abstract We find that an InAs/GaSb based electron–Hole System exhibits insulating behaviour when the numbers of occupied electron and Hole Landau levels are equal. In this insulating state, the Hall resistance becomes symmetric under field reversal, and both the Hall and longitudinal resistances display reproducible fluctuations. We propose a simple model based on edge states to account for these properties, and show that a comparison to the conductivity measured from a Corbino disc is consistent with the model.
Tod R Lauer - One of the best experts on this subject based on the ideXlab platform.
-
a candidate sub parsec supermassive binary black Hole System
Nature, 2009Co-Authors: Todd A Boroson, Tod R LauerAbstract:Binary supermassive black Hole Systems should be quite common, as the products of mergers between large galaxies, most of them with a black Hole at their centre. In a trawl for novel quasars in the Sloan Digital Sky Survey, Todd Boroson and Tod Lauer have now uncovered one such object, J153636.22+044127.0. It shows two broad-line emission Systems with different redshifts — 0.3727 and 0.3889 — equivalent to a velocity difference of 3,500 kilometres per second. They interpret the object as a binary System of two black Holes, with masses of 107.3 and 108.9 solar masses separated by about 0.1 parsec and with an orbital period of about 100 years. The discovery of this object provides support for theories that predict the formation of binary black Holes during galactic mega-mergers. The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black Holes in their nuclei, implies that binary supermassive black Hole Systems should be common. This study reports that the quasar SDSS J153636.22+044127.0 is a candidate binary, and shows two broad-line emission Systems, separated in velocity by 3,500 km s−1. The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black Holes in their nuclei1, implies that binary supermassive black Hole Systems should be common. Here we report that the quasar SDSS J153636.22+044127.0 is a plausible example of such a System. This quasar shows two broad-line emission Systems, separated in velocity by 3,500 km s-1. A third System of unresolved absorption lines has an intermediate velocity. These characteristics are unique among known quasars. We interpret this object as a binary System of two black Holes, having masses of 107.3 and 108.9 solar masses separated by ∼0.1 parsec with an orbital period of ∼100 years.