Person: Primiani, Rurik
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Primiani
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Rurik
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Primiani, Rurik
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Publication Jet-Launching Structure Resolved Near the Supermassive Black Hole in M87(American Association for the Advancement of Science (AAAS), 2012) Doeleman, Sheperd; Fish, V. L.; Schenck, D. E.; Beaudoin, C.; Blundell, Raymond; Bower, G. C.; Broderick, Alithia Carol; Chamberlin, R.; Freund, R.; Friberg, P.; Gurwell, Mark; Ho, Po-Yi; Honma, M.; Inoue, M.; Krichbaum, T. P.; Lamb, Justin; Loeb, Abraham; Lonsdale, C.; Marrone, D. P.; Moran, James; Oyama, T.; Plambeck, R.; Primiani, Rurik; Rogers, A. E. E.; Smythe, D. L.; SooHoo, J.; Strittmatter, P.; Tilanus, R. P. J.; Titus, M.; Weintroub, Jonathan; Wright, Bennett Bennett; Young, K. H.; Ziurys, L. M.Approximately 10% of active galactic nuclei exhibit relativistic jets, which are powered by accretion of matter onto super massive black holes. While the measured width profiles of such jets on large scales agree with theories of magnetic collimation, predicted structure on accretion disk scales at the jet launch point has not been detected. We report radio interferometry observations at 1.3mm wavelength of the elliptical galaxy M87 that spatially resolve the base of the jet in this source. The derived size of 5.5 +/- 0.4 Schwarzschild radii is significantly smaller than the innermost edge of a retrograde accretion disk, suggesting that the M87 jet is powered by an accretion disk in a prograde orbit around a spinning black hole.Publication Fine-Scale Structure of the Quasar 3C 279 Measured with 1.3 mm Very Long Baseline Interferometry(American Astronomical Society, 2013) Lu, Ru-Sen; Fish, Vincent L.; Akiyama, Kazunori; Doeleman, Sheperd; Algaba, Juan C.; Bower, Geoffrey C.; Brinkerink, Christiaan; Chamberlin, Richard; Crew, Geoffrey; Cappallo, Roger J.; Dexter, Matt; Freund, Robert; Friberg, Per; Gurwell, Mark; Ho, Paul T. P.; Honma, Mareki; Inoue, Makoto; Jorstad, Svetlana G.; Krichbaum, Thomas P.; Loinard, Laurent; MacMahon, David; Marrone, Daniel P.; Marscher, Alan P.; Moran, James; Plambeck, Richard; Pradel, Nicolas; Primiani, Rurik; Tilanus, Remo P. J.; Titus, Michael; Weintroub, Jonathan; Wright, Melvyn; Young, Ken; Ziurys, Lucy M.We report results from five day very long baseline interferometry observations of the well-known quasar 3C 279 at 1.3mm (230 GHz) in 2011. The measured nonzero closure phases on triangles including stations in Arizona, California, and Hawaii indicate that the source structure is spatially resolved. We find an unusual inner jet direction at scales of ~1 pc extending along the northwest-southeast direction \((P.A. = 127^{\circ} \pm 3^{\circ})\), as opposed to other (previously) reported measurements on scales of a few parsecs showing inner jet direction extending to the southwest. The 1.3mm structure corresponds closely with that observed in the central region of quasi-simultaneous super-resolution Very Long Baseline Array images at 7 mm. The closure phase changed significantly on the last day when compared with the rest of observations, indicating that the inner jet structure may be variable on daily timescales. The observed new direction of the inner jet shows inconsistency with the prediction of a class of jet precession models. Our observations indicate a brightness temperature of \(\sim 8 \times 1010 K\) in the 1.3mm core, much lower than that at centimeter wavelengths. Observations with better uv coverage and sensitivity in the coming years will allow the discrimination between different structure models and will provide direct images of the inner regions of the jet with 20-30 μas (5-7 light months) resolution.Publication 230 GHz VLBI observations of M87: event-horizon-scale structure at the enhanced very-high-energy γ-ray state in 2012(IOP Publishing, 2015) Akiyama, Kazunori; Lu, Ru-Sen; Fish, Vincent; Doeleman, Sheperd; Broderick, Avery; Dexter, Jason; Hada, Kazuhiro; Kino, Motoki; Nagai, Hiroshi; Honma, Mareki; Johnson, Michael; Algaba, Juan; Asada, Keiichi; Brinkerink, Christiaan; Blundell, Raymond; Bower, Geoffrey; Cappallo, Roger; Crew, Geoffrey; Dexter, Matt; Dzib, Sergio; Freund, Robert; Friberg, Per; Gurwell, Mark; Ho, Paul; Inoue, Makoto; Krichbaum, Thomas; Loinard, Laurent; MacMahon, David; Marrone, Daniel; Moran, James; Nakamura, Masanori; Nagar, Neil; Ortiz-Leon, Gisela; Plambeck, Richard; Pradel, Nicolas; Primiani, Rurik; Rogers, Alan; Roy, Alan; SooHoo, Jason; Tavares, Jonathan-León; Tilanus, Remo; Titus, Michael; Wagner, Jan; Weintroub, Jonathan; Yamaguchi, Paul; Young, Ken; Zensus, Anton; Ziurys, LucyWe report on 230 GHz (1.3 mm) VLBI observations of M87 with the Event Horizon Telescope using antennas on Mauna Kea in Hawaii, Mt. Graham in Arizona and Cedar Flat in California. For the first time, we have acquired 230 GHz VLBI interferometric phase information on M87 through measurement of closure phase on the triangle of long baselines. Most of the measured closure phases are consistent with 0◦ as expected by physically-motivated models for 230 GHz structure such as jet models and accretion disk models. The brightness temperature of the event-horizon-scale structure is ∼ 1 × 1010 K derived from the compact flux density of ∼ 1 Jy and the angular size of ∼ 40 µas ∼ 5.5 Rs, which is broadly consistent with the peak brightness of the radio cores at 1-86 GHz located within ∼ 102 Rs. Our observations occurred in the middle of an enhancement in very-high-energy (VHE) γ-ray flux, presumably originating in the vicinity of the central black hole. Our measurements, combined with results of multi-wavelength observations, favor a scenario in which the VHE region has an extended size of ∼20-60 Rs.Publication 1.3 mm Wavelength VLBI of Sagittarius A*: Detection of Time-Variable Emission on Event Horizon Scales(IOP Publishing, 2011) Fish, Vincent L.; Doeleman, Sheperd; Beaudoin, Christopher; Blundell, Raymond; Bolin, David E.; Bower, Geoffrey C.; Chamberlin, Richard; Freund, Robert; Friberg, Per; Gurwell, Mark; Honma, Mareki; Inoue, Makoto; Krichbaum, Thomas P.; Lamb, James; Marrone, Daniel P.; Moran, James; Oyama, Tomoaki; Plambeck, Richard; Primiani, Rurik; Rogers, Alan E. E.; Smythe, Daniel L.; SooHoo, Jason; Strittmatter, Peter; Tilanus, Remo P. J.; Titus, Michael; Weintroub, Jonathan; Wright, Melvyn; Woody, David; Young, Ken; Ziurys, Lucy M.Sagittarius A*, the ~4 × 106 M ☉ black hole candidate at the Galactic center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength very long baseline interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the Arizona Radio Observatory's Submillimeter Telescope on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat in California. Both Sgr A* and the quasar calibrator 1924–292 were observed over three consecutive nights, and both sources were clearly detected on all baselines. For the first time, we are able to extract 1.3 mm VLBI interferometer phase information on Sgr A* through measurement of closure phase on the triangle of baselines. On the third night of observing, the correlated flux density of Sgr A* on all VLBI baselines increased relative to the first two nights, providing strong evidence for time-variable change on scales of a few Schwarzschild radii. These results suggest that future VLBI observations with greater sensitivity and additional baselines will play a valuable role in determining the structure of emission near the event horizon of Sgr A*.Publication Resolved magnetic-field structure and variability near the event horizon of Sagittarius A(American Association for the Advancement of Science (AAAS), 2015) Johnson, Michael; Fish, V. L.; Doeleman, Sheperd; Marrone, D. P.; Plambeck, R. L.; Wardle, J. F. C.; Akiyama, K.; Asada, K.; Beaudoin, C.; Blackburn, Lindy; Blundell, Raymond; Bower, G. C.; Brinkerink, C.; Broderick, A. E.; Cappallo, R.; Chael, Andrew; Crew, G. B.; Dexter, J.; Dexter, M.; Freund, R.; Friberg, P.; Gold, R.; Gurwell, M. A.; Ho, P. T. P.; Honma, M.; Inoue, M.; Kosowsky, Michael; Krichbaum, T. P.; Lamb, J.; Loeb, Abraham; Lu, R.-S.; MacMahon, D.; McKinney, J. C.; Moran, James; Narayan, Ramesh; Primiani, Rurik; Psaltis, D.; Rogers, A. E. E.; Rosenfeld, Katherine; SooHoo, J.; Tilanus, R. P. J.; Titus, M.; Vertatschitsch, L.; Weintroub, Jonathan; Wright, M.; Young, Ken; Zensus, J. A.; Ziurys, L. M.Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizonscale magnetic-field structure. We report interferometric observations at 1.3- millimeter wavelength that spatially resolve the linearly polarized emission from the Galactic Center supermassive black hole, Sagittarius A*. We have found evidence for partially ordered fields near the event horizon, on scales of ∼6 Schwarzschild radii, and we have detected and localized the intra-hour variability associated with these fields.