Browsing Faculty of Arts and Sciences by Author "Doeleman, Sheperd S."

Now showing items 1-13 of 13

    • Constraining the Structure of Sagittarius A*'s Accretion Flow with Millimeter Very Long Baseline Interferometry Closure Phases 

      Broderick, Avery E.; Fish, Vincent L.; Doeleman, Sheperd S.; Loeb, Abraham (American Astronomical Society, 2011)
      Millimeter wave very long baseline interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, on sub-horizon scales. ...

    • Detecting Changing Polarization Structures in Sagittarius A* With High Frequency Vlbi 

      Fish, Vincent L.; Doeleman, Sheperd S.; Broderick, Avery E.; Loeb, Abraham; Rogers, Alan E. E. (American Astronomical Society, 2009)
      Sagittarius A* is the source of near infrared, X-ray, radio, and (sub) millimeter emission associated with the supermassive black hole at the Galactic Center. In the submillimeter regime, Sgr A* exhibits time-variable ...

    • Detecting Flaring Structures in Sagittarius A* With High-frequency Vlbi 

      Doeleman, Sheperd S.; Fish, Vincent L.; Broderick, Avery E.; Loeb, Abraham; Rogers, Alan E. E. (American Astronomical Society, 2009)
      The super-massive black hole candidate, Sagittarius A*, exhibits variability from radio to X-ray wavelengths on timescales that correspond to < 10 Schwarzschild radii. We survey the potential of millimeter wavelength ...

    • Estimating the Parameters of Sagittarius A*'s Accretion Flow Via Millimeter Vlbi 

      Broderick, Avery E.; Fish, Vincent L.; Doeleman, Sheperd S.; Loeb, Abraham (American Astronomical Society, 2009)
      Recent millimeter-VLBI observations of Sagittarius A* (Sgr A*) have, for the first time, directly probed distances comparable to the horizon scale of a black hole. This provides unprecedented access to the environment ...

    • The Event Horizon of M87 

      Broderick, Avery E.; Narayan, Ramesh; Kormendy, John; Perlman, Eric S.; Rieke, Marcia J.; Doeleman, Sheperd S. (IOP Publishing, 2015)
      The 6 × 109M⊙ supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event Horizon Telescope have localized the emission from the ...

    • Event Horizon Telescope Evidence for Alignment of the Black Hole in the Center of the Milky Way With the Inner Stellar Disk 

      Psaltis, Dimitrios; Narayan, Ramesh; Fish, Vincent L.; Broderick, Avery E.; Loeb, Abraham; Doeleman, Sheperd S. (IOP Publishing, 2014)
      Observations of the black hole in the center of the Milky Way with the Event Horizon Telescope at 1.3 mm have revealed a size of the emitting region that is smaller than the size of the black-hole shadow. This can be ...

    • Evidence for Low Black Hole Spin and Physically Motivated Accretion Models From Millimeter-vlbi Observations of Sagittarius A* 

      Broderick, Avery E.; Fish, Vincent L.; Doeleman, Sheperd S.; Loeb, Abraham (American Astronomical Society, 2011)
      Millimeter very long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive ...

    • High-resolution Linear Polarimetric Imaging for the Event Horizon Telescope 

      Chael, Andrew A.; Johnson, Michael D.; Narayan, Ramesh; Doeleman, Sheperd S.; Wardle, John F. C.; Bouman, Katherine L. (American Astronomical Society, 2016)
      Images of the linear polarizations of synchrotron radiation around active galactic nuclei (AGNs) highlight their projected magnetic field lines and provide key data for understanding the physics of accretion and outflow ...

    • Imaging an Event Horizon: Mitigation of Scattering Toward Sagittarius A* 

      Fish, Vincent L.; Johnson, Michael D.; Lu, Ru-Sen; Doeleman, Sheperd S.; Bouman, Katherine L.; Zoran, Daniel; Freeman, William T.; Psaltis, Dimitrios; Narayan, Ramesh; Pankratius, Victor; Broderick, Avery E.; Gwinn, Carl R.; Vertatschitsch, Laura E. (IOP Publishing, 2014)
      The image of the emission surrounding the black hole in the center of the Milky Way is predicted to exhibit the imprint of general relativistic (GR) effects, including the existence of a shadow feature and a photon ring ...

    • Measuring the Direction and Angular Velocity of a Black Hole Accretion Disk Via Lagged Interferometric Covariance 

      Johnson, Michael D.; Loeb, Abraham; Shiokawa, Hotaka; Chael, Andrew A.; Doeleman, Sheperd S. (American Astronomical Society, 2015)
      We show that interferometry can be applied to study irregular, rapidly rotating structures, as are expected in the turbulent accretion flow near a black hole. Specifically, we analyze the lagged covariance between ...

    • Resolving the Inner Jet Structure of 1924-292 with the Event Horizon Telescope 

      Lu, Ru-Sen; Fish, Vincent L.; Weintroub, Jonathan; Doeleman, Sheperd S.; Bower, Geoffrey C.; Freund, Robert; Friberg, Per; Ho, Paul T. P.; Honma, Mareki; Inoue, Makoto; Krichbaum, Thomas P.; Marrone, Daniel P.; Moran, James M.; Oyama, Tomoaki; Plambeck, Richard; Primiani, Rurik; Shen, Zhi-Qiang; Tilanus, Remo P. J.; Wright, Melvyn; Young, Ken H.; Ziurys, Lucy M.; Zensus, J. Anton (American Astronomical Society, 2012)
      We present the first 1.3 mm (230 GHz) very long baseline interferometry model image of an active galactic nucleus (AGN) jet using closure phase techniques with a four-element array. The model image of the quasar 1924-292 ...

    • Testing General Relativity with Accretion-Flow Imaging of Sgr A * 

      Johannsen, Tim; Wang, Carlos; Broderick, Avery E.; Doeleman, Sheperd S.; Fish, Vincent L.; Loeb, Abraham; Psaltis, Dimitrios (American Physical Society, 2016)
      The Event Horizon Telescope is a global, very long baseline interferometer capable of probing potential deviations from the Kerr metric, which is believed to provide the unique description of astrophysical black holes. ...

    • Using Millimeter Vlbi to Constrain Riaf Models of Sagittarius A* 

      Fish, Vincent L.; Broderick, Avery E.; Doeleman, Sheperd S.; Loeb, Abraham (American Astronomical Society, 2009)
      The recent detection of Sagittarius A* lambda = 1.3 mm on a baseline from Hawaii to Arizona demonstrates that millimeter wavelength very long baseline interferometry (VLBI) can now spatially resolve emission from the ...