Ramesh Narayan

About

Ramesh Narayan is the Thomas Dudley Cabot Professor of the Natural Sciences at Harvard University. He is affiliated with the Harvard-Smithsonian Center for Astrophysics, located at 60 Garden Street, MS-51, Cambridge, MA. His contact information includes an office phone number (617) 496-9393, fax (617) 495-7093, and email rnarayan@cfa.harvard.edu. The available information references his curriculum vitae, recent publications, and links to the Harvard-Smithsonian Center for Astrophysics and Harvard University Astronomy Department. No additional details about his research focus, background, or key contributions are provided in the text.

Research topics

• Astrophysics
• Physics
• Astronomy
• Computational physics
• Optics
• Computer Science
• Geology
• Nuclear physics
• Quantum mechanics
• Remote sensing

Selected publications

• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way

  The Astrophysical Journal Letters · 2022 · 1712 citations

  Abstract We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), the Galactic center source associated with a supermassive black hole. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT data resolve a compact emission region with intrahour variability. A variety of imaging and modeling analyses all support an image that is dominated by a bright, thick ring with a d…

  DOI

• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon

  The Astrophysical Journal Letters · 2021 · 640 citations

  Abstract Event Horizon Telescope (EHT) observations at 230 GHz have now imaged polarized emission around the supermassive black hole in M87 on event-horizon scales. This polarized synchrotron radiation probes the structure of magnetic fields and the plasma properties near the black hole. Here we compare the resolved polarization structure observed by the EHT, along with simultaneous unresolved observations with the Atacama Large Millimeter/submillimeter Array, to expectations from theoretical mo…

  DOI

• First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric

  The Astrophysical Journal Letters · 2022 · 627 citations

  Abstract Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein’s equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A*). We calibrate the relationship between the geometrically defined black hole shadow and the obser…

  DOI

• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole

  The Astrophysical Journal Letters · 2022 · 514 citations

  Abstract In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal an…

  DOI

• Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

  The Astrophysical Journal Letters · 2021 · 98 citations

  In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ~6.5 × 109M⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of…

  DOI

Recent grants

• Three Dimensional Radiation GRMHD Simulations of Accretion Flows Around Black Holes

  NSF · $698k · 2013–2019

• Measuring Black Hole Spin: Physics of the Inner Region of an Accretion Disk

  NSF · $131k · 2008–2012

• Studies of Accretion onto Black Holes

  NSF · $331k · 2018–2023

Frequent coauthors

• G. Desvignes

  596 shared

• Jonathan Weintroub

  Center for Astrophysics Harvard & Smithsonian

  546 shared

• Kazunori Akiyama

  516 shared

• Ue‐Li Pen

  476 shared

• Shiro Ikeda

  The University of Tokyo

  465 shared

• Sheperd S. Doeleman

  423 shared

• Lindy Blackburn

  Center for Astrophysics Harvard & Smithsonian

  412 shared

• R. P. J. Tilanus

  Dutch Research Council

  405 shared

Education

• Ph.D., Astronomy

  Harvard University

  1991

• M.S., Astronomy

  Harvard University

  1986

• B.S., Physics

  Harvard University

  1983

Similar researchers at Harvard University

• Christopher Stubbsh-126
• David Charbonneauh-112
• Robert P. Kirshnerh-112