Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗

Ru Sen Lu, Thomas P. Krichbaum, Alan L. Roy, Vincent L. Fish, Sheperd S. Doeleman, Michael D. Johnson, Kazunori Akiyama, Dimitrios Psaltis, Walter Alef, Keiichi Asada, Christopher Beaudoin, Alessandra Bertarini, Lindy Blackburn, Ray Blundell, Geoffrey C. Bower, Christiaan Brinkerink, Avery E. Broderick, Roger Cappallo, Geoffrey B. Crew, Jason DexterMatt Dexter, Heino Falcke, Robert Freund, Per Friberg, Christopher H. Greer, Mark A. Gurwell, Paul T.P. Ho, Mareki Honma, Makoto Inoue, Junhan Kim, James Lamb, Michael Lindqvist, David Macmahon, Daniel P Marrone, Ivan Marti-Vidal, Karl M. Menten, James M. Moran, Neil M. Nagar, Richard L. Plambeck, Rurik A. Primiani, Alan E.E. Rogers, Eduardo Ros, Helge Rottmann, Jason Soohoo, Justin Spilker, Jordan Stone, Peter A Strittmatter, Remo P.J. Tilanus, Michael Titus, Laura Vertatschitsch, Jan Wagner, Jonathan Weintroub, Melvyn Wright, Ken H. Young, J. Anton Zensus, Lucy M Ziurys

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A∗, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ∼30 μas (∼3 Schwarzschild radii) for Sgr A∗. The source is detected even at the longest baselines with visibility amplitudes of ∼4%-13% of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of ∼3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.

Original languageEnglish (US)
Article number60
JournalAstrophysical Journal
Volume859
Issue number1
DOIs
StatePublished - May 20 2018

Fingerprint

radii
Chile
flux density
phase rule
visibility
brightness distribution
asymmetry
spatial resolution
bears
scattering
closures
horizon
brightness
stations
telescopes
detection
sensitivity
distribution
station
physical process

Keywords

  • Galaxy: center
  • submillimeter: general
  • techniques: high angular resolution
  • techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗. / Lu, Ru Sen; Krichbaum, Thomas P.; Roy, Alan L.; Fish, Vincent L.; Doeleman, Sheperd S.; Johnson, Michael D.; Akiyama, Kazunori; Psaltis, Dimitrios; Alef, Walter; Asada, Keiichi; Beaudoin, Christopher; Bertarini, Alessandra; Blackburn, Lindy; Blundell, Ray; Bower, Geoffrey C.; Brinkerink, Christiaan; Broderick, Avery E.; Cappallo, Roger; Crew, Geoffrey B.; Dexter, Jason; Dexter, Matt; Falcke, Heino; Freund, Robert; Friberg, Per; Greer, Christopher H.; Gurwell, Mark A.; Ho, Paul T.P.; Honma, Mareki; Inoue, Makoto; Kim, Junhan; Lamb, James; Lindqvist, Michael; Macmahon, David; Marrone, Daniel P; Marti-Vidal, Ivan; Menten, Karl M.; Moran, James M.; Nagar, Neil M.; Plambeck, Richard L.; Primiani, Rurik A.; Rogers, Alan E.E.; Ros, Eduardo; Rottmann, Helge; Soohoo, Jason; Spilker, Justin; Stone, Jordan; Strittmatter, Peter A; Tilanus, Remo P.J.; Titus, Michael; Vertatschitsch, Laura; Wagner, Jan; Weintroub, Jonathan; Wright, Melvyn; Young, Ken H.; Zensus, J. Anton; Ziurys, Lucy M.

In: Astrophysical Journal, Vol. 859, No. 1, 60, 20.05.2018.

Research output: Contribution to journalArticle

Lu, RS, Krichbaum, TP, Roy, AL, Fish, VL, Doeleman, SS, Johnson, MD, Akiyama, K, Psaltis, D, Alef, W, Asada, K, Beaudoin, C, Bertarini, A, Blackburn, L, Blundell, R, Bower, GC, Brinkerink, C, Broderick, AE, Cappallo, R, Crew, GB, Dexter, J, Dexter, M, Falcke, H, Freund, R, Friberg, P, Greer, CH, Gurwell, MA, Ho, PTP, Honma, M, Inoue, M, Kim, J, Lamb, J, Lindqvist, M, Macmahon, D, Marrone, DP, Marti-Vidal, I, Menten, KM, Moran, JM, Nagar, NM, Plambeck, RL, Primiani, RA, Rogers, AEE, Ros, E, Rottmann, H, Soohoo, J, Spilker, J, Stone, J, Strittmatter, PA, Tilanus, RPJ, Titus, M, Vertatschitsch, L, Wagner, J, Weintroub, J, Wright, M, Young, KH, Zensus, JA & Ziurys, LM 2018, 'Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗', Astrophysical Journal, vol. 859, no. 1, 60. https://doi.org/10.3847/1538-4357/aabe2e
Lu, Ru Sen ; Krichbaum, Thomas P. ; Roy, Alan L. ; Fish, Vincent L. ; Doeleman, Sheperd S. ; Johnson, Michael D. ; Akiyama, Kazunori ; Psaltis, Dimitrios ; Alef, Walter ; Asada, Keiichi ; Beaudoin, Christopher ; Bertarini, Alessandra ; Blackburn, Lindy ; Blundell, Ray ; Bower, Geoffrey C. ; Brinkerink, Christiaan ; Broderick, Avery E. ; Cappallo, Roger ; Crew, Geoffrey B. ; Dexter, Jason ; Dexter, Matt ; Falcke, Heino ; Freund, Robert ; Friberg, Per ; Greer, Christopher H. ; Gurwell, Mark A. ; Ho, Paul T.P. ; Honma, Mareki ; Inoue, Makoto ; Kim, Junhan ; Lamb, James ; Lindqvist, Michael ; Macmahon, David ; Marrone, Daniel P ; Marti-Vidal, Ivan ; Menten, Karl M. ; Moran, James M. ; Nagar, Neil M. ; Plambeck, Richard L. ; Primiani, Rurik A. ; Rogers, Alan E.E. ; Ros, Eduardo ; Rottmann, Helge ; Soohoo, Jason ; Spilker, Justin ; Stone, Jordan ; Strittmatter, Peter A ; Tilanus, Remo P.J. ; Titus, Michael ; Vertatschitsch, Laura ; Wagner, Jan ; Weintroub, Jonathan ; Wright, Melvyn ; Young, Ken H. ; Zensus, J. Anton ; Ziurys, Lucy M. / Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗. In: Astrophysical Journal. 2018 ; Vol. 859, No. 1.
@article{7e615afee15a4a88a2e03791b430b0ec,
title = "Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗",
abstract = "We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A∗, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ∼30 μas (∼3 Schwarzschild radii) for Sgr A∗. The source is detected even at the longest baselines with visibility amplitudes of ∼4{\%}-13{\%} of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of ∼3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.",
keywords = "Galaxy: center, submillimeter: general, techniques: high angular resolution, techniques: interferometric",
author = "Lu, {Ru Sen} and Krichbaum, {Thomas P.} and Roy, {Alan L.} and Fish, {Vincent L.} and Doeleman, {Sheperd S.} and Johnson, {Michael D.} and Kazunori Akiyama and Dimitrios Psaltis and Walter Alef and Keiichi Asada and Christopher Beaudoin and Alessandra Bertarini and Lindy Blackburn and Ray Blundell and Bower, {Geoffrey C.} and Christiaan Brinkerink and Broderick, {Avery E.} and Roger Cappallo and Crew, {Geoffrey B.} and Jason Dexter and Matt Dexter and Heino Falcke and Robert Freund and Per Friberg and Greer, {Christopher H.} and Gurwell, {Mark A.} and Ho, {Paul T.P.} and Mareki Honma and Makoto Inoue and Junhan Kim and James Lamb and Michael Lindqvist and David Macmahon and Marrone, {Daniel P} and Ivan Marti-Vidal and Menten, {Karl M.} and Moran, {James M.} and Nagar, {Neil M.} and Plambeck, {Richard L.} and Primiani, {Rurik A.} and Rogers, {Alan E.E.} and Eduardo Ros and Helge Rottmann and Jason Soohoo and Justin Spilker and Jordan Stone and Strittmatter, {Peter A} and Tilanus, {Remo P.J.} and Michael Titus and Laura Vertatschitsch and Jan Wagner and Jonathan Weintroub and Melvyn Wright and Young, {Ken H.} and Zensus, {J. Anton} and Ziurys, {Lucy M}",
year = "2018",
month = "5",
day = "20",
doi = "10.3847/1538-4357/aabe2e",
language = "English (US)",
volume = "859",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Detection of Intrinsic Source Structure at ∼3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A∗

AU - Lu, Ru Sen

AU - Krichbaum, Thomas P.

AU - Roy, Alan L.

AU - Fish, Vincent L.

AU - Doeleman, Sheperd S.

AU - Johnson, Michael D.

AU - Akiyama, Kazunori

AU - Psaltis, Dimitrios

AU - Alef, Walter

AU - Asada, Keiichi

AU - Beaudoin, Christopher

AU - Bertarini, Alessandra

AU - Blackburn, Lindy

AU - Blundell, Ray

AU - Bower, Geoffrey C.

AU - Brinkerink, Christiaan

AU - Broderick, Avery E.

AU - Cappallo, Roger

AU - Crew, Geoffrey B.

AU - Dexter, Jason

AU - Dexter, Matt

AU - Falcke, Heino

AU - Freund, Robert

AU - Friberg, Per

AU - Greer, Christopher H.

AU - Gurwell, Mark A.

AU - Ho, Paul T.P.

AU - Honma, Mareki

AU - Inoue, Makoto

AU - Kim, Junhan

AU - Lamb, James

AU - Lindqvist, Michael

AU - Macmahon, David

AU - Marrone, Daniel P

AU - Marti-Vidal, Ivan

AU - Menten, Karl M.

AU - Moran, James M.

AU - Nagar, Neil M.

AU - Plambeck, Richard L.

AU - Primiani, Rurik A.

AU - Rogers, Alan E.E.

AU - Ros, Eduardo

AU - Rottmann, Helge

AU - Soohoo, Jason

AU - Spilker, Justin

AU - Stone, Jordan

AU - Strittmatter, Peter A

AU - Tilanus, Remo P.J.

AU - Titus, Michael

AU - Vertatschitsch, Laura

AU - Wagner, Jan

AU - Weintroub, Jonathan

AU - Wright, Melvyn

AU - Young, Ken H.

AU - Zensus, J. Anton

AU - Ziurys, Lucy M

PY - 2018/5/20

Y1 - 2018/5/20

N2 - We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A∗, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ∼30 μas (∼3 Schwarzschild radii) for Sgr A∗. The source is detected even at the longest baselines with visibility amplitudes of ∼4%-13% of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of ∼3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.

AB - We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A∗, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ∼30 μas (∼3 Schwarzschild radii) for Sgr A∗. The source is detected even at the longest baselines with visibility amplitudes of ∼4%-13% of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of ∼3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.

KW - Galaxy: center

KW - submillimeter: general

KW - techniques: high angular resolution

KW - techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=85048028220&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85048028220&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aabe2e

DO - 10.3847/1538-4357/aabe2e

M3 - Article

AN - SCOPUS:85048028220

VL - 859

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 60

ER -