The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA

S. Issaoun; M. D. Johnson; L. Blackburn; C. D. Brinkerink; M. Mościbrodzka; A. Chael; C. Goddi; I. Marti-Vidal; J. Wagner; S. S. Doeleman; H. Falcke; T. P. Krichbaum; K. Akiyama; U. Bach; K. L. Bouman; G. C. Bower; A. Broderick; I. Cho; G. Crew; J. Dexter; V. Fish; R. Gold; J. L. Gómez; K. Hada; A. Hernández-Gómez; M. Janßen; M. Kino; M. Kramer; L. Loinard; R. S. Lu; S. Markoff; D. P. Marrone; L. D. Matthews; J. M. Moran; C. Müller; F. Roelofs; E. Ros; H. Rottmann; S. Sanchez; R. P.J. Tilanus; P. De Vicente; M. Wielgus; J. A. Zensus; G. Y. Zhao

doi:10.3847/1538-4357/aaf732

The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA

S. Issaoun, M. D. Johnson, L. Blackburn, C. D. Brinkerink, M. Mościbrodzka, A. Chael, C. Goddi, I. Marti-Vidal, J. Wagner, S. S. Doeleman, H. Falcke, T. P. Krichbaum, K. Akiyama, U. Bach, K. L. Bouman, G. C. Bower, A. Broderick, I. Cho, G. Crew, J. DexterV. Fish, R. Gold, J. L. Gómez, K. Hada, A. Hernández-Gómez, M. Janßen, M. Kino, M. Kramer, L. Loinard, R. S. Lu, S. Markoff, D. P. Marrone, L. D. Matthews, J. M. Moran, C. Müller, F. Roelofs, E. Ros, H. Rottmann, S. Sanchez, R. P.J. Tilanus, P. De Vicente, M. Wielgus, J. A. Zensus, G. Y. Zhao

Astronomy

Research output: Contribution to journal › Article › peer-review

88 Scopus citations

Abstract

The Galactic center supermassive black hole Sagittarius A∗ (Sgr A∗) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A∗ is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A∗ with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ∼87 μas, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A∗ at 3.5 mm, mitigating the effects of interstellar scattering. The unscattered source has a major-axis size of 120 ±34 μas (12 ±3.4 Schwarzschild radii) and a symmetrical morphology (axial ratio of ), which is further supported by closure phases consistent with zero within 3σ. We show that multiple disk-dominated models of Sgr A∗ match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A∗, and we show that refractive scattering effects are likely to be weak for images of Sgr A∗ at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A∗, demonstrating the exceptional contribution of ALMA to millimeter VLBI.

Original language	English (US)
Article number	30
Journal	Astrophysical Journal
Volume	871
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aaf732
State	Published - Jan 20 2019

Keywords

Galaxy: center
accretion, accretion disks
galaxies: individual (Sgr A∗)
techniques: interferometric

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.3847/1538-4357/aaf732

Cite this

Issaoun, S., Johnson, M. D., Blackburn, L., Brinkerink, C. D., Mościbrodzka, M., Chael, A., Goddi, C., Marti-Vidal, I., Wagner, J., Doeleman, S. S., Falcke, H., Krichbaum, T. P., Akiyama, K., Bach, U., Bouman, K. L., Bower, G. C., Broderick, A., Cho, I., Crew, G., ... Zhao, G. Y. (2019). The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA. Astrophysical Journal, 871(1), Article 30. https://doi.org/10.3847/1538-4357/aaf732

Issaoun, S, Johnson, MD, Blackburn, L, Brinkerink, CD, Mościbrodzka, M, Chael, A, Goddi, C, Marti-Vidal, I, Wagner, J, Doeleman, SS, Falcke, H, Krichbaum, TP, Akiyama, K, Bach, U, Bouman, KL, Bower, GC, Broderick, A, Cho, I, Crew, G, Dexter, J, Fish, V, Gold, R, Gómez, JL, Hada, K, Hernández-Gómez, A, Janßen, M, Kino, M, Kramer, M, Loinard, L, Lu, RS, Markoff, S, Marrone, DP, Matthews, LD, Moran, JM, Müller, C, Roelofs, F, Ros, E, Rottmann, H, Sanchez, S, Tilanus, RPJ, Vicente, PD, Wielgus, M, Zensus, JA & Zhao, GY 2019, 'The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA', Astrophysical Journal, vol. 871, no. 1, 30. https://doi.org/10.3847/1538-4357/aaf732

@article{318e6637a5b9431ebb5c95c3ed90ae1c,

title = "The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA",

abstract = "The Galactic center supermassive black hole Sagittarius A∗ (Sgr A∗) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A∗ is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A∗ with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ∼87 μas, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A∗ at 3.5 mm, mitigating the effects of interstellar scattering. The unscattered source has a major-axis size of 120 ±34 μas (12 ±3.4 Schwarzschild radii) and a symmetrical morphology (axial ratio of ), which is further supported by closure phases consistent with zero within 3σ. We show that multiple disk-dominated models of Sgr A∗ match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A∗, and we show that refractive scattering effects are likely to be weak for images of Sgr A∗ at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A∗, demonstrating the exceptional contribution of ALMA to millimeter VLBI.",

keywords = "Galaxy: center, accretion, accretion disks, galaxies: individual (Sgr A∗), techniques: interferometric",

author = "S. Issaoun and Johnson, {M. D.} and L. Blackburn and Brinkerink, {C. D.} and M. Mo{\'s}cibrodzka and A. Chael and C. Goddi and I. Marti-Vidal and J. Wagner and Doeleman, {S. S.} and H. Falcke and Krichbaum, {T. P.} and K. Akiyama and U. Bach and Bouman, {K. L.} and Bower, {G. C.} and A. Broderick and I. Cho and G. Crew and J. Dexter and V. Fish and R. Gold and G{\'o}mez, {J. L.} and K. Hada and A. Hern{\'a}ndez-G{\'o}mez and M. Jan{\ss}en and M. Kino and M. Kramer and L. Loinard and Lu, {R. S.} and S. Markoff and Marrone, {D. P.} and Matthews, {L. D.} and Moran, {J. M.} and C. M{\"u}ller and F. Roelofs and E. Ros and H. Rottmann and S. Sanchez and Tilanus, {R. P.J.} and Vicente, {P. De} and M. Wielgus and Zensus, {J. A.} and Zhao, {G. Y.}",

year = "2019",

month = jan,

day = "20",

doi = "10.3847/1538-4357/aaf732",

language = "English (US)",

volume = "871",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

TY - JOUR

T1 - The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz

T2 - First VLBI with ALMA

AU - Issaoun, S.

AU - Johnson, M. D.

AU - Blackburn, L.

AU - Brinkerink, C. D.

AU - Mościbrodzka, M.

AU - Chael, A.

AU - Goddi, C.

AU - Marti-Vidal, I.

AU - Wagner, J.

AU - Doeleman, S. S.

AU - Falcke, H.

AU - Krichbaum, T. P.

AU - Akiyama, K.

AU - Bach, U.

AU - Bouman, K. L.

AU - Bower, G. C.

AU - Broderick, A.

AU - Cho, I.

AU - Crew, G.

AU - Dexter, J.

AU - Fish, V.

AU - Gold, R.

AU - Gómez, J. L.

AU - Hada, K.

AU - Hernández-Gómez, A.

AU - Janßen, M.

AU - Kino, M.

AU - Kramer, M.

AU - Loinard, L.

AU - Lu, R. S.

AU - Markoff, S.

AU - Marrone, D. P.

AU - Matthews, L. D.

AU - Moran, J. M.

AU - Müller, C.

AU - Roelofs, F.

AU - Ros, E.

AU - Rottmann, H.

AU - Sanchez, S.

AU - Tilanus, R. P.J.

AU - Vicente, P. De

AU - Wielgus, M.

AU - Zensus, J. A.

AU - Zhao, G. Y.

PY - 2019/1/20

Y1 - 2019/1/20

N2 - The Galactic center supermassive black hole Sagittarius A∗ (Sgr A∗) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A∗ is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A∗ with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ∼87 μas, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A∗ at 3.5 mm, mitigating the effects of interstellar scattering. The unscattered source has a major-axis size of 120 ±34 μas (12 ±3.4 Schwarzschild radii) and a symmetrical morphology (axial ratio of ), which is further supported by closure phases consistent with zero within 3σ. We show that multiple disk-dominated models of Sgr A∗ match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A∗, and we show that refractive scattering effects are likely to be weak for images of Sgr A∗ at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A∗, demonstrating the exceptional contribution of ALMA to millimeter VLBI.

AB - The Galactic center supermassive black hole Sagittarius A∗ (Sgr A∗) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A∗ is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A∗ with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ∼87 μas, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A∗ at 3.5 mm, mitigating the effects of interstellar scattering. The unscattered source has a major-axis size of 120 ±34 μas (12 ±3.4 Schwarzschild radii) and a symmetrical morphology (axial ratio of ), which is further supported by closure phases consistent with zero within 3σ. We show that multiple disk-dominated models of Sgr A∗ match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A∗, and we show that refractive scattering effects are likely to be weak for images of Sgr A∗ at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A∗, demonstrating the exceptional contribution of ALMA to millimeter VLBI.

KW - Galaxy: center

KW - accretion, accretion disks

KW - galaxies: individual (Sgr A∗)

KW - techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=85062038601&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85062038601&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aaf732

DO - 10.3847/1538-4357/aaf732

M3 - Article

AN - SCOPUS:85062038601

SN - 0004-637X

VL - 871

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 30

ER -

The Size, Shape, and Scattering of Sagittarius A∗ at 86 GHz: First VLBI with ALMA

Abstract

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this