Testing the no-hair theorem with event horizon telescope observations of sagittarius A*

Avery E. Broderick, Tim Johannsen, Abraham Loeb, Dimitrios Psaltis

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The advent of the Event Horizon Telescope (EHT), a millimeter-wave very long baseline interferometric array, has enabled spatially resolved studies of the subhorizon-scale structure for a handful of supermassive black holes. Among these, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), presents the largest angular cross section. Thus far, these studies have focused on measurements of the black hole spin and the validation of low-luminosity accretion models. However, a critical input in the analysis of EHT data is the structure of the black hole spacetime, and thus these observations provide the novel opportunity to test the applicability of the Kerr metric to astrophysical black holes. Here we present the first simulated images of a radiatively inefficient accretion flow (RIAF) around Sgr A* employing a quasi-Kerr metric that contains an independent quadrupole moment in addition to the mass and spin that fully characterize a black hole in general relativity. We show that these images can be significantly different from the images of an RIAF around a Kerr black hole with the same spin and demonstrate the feasibility of testing the no-hair theorem by constraining the quadrupolar deviation from the Kerr metric with existing EHT data. Equally important, we find that the disk inclination and spin orientation angles are robust to the inclusion of additional parameters, providing confidence in previous estimations assuming the Kerr metric based on EHT observations. However, at present, the limits on potential modifications of the Kerr metric remain weak.

Original languageEnglish (US)
Article number7
JournalAstrophysical Journal
Volume784
Issue number1
DOIs
StatePublished - Mar 20 2014

Fingerprint

event horizon
hair
theorems
accretion
telescopes
cross section
Very Long Baseline Array (VLBA)
millimeter waves
inclination
relativity
confidence
astrophysics
quadrupoles
luminosity
inclusions
moments
deviation
cross sections

Keywords

  • accretion, accretion disks
  • black hole physics
  • Galaxy: center
  • gravitation
  • submillimeter: general
  • techniques: interferometric

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Testing the no-hair theorem with event horizon telescope observations of sagittarius A*. / Broderick, Avery E.; Johannsen, Tim; Loeb, Abraham; Psaltis, Dimitrios.

In: Astrophysical Journal, Vol. 784, No. 1, 7, 20.03.2014.

Research output: Contribution to journalArticle

Broderick, Avery E. ; Johannsen, Tim ; Loeb, Abraham ; Psaltis, Dimitrios. / Testing the no-hair theorem with event horizon telescope observations of sagittarius A*. In: Astrophysical Journal. 2014 ; Vol. 784, No. 1.
@article{5c92925e45da42bbb132692675fcb5f0,
title = "Testing the no-hair theorem with event horizon telescope observations of sagittarius A*",
abstract = "The advent of the Event Horizon Telescope (EHT), a millimeter-wave very long baseline interferometric array, has enabled spatially resolved studies of the subhorizon-scale structure for a handful of supermassive black holes. Among these, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), presents the largest angular cross section. Thus far, these studies have focused on measurements of the black hole spin and the validation of low-luminosity accretion models. However, a critical input in the analysis of EHT data is the structure of the black hole spacetime, and thus these observations provide the novel opportunity to test the applicability of the Kerr metric to astrophysical black holes. Here we present the first simulated images of a radiatively inefficient accretion flow (RIAF) around Sgr A* employing a quasi-Kerr metric that contains an independent quadrupole moment in addition to the mass and spin that fully characterize a black hole in general relativity. We show that these images can be significantly different from the images of an RIAF around a Kerr black hole with the same spin and demonstrate the feasibility of testing the no-hair theorem by constraining the quadrupolar deviation from the Kerr metric with existing EHT data. Equally important, we find that the disk inclination and spin orientation angles are robust to the inclusion of additional parameters, providing confidence in previous estimations assuming the Kerr metric based on EHT observations. However, at present, the limits on potential modifications of the Kerr metric remain weak.",
keywords = "accretion, accretion disks, black hole physics, Galaxy: center, gravitation, submillimeter: general, techniques: interferometric",
author = "Broderick, {Avery E.} and Tim Johannsen and Abraham Loeb and Dimitrios Psaltis",
year = "2014",
month = "3",
day = "20",
doi = "10.1088/0004-637X/784/1/7",
language = "English (US)",
volume = "784",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Testing the no-hair theorem with event horizon telescope observations of sagittarius A*

AU - Broderick, Avery E.

AU - Johannsen, Tim

AU - Loeb, Abraham

AU - Psaltis, Dimitrios

PY - 2014/3/20

Y1 - 2014/3/20

N2 - The advent of the Event Horizon Telescope (EHT), a millimeter-wave very long baseline interferometric array, has enabled spatially resolved studies of the subhorizon-scale structure for a handful of supermassive black holes. Among these, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), presents the largest angular cross section. Thus far, these studies have focused on measurements of the black hole spin and the validation of low-luminosity accretion models. However, a critical input in the analysis of EHT data is the structure of the black hole spacetime, and thus these observations provide the novel opportunity to test the applicability of the Kerr metric to astrophysical black holes. Here we present the first simulated images of a radiatively inefficient accretion flow (RIAF) around Sgr A* employing a quasi-Kerr metric that contains an independent quadrupole moment in addition to the mass and spin that fully characterize a black hole in general relativity. We show that these images can be significantly different from the images of an RIAF around a Kerr black hole with the same spin and demonstrate the feasibility of testing the no-hair theorem by constraining the quadrupolar deviation from the Kerr metric with existing EHT data. Equally important, we find that the disk inclination and spin orientation angles are robust to the inclusion of additional parameters, providing confidence in previous estimations assuming the Kerr metric based on EHT observations. However, at present, the limits on potential modifications of the Kerr metric remain weak.

AB - The advent of the Event Horizon Telescope (EHT), a millimeter-wave very long baseline interferometric array, has enabled spatially resolved studies of the subhorizon-scale structure for a handful of supermassive black holes. Among these, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), presents the largest angular cross section. Thus far, these studies have focused on measurements of the black hole spin and the validation of low-luminosity accretion models. However, a critical input in the analysis of EHT data is the structure of the black hole spacetime, and thus these observations provide the novel opportunity to test the applicability of the Kerr metric to astrophysical black holes. Here we present the first simulated images of a radiatively inefficient accretion flow (RIAF) around Sgr A* employing a quasi-Kerr metric that contains an independent quadrupole moment in addition to the mass and spin that fully characterize a black hole in general relativity. We show that these images can be significantly different from the images of an RIAF around a Kerr black hole with the same spin and demonstrate the feasibility of testing the no-hair theorem by constraining the quadrupolar deviation from the Kerr metric with existing EHT data. Equally important, we find that the disk inclination and spin orientation angles are robust to the inclusion of additional parameters, providing confidence in previous estimations assuming the Kerr metric based on EHT observations. However, at present, the limits on potential modifications of the Kerr metric remain weak.

KW - accretion, accretion disks

KW - black hole physics

KW - Galaxy: center

KW - gravitation

KW - submillimeter: general

KW - techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=84896761367&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84896761367&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/784/1/7

DO - 10.1088/0004-637X/784/1/7

M3 - Article

VL - 784

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 7

ER -