Overview of the first EHT results

Fumie Tazaki

Mizusawa VLBI Observatory, NAOJ

On Behalf of the EHT Collaboration

ESO/L. Calçada, Digitized Sky Survey 2, ESA/Hubble, RadioAstron, De Gasperin et al., Kim et al., EHT CollaborationSnapshot of Black Hole Shadow

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Series of EHT First Result Papers
Published from Astrophysical Journal Letters•

Paper I: The Shadow of the Supermassive Black Hole•Paper II: Array and Instrumentation•Paper III: Data Processing and Calibration•Paper IV: Imaging of the Central Black Hole in M87•Paper V: Physical Origin of the Asymmetric Ring•

Paper VI: The Shadow and Mass of the Central Black44 pageHole17 page

28 page
32 page
52 page

31 page

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Event Horizon Telescope (EHT)
EHT2017
8 telescopes at 6 locations
observation wavelength: 1.3 mm
longest baseline: 10,700 km
diffraction limit: ~ 25 uas

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Event Horizon Telescope Collaboration
EHTC consists of more than 200 scientists in 18
countries/regions.

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020Observation with 8 telescopes

April, 2017

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Correlation ＠MIT/MPIfR
Correlation was performed at MIT &MPIfR, to detect signal from target
sources.
Correlator in MIT

1 module = 8TB 8HDD
x 92 modules

credit: Bryce Vickmark

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Data Calibartion
Data processing pipelines: HOPS / CASA / AIPS
M87

April 11Ring model
diameter = 46 uas

Imaging
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

ImagingImaging

Ø Imaging Tools
Conventional:

DIFMAP

US Team:eht-imagingCheal+2016,2018

Japan+ Team:SMILI

Akiyama+2017a,b

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

2nd Imaging WS for M87 (July, 2018)• Independent imaging by 4 teams.
• Share the results in the WS.

Team 2Imaging GroupTeam 1Team 2

Team 3

Team 4

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Imaging Parameter Survey
Training image

Pseudo data

2000 imagesof M87

Imaging with 50,000
parameter sets

Real observed data ofM87“Good” imaging
parameter set: 2000

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Final Images of M87• 2000 images for each observational date.
• All images show asymmetric ring withenhanced brightness to the south.
April 5th 6th

10th

11th

Conventional:

DIFMAP
US Team:eht-imaging
Japan Team:SMILIAGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Orientation angle ()Diameter (uas)Ring Parameters

41 3 uas (Apr. 11)

April 5 6

10 11

April 5 6

10 11

Diameter: Consistent among tools / dates.
Orientation angle：Consistent among tools
Systematic difference among dates

Hotspot position changed!
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Image with Closure quantities
visibility amplitude,
closure phase,closure amplitude+ self-calibration

closure phase, closure amplitude(NO baseline-base error)
Ring-like structure can bereconstructed independently
from data calibration
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Final Image for Outreach Purpose

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

General Relativistic Magnetohydrodynamic(GRMHD) Simulations

Construct a large library of GRMHD models, and compare withobserved quantities.

AGN Jet Workshop
2020, Jan. 20th ‒ 22nd, 2020
credit: EHT Theory and Simulation Working GroupWhat Cause Ring Asymmetry?
More likely
Black HoleJet
Accretion Disk
Credit: NAOJ/AND You Inc.

Consistent with clockwise black hole spin.
→ Mizuno-sanʼs talk
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

MBH = (6.5 0.7) x 109 Msun
42 3 uas

Asymmetric ring
→ direction of black hole spin
is clockwise
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Press Release (April 10th, 2019)
Tokyo

BrusselWashington D.C.

ShanghaiTaipei

Santiago

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Next Goal of EHT Collaboration•Black hole shadow of Sgr A* (supermassive black holeat the center of our galaxy)•Movie reconstruction•

Polarimetric imaging

Future of EHT array•

Increase telescopes→ higher sensitivity image•

Higher frequency observation (345GHz)→ higher resolution→ Akiyama-sanʼs talk

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Synergy of EHT and East Asia

East Asian VLBI Network

EHT

GRMHD simulationof Jet Base

→ Kawashima-sanʼs talkKawashima, Kino, Toma, Nakamura+

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

Summary•

We EHT Collaboration captured the supermassive
black hole at the center of M87.

•Observation of M87 core with the global VLBI array(EHT) was performed in April, 2017.

•Careful imaging and large survey of GRMHD
simulation were performed with well-calibrated data,to confirm the results.

•The first ever image of black hole shadow is thebeginning of a new astrophysics era by “seeing” blackhole.
AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020

AGN Jet Workshop 2020, Jan. 20th ‒ 22nd, 2020