Summary of
Event Horizon Telescope

Mahito Sasada (NAOJ)
and EHT teamThe Shadow of Black HoleSgr A* ~ 0.1 AU (4 x 106 Msolar):
10 μas @ 8 kpc• Light cannot escapefrom the black hole
• The black hole makesa shadow(Broderick & Loeb 2006)

Non-spinning Black Hole

BH

5.2 RsMaximumly spinning BH

BH

4.8 Rs(Courtesy of Hung-Yi Pu)

Sizes of Black-Hole Shadow
Credit: Hotaka Shiokawa

SourceBH Mass(Msolar)

Distance(Mpc)

Angularradius of Rs(μas)

Sgr A*GalacticCenter4 x 1060.008

10Sgr A*Credit: NRAO/AUI/NSF

M87
Virgo A

3 - 6 x 109

17.8

3.6 - 7.3

M104
SombreroGalaxy

1 x 109

102Cen A

5 x 107

40.25

M 87

longer-wavelength VLBI is 22 mas along a position angle 80u degrees
east of north on the sky, closely aligned with the orientation of theARO/SMT–JCMT baseline. Removing the scattering effects results ina 3s range for the intrinsic size of Sgr A* equal to 37z16{10 mas. The 3s
intrinsic size upper limit at 1.3 mm, combined with a lower limit tothe mass of Sgr A* of 4 3 105 solar masses, M[, from proper-motion
work14,15, yields a lower limit for the mass density of
9.3 3 1022 M[ pc23. This limit is an order of magnitude larger thanprevious estimates7, and two orders of magnitude below the criticaldensity required for a black hole of 4 3 106 M[. This density lower

Results of Early Observations: Sgr A* ①

wide range of w
weighted least
ments. At 1.3
than the intrin
can directly deintrinsic size dconfirms thatwavelengths pr
an improved elengths consist

Doeleman+ 20081003The Astrophysical Journal Letters, 727:L36 (6pp), 2011 February 1Fish et al.

unresolved• Compact emission region

on ISCO scale.

resolved

21Gaussian~ 4 RS

FWHM size (mas)• Compact emission is variable

Correlated flux density (Jy)

• Gaussian or ring models

10Sou

10.1

Ring
00

1,000

2,000

3,000

4,000

6Baseline (10 λ)Figure 1 | Fitting the size of Sgr A* with 1.3 mm wavelength VLBI. Shownare the correlated flux density data on the ARO/SMT–CARMA and ARO/
SMT–JCMT baselines plotted against projected baseline length (errors are1s). Squares show ARO/SMT–CARMA baseline data and triangles show
ARO/SMT–JCMT data, with open symbols for 10 April and filled symbols
for 11 April. The solid line shows the weighted least-squares best fit to acircular Gaussian brightness distribution, with FWHM size of 43.0 mas. The
dotted line shows a uniform thick-ring model with an inner diameter of
35 mas and an outer diameter of 80 mas convolved with scattering effects dueto the interstellar medium. The total flux density measurement made with
the CARMA array over both days of observing (2.4 6 0.25 Jy : 1s) is shown asa filled circle. An upper limit for flux density of 0.6 Jy, derived from nondetections on the JCMT–CARMA baseline, is represented with an arrownear a baseline length of 3,075 3 106l.

0.01

0.1

Figure 2 | Obser
wavelength. Re
VLBI observatio
are from ref. 13,
the observations
from ref. 13, andthis line, measu
scattering effectintrinsic structu
dominated’ regi
from 2 cm , l ,1s) shown as a d
the power-law e©2008 Macmillan Publishers Limited. All rights reFish+ 2011
Figure 3. Correlated gain-corrected flux density plots. Solid lines show best-fit circular Gaussian models of the compact emission in Sgr A* and are consistent with a

Results of Early Observations: Sgr A* ②
Discovery of non-Gaussianity in the structure

Johnson+ 2015

Fig. S5. Total-intensity VLBI of Sgr A⇤ and fitted geometrical models. Normalized, deblurredResults of Early Observations: M87 ①

The emission region is very compact.
Figurecollimation
5. Left: cross section of the total
intensity in theoftranseverse
directionto the jet axis at 5Consistent with the parabolic
proﬁlethejetThree ridgelines corresponding to the inner and outer two ridgelines are clearly seen. Right: theouter ridgelines are more evident at 1.6 GHz.

5 April

5.5 RSEHT
Doeleman+ 2012

Figure 6. Left: distribution of the radius of the jet as a function of the de-projected distance
Asada& Figure3
Nakamura
2012,et description.
al. 2012
Nakamura(2012) andin Nakamura& AsadaDoeleman(2013) for a detailed
VSOP dthe linear least-square ﬁt for the data points except the three inner cores (VLBA at 43/86 GHz aNakamura & Asada 2013, Hada et al. 2013, 2016
law index of 1.73±0.05. The dashed line indicates the conical streamline with a power law of5
rs. The black area show
denotesAsadathe Bondi etaccretion
radius locatedat Bondi radius 3.8×10
al. 2016,Nakamura+in prep.
hole with maximum spin. The gray area indicates the size of the major axis of the event horizon

2012
2012
2012
2012
2012
2012
2012
2012
2012
2012

81
81
81
81
81
81
81
81
81
81

566610
1111
10
11
1149
326
49
43
633
43
633

SPF
SPFSPFSPFSPDSPDSPD
SPF
SPF
SPF−2336.473−2483.493−2704.560−2898.263−3029.578−2858.690−2621.320−3029.578−2858.690−2621.320−426.660−458.173−513.928−574.140−1284.919−1348.199−1417.355−1284.919−1348.199−1417.355

1997.198
2113.293
2286.622
2436.814
2439.510
2289.791
2084.597
2439.508
2289.783
2084.583

847.338874.212921.497972.258
1556.894
1607.719
1662.922
1556.955
1607.779
1662.983

339.275
370.200
417.939461.449590.067568.899536.723590.070568.906
536.737−420.677−416.039−407.569−398.118−271.975−259.520−245.567−272.036−259.581−245.628

2.40
0.70
−0.50
2.70
−0.20
−7.30
3.00
−1.20
−0.60
−0.80

Results of Early Observations: M87 ②

Event Horizon Scale structure is stable during
anenhanced
gamma-ray state (2012)(This table isavailable
in machine-readable TeVform.)

Hada+ 2014, Beilicke+ 2012

TeV γ-ray43 GHz
22 GHz

TeV emission region ~ 20 - 60 Rs
Akiyama+ 2015

Figure 2. The measured correlated ﬂux density of M87. Circles and crosses indicate the correlated ﬂux density observed in 2012 (this work) and 2009 (DArrays in April 2017
Sgr A*
EHT
50μas
Shiokawa+

1.3 mm (230 GHz)
Full Polarization~ 20 μas

M87
EHT
35μas

Moscibrodkza, Dexter+17

Additional telescopes in April 2017
ALMASPT

Conﬁguration in 2017/2018

Interviews in NHK and othersNHK

http://www.nhk.or.jp/ohayou/digest/2017/04/0411.html

BBC

http://www.bbc.com/news/science-environment-38937141

Reduction and analysis of the 2017th data is ongoing.

EHT Working Teams
Backends, Receivers,
Phased Arrays

Instrumentation
Working Group

Instrument Rollout& Testing

Data Collection & Processing
Working Group

Planning & Mounting
Observations

Raw Data

Calibrated
Data Products
Mock
Data

Data Analysis
Working Group

DataAnalysis

ScienceResults

Software and Data
Compatibility Working Group

Talks &Public Outreach

Publications

Products
Working Group

Science Utilization
Working GroupEHTC – Project Plan

15-Mar-2017

EHT Teams and Coordinators
EHT WORKING GROUP MEMBERSHIP — MARCH 1, 2017
Working Group

Instrumentation

Data Collection &Processing

Data Analysis

Task

Coordinating Members

Instrumentation

Gopal Narayanan, Jonathan Weintroub

Integration & Testing

Alan Roy, Andre Young, Satoki Matsushita

Monitor & Control

Daan van Rossum, Nimesh Patel

Proposal Coordination

Michael Johnson, Eduardo Ros, Keiichi Asada, Sera Markoff, +MT

Science Operations

Vincent Fish, Thomas Krichbaum

Correlations

Walter Alef, Geoff Crew

Synthetic Data Generation

Vincent Fish, Roger Dean

Calibration & Error Analysis

Lindy Blackburn, Ilse van Bemmel

Imaging

Michael Johnson, Kazu
Akiyama
Kazu
AkiyamaScattering

Geoff Bower, Ramesh Narayan

Time Variability

Dan Marrone, Atish Kamble

Theoretical Models &Simulations

Charles Gammie, Yosuke Mizuno, Hung-Yi PuNear Horizon
Model Comparison &Science Utilization
Feature Extraction
Parameter Definition
Beyond Horizon Multiwavelength Science
Science Utilization Active Galactic Nuclei

Feryal Ozel, Jason Dexter
Heino Falcke, Keiichi Asada
Sera Markoff, Kazuhiro
Hada
Kazuhiro
Hada
Thomas Krichbaum, Svetlana Jorstad, Neil Nagar

Summary• The EHT project is progressing, and makes a lot of scientiﬁcresults.
• The compact region close to the black hole shadow is
detected by EHT observations in Sgr A*. The region of thiscompact emission is good agreement with the ring model.
• There is a compact region in the jet of M87. The region
was not associated with the gamma-ray variability.
• The 2017th observation was performed. The reduction andanalysis is ongoing.

Backup

2009
2009
2009
2009

93
93
93
93

13.4583
13.4583
13.8750
13.8750

H
L
H
L

CJS
CJS
CJS
CJS

4.3
−3.0
18.3
33.7

7.03
7.30
6.97
8.53

−2788.0−2788.0−2747.3−2747.3−1026.1−1026.1−879.2−879.2

Results of Early Observations: Sgr A* ③(16pp),
2016 April 1Notes.
aHigh or Low band, as deﬁned in Section 2.
bStation codes are deﬁned in Table 1.

Discovery
asymmetry in the structure
is a clear
separation ofbetween(This table is available in its entirety in machine-readable form.)
ations.
cause the perturbations are
Median Closure Phases of Sgr A
d term in Equation (14) may
is realized in practice. That is,Year
Day(s)
N
u0 is the baseline length above
200909311
substantially. In the interest of2009
096
32009
097
10
at2009All
24

u < u01u > u0,)(15)

ypical of that arising from theimages for RIAFs. As a result,2011088
720110902Fish+ 2016
2011091
5Broderick+2016
2011094
172011All
31
25
Figure 10. Input 2012
image (left)081and examp
2013
080
28
ﬁt model.
2013
081
102013082
15

Additional telescopes in April 2017
ALMASPTList of Array
1. Arizona Radio Observatory (ARO)
2. Submillimeter-wave Astronomy (SMT)
3. Atacama Pathﬁnder EXperiment (APEX)
4. Atacama Submillimeter Telescope Experiment (ASTE)
5. IRAM 30-meter telescope
6. James Clerk Maxwell Telescope (JCMT)
7. The Large Millimeter Telescope (LMT)
8. The Submillimeter Array (SMA)
9. Atacama Large Millimeter/Submillimeter Array (ALMA)
10. South Pole Telescope