Imaging of Black Hole Shadow
from the Arctic Region

TCHoU Tsukuba 50th Anniversary

Paul Ho, ASIAA/EAO

Recent BLACK HOLE Research— Hear it, Feel it, (Not) See it• Detection of Gravitational Waves (tens of cases)• Orbital Motions at the Event Horizon (one)• Imaging of the Event Horizon (two)• GR Effects• common technique: Lasers and Interferometry(optics and missing information problem)• are these Nobel Prize winning work? 2017, 2020

“Hearing” Gravitational Waves

Where is GW091415: LMC ?
★TIME DELAYS★Detection at :★LIGO at Livingston★followed by 7 x 10-3 sec★LIGO at Hanford★positioning will improve★with VIRGO and KAGRA

Subaru Hyper Suprime Cam ProjectTarget Dark Matter and Dark Energy★

Weak Gravitational Lensing: Cosmic Shear★1.5 degree FOV, 10 x FOV (Surpime Camera)★40 M USD Budget (Taiwan 5M) , 5 year timescale★ASIAA: Filter Exchanger, CCD and Lens Testing★Weak Lensing Tomography; z>6• ASIAA delivered 2011
• HSC on Subaru 02.12• HSC commission 08.12• HSC survey papers 2018
raw image of M31

HSC Integrated on Subaru★

Taiwan Industry: CSIST played Key Role!

Subaru optical-infrared follow-up of the binary
neutron star merger GW170817
2017.08.18-19

2017.08.24-25

NGC4993

HSC: z-band, IRSF: H, Ks-bands
Subaru HSC & MOIRCS succeeded to
get the optical – near-infrared lightfrom a binary neutron star merger
event GW170817.
Ustumi et al. 2017

We surveyed ~70% of the 90% credible areaof the localization skymap of GW170817 with
HSC. ! The OT at NGC4993 is the mostpromising candidate for the opticalcounterpart of GW170817
Tominaga et al. 2017★

5GW Detectors: LIGO, VIRGO, KAGRA

Nobel Prizes for Gravity Wave Detection★Taylor and Hulse (1993)★Weiss, Thorne, and Barish (2017)★Ray Weiss working on Detectors in 70’s

“Feeling’’ Gravity Pull★

The movement of stars - accelerated
to a fraction of the speed of lightaround an invisible object - showed
SgrA* is likely a supermassive blackhole at the center of our galaxy★

Keck telescopes and GRAVITY(VLT) have tracked them over 20
years (Andrea Ghez, ReinhardGenzel)

ESO VLTIWorking Principle of “Gravity”★Guide Star for Adaptive Optics (atmospheric seeing)★Fringe Tracking Star for Phase (interferometer baselines)★VLTI for Interferometry (high angular resolution)★6 baselines; 3 x 10-3 ” resolution; ~40 x 10-6 ” astrometry

Stars in Orbit around SgrA*
26 years of observations of S2

GRAVITY collaboration+18a, A&A 615, L10

★Orbit of S2 relative to SgrA*
Motion of S2 seen fromday to day
June
3Peri 19 May
13027May

24
4 2Moving at 8000 km/s

28 26AprilMotion of S2 A&Ashows
GR Redshift
proofs: manuscript no. s2_20180702_revised_language_

3.3. Posterior Analysis

vz−vz Kprior (km/s)

200

Because of the uncertai
ular, in the strongly cor
vative approach is to deter f a posteriori, inclu
values of all parameters
to realise that the infer
RS e↵enated by systematicor more very di↵erent m
Appendix A.6 for a mo
NACO measurements
rors, for example fromSari 2018), which typi
ble in size to the statis
the NACO data into 10
projected orbit (Fig. 4,a lower weight of 0.5.
or averaging scheme w
ing all data between 1
0.85 and 1.09. With afind f = 0.90 ± 0.09 (FNewtonian physics ( f =★PPN1 (λ)
10002015

2017Year2019

Nobel Prize Physics 2020: Black Hole
★Roger Penrose (Oxford)★Reinhard Genzel Group (MPI)★Andrea Ghez Group (UCLA)

“Seeing” GRAVITY ?
Take a Picture of Black Hole ?
• M87 black hole ~ 1 x 1043 g ~ 130 AU• But M87 is very far! 53 Million Light Years— 5 x 1020 km from us• Schwarzschild Radius ~ 10 micro arcsecond
Sun or Moon ~ 30 arc minutes
M87 black hole ~ 5 x 10-9 size of moon

Gravity affects Geometry of Space•

Mass will distort space-time until
even light cannot escape•

Einstein predicted the existence ofblack holes - though even he was
not comfortable with theconclusions from his equations

Gravity/Geometry instead of Material/Dielectric to bend Light

Shadow comes from General Relativity
Shadow Diameter ~ 5.2 Rsch

Directly Resolving the Black Hole“because Seeing is Believing”★Target Supermassive Black Hole
★Nearest Examples (SgrA*, M87)★

(Shadow: ~5Rsch ~40 x 10-6 ’’)★Very Long Baseline Interferometryat Submm Wavelength
Precision ~ 10-10

Very Long Baseline Interferometer• Simulate a Very Large Telescope (Intercontinental Distance)• Link Telescopes by synchronizing Wave Front• Precision at 1/20 wavelength (40µm), over ~10,000 km— distance between telescopes— arrival of wavefront at each telescope— compensate for differential atmospheric effects— compensate for differential electronics effects— compensate for individual telescope response— correct for sparsely sampled telescope surface• VLBI is one of Nobel Prizes in Radio Astronomy(Ryle and Hewish 1974) — IMAGE RECONSTRUCTION

Case of M87

60''tist'simpression!

100µasAr20''
5''

Zhou, Owen & Biretta

Image Credit: Bill Saxton NRAO/AUI/NSF

10mas

Walker et al (2008)

VLBA 43 GHz

VLA 15 GHz

VLA 20cm

Case of M87: HST and VLBA data

5 mas

HST Spectroscopy Yields Mass

VLBA Imaging Yields Jet

Macchetto+ 1997

Walker et al 2008

Gebhardt & Thomas 2009

Distance:*16*Mpc*
Mass:*3.2*(6.4)*×*109***Mo*
rg#=#2#(4)#μas#

SMBH:**Source*of*Jet*
AccreAon*Disk:**Shadow
Shadow*~*20*(40)μas*

Appearance of the shadow of the SMBH
Size = Msss
Geometry / Spin

Shape = Spin + Geometry

No rotating BH

Maximum rotating BH

In optically thin flow andspherical geometry

In optically thick flow andgeometrically thin diskTakahashi 2004

Image simulation of M87

Model image with a 6 x 109 Mo
SMBH and optically thinaccreting matter, derived by theRay Tracing method.

Observed image simulation
with the submm VLBI at 345
GHz. Inoue&et&al.&2014&

★Taiwan is partner on ALMA,SMA, and JCMT★
• Atacama Large Millimeter Array (ALMA), Chile• ALMA Pathfinder Experiment (APEX), Chile• James Clerk Maxwell Telescope (JCMT), Hawaii• Large Millimeter Telescope (LMT), Mexico• IRAM 30-meter Telescope, Spain• Submillimeter Array (SMA), Hawaii• Submillimeter Telescope (SMT), Arizona★ Event Horizon Telescope in 2017

★M. Johnson/SAO• South Pole Telescope (SPT), South Pole

★Aperture Synthesis: Building up UV Coverage★
Visibility = Sampling . Source + Error

★Removing “Errors”★before ad-hoc phasing★after ad-hoc phasing★Blazar OJ 287; Hawaii-Spain (SMA-IRAM)★ baseline 420-second integration★Ad-hoc phasing with ALMA corrects for atmospheric fluctuations and allows★for strong detections in short time intervals on very long baselines.
★

★ Phase Referencing with ALMA

★Removing “Defects”
Imaging of M87
Dirty Map

Final map after imaging process
Imaging Team4
G. Y. Zhao
(KASI)

K. J. Koay
(ASIAA)

H. Nagai(NAOJ)

W. P. LoI. Cho(NTU/ASIAA)(KASI) S. Koyama(ASIAA)
K. Asada(ASIAA)

2019 May 14th NTU★UV-weighting, Clean, Phase Self-Calibrate, Amplitude Self-Calibrate

★ What does the Image Say?

42μas

★

★It’s Black, and Looks like a Hole

★Physical Parameters?
• Photon Ring: ~42µas or ~400au, round• Schwarzschild radius: rs = 2 GM /c2• Shadow Size ~5 times rs (Event Horizon radius)—— as expected by General Relativity—— deduced mass ~ 6.5 billion solar mass
• Ring Brightness: ne ~ 104 cm-3, B ~ 3G, Maccr ~ 10-3 Msun yr-1
• Ring Asymmetry: Brighter on Bottom Side—— consistent with rotation with doppler boosting• Tipped Disk: Perpendicular to Relativistic Jet• Spin of Black Hole: Pointed away from Earth★Simulation of Doppler Boosting★G. Wong, B. Prather, C. Gammie (Illinois)

★Doppler Boosting of Approaching Part of Rotating Ring

★Inner Rotation must lock to Black Hole Rotation

The Galactic Center is Invisible in Optical Light
Milky Way Center Seen from Hehuanshan,
Taiwan (optical light blocked by dust)

Milky Way Center in radio waves

SgrA**

Photo Credit: Wang Wei-Hao,ASIAA

2022 May 12th, Academia Sinica★
★

2022 May 12th,Academia Sinica

★Sgr A*: Seeing is Believing?
★The Nobel Prize in Physics 2020● discovery of “a supermassive compact
object at the center of our Galaxy”★We now constrain this compact object into a
region that is 1000 times smaller!
Our SgrA* images provide the firstvisual evidence that this compact
object indeed looks like a black hole!

★

Sgr A*

Sgr A*: Einstein is right again!
Measured ring size is about 50 µarcsec● 100 millionth of a degree(0.000000001°) on the sky● similar to the size of a donut on theMoon as seen from Earth.
● this is the same size predicted based on
the known mass and distance of theblack hole!

Sgr A*

0.000000001°

Sgr A*: A Tiny Monster?
Comparison: Physical shadow sizeof M87* (first black hole we saw)is ~ 100 billion km in diameterbecause M87*:M87

Sgr A*

Orbit of Pluto● ~ 2000 times larger than SgrA*● ~ 2000 times more mass

Sun diameter

Mercury orbit

100 billion km
credit: based on xkcd illustration

6千萬公⾥

60 million km

60 million
kmSummary• Current Research depends on Angular Resolution• Gravity Wave Research probes Coalescence Process inbuilding larger Black Holes• Optical/IR Interferometry probes dynamics at Event Horizon
and test GR effects• Submm Very Long Baseline Interferometry probes structuresof Event Horizon and physical processes and test GR effects• Next Generation Instruments will have more resolution andmore sensitivity (time domain, energy domain, dynamicsdomain)• Asia will play a leading role in this Frontier in Optics/Physics!
★

★ 39

Building The Largest Telescope Ever:
Greenland Telescope leverages SMA and ALMA
and JCMT

JCMT

Aim: LOW PMV
Sensitivity: ALMA Surface Area

Arrival in Greenland 07.16.16 !

Assembly of Antenna Mount 09.10.16

Telescope Assembled July 28, 2017

Operations from Thule and Taipei

GLT operational very quickly— Working Season very Short
After Finishing Construction● 2017 Nov. 30: Antenna construction finished.
● 2017 Dec. 1 : Commissioning started.
● 2017 Dec. 17: First Light with artificial light !!!
● 2017 Dec. 25: Astronomical First Light with Moon !!!
● 2017 Jan. 12: First Detection of Line source !!!
● 2018 Jan. 28 : Joined the EHT Dress Rehearsal !!!
● 2018 Mar. 20: First Fringe detected at 230 GHz!!
● 2018 Apr. 12-17: Joined the GMVA observations !!!
● 2018 Apr. 20-27: Joined the EHT Observations!!!

GLT operating since 2018
Stable operation nowDateArray

2018 Jan.

EHT2018 Feb.

EB, Yb, PV

2018 Mar.

Freq.

Noteresults

230

Fringe test

Fringe!!!, low sensitivity (η~25%?)

86/(230)

Fringe test

Missing one module

GMVA

86

Science run

Fringe!!!, dual linear polarization, Published !!

2018 Apr.

EHT

230

Science run

Fringe, low sensitivity (η~25%?), to be submitted !!

2018 Sep.

GMVA

86

Science run

Fringe, dual linear polarization, Published !!

2018 Oct.

EHT

345/230

Fringe test

No Fringe

2019 Jan.

EHT

230

Fringe test

Fringe2019 Mar.

EAVN

230

Fringe test

No Fringe

2019 Mar.

EHT

230

Science run

Canceled

2019 Apr.

GMVA86Science run

Fringe2019 Sep.

GMVA

86

Science run

Fringe2019 Dec.

EHT

230

Fringe test

Data arrived at HO2020 Jan.

EHT

230

Fringe test

Fringe2020 Feb.

EAVN

230

Fringe test

Fringe!!!

2020 Apr.

EHT

230

Science run

Canceled

2021 Mar.

EHT

230

Fringe test

Fringe2021 Apr.

EHT

230

Science run

Fringe2021 Apr.

EHT

345

Fringe test

Fringe!!!

2021 Apr.

GMVA

86

Science run

Fringe2022 Jan.

EHT

230

Fringe test

Fringe2022 Mar.

EHT

230

Science run

Fringe2022 Apr.

GMVA/G-VLBI

86

Science run

Fringeafter 2019, Surface Accuracy Improved
After the first season● Aperture Efficiency○

Photogrammetry Before & After:■○

Surface accuracy improved
from 180 μm to 21 μm.

Aperture efficiency Improved:[Freq.:2018 2019 2020]■

86 GHz : 48% ------ 75%■

230 GHz: 22% 60% 65%

17after 2019, Pointing Accuracy Improved
After the first season● Pointing○

There was an issue on pointing, especially at
low elevation, in 2018

○Pointing model was not good enough○We have improved it since 2019

RMS Pointing error (arcsec)
ReceiverAZ

EL86 GHz

2.9

2.8

230 GHz

1.9

1.9345 GHz

1.8

1.916

Astronomers living in Thule
Living in Thule21Astronomers must be able to Clean
Stable operation now

25Astronomers must be able to Cook!
Who cooked this?
MexicanFrench

激悪めしPasta

Italian

MalaysianAmerican

IndianKoreanChinese20

Astronomers also need to Play
Living in ThuleSome enjoys other things in Thule
Living in Thule23

VIP Visits to the GLTNiel deGrasse Tyson

2018/03/15

2018/10/29

The Prime Minister of Denmark(Carl Sagan in 21th Century)

Nikolaj Coster-Waldau(Jaime Lannister of Game of Thrones)
2018/08/09

Barbara Barret(Secretary of US Air Force & 2019/11/29
Smithsonian Institution Board Member)First GLT Result: Connect BH to Jet
see Accretion onto BH “Donut”
First results with GLTLu, Asada et al, 2023

EHTC et al. 2023 to be submitted

EHTCelta.

120926

Goal is to get to the Summit
GLT summit

Thule

SummitMatsushita et al. 2019

2011

Thule
Summit(winter)- 20℃
5Current and Future Resolution of EHT 
EHT with GLT
220 GHz5 x 5 pix (25 pix)

EHT 2017
GLT @ Summit
220 GHz660 GHz3 x 3 pix (9 pix) 15 x 15 pix (225 pix)

M31 (Andromeda)
Black HoleWe will have better
resolution & sensitivity on
M87 black hole shadow & jet.

We will have much better
resolution for black holeshadows in various galaxies.

Summary of Talk
• Black Hole Imaging is one of 3 key Gravity Experiments• Asia played a key role in the BH Experiment• Lasers and Interferometry are the key Techniques• Black Hole Shadow Image verifies General Relativity, withdeep implications for astrophysics and fundamentalphysics• Asia is working on next steps in this field• Excellence requires strong support from Government,
Research Organization, Industry, Universities

and, Scienceis theDeploying
Product of GLT
Teamwork
Summary:•••••••••

Students
st from Tsukuba?

Goal:
Goal:
Goal:Goal:Goal:
Team:Asset:
Site:
Why?

1 Major Arctic Observatory
Highest Angular Resolution in Astronomy @ 10-5 arc second
Direct Proof of Black Hole Existence
1st Measurement of Mass and Spin for SMBH
1st Wide-Field Imaging at THz
ASIAA, CSIST; SAO, Haystack, NRAO
SMA, ALMA, GLTBest Site in the Northern Hemisphere
Because It Is Hard!

• Boat is only Once per Year
• Funding Up Front for Mobilization• Fast Start, Sustained Pace