6 @Qband

5 @KbandPreliminary results of M87 in2017 EAVN observations nearin-time with EHT
Yuzhu, Cui (D1)
Kazuhiro, Hada
Mareki, Honma
On behalf of EAVN AGN Science Working GroupNAOJ / SOKENDAIContent
1. EAVN 2017 campaign;
2. EHT observation in 2017;
3. Possible connections between EAVN and EHT;
4. Future planFrom VERA to KaVA, then to EAVN

SejongTianma

YonseiUlsan

EAVN 2017 campaign:• 14 antenna: VERA (4) +KaVA (3) + Tianma+…
• 17 epochs: M87 @14, Sgr A @9• 2 frequencies: 22 GHz & 43 GHz

Mizusawa

Ishigaki

Iriki

Ogasawara

100 mJy

We may have a chance to see:
• How does matter accrete/outflow near a BH?
• Where is jet base?
BH launching the jet?
• How does
EHTnature of BHs
Quantum•• Formation of jet•…

230 GHz20 µasComparison between EHT and EAVN

VN
EAondwiw

EHT resolved region

M87: MBH = 6.6 ✖109 Msun,
Rs = 7.79 µas; D = 15 Mpc

EHT

EAVN

Frequency (GHz)23043Angular resolution(µas)

20700

Scale_M87 (Rs)390

• EHT : imaging the BH shadow• EAVN:- Over all jet structure;- Proper motion informations;- Position angle information;- Amplitude variance;- Spectrum index

Will be very helpful supplements for each other !!!

Possible connection:

Expected
flux density

1. Can we detect the emission
around the BH?
?

Simulation of M87, Akiyama+ 2017

αSpectral Index Map ( Sν ∝ ν )Blue: a17107 @K
Red: a17108 @Q• With the 22 GHz & 43 GHz data, wecan get 4 pairs of spectral index
maps to check the particle
distribution of M87 by Sν ∝ ν αSν1ν
= ( 1 )αSν2
ν2log(Sν1ν) = α log( 1 )Sν2
ν2Jet regionSν1α =

Optically Optically thinthick

α = -0.32
α = -0.032

20 uas core shift appliedlog( S )ν2
ν1log( ν )= -0.32

2• Assuming the particle distribution issame with the jet. Score,43GHz = 586m J y @V L B A
log(Core region

Score,230GHz
Score,43GHz) = α log(

ν230GHzν43GHz)Detectable!

Score,230GHz = 340 m J y @E H T

Expectedposition angle

2. What is the direction of theemission?
?
?

?
Simulation of M87, Akiyama+ 2017

Position angle changing of M87
VLBA 2013/2016

2 mas

EAVN 2017

VLBA 2017

More obvious changing
happened in the inner part:
Horizontal?

Walker+ 2018

Agudo+ 2009

Initial Jet direction during EHT
period?
EAVN

KaVAHorizontal ?

EHT period

VLBA

Propermotion & newejection

3. When was the new component
ejected?

2017/04/05

2017/04/10

2017/04/15✴ These dates are example

Simulation of M87, Akiyama+ 2017

Possible proper motion

Time interval:
8 daysSuper resolution:
Beam size: 0.416 ✖ 0.21 mas

8 days0.4 mas / 8 days
~4 c

0.6 mas / 5 days ?
5 days

5 days4 daysRough estimation:
If we expect 1c motion, namely:->1c = 4 mas / year-> 0.1 mas / 7 days-> 12.8 Rs / 7 days

Light curve (Q band)——new ejection during EHT period?
May due to new ejection

Location: 0.4 mas (~ 51 Rs)

Assuming 4 c proper motion
60

Epoch: a17099a45

Rs

30

New
component on
April 04 ?

15EHT field of view ~15 Rs
0M87: MBH = 6.6 ✖109 Msun, 4c~51.2 Rs /7 days
Rs = 7.79 µas; D = 15 Mpc-1592

April 499

Days

Future work
✤ Technical part:• Finish the evaluation of Tianma’s performance;• Double check the data;• Finish the technical paper✤ Scientific part:• Spectral index of K band and Q band;• Calculation of proper motion;• Finish the scientific paper with EHT