1. AGN studies with EHT and EATING VLBI
Mareki Honma
Mizusawa VLBI observatory, NAOJ
----- Meeting Notes (9/19/12 11:07) -----
Check whether ALMA should be listed
Take off Onsala? Where listed in the PIP.

2. Touching the event horizons of BHs
AGN core is most-likely a
super-massive black hole.
Yet, there is no confirmation
of existence of event horizon
Direct detection of BH shadow is an ultimate confirmation of existence of BH. (or negative results may indicate an existence of naked singularity !?)
New breakthrough for experimental BH physics!?
Fukue et al 1989 2

3. BH size source MBH/Msun Distance Angular radius Sgr A* 4 x 10^6 8 kpc
10μas
M87
6 x 10^9
15 Mpc
7μas
M104
1 x 10^9
10 Mpc
2μas
Cen A
5 x 10^7
4 Mpc
0.25μas
Shadow diameter : 1~5 times Schwartshild radius
For imaging shadow, ~ 10μas resolution is required

4. Angular resolution of telescopes
Wavelength – angular resolution diagram
cm wave
mm wave IR
optical
AKARI
1 arcsec
Connected
array
HST
Resolution in mas
VLBI
SUBARU
Single dish
ALMA
VERA
1 mas
VLBA
VSOP-2
Submm VLBI
Sgr A* BH size λ

5. Event Horizon Telescope
Global network of mm/sub-mm VLBI
to Image BH shadow, jet-root etc.
Target source : Sgr A*, M87, Blazars, etc.
Target resolution : ~20 uas or higher
Hawaii
CARMA
SMTO
ASTE/APEX
Pico Veleta
Planned Array around 2015
Green land
ALMA
LMT
Phase-up ALMA joining in ~2015

6. Doeleman+(2008) 230GHz VLBI with JCMT – SMTO – CARMA
ARO/SMT－CARMA(600km)
ARO/SMT－JCMT
Non-imaging analysis (traditional UV distance plot)
37±(16,10) uas as intrinsic diameter of Sgr A*
As compact as ~ 4 R_s 6

7. Sgr A* in 2009 April 3-day obs. with Hawaii-SMTO-CARMA
Detection with all baselines
Variation with SMTO-CARMA baseline
Structure variation at 0.4 mas scale (~ 4 AU, ~ 40 R_g)
Fish +(2011)

8. Sgr A* parameters up-dated
Fish+(2011), Broderick+(2011)
constraining parameters with 4-nights data
(2007, + 3 days in 2009)
Low inclination/extreme Kerr case is ruled out (?)

9. M87 jet-base detection
M87 optical image with Subaru M87 Jet observed with VLBA
Jet launching point ?
Doeleman+(2012), Science
Resolved a structure with
5.5 R_sch scale

10. M87 : spinning BH ? Observed size: smaller than ISCO of a=0 BH
Position : within ~2 Rs
(if Hada+11 applies
to 230 GHz)
Sheath launched from AD ?
> if so, suggests spinning BH

11. Science 338, 355 (2012)
毎日新聞　2012年9月28日
There is a song with this paper’s abstract as lyrics
song by Jonathan Mann (please visit “you tube”)
We are touching BH!

12. Blazar jets Jet root images at 230G !! (θ ~ 60 μas) J1924 by Lu+(2012)
NRAO530 by Akiyama+

13. 3C279 case
Jet bending w.r.t. large scale jet

14. Interpretation of bending jet
Small jet-angle variation
Press release at 2012 ASJ meeting
朝日新聞　2012年9月19日

15. Fringe detection with APEX
First fringes with Chilean station at 230G
3C279 in 2012 May
Fringe spacing : ~30 μas !!

16. Status of APP (ALMA phasing project)
Phasing-up 64 of ALMA antenna for sub-mm VLBI
MRI proposal already approved (2011)
PDR meeting held in
Nov 1~2.
APP conditionally
approved by ALMA board
(15 Nov 2012)

17. New imaging technique for EHT era
UV coverage of VLBI is sparse
FFT from UV plane to image is usually done with 0 padding (otherwise ill-posed problem)
“Compressive sensing” is a way to directly solve ill-posed linear equations under the condition that the solution is sparse.
No 0-padding allows us to get super resolution !

18. New technique Interferometry equation in the form of linear equations
Limited (u,v) coverage makes this set equation as ill-posed problem. It cannot be solved because number of solved parameters is larger than that of equations
If we can solve these equations directly (i.e., without 0 padding), the image should be free from 0-padding effect (no side-lobes, super-resolution !?)

19. Example : multiple point sources
True image convolved with
Normal beam
true image
Point sources within
synthesized beam
“Standard image”
cannot distinguish them
Compressive sensing
image can separate them
True image convolved with
Super-resolution beam
Super-resolution image
with compressive sensing

20. BH Shadow “Standard image” marginally resolve the BH shadow shape
true image
“Standard image” marginally
resolve the BH shadow shape
CS image can trace the
ring / crescent shape 　→
CS will significantly boost
imaging with sub-mm VLBI
Convolved with standard
beam
True image convolved with
Super-resolution beam
Super-resolution image
with compressive sensing

21. Something on KVN + VERA Key features
KVN+VERA provides much denser UV coverage
7 stations, 21 Baselines with 300 – 2000 km
Frequency 22 or 43 GHz (+86, 129 for KVN)
Multi-frequency monitor with
KVN +VERA of Sgr A*, M87,
and gamma-ray blazars

22. Improved M87
Data analysis: K. Niinuma
Beam~140Rs
With KVN+VERA, we can clearly chase

23. M87 Jet launch/acceleration
Asada+ 11
“Key-Zone”
@1~10mas
Flare?
Acciari+09
βapp =1
Quiescent?
Ly+07

24. GENJI : Blazar monitor
Example : 3C84, radio jet detection (VERA) after γ-ray flare (Fermi)
VLBI map (2 x 2 pc), at 22 GHz
Nagai+(2010)
Radio light curve
SSC model
for Mrk 501
(Kino+2001)
γ-ray mitting
region:<1000 AU
cm + (sub-)mm VLBI will lead
comprehensive understanding
(higher resolution &
lower optical depth …)

25. Sgr A* 2013 event Trajectory of the dusty cloud (G2) VLT@3.76μm 2011.3
2008.3
2004.5

26. KVN+VERA has better (u,v) coverage than VLBA+GBT @ 43GHz!!!
Pink: KVN
Orange: KVN+VERA
Yellow: VERA only
Pink: VLBA+GBT
Orange: VLBA only

27. Plan for 2013 Sgr A* event
VERA monitoring every 3 weeks (proposed by Akiyama)
Additional VERA+KVN imaging (TOO-type ?, but still commissioning phase)
Collaboration with KVN team
Single dish monitoring (22/43/86/129 GHz)
+ 3 station imaging up on flaring status

28. What to do with “EATING” VLBI
EATING (East Asia To Italy Nearly Global) VLBI
Target sources: M87/Sgr A*, Blazars (+ masers)
Monitoring with higher resolution !
(better image, better astrometry)
(one way to fill up the UV hole is to include Green Land Telescope)

29. Role of EATING VLBI in EHT era
Follow-up with mm/cm VLBI with VERA/ KVN/ Italian VLBI network will be important
Sgr A* : monitoring flare in 2013 ?
multi-freq. variability
M87 : mm-wave imaging and monitoring of
jet acceleration
blazars : GENJI-type monitoring
tracing both optically thin / thick regimes

30. Let’s do some test observations !
Project codes for test observations
KERA (KVN/VERA) with Noto
VLBI Including Noto
VINO
with Medicina
Medicina and KERA Global
Observatory Link
MAKGOLI
with Sardinia
Sardinia and KERA Experiment
SAKE

31. 喰　
&飲
eating
drinking
They make everyone happy !!