AGN studies with EHT and EATING VLBI

Mareki Honma

Mizusawa VLBI observatory, NAOJ

Touching the event horizons of BHs

Fukue et al 1989

•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!?

BH size

source MBH/Msun DistanceAngular

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 radiusFor imaging shadow, ~ 10μas resolution is required

Angular resolution of telescopes• Wavelength – angular resolution diagram

VSOP-2

VLBA

VERA ALMA

AKARI

SUBARUHST

cm wave IR opticalmm wave

VLBIConnectedarray

Single dish

Res

olut

ion

in m

as

λ

1 mas

1 arcsec

Submm VLBISgr A* BH size

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

CARMASMTO

ASTE/APEX

Pico Veleta

Planned Array around 2015

Green land

ALMA

LMT

Phase-up ALMA joining in ~2015

Doeleman+(2008)

• 37±(16,10) uas as intrinsic diameter of Sgr A*• As compact as ~ 4 R_s

ARO/SMT － CARMA(600km)

ARO/SMT － JCMT

Non-imaging analysis (traditional UV distance plot)

• 230GHz VLBI with JCMT – SMTO – CARMA

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)

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 (?)

Jet launching point ?Doeleman+(2012), Science

M87 jet-base detection

Resolved a structure with5.5 R_sch scale

M87 optical image with Subaru M87 Jet observed with VLBA

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

Science 338, 355 (2012)

There is a song with this paper’s abstract as lyrics

毎日新聞　 2012 年 9 月 28 日

We are touching BH!song by Jonathan Mann (please visit “you tube”)

Blazar jets• Jet root images at 230G !! (θ ~ 60 μas)

J1924 by Lu+(2012) NRAO530 by Akiyama+

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

Interpretation of bending jet

• Small jet-angle variation

Press release at 2012 ASJ meeting 朝日新聞　 2012 年 9 月 19 日

Fringe detection with APEX

• First fringes with Chilean station at 230G

• 3C279 in 2012 May

• Fringe spacing : ~30 μas !!

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)

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 !

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 !?)

Example : multiple point sources

• Point sources within

synthesized beam

• “Standard image”

cannot distinguish them

• Compressive sensing

image can separate them

True image convolved withSuper-resolution beam

Super-resolution imagewith compressive sensing

True image convolved withNormal beamtrue image

BH Shadow• “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

true image

Convolved with standardbeam

True image convolved withSuper-resolution beam

Super-resolution imagewith compressive sensing

Something on KVN + VERAKey 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

Improved M87 image @22GHz

With KVN+VERA, we can clearly chase βapp@1~10mas.

Beam~140Rs

Data analysis: K. Niinuma

M87 Jet launch/acceleration

Asada+ 11

Acciari+09

Flare?

“Key-Zone” @1~10mas

Ly+07

βapp =1 Quiescent?

GENJI : Blazar monitor• Example : 3C84, radio jet detection (VERA) after

γ-ray flare (Fermi)

Radio light curve

VLBI map (2 x 2 pc), at 22 GHz

Nagai+(2010)

cm + (sub-)mm VLBI will lead comprehensive understanding (higher resolution & lower optical depth …)

SSC modelfor Mrk 501(Kino+2001)

γ-ray mittingregion:<1000 AU

Sgr A* 2013 event

Trajectory of the dusty cloud (G2)VLT@3.76μm

2004.52008.3

2011.3

KVN+VERA has better (u,v) coveragethan VLBA+GBT @ 43GHz!!!

Pink: VLBA+GBT Orange: VLBA only

Pink: KVNOrange: KVN+VERAYellow: VERA only

KVN+VERA VLBA+GBT

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

What to do with “EATING” VLBIEATING (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)

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

Let’s do some test observations !Project codes for test observations•KERA (KVN/VERA) with Noto

VLBI Including Noto

VINO VINO •with Medicina

Medicina and KERA Global

Observatory Link

MAKGOLIMAKGOLI•with Sardinia

Sardinia and KERA Experiment

SAKESAKE

喰　&

飲eating drinkingThey make everyone happy !!