agn studies with eht and eating vlbi mareki honma mizusawa vlbi observatory, naoj
TRANSCRIPT
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
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 !!