Sub-mm VLBI for resolving super-massive black hole Mareki Honma VERA / Mizusawa VLBI observatory, NAOJ.

sub-mm VLBI for resolving super-massive black hole

Mareki Honma

VERA / Mizusawa VLBI observatory, NAOJ

Target : 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 3 ~ 6 x 10^9 15 Mpc 4 ~ 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

Doeleman+(2008)

･ 37±(16,10) Intrinsic diameter of Sgr A* ･ Non detection on the JCMT-CARMA （ 3075 km ）

ARO/SMT － CARMA(600km)

ARO/SMT － JCMT

Non-imaging analysis (traditional UV distance plot)

• 230GHz VLBI with JCMT – SMTO – CARMA

Sub-mm VLBI of Sgr A*

1995 Mar IRAM30m-PdB Krichbaum+ (1998)

…

2006 Mar Hawaii-SMTO-CARMA failed

2007 Mar JCMT-SMTO-CARMA Doeleman+(2008)

but IRAM/PdB failed

2009 Mar Hawaii-SMTO-CARMA

SMA phase-up Fish+(2011)

2010 Mar Hawaii-SMTO-ASTE

2011 Mar Hawaii-SMTO-CARMA-APEX-IRAM

but not fringes from Chile and Europe …

Sub-mm VLBI with ASTE (2010)Chilean station will be a key for Sgr A* observations

good site & longest baselines

JCMT

CARMA

ASTE

SMTO

UV coverage for Sgr A*（ red: UV with ASTE ）fringe spacing ~30μas

Sub-mm VLBI in 2011 Mar/Apr

International campaign from Mar. 28 to Apr. 5

Hawaii

CARMASMTO

(APEX)

(Pico Veleta)

Planned Array for April 2011 obs.

US array (Hawaii-CARMA-SMTO) is the coreEuropean stations may join (APEX / IRAM 30m)

Steps toward future• Re-trial with Chilean stations (ASTE/APEX) ?• Green land (ASIAA) : ALMA prototype move in 2013 ?• LMT : VLBI capability ?

• ALMA phase-up is the key (both sensitivity & imaging capability)

Proposal to NSF MRI in 2011

Haystack/ NRAO/ MPI/ NAOJ/ ASIAA etc.

Highly-ranked by NSF review and

will be funded this year.

observation from ~2015 (?)• Large (sub-)mm telescope will be very

useful.

ALMA phase-up plan• Phased-sum in

baseline correlator

data transfer to OSF

& recording there

• Japan’s part :

optical-fiber transmission

between ALMA – OSF

OSF(@2900m)

Optical fiber (8 x 8Gbps)

Correlator (sum-up)

Science cases• BH shadows : Sgr A* & M87• Jet monitor: launch/accelaration mechanism• Detailed structure of accretion disk• Time variation (Sgr A*: 15min, M87 : a few days)

of structure near BH• Rotation of hot spot/disk patch > test of General

Relativity in strong gravity field.

+ non-BH sciences

SFR/AGB masers, astrometry

(LMC/SMC, for instance)

M87 at 43G

BH simulationGammie & Noble

New laboratory for “Black Hole Physics”

Discriminating models for M87• Simple simulations how ALMA works out

Ring between 15.0 - 25.5μas 　Gaussian with 13.0-μas-

radius shadow 　

Gaussian with 38μas FWHM Disk with 30μas radius

Chilebaselines

Simulated and observedvisibilities vs. UV distance

Chilebaselines

γ-ray emitting AGNs• 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

Science cases around 2020Basic assumption : BH shadow itself is already seen

•Jet monitor: launch/accelaration mechanism

•Detailed structure of accretion disk

•Time variation (Sgr A*: 15min, M87 : a few days)

of structure near BH

•Rotation of hot spot/disk patch > test of General

Relativity in strong gravity field.

M87 at 43G

BH simulationGammie & NobleNew laboratory for “Black Hole Physics”

role of new large telescope in Chile in VLBI

• Even if ALMA phase-up goes, machine time should be very limited (machine time is very important, e.g., for monitor). 50m(?) in Chile will expand possibility of doing VLBI.

• Combination of 50m in Chile and phase-up ALMA (50 of 12-m) equivalent to 98-m dish !!

• 50m-ALMA for short baseline obs. (30 km – 100 km?)

Providing new “longest” baseline for ALMA

> additional science cases, such as resolving nearby giant stars

Summary• Sub-mm VLBI will open up wonderful science

cases with ultra-high resolution:

resolving BH shadows, Jet launching / gamma-ray-jet connection and more…

• Large (sub-)mm telescope will be useful to expand science cases with sub-mm VLBI (e.g., monitor etc.)