Post on 02-Jan-2016
Search for
Binary Black Holesin Galactic Nuclei
Hiroshi SUDOU
(Gifu Univ., Japan)
sudou@gifu-u.ac.jp
EAVN Workshop, Seoul, 2009 March 19
Outline
Introduction to Binary (supermassive) Black Hole (BBH)
Possible evidence for BBHs Ideas for KVN/EAVN observations Prospects for VSOP-2
Begelman et al. 1980
Evolution
Dynamical Friction
Gravitational Wave
Basic scenario:
1) a galaxy have a SMBH 2) galaxy merging often occurs 3) merged galaxy should have two SMBH in its center 4) two BH forms BBH system 5) they finally merge into one with gravitation wave burst
Good Target for VLBI
Lifetime of BBH can be the longest between DF phase and GW phase
The most observable examples of BBHs will have
Separation ~ 0.01 - 1 pc (20 - 2000 micro-as @ 100Mpc)
Orbital period ~ 1 – 100 yr
Schematic View of BBH NLR
BLR
Accretion Disk
Jet
Torus
BH
10pc0.1pc
0.1pc
10-100pc
Detection of orbital motion of BH is direct evidence for BBH !
Possible Evidence (1)Periodic Flux Variations
OJ287 (Sillanpaa et al. 1998)
Possible Evidence(2)Jet shape
Roos et al. 1993
Owen et al. 1985Yokosawa and Inoue 1985
Twin jet (3C75) Precession jet (1928+738)
Possible Evidence (3)Double AGN core
Komossa et al. 2003 Mines et al. 2004
r ~ 1 kpc
r ~ 10 pc
Chandra VLBA
Detecting BBH with VLBI r [pc] P [yr] Phenonema Detection Methods facility
< 0.001 <1 Gravitational
wave
Pulsar timing SKA ?
0.01 1 Double core High spatial resolution imaging
VSOP-2
0.1 10 Core motion VLBI astrometry VERA/VLBA
Periodic flare Flux monitoring KVN
>1 >1000 Wiggling jet Sensitive imaging EAVN/VLBA
Combination of these methods is very important
Periodic flare due to BBH How to find characteristic variation due to
BBH ? What is variation mechanism ? Theoretical study / simulations
Hayasaki et al. 2006
Multi-frequency observations are important
Flux monitoring with KVN Searching for periodic variation with period of
< a few yr KVN is suitable for this project
• sensitive mm-wave (less jet contamination)• multi-frequency (22-120 GHz)
Combination with other wavelength • Note: X-ray all-sky monitoring facility MAXI will be
on board ISS in 2009
Based on monitoring results, we can go to further BBH search
Problems of this idea
Clarify importance of multi radio-frequency• What is flaring mechanism at mm-wavelength ?• More theoretical study must be needed
Source selection criteria (merging or merged galaxy ? Sensitivity limited ?)
Probability to detect orbiting BHs• GW emitting phase would be very short (< 104 yr)
compared with AGN timescale (108 yr ?)
More detailed discussion needed
BBH is important target for VSOP-2
Longest baseline: 25,000 kmFrequency: 8, 22, and 43 GHzSpatial resolution: 40 micro-arcsec @ 43GLaunch: FY2012
High spatial resolution is essential, 40 micro-as 0.02 pc @ 100Mpc for detecting harder BBHs emitting gravitation wave!
Summary
BBHs with r~0.1pc, P~10 yr would be most observable examples
Proposing idea of flux monitoring with KVN, but needed more discussion
Based on monitoring results, VSOP-2 could confirm the presence of BBH emitting gravitation wave
Hoping to much friendly collaborate with East-Asia people !
Possible evidence (x) Core motion
α
δ
12
3
4
56
@8GHz
8 GHz 50 micoro-as
Radio Galaxy 3C66B
Further observations are needed !
MAXI
Monitor of all-sky X-ray image 0.5 – 30 keV Position accuracy ~ 6 arcmin Every 90 min (1 orbit), all-sky image will
be obtained 1000 X-ray source is expected to be
detected, including AGN, X-ray binary, etc
0.01
0.1
1
10
100
1000
10000
100000
0.0001 0.001 0.01 0.1 1 10
r [pc]
P [
yr] 10̂ 7Msolar
10̂ 8Msolar10̂ 9Msolar
Orbital period
yr10cm10
r50
2/1
solor8
2/3
17
M
MP
The most observable examples of BBHs will have P ~ 1 - 100 yr
Comparison between Binary Pulsar and BBH
Binary Pulsar BBH
Object Nutron Star SMBH
Mass 1 Msolar 10^8 Msolar
Separation 10^11cm 10^17 cm
Period 3days 50yrs
GW frequency kHz mHz