Title: eVLBI and High Energy Radio Astronomy: Exploring Black Hole Microquasar Phenomena SoonWook Kim Inter
111th Italian-Korean Symposium on Relativistic
Astrophysics The Sun, the Stars, the Universe
General Relativity (2009 Nov. 2-4, Sogang
Univ., Seoul) Cataclysmic Flares Relativistic
Jets in Black Hole Microquasar Candidates
Soon-Wook KimInternational Center for
AstrophysicsKorea Astronomy and Space Science
Institute
Collaboration with J.S. Kim (KASI), T. Sasao
(Aju Univ.), T. Kurayama (Kagoshima Univ.), T.
Oyama, M. Honma (VERA/NAOJ)
2Contents
- What are microquasars microquasar phenomena ?
- Milli-arcsecond scale observations of
microquasars - VLBI, very long baseline interferometry
- VERA observations of a black hole candidate
Cygnus X-3
3radio
What is Microquasar ?
Relativistic Jets 0.99c ? perpendicular to
the disk plane
- jet-emitting X-ray Binaries
- basic components spinning BH/NS disk normal
star - collimated bipolar, relativistic jets
micro-quasars (ly vs. millions of ly) - a few tens of confirmed and candidate BH
microquasars with multi-component jets known NS
microuqasars 2-3 White Dwarf 1 ?
IR
NS(1.4M?) / BH (gt3.2M?)
X-rays
accretion disk
mass accretion
???
flares
jets
(????, ???, ????, ???, ??, ???,????)
4Accreting Relativistic Objects Radiation
Processes
Synchrotron Self-Compton, boosting
TeV
RADIO
?
HX
Relativistic Jet (v0.99c)
Radio/IR/optical/UV
SX
Corona (109-1012K)
(107K)
Accretion Disk (gt106, gt109 km) aournd 10, gt106 M?
Strong Magnetic Fields (lt1015G)
Jet
GRB
flux fbb fcyc fbr fsyn fic fssc
fleptonic(ee-) fhadronic(pp(??),)
flux
light-hours
time
5 days
5Cyg X-3 Restless, Frequently Flaring BH (?)
Microquasars
- Difficulty for catching the radio jets
(microquasar phenomena) in BH/NS X-ray binaries
is due to their unpredictable, transient nature
with the recurrence time-scale of a few to
hundred years, while they are undetectable in
quiescence.
X-rays
GRS 1915105
Cygnus X-3
radio
500 days
- Two radio-bright, frequently flaring
microquasars GRS 1915105 Cyg X-3. - Numerous very long baseline interferometry
(VLBI) observations of GRS 1915105.
200 days
- Cyg X-3, the radio-brightest, has been poorly
studied (only a handful of previous VLBI for
small giant flares before our observations), in
spite of long-term monitoring for two decades ?
motivation - Goal catching variability (flares) imaging
(jets) to study related physics of accretion and
radiation processes in microqusars
6Flares associated Jets in Cygnus X-3
VLBA in 1997 February 6, 7 11
The largest microquasar system GRS 1915105 at 10
kpc(3x1017 km) has 10 M? BH with event horizon
of 60km disk of lt1013cm (lt1AU), much smaller
than a mas.
1 mas
10 mas
core lt 1mas
One-sided jet
1 degree
1 mas
At a mas, milli-arcsecond, in the Earth, one can
distinguish a human standing on the Moon. To
achieve a mas, interferometric instrument is
necessary very long baseline interferometry
(VLBI) Currently it can be achievable ony in the
radio (tens of µas possible in X-rays, arc-sec)
Radio flux
5 days
Time (days)
7Principle of VLBI (Very Long Baseline
Interferometry)
- VLBI allows simultaneous observations of an
celestial object by many connected telescopes,
having an effective diameter of a telescope of
diameter D, the length of the maximum
interferometer spacing.
20m
20m
- To observe a desired distinct interference
fringe (or, to get a desired high angular
resolution), distance between telescopes, D,
should be larger for a given wavelength by a
principle of interference, van Cittert-Zernike
theorem T ?/D - (T angular resolution or resolving power, ?
wavelength).
20m
20m
? To observe a desired distinct interference
fringes (or, to get a desired high angular
resolution), distance between telescopes should
be larger for a given wavelength.
target
reference
- VLBI is in particular very powerful to observe
weak sources (with long time integration), high
resolution imaging and high precision astrometry.
- Simultaneous (dual beam) or nearly simultaneous
(fast switching) observation of two adjacent
sources results in a compensation of irregular
phase variation due to the atmosphere and clock
(hydrogen maser frequency standard).
Tetsuo Sasaos lecture note
8VERA (VLBI Exploration of Radio Astrometry )
11th Italian-Korean Symposium on Relativistic
Astrophysics
Mizusawa 20m ( 10m)
Mizusawa
Seoul
Correlation Center at Mitaka/NAOJ
Iriki
Ogasawara
Iriki 20m
Ishigaki
Ishigaji-jima 20m
Ogasawara 20m
9RATAN monitoring in 2007
RATAN monitoring (one day average)
May
January
time (days)
- We carried out VERA observation in January
around the peak of a small, precursor flare,
prior to the giant flare of 5.5 Jy at 22 GHz (gt 8
Jy at 43 GHz). - Unlike in the case of January, no radio
monitoring so far has been reported before our
May observation hard to tell what was going on.
102007 Jan. VERA observation of Cyg X-3
flux
Time (days)
Long baseline
ISH-MIZ
ISH-OGA
MIZ-OGA
- Results of Fringe Search with AIPS (Astronomical
Image Processing System) - Cyg X-3 flared up to 1Jy plausibly at least 2
or 3 flares - Image larger than the beam probable structure
due to jet ejections during the small flare(s)
flux
MIZ-IRI
IRI-OGA
IRI-ISH
Short baseline
Time (hours)
112007 May VERA observation of Cyg X-3
flux
Time (days)
- In the later half, Cyg X-3 flared up to a few
hundred mJy, lasting 2-3 hours, consistent for
all baselines. - Possible flare(s) in the earlier epochs?
- Jet-like structure is more evident than that in
2007 January.
Time (hours)
Baseline Long-gt short
12What happened in 2007 Feb-May ?
X-ray flux
?
Radio flux
Time (days)
- Origin of image (jet) observed ?
- Unlike in the case of January, no radio
monitoring so far has been reported before/during
and right after our VERA observation - ? hard to tell what causes the jet like image
- ? further investigation is necessary to check up
with other radio and multi-wavelength
observations (e.g., IR, X-rays Gamma-rays).
13?????Thank you