eVLBI and High Energy Radio Astronomy: Exploring Black Hole Microquasar Phenomena SoonWook Kim Inter

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11th 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)
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Contents

• 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

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radio
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
(????, ???, ????, ???, ??, ???,????)
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Accreting 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
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Cyg 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

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Flares 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)
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Principle 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
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VERA (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
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RATAN 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.

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2007 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)
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2007 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
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What 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).

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?????Thank you