Transcript che

SS 433 – a Supercritically
Accreting Microquasar with
Black Hole.
Sternberg Astronomical Institute,
Moscow University
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Quasar and Microquasar:
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SS 433 – 30 years after discovery.
Clark and Murdin (1978); Margon et al. (1979).
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Pprec = 162d.5
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Milgrom (1979), Fabian
and Rees (1979),
Cherepashchuk (1981)
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SS 433 – close binary system.
Crampton, Cowley, Hutching (1980).
Porb ≈ 13d.1 (LMXB).
SS 433 – massive eclipsing binary system.
Cherepashchuk (1981). Discovery of
optically bright precessing accretion disk.
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Optical light curves of SS 433.
Goranskij, Esipov, Cherepashchuk (1998).
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Stability of orbital, precessional
and mutational periods.
Davydov, Esipov, Cherepashchuk (2008).
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X-ray data.
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INTRODUCTION: SS
433
• A massive eclipsing binary
system
• Consists of a massive donor
star and a compact
object, surrounded by
precessing accretion disk
• Narrow-collimated relativistic
jets (v ~ 0.26 c)
• Precessional period P=162.5 d
• Orbital period p=13.082 d
• A problem with spectral
classification of the optical star
(the disk is significantly more
luminous)
One of the main questions - the nature of
the relativistic object (BH or NS ?)
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New high-resolution spectroscopy of
SS433 (Hillwig & Gies 2008)

Reliable detection of
absorption lines of the
optical A3-7I star

Reliable radial velocity
curve of the optical
component
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
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Kv=58.2+/-3.1 km/s (from absorption lines)
Kx=168+/-18 km/s (from HeII emission line)
Mass ratio q=Mx/Mv=0.35
Optical star mass function fv(M)=0.268 M
Masses os the components:
Mv=12.3+/-3.3 M
Mx=4.3 +/- 0.8 M
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Main hard X-ray features revealed by
INTEGRAL AO1-AO5
First observations gave a surprise: SS433 is a hard X-ray source
with emission clearly detected up to 100 keV  SS433 is
galactic microquasar with hard X-ray spectrum (AMCh et al
2003)
 Strong precessional variability in hard X-rays with an
amplitude Lxmax/Lxmin ~ 7
 Peculiar and variable shape of ascending eclipse branch
 Wide, deep hard X-ray eclipse
HOT
(wider than in soft X-rays!)
EXTENDED
 Hard X-ray spectrum independent
CORONA
of the precessional phase

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All INTEGRAL observations
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Precessional variability

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Strong precessional 162-d
variability was found with a
maximum to minimum flux
ratio of ~7
Flux at primary minima is nonzero: ~ 3 mCrab, suggesting
extended hard X-ray emitting
region
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Analysis of hard X-ray spectra

To increase statistical
significance, we
splitted the
precessional light
curve on two parts:
“high” (maximum Xrya flux) and “low”
(<10 mCrab). Both are
consistent with power
law.
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T3
Average precessional light curve with AO5 data added
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II(1.025<Ψprec <1.125 &
0.875<Ψprec <0.975)
I (0.975<Ψprec <1.025)
III (0.5<Ψprec <0.8 &
1.2<Ψprec <1.5)
20-200 keV spectra (IBIS/ISGRI).
Power-law photon index Γ=2.8 for all spectra!
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Orbital eclipses
primary max.

Several orbital
eclispses were
observed at different
precessional phases
crossover I
Second. max. crossover II
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Individual eclipses at T3
IBIS/ISGRI
18-60 keV
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Mass ratio from hard X-ray eclipses
In the standard X-ray range 1-10 keV:
q~0.1-0.15 (Kawai et al. 1989, Kotani et al. 1996);
due to a very wide X-ray eclipse
 In the hard X-ray range (18-60 keV) the eclipse
form and width are very variable.
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Egress from the primary
eclipse is extremely
variable (presumably due
to gaseous streams from
ther star and stellar wind
from the disk)
Ingress to the primary
eclipse is much more
stable
Interpretation of the
primary eclipse by
geometrical model should
be based on the upper
envelope of the eclipse
ingress
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Fitting of the primary eclipse (ingress) together with
precessional light curve yields q=0.3, in agreeement with
optical spectroscopic determination by Hillwig & Gies
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Model for variability
• The optical star fills it Roche lobe
• The accretion disk is approximated by an oblate spheroid
• X-ray flux is emitted by the hot “corona” around the base
of the narrow relativistic jets
• The “corona” is approximated by the spheroid and
precesses along with disk
• The “corona” is placed inside the “funnel” at the inner parts
of the disk
• During the orbital and precessional moving the “corona” is
eclipsed by the star and disk bodies
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Results for q=0.1: Good fit to eclipse,
bad fit to precessional variability

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In principle, long thick
X-ray jet yields a good fit
to the orbital eclipse, but
totally fails to describe
the precessional light
curve!
 Joint analysis is
needed.
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Joint analysis of orbital eclipses (ingress only)
and precessional variability: q=0.3
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Orbital + precessional chi-2 for
different q
Mv<15 M
Sum of the reduced orbital
and precessional chi-2
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Monte-Carlo analysis of broadband (2-100 keV) Xray spectrum and parameters of hard X-ray corona
JEMX+IBIS
May 2003
(Krivosheev et al. 2008)
Corona:
kTc~20 keV
Rc~6x1011cm
τc~ 0.2-03
ne~ 4x1012cm-3
Jet:
dM/dt~
10-7 M /yr
Lkin~1039 erg/s
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Conclusions

Our correct analysis of hard X-ray eclipses and
precessional variability in SS433 allowed
independent determination of the binary mass
ratio q=Mx/Mv=0.3, in full agreement with optical
spectroscopic result by Hillwig & Gies (2008). The
compact object mass is Mx=5.3 M , Mv=17.7 M
confirming its nature as a black hole
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
INTEGRAL orbital and precessional light curves
of SS433 can be interpreted by an extended corona
above the superaccreting disk around the black
hole. Thin relativistic jets shining in soft X-rays are
generated from the center of the corona that is
observed in hard X-rays
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