Transcript Astrophysical black holes

Astrophysical black holes
Chris Reynolds
Department of Astronomy
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Topics

Observational evidence for black holes
 X-ray studies of strong-gravity region
 First observational studies of BH spin
 Future directions
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Observational evidence for
black holes
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Early X-ray observations
[1965] discovered a
powerful X-ray source in
Cygnus
 Cygnus X-1
– Binary star system… black
hole in orbit around a
massive O-star
– Black hole mass 7-13 M
– X-rays produced due to
accretion of stellar wind
from O-star
– 2kpc away
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How do we know the black
hole mass?
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Period 5.6 days
K = V sin i = 75km/s
Newtonian analysis…
– MBH>f
– Cyg X-1… f=0.24MBH
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Feed in knowledge of i
and companion mass…
M=7-13Msun
6 “golden” cases with
f>3Msun
Brocksopp et al. (1998)
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Strong evidence for a
3-4 million solar mass
BH at the Galactic
Center (closest stellar
approach only 40AU!)
A. Ghez (UCLA)
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X-ray studies of black holes
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Chandra+VLA image of GC (Baganoff et al. 2001)
3C273 (Quasar)
LX ~1038 W
MCG-6-30-15 (Seyfert gal)
(LX~1036 W)
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X-ray “reflection” imprints well-defined features
in the spectrum
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Relativistic effects imprint characteristic profile
on the emission line…
Iron line profile in
MCG-6-30-15
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MCG-6-30-15 Suzaku
(Miniutti et al. 2006)
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Systematic surveys of the XMM archive are showing that ~1/2
of type-1 AGN show broad iron lines (largely confirming ASCA
results)
NGC2992
IRAS 18325 (Iwasawa 2004)
MCG-5-23-16 (Dewangan 2003)
Also see Suzaku results on broad iron lines at this meeting:
• MCG-5-23-16 (Reeves et al.)
• NGC 3516 (Markowitz et al.)
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XMM analysis of
MCG-6-30-15
Assuming no
emission from
within rms
a>0.987 (formal 90% limit)
Brenneman & Reynolds (2006)
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Black Hole Quasi-periodic
oscillations
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High-frequency QPOs
– Comparable frequency to
orbital frequency in inner
accretion flow
– Often found in pairs with
3:2 ratio
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Stable frequencies
– probably determined by
gravitational potential
– Could be an excellent probe
of the mass and spin!!
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QPO theory
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Lack of standard QPO
theoretical framework is
problem
Global modes of accretion disk
– “Diskoseismology”; Wagoner,
Nowak, Kato…
– Produce g-, p-, and c-modes
– Linear theory… no natural
explanation for 3:2 ratio
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Resonance model
– Parametric resonance between
vertical/radial epicyclic
frequencies (Abramowicz &
Kluzniak)
– Source of free energy?
Fundamental g-mode (Nowak & Wagoner)
Movie by Mike Nowak
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The Future of BH X-ray Studies
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Dynamical timescale
variability… probes
orbital motions in
accretion disk
Armitage & Reynolds (2004)
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Powerful probe of
turbulent disk physics.
Also, arcs approximately
trace test-particle
Keplerian orbits in =
plane.
Iwasawa et al. (2004)
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Light crossing timescale
allows reverberation
effects to be studied.
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Chandra Deep Field
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Constellation-X simulations…
Simulated 100ks; F2-10=10-12erg/s/cm2
Simulated 1Ms; z=1; F2-10=10-14erg/s/cm2
~4 such source per Con-X field
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Imaging a black hole
mm-VLBI
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Imaging a black hole
Micro-arcsecond X-ray Imaging
Mission (MAXIM)
HST (0.1 arcsec)
MAXIM (0.05 -arcsec)
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Current MAXIM concept
Group and package Primary and Secondary
Mirrors as “Periscope” Pairs
~20,000 km
~500-1000 m Baseline
•“Easy” Formation Flying (microns)
•All s/c act like thin lenses- Higher Robustness
•Possibility to introduce phase control within one
space craft- an x-ray delay line- More Flexibility
A scalable MAXIM concept.
•Offers more optimal UV-Plane coverage- Less
dependence on Detector Energy Resolution
•Each Module, self contained- Lower Risk. 31