Transcript What happens close to a black hole?

‘Symposium on High Energy Astrophysics’
HRI, Feb 18, 2012
What Happens
Close to a Black
Hole ?
We don’t know
A. R. Rao, TIFR, Mumbai
Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
Black Holes
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Stellar Structure theory
Dynamical mass measurements: compact stars
heavier than a few solar masses
A massive object at the center of our galaxy
Active Galactic Nuclei
Ultra-luminous X-ray (ULX) sources
Gamma-ray bursts
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Force equation:
Radiation pressure and gas pressure.
“I do not see how a star which has once got
into this compressed state is ever going to get
out of it ... It would seem that the star will be in
an awkward predicament when its supply of
subatomic energy fails.”
–Sir Arthur Eddington
Chandrasekhar limit
Stellar mass Black Holes
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Compact objects heavier than neutron stars/ white
dwarfs
Mass function f(M) = P K3 / 2  G
= M sin³ i / (1 + q)²
Cyg X-1: P = 5.6 d
M2 > 9 M (~30 M)
Last 15 years:
several new sources : transients
Some statistics
20 black hole binaries known
300 million estimated
5% of baryonic mass
10% of X-ray Binaries
17 transient LM-XRB
(3 always bright)
0.17 - 33.5 days
13 radio bright (5 jets)
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Lightest known black hole: GRO J1655-40
M = (5.8 – 6.8 M) (95% confidence limit)
Most massive: IC 10 X-1: 33+3 M(> 21 M)
A Black Hole in the centre of our Galaxy
2.9 million x mass of the Sun
Doelman et al. 08
Active Galactic Nuclei
• Dynamical centers of some galaxies
• Large lumonisity in tiny spaces
• Powerful sources at all wavelengths
- strong continuum
– X-ray emission most generic property
• Seyfert 1 and Seyfert 2 galaxies, NLS1s,
QSOs, LINERs etc
• BLRGs, NLRGs, BL Lac objects, Blazars etc
Reverberation mapping
Peterson (1997)
– Broad Line region: 0.01 - 1pc;
Illuminated by the AGN's
photoionizing continuum radiation
and reprocess it into emission lines
– RBLR =c  t
– V estimated by the FWHM of broad
emission line
- M = f (r V 2 /G)
Mass from optical emission lines in M 87
M =2.4 109 M
Macchetto et al. (1997)
Mass from maser observations
22 GHz microwave emission
NGC 4258 M=4 107 M
Miyoshi et al. (1995)
Black Hole Census
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Two dozen dynamical mass measurements of
Stellar mass black holes
Five dozen super-massive black holes
(reverberation mapping, stellar/gas dynamics,
water maser)
Another two dozen stellar mass and a several
thousand AGN from correlations and scaling
laws.
Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
Accretion onto Black Holes
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Rs = 2 GM/c² = 3 km M/ M
ISCO = 3 Rs ; 2200 Hz (Rs/2)
 = 0.057 – 0.42
Accretion (angular mtm Transport) driven
by MHD turbulence
Can support B-fields that thread the black
hole (stretched) horizon
Spectral states
Rs = 2 GM/c² = 3 km M/M
ISCO = 3 Rs ; 2200 Hz
(Rs/2)
 = 0.057 – 0.42
AGN X-ray spectrum
Broad Iron fluorescence lines
Iron line profile in
MCG-6-30-15
(Tanaka et al. 1995)
Galactic: Miller 2007
Spin measurement by
Blackbody Spectral
fitting
Narayan & McClintock
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Inner radius  BH spin
L  T4
Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
GRS 1915+105: A Micro-quasar
 Proper motions:
µa = 17.6 ± 0.4, µr = 9.0 ± 0.1 mas d-1
 From line of sight HI absorption
D = 12.5 ± 1.5 kpc
 Apparent velocities on the plane of sky
1.25±0.15 c and 0.65±0.08 c
 sin 
c
 r ,a 
(1   cos ) D
 True speed of ejecta  = 0.92 ± 0.08
 Jet angle  = 70o ± 2o to the of sight
 1997 observations show higher proper
motions  smaller distance and angle
VLA observations
Mirabel & Rodriguez 1994,
Nature, 371, 46
Spectral States
and Jets
Definite pattern of jet activity
seen as a function of spectral
state (Fender et al. 2004)
Fender, Belloni & Gallo (2004)
X-ray Radio correlation in Galactic Black Hole Sources
(Brocksopp et al. 99; Corbel et al. 00; Gallo et al. 02; Markoff et al. 02)
Gallo et al. 2003
Black Holes: The power behind the
scene
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Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
Quasars/ micro-quasars
Variability, Luminosity & Mass of
Black Holes
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McHardy et al. 2006, Nature, 444, 730
TB : MBH2 / Lbol
Arevalo et al. 2008
QPO in AGNs
RE J1034+396: Gierlinski et al. 2008
Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
• Mass
measurements
available for 39
AGNs and 17
XRBs.
• Typical accuracy
~ 30% for AGNs
~ 10% for XRBs
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Black hole mass measurements
Spectrum
Lx/ LEdd
Radio
Timing
Accretion onto Black holes
Observers can define a
``small number of states and their
association with jets providing a
good frame work to base theoretical
studies'‘ (Belloni et al, 2011, arxiv1109.3388
Theorists, claiming that
there is remarkable success in
the study of black hole
``We are still a long way
accretion disks, lament that the
From a theory of accretion
most pressing problem of the day
Discs with real predictive
is to match
Power’’ – King, arXiv1201.2060
``our theretical knowledge
to actual observed phenomena''
(Abramowicz \& Fragile, arxiv1104.5400)
Cyg X-1 hard:
disk (scattered)
Compt.
Reflection
Cyg X-1 soft:
non-thermal Compt
XTE J1550-564:
VHS/IS
RXTE-PCA
HEXTE
OSSE
GRS 1915+105
dN/dE = E- Photons/cm2/s/keV
E*E-  keV/cm2/s/keV (cm2/s)
E² * E- keV(keV/cm2/s/keV)
Abs*(diskbb+cpompST)
Wide band spectrum of a black hole candidate
EQPair: Zdziarski et al.
Eqpair for multiple sources
GRS 1915+105
Crab
Cyg X-3
Plan
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Black Holes in the Universe
Accretion theory
Disks, Jets and outflows
Across Mass scales
The difficulties
The Astrosat project
Conclusions
ASTROSAT
SXT
UVIT
LAXPC
CZT
SSM
Astrosat Instruments
1. LAXPC : Large Area X-ray Proportional Counters;
Aeff ≈ 6000 cm2; FOV =10 X 10; 3-80 keV; E/ΔE ≈ 5 to 12.
2. CZT Imager: Cadmium-Zinc-Telluride array with Coded Aperture Mask;
Aeff = 500 cm2; FOV = 60 X 60;10 – 100 keV; E/ΔE ≈ 20 to 30.
3. SXT : Soft X-ray Telescope using conical-foil mirrors
A eff ≈ 200 cm2 ; FOV = 0.50; (~3‘ res); 0.3-8 keV; E/ΔE ≈ 20 to 50.
4. SSM : Scanning Sky Monitor (SSM) with 3 PSPCs and
coded aperture mask; A eff ≈ 30 cm2 (each); 2-20 keV.
5. UVIT : Ultraviolet Imaging Telescope (UVIT)
two telescopes each with 38 cm aperture;
near-uv , far-uv and visible bands.
Astrosat Science Objectives…
• Multi-wavelength studies (UV to X-rays)
spectra, variability.
• Periodic and aperiodic variability.
• Broad band X-ray spectroscopy
non-thermal components,
cyclotron lines.
• Surveys
All-sky, Galactic plane, deep.
Suzaku Vs CZT-Imager
Mrk 110
Binary X-ray Pulsars with Astrosat
Simulated 10 ks observations of a hard X-ray pulsar spectrum. The
cyclotron lines are nicely resolved by ASTROSAT .
Conclusions
• The inner-most regions of the accretion disk in
Black Hole sources are emitters of non-thermal
radiation.
• Precise hard X-ray continuum spectroscopy is
needed to understand this region.
• Implications for a variety of phenomena in high
energy astrophysics: GRBs, accretion physics,
AGN growth….
• Astrosat would be a small but decisive step
forward.