Photon Spectra of Super-Critical
Black Hole Accretion Flows
Tomohisa KAWASHIMA (NAOJ)
in collaboration withKen OHSUGA (NAOJ)
Hiroyuki TAKAHASHI (NAOJ)
Shin MINESHIGE (Kyoto U.)
Tessei YOSHIDA (NAOJ)
Ryoji MATSUMOTO (Chiba U.)

Supercritical Accretion Flows• spherical accretion:
sub-Eddington( ：Eddington luminosity)• disk accretion:
anisotropic radiation→ supercritical accretionis feasible→ super-Eddington L LE
• candidates：
powerful jet sources (SS433, S26)
Narrow Line Seyfert I, OVV quasars,
microquasar (GRS1915+105),
ultraluminous X-ray sources

Ultraluminous X-Ray Sources (ULXs)•ULXs are observed in off-center regionof nearby galaxies.

39 411
L=10[erg·s]• Luminosity: X

for stellar-mass BHs(A)subcritically accretingintermediate mass BH?
or(B)supercritically accretingstellar-mass BH?
http://www.sciencedaily.com# Recently, the discovery of a supercritically accreting NS (M82 X-2) has been reported (Bachetti et al. 2014)

ULXs show spectral features different with galactic BHCs nor AGNs.
Studies of SEDS are expected to be a key to understand ULXs.

SEDs of ULXs - New Spectral State!
(e.g. Gladstone et al. 2009)

0.01

0.01

NGC1313X2

0.001

IC342-X1

EF_E

EF_E

0.001

0.00010.0001

110Energy (keV)

110Energy (keV)# The data are kindly sent to us by Dr. Gladstone.

ULXs show the hard power-law component, which(1) rolls over around 5 keVor (2) extends up to 10 keV.
Rad-HD simulations are needed to study super-Eddington Flows.

Structure of Super-Critical Accretion Flowwith Compton-Cooled Outflow(Axisymmetric 2D Rad-HD Simulation, MBH = 10M )(a)6(b)
78-10-8-66-47-108-8-6-4

10500

500-5-500-500

0cool( 10 K), dense andslow( < 10 2 c ) outﬂow
6.5500-10-10

mildly hot ( 108 K ),sub-relativistic
funnel jet-50

shock-heatedregion( 108 K )510rad. pressure
dominant disk

Calculation Model of SEDs
Rad-HD simulation
solve the photon transport using Monte-Carlo method678-10-8-6-4500

2. generate seed photon from a point
above the surface obtained by step (1)✤ consider bremss. emission✤ Taking into account special
relativistic effects (Doppler shift &aberration due to bulk motion)
3. Solve photon transport by using
Monte-Carlo method✤
free-free absorption✤
photon-trapping effect✤thermal & bulk Comptonizaton

0-500-500

1. Identify surface where0500

output SED

Effect of Compton Scattering on SED
with thermal +bulk Compton
with thermal Compton
without Compton (Thomson scattering)swallowed by BH (with thermal+bulk Compton)•Thermal and bulk Comptonization harden SEDs.
•In the hot plasma formed near the BH, the photons are upscatteredby thermal inverse Compton scattering.

Dependence ofon SEDs
short range power-law,which is flatter thanthat of SADM

rollover at•When the mass accretion rate is lower,

the power-law extending up to 20 keV appears.

•When the mass accretion rate is higher,
rollover at 5 keV appears.

5keV

Dependence of SEDs on the viewing angle “i”

678-10-8-6-4500

0-500
-500

0500

•When the viewing angle is smaller,
SEDs become harder.
, the rollover•Foraround 5keV also appears when theviewing angle is large.

Spectral Softening in the Outflow
Comtonization in the outflow
is forbidden artificially.

678-10-8-6-4500

0-500-500

downscattering

0500

When is higher or
inclination angle is larger,
SEDs become softer.
This is because more ofobservable photons are
Compton downscattered in
the cool outflow.

Structure of Super-Eddington Accretion Flow
& Trajectories of Photons
high luminosity
hard spectrum

low luminosity
soft spectrum(2) sub-relativistic,

mildly hot funnel jetabsorption(3) cool, dense, andcentrifugal barrierbulk Compton

reflectedshock

slow outflow

downscattering

BH
thermal Compton(4) shock-heatedupscattering

region(1) radiation pressure

dominant disk

photontrapping•hot coronal inflows upscatter the photons (i.e., inverse-Compton scattering).
•cool coronal outflows downscatter the photons (i.e., Compton scattering)Comparison with ULXs
•colored curves: calculated spectra•black points: XMM-Newton Datacorrected for absorption(provided by Dr. Gladstone)

NGC1313 X-2
10.1

IC342 X-1

Calculated SEDs are similar to
those of ULXs!
(rollover at 5keV, power-low shape)

10.1

However, the soft excess are not
reproduced in our simulations, because theemission fromis too weak tosignificantly contribute to the SEDs.
<— Larger simulation box containing larger
outflowing photosphere may solve thisproblem. And/or the effects of the magnetic
dissipation may be important.

NGC5204 X-1
10.1

0.3

110

A little more about the spectral state of ULXs
• Variability of SEDs of soft state and dim

our result

hard state seems to be explained by ournumerical model.

• Bright hard state (cyan) is , however,

hard to be explained by our model.
We need more sophisticatedtheoretical models!

observation

IC342X-1(yoshida et al. 2013)

HolmbergIX X-1(Vierdayanti et al. 2010)

(高橋博之さんのスライドより)Second Topic: Where is the hot corona formed
3-dim. General Relativistic Radiation MHD simulation

non rotating BH.
initially poloidal magnetic fieldDevelopment of GR radiative transfer code

• The accumulation of the poloidal magnetic fields threading the spinning BH

results in the formation of the hot corona in the vicinity of the BH. (Takahashi etal. in prep.)•I am now developing the GR radiative transfer code to calculate the moresophisticated SEDs of black hole accretion flows!

spin a = 0.99M

spin a = -0.99M

Discovery of Absorption Line in ULXs?
et al. (2014) reported discovery of a blue-shifted• Middleton
absorption line with v~0.1c in NGC 5408 X-1 and NGC6946
X-1, which may be the evidence of the outflow.

ULXs show soft X-ray spectra. This indicates that we• Theseobserve this source with higher inclination angle.
is important to theoretically reveal the dependence of the• Itabsorption
line on the viewing angle.
Middleton et al. (2014)

Middleton et al. (2011)

Summary
Compton effects are very important in super-critically• The
accreting black holes.
inflow is hot and upstaters the seed disk photons..
• Coronal
The upscattered photons are downscattered by the coronalcool outflow and the spectral rollover at ~5keV is formed.

accretion flows onto stellar-mass black holes• Super-critical
can explain the spectral features of ULXs.
calculations including the effects of GR and line transfer• Theare future work.
hopefully think we can apply our numerical methods to the• Istudiesof AGNs.

Dependence of Viewing Angle: (2) Luminosityforis lower than that for, partly
because more amount ofphotons are swallowed by
BH and partly because
along the funnel jetfor.
Isotropic luminosity increases when the viewing angle is smaller.

mildly collimated by the thick disk
and mildly beamed by the funnel jet!

(高橋博之さんのスライドより)

gas temperature on the equatorial plane
non-rotating BH rotating BH(a=0.94)
initially poloidal
mag. ﬁeld(r-θ)

ISCOprelim

ina
ry

res
u

lt

initially toroidal
mag. ﬁeld(φ)

high temp.
regionTg >> Trlow temp.
region (in LTE
Tg = Tr(高橋博之さんのスライドより)temperature inside the disk
prelimina
ryres
toroidalu
ISCO(a=0.94) ISCO(a=0.0)

lt

a=0, poloidal
a=0.94, poloidal
a=0, toroidal
a=0.94, toroidal

poloidalgas temperaturerad. temperaturer/rg
The gas is overheated near BH in all model.
The deviation starts at a larger radius for the poloidal model than thetoroidal model.
The deviation starts from the radius (slightly) larger than the ISCO.