What do we know about L~Ledd accretion – BHB, ULX –

and how does Astro-H help?

Chris Done, Chichuin Jin, Mari KolehmainenUniversity of Durham

Astro-H

• Next Japanese X-ray satellite due for launch in Dec 2015

• Calorimeter 5eV spectral resolution

• Broad bandpass 0.5-500 keV

Astro-H: Calorimeter

Astro-H: bandpass

• Dramatic changes in continuum – single object, different days

• Underlying pattern in all systems

• High L/LEdd: soft spectrum, peaks at kTmax often disc-like, plus tail

• Lower L/LEdd: hard spectrum, peaks at high energies, not like a disc (McClintock & Remillard 2006)

Black hole binaries

• Observe dramatic changes in SED with mass accretion rate onto black hole

Moving disc – moving QPO• Energy spectra: disc moves 50-6ish Rg as make transition• Power spectra: low frequency break moves correlated with

QPO, high frequency power more or less constant! • Large radius moves, Small radii constant

Moving disc – moving QPO• Energy spectra: disc moves 50-6ish Rg as make transition• Power spectra: low frequency break moves correlated with

QPO, high frequency power more or less constant! • Large radius moves, Small radii constant

Variability of disc

• L/LEdd AT4max (Ebisawa et al 1993; Kubota et al 1999; 2001)

• Constant size scale – last stable orbit!! BH spin

Kolehmainen & Done 2010

Disc spectra: last stable orbit

• L/LEdd T4max Ebisawa et al 1993; Kubota et al 1999; 2001

• Constant size scale – last stable orbit!!

• Not quite as simple as this • BHSPEC - Proper

relativistic emissivity (Novikov-Thorne)

• corrections for spectrum not being blackbody (fcol)

• Corrections for relativistic propagation effects Davis et al 2005

Relativistic effects

Fabian et al. 1989

Energy (keV)

flux

• Relativistic effects (special and general) affect all emission (Cunningham 1975)

• Emission from the side of the disc coming towards us is blueshifted and boosted by Doppler effects, while opposite side is redshifted and suppressed.

• Also time dilation and gravitational redshift

• Broadens spectrum at a give radius from a narrow blackbody

• Surely even disc spectra aren’t this simple!!!!

• Disc annuli not blackbody – too hot, so little true opacity. Compton scattering important.

• Modified blackbody Shakura & Sunyaev 1973

• Describe by colour temperature fcol

• And relativistic smearing effects on the spectra at each radius

Theoretical disc spectra

Log n

Log

n f

()

n

kTefffcol kT

Fcol changes but OK <LEdd

XMM RXTE

• Fcol up to 2 so peaks in vfv<4keV for Teff=0.5 keV disc

BHB Disc spectra:10 M L/LEdd ~1

Kolehmainen et al 2013 • LMC X-3• Peak at 3.5 keV for

~0.8LEdd

• 3.5 x (10/107)1/4~0.1keV for 107 AGN (Ross, Fabian & Mineshige 1991)

• ‘broadened disc’

Moving disc – moving QPO• Energy spectra: disc moves 50-6ish Rg as make transition• Power spectra: low frequency break moves correlated with

QPO, high frequency power more or less constant! • Large radius moves, Small radii constant

Kubota & Done 2004

Radius no longer constant!

very high

disk dominated

high/soft

• Radius can be higher or lower when disc NOT dominant (steep PL)

• Don’t do this!!

• Disc AND tail have roughly equal power. BE CAREFUL!!!

• Now depends on models - Comptonized spectrum is NOT a power law close to seed photons!

Very High State: SpectrumKubota & Done 2004

• Disc dominated (low L / high L)• Very high state (comp < disc)• Very high state (comp > disc)

Log E

Log

n f

(n)

• Disc AND tail have roughly equal power. BE CAREFUL!!!

• Now depends on models - Comptonized spectrum is NOT a power law close to seed photons!

Very High State: SpectrumKubota & Done 2004

• Disc dominated (low L / high L)• Very high state (comp < disc)• Very high state (comp > disc)

Log E

Log

n f

(n)

• But Comptonised photons come from the disc – optically thick so suppresses apparent disc emission

• Correct for this

Very High State: photonsKubota & Done 2004

Log E

Log

n f

(n)

• But ENERGY of corona came from disc as well. Lower T under corona but more importantly lower L enhancing outer disc

Very High State: energyKubota & Done 2004

L(R

)

R

R-3

• But ENERGY of corona came from disc as well. Lower T under corona but more importantly lower L enhancing outer disc (Svensson & Zdziarski 1994)

Very High State: energyDone & Kubota 2005

L(R

)

R

R-3

Disk + Compton! Bandpass!!

• All high L states have disc plus tail

• Disc – low E, constant on short timescales

• Compton – high E, varies on short timescales

• Steep power law state is HARD at low E

Disk + Compton! Bandpass!!

• XTEJ1550-564• ASCA-RXTE-

OSSE• Steep power law

state is HARD at low E

• low kTbb~0.6keV, high kTe~20keV compared to ULX

GRS1915+105 (Nh 4-6e22!) kTe~7keV kTe~3keV

Don

e et

al 2

004

ULX state ?

Gladstone Roberts & Done 2008

ULX state ?

Gladstone Roberts & Done 2008

Modifies optical continuum

• X-rays illuminate outer disc where intrinsic flux is low so reprocessed can dominate (van Paradijs 1996)

• SWIFT/XMM X-opt simultaneously

• XTE J1817-330 - trace scattered fraction through outburst SWIFT+RXTE

• Lopt ~ 0.002 Ldisc in high/soft state.

• Big changes at transition to low/hard state….

Gierlinski Done & Page 2007

Luminosity > LEdd ?

Log n

Log

n f

()

n

• Standard disc assumes that energy liberated locally through mass accretion is radiated locally

• Not necessarily true – can be carried radially along with the flow is accretion timescale < radiated timescale

• Optically thick advection – slim discs (Abramowicz et al 1988) only different L>LEdd

• Heats next ring in – but can advect that also. Then lose does the black hole!

• L=LEdd log(1+mdot/mdotEdd)

Luminosity > LEdd ?• Standard disc assumes that

energy liberated locally through mass accretion is radiated locally

• Not necessarily true – can be carried radially along with the flow is accretion timescale < radiated timescale

• Optically thick advection – slim discs (Abramowicz et al 1988) only different L>LEdd

• Heats next ring in – but can advect that also. Then lose does the black hole!

• L=LEdd log(1+mdot/mdotEdd)

Log n

Log

n f

()

n

Luminosity > LEdd ?

Log n

Log

n f

()

n

• Standard disc assumes that mdoty constant with R

• Not necessarily true – can lose mass in a wind is L>LEdd (Shakura & Sunyaev 1973)

• L=LEdd log(1+mdot/mdotEdd) i.e. same as before but for different reason

Luminosity > LEdd ?• Standard disc assumes that

mdoty constant with R• Not necessarily true – can lose

mass in a wind is L>LEdd (Shakura & Sunyaev 1973)

• L=LEdd log(1+mdot/mdotEdd) i.e. same as before but for different reason – local flux at disc surface has to be <LEdd

• Two possible responses – so disc probably does both as seen in numerical simulations

Log n

Log

n f

()

n

Modifies optical continuum

• Expect f_opt,int/f_x to increase

• X-rays decrease via advection and/or mass loss

• Optical determined by irradiation – depends on geometry

• If see irradiation then CAN’T be strongly beamed

Modifies optical continuum

• Expect f_opt,int/f_x to increase

• X-rays decrease via advection and/or mass loss

• Optical determined by irradiation – depends on geometry

• If see irradiation then CAN’T be strongly beamed

• M81 X6 Sutton et al 2014

Conclusions:• BHB spectral states: disk (low E) plus tail (high E) • Bandpass makes a difference RXTE (BHB) XMM (ULX) • High L~Ledd can show disc (constant radius)• Fraction illuminating outer disc is small• Disky ULX – fraction illuminating outer disc small• Or very high state – larger size scale, lower kTe –

connects to ULX?• But then got more extreme ULX states – higher mdot?• fopt determined by irradiation – so irradiating disc so not

highly collimated….• NOT like expect for mdot~1000