1. Chris Done, Chichuin Jin, Mari Kolehmainen
What do we know about L~Ledd accretion – BHB, ULX – and how does Astro-H help?
Chris Done, Chichuin Jin, Mari Kolehmainen
University of Durham

2. Astro-H Next Japanese X-ray satellite due for launch in Dec 2015
Calorimeter 5eV spectral resolution
Broad bandpass
keV

3. Astro-H: Calorimeter

4. Astro-H: bandpass

6. Black hole binaries
Observe dramatic changes in SED with mass accretion rate onto black hole
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)

7. 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

8. 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

9. Variability of disc
L/LEdd AT4max (Ebisawa et al 1993; Kubota et al 1999; 2001)
Constant size scale – last stable orbit!! BH spin

10. 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
Kolehmainen & Done 2010

11. Relativistic effects
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
flux
Another area where Astro e2 will give major progress in an independent test of the accretion flow models. The accretion disc moves fast in a strong gravitational field, so both special and general relativistic effects modify its spectrum. Doppler shifts and length contraction mean that the emission from the disc moving towards us is blueshifted and boosted, while that moving away is redshifted and suppressed. Then time dilation and gravitational redshift drag everything redwards. The strength of these all effects decrease with radius. All emission from the disc is affected, but its much easier to see on intrinsically narrow features – lines. X-ray illumination of the disc gives iron Kalpha line. Moving inner disc models predict broader line in softer spectra. But the measured line profile can be distorted by narrow absorption features superimposed on the emission. The high spectral resolution of Astro e2 will unambiguously show these, enabling the intrinsic line profile to be measured.
Energy (keV)
Fabian et al. 1989

12. Theoretical disc spectra
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
kTeff
fcol kT
Log n f(n)
Log n

13. Fcol changes but OK <LEdd
XMM RXTE
Another area where Astro e2 will give major progress in an independent test of the accretion flow models. The accretion disc moves fast in a strong gravitational field, so both special and general relativistic effects modify its spectrum. Doppler shifts and length contraction mean that the emission from the disc moving towards us is blueshifted and boosted, while that moving away is redshifted and suppressed. Then time dilation and gravitational redshift drag everything redwards. The strength of these all effects decrease with radius. All emission from the disc is affected, but its much easier to see on intrinsically narrow features – lines. X-ray illumination of the disc gives iron Kalpha line. Moving inner disc models predict broader line in softer spectra. But the measured line profile can be distorted by narrow absorption features superimposed on the emission. The high spectral resolution of Astro e2 will unambiguously show these, enabling the intrinsic line profile to be measured.
Fcol up to 2 so peaks in vfv<4keV for Teff=0.5 keV disc

14. 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’

15. 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

16. Radius no longer constant!
Radius can be higher or lower when disc NOT dominant (steep PL)
Don’t do this!!
very high
disk dominated
high/soft
Kubota & Done 2004

17. Very High State: Spectrum
Kubota & Done 2004
Disc AND tail have roughly equal power. BE CAREFUL!!!
Now depends on models - Comptonized spectrum is NOT a power law close to seed photons!
Log n f(n)
Disc dominated (low L / high L)
Very high state (comp < disc)
Very high state (comp > disc)
Log E

18. Very High State: Spectrum
Kubota & Done 2004
Disc AND tail have roughly equal power. BE CAREFUL!!!
Now depends on models - Comptonized spectrum is NOT a power law close to seed photons!
Log n f(n)
Disc dominated (low L / high L)
Very high state (comp < disc)
Very high state (comp > disc)
Log E

19. Very High State: photons
Kubota & Done 2004
But Comptonised photons come from the disc – optically thick so suppresses apparent disc emission
Correct for this
Log n f(n)
Log E

20. Very High State: energy
Kubota & Done 2004
But ENERGY of corona came from disc as well. Lower T under corona but more importantly lower L enhancing outer disc
L(R)
R-3 R

21. Very High State: energy
Done & Kubota 2005
But ENERGY of corona came from disc as well. Lower T under corona but more importantly lower L enhancing outer disc (Svensson & Zdziarski 1994)
L(R)
R-3 R

22. 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

23. Disk + Compton! Bandpass!!
XTEJ
ASCA-RXTE-OSSE
Steep power law state is HARD at low E
low kTbb~0.6keV, high kTe~20keV compared to ULX

24. GRS (Nh 4-6e22!)
kTe~7keV kTe~3keV
Done et al 2004

25. Gladstone Roberts & Done 2008
ULX state ?
Gladstone Roberts & Done 2008

26. Gladstone Roberts & Done 2008
ULX state ?
Gladstone Roberts & Done 2008

27. 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 J trace scattered fraction through outburst SWIFT+RXTE
Lopt ~ Ldisc in high/soft state.
Big changes at transition to low/hard state….
Gierlinski Done & Page 2007

28. 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 f(n)
Log n

29. 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 f(n)
Log n

30. 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
Log n f(n)
Log n

31. 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 f(n)
Log n

32. 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

33. 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

34. 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