what do we know about l~ledd accretion – bhb, ulx – and how does astro -h help?
DESCRIPTION
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. Astro -H. Next Japanese X-ray satellite due for launch in Dec 2015 Calorimeter 5eV spectral resolution Broad bandpass 0.5-500 keV. - PowerPoint PPT PresentationTRANSCRIPT
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 nLo
g 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