Accreting black holes at low L/LEdd

Chris Done University of Durham

• Truncated disc/hot inner flow geometry very successful in explaining:– Range of low/hard spectra– Correlated change in PDS– Transition to soft state– Correlated collapse of jet

• But still controversial…– Untruncated disc in LHS (very

broad iron line, hot disc)?• TEST!! All hot inner flows

(ADAF, ADIOS, CDAF) require protons have some (large) fraction of virial kT

• Will get p + p 0

Truncated disc model at low L/LEdd Spectral softness +

PDS frequencies

• Not much change in Lbol. Soft is disc dominated – radiatively eff, no hot flow so no 0 and would absorb anyway!

• Hard state NOT disc dominated. Should have hot flow and hence 0

and absorption depth < 1 except for brightest hard states.

Transitions: Cyg X-1

Observable decays?• Thermal (ADAFs): Make X-ray spectrum! proton kT~1012-13 K (virial

temperature). Electrons get energy from Coulomb collisions with protons and have kT ~ 109 K (100 keV). Get 0 (+ little sync. emission from the +/-).

• If non-thermal then have more above the rest mass energy threshold so make more 0 (and relativistic +/- and e+/-) Mahadevan, Narayan & Krolik 1997; Mahadevan 1999; Oka & Manmota 2003

Mahadevan 1999

Ther

mal

Non

The

rmal

Observable decays?If the protons are non-thermal then decay gives relativistic e+/- so get synchrotron as well as rays from 0 – predicts non-thermal tail!!!!

OSSE COMPTEL

Egret already rules out nonthermal protons!! Must be thermal if p are heated….

EGRET

Mahadevan 1999

McConnell et al 2000

Observable decays?

OSSE COMPTEL

EGRET

Pretty close to constraining thermal models – GLAST!!! (30x better)

• Appearance of BH should depend only on mass and spin (black holes have no hair!)

• Plus mass accretion rate – L/LEdd

• 104-1010 M: Quasars • 3-20 M: Galactic black holes

Black holes