Marco Salvati

INAF (Istituto Nazionale di Astrofisica)

Osservatorio Astrofisico di Arcetri

Black holes and revelations: two or three revelations we are still missing

or…

The seven pillars of wisdom

or…

We need one more to open the eightfold

path to enlightenment

1. The core of the engine is a supermassive black hole

…now it seems trivial, but:spinars, ensemble of

pulsars or SNe, quark factories…

(a BH to stabilize a spinar, some Liners could be ensembles of stellar objects)

Rees, ARA&A 22 (1984)“Black hole models for AGNs”

Note: the “s” appears in the original !

2. Bondi accretion is inefficient, you need a disk (stable, ie non self-gravitating)

At the beginning there was Shakura & Sunyaev, then came: warped disks, 2T disks, coronae above disks, ion supported tori, Adafs, Adios…

Pringle, ARA&A 19 (1981) “Accretion discs in astro physics”

Note: Lynden-Bell (1969), S&S (1973)

3. Jets are not oddities (eg, M87)they are a basic ingredient amenable to “simple” equations

How Blandford & Rees jet paper

was announced in Erice in lieu of the sheduled lecture on something entirely different (maybe globular clusters !?)

B&R MNRAS 169 (1974) “A twin-exhaust model for double radio sources”

4. Finding the right radiation process(es)

From jets to magnetic fields to excessive faith in non thermal processes: playing with “beach balls”, hiding a blazar inside NGC4151…

“…in filaments…only a few metres across”

Salvati, unpublished and lost forever…

4. cont.d The disk-plus-corona model

One of the several instances of the “generalized equipartition assumption”… see also the “gain equal losses” approach in blazar models

Haardt & Maraschi ApJ 413 (1993)“Xray spectra from two-phase accretion disks”

5. Unification

Unification came in two main flavors: for radio quiet AGN (Antonucci & Miller 1985), and for radio loud, jetted AGN (Barthel 1989, not so much radio galaxies vs radio quasars, rather blazars vs non blazars)

6. BH spin and radio loudness

What is the parameter deciding the radio loudness, ie, the formation of a jet ? (btw, why jets and radio loudness go together ?)

The key issue here is the high required efficiency

6. cont.d Blandford & Znajek (1977)

Jets can be more powerful than disks, hence magnetic braking AND maximal rotation

Additional evidence: core vs power law profiles, and mass bias of radio loud galaxies (Capetti & Balmaverde 2006)

7. Integral constraints

Soltan (1982), total AGN light vs relic BH mass density in the local Universe

CXRB (more precisely, HXRB from SXR counts AND unification)

Setti & Woltjer (1979)

Comastri et al. (1995)

8. BH mass – galaxy bulge relations, coevolution, feedback, etc

This is FAR from settled… we can claim seven “pillars” with some confidence, but not eight yet: for instance, what if indeed BH mass grows first at high z ?

Two stones of the mosaic:

-low luminosity AGN from low mass black holes

-low luminosity AGN from high mass black holes

LLAGN are (almost always) Liners, ie (almost certainly) ADAF-like (no absorption…)

They appear to continue smoothly the AGN sequence

They are too numerous to reside only in massive bulges, ie their typical BHs have low masses

But… consider the 3C catalogue, and plot the Xray vs the high frequency radio luminosity:at the high end, both come from a boosted jet; then the Xrays are dominated by the isotropic disk; at the low end, only the jet is there (no visible accretion… a super-ADAF state ?)