What can we learn on the BLR from the smallest AGN?

Or, how do the BLR properties change with luminosity, and what is it telling us?

Specifically

• The BLR radius vs. luminosity

• The BL profiles vs. luminosity

• Objects without a BLR.

The AGN Paradigm

Is it luminosity dependent?

Weak luminosity dependence Ionization level and density are ~ constant Ionizing flux at the BLR~ constant RBLR L1/2

How far down in L does RBLR L1/2 holds?

The Baldwin relation

C III]

LyαC IVO VI

Laor et al. (1995) Baskin & Laor (2004)

The RBLR vs. L relation

~15 year of reverberation mappings

Kaspi et al. (2005)

?

NGC 4395

The lowest luminosity type 1 AGN

L 1039×6) =Å5100(

?

NGC 4395 should have a tiny BLR, ~ 1 light hour

NGC 4395

NGC 4395 – The lowest luminosity type 1 AGN

normal line + continuum emission

Lbol~1040 erg/s, But

C III]HeII

O III]

C IV

Moran et al. (1999)

Reverberation mapping campaign on NGC 4395 (2004, 2006)

HST

Chandra

Lick + Wise

April 10-11th 2004 (Desroches et al. 2006)

CoIs - Ho, Filippenko, Maoz, Moran, Peterson, Quillen

What is The size of the BLR?

The C IV time delay is:

Peterson et al. (2005)

48±20 min in visit 2, 66±20 min visit 3

The most compact BLR known

The RBLR vs. L Relation for C IV+

Kaspi et al. (2006)

RBLR L1/2 established over a range of ~106(!) in L

Peterson et al. (2005)

Why does RBLR L1/2 ?

Dust suppression of line emission.

Theory Netzer & Laor (1993)

BLR IR cont’ NLR

Σion=1023U, U=nγ/ne

IRLines

Dusty gas

Dust= Σ/1021=100U

Line suppression for U>0.01

Dust sublimation.

Rsub≤0.2L461/2 pc

BLR is dust bounded

Inevitable & no free parameters

IR reverberation

Observation

Suganuma et al. (2006)

BLR is bounded by dust sublimation

Applies over a range of 106 in L

Dust

BLR

BLR

Dust

What are the BLR “Clouds?”

In photoionized gas: Σion=1023U, U=nγ/ne

in the BLR: ne~1010, U~0.1 Σion=1022

The thickness of the photoionized layer is d~1012 cm

>>RBLR~1016-1017 cm in luminous AGN

The BLR gas filling fraction is 10-5-10-6

A smooth flow? (e.g. disk ablation)

A clumped flow? (e.g. bloated stars)

The BLR “clouds”=A stellar origin?

Bloated stars

Stellar contrails

Star-disk interactions

Kazanas (1989)

Scoville & Norman (1995)

Zurek et al

Implied emission line profiles

Stellar tidal disruption

Discrete clouds fluctuations

Profile smoothness limit on nc

Capriotti et al) .1981,( nc 100= nc 500=

nc 1000= nc 2000=

nc 5000= nc 10000=

xample:

Bogdanovic et al. (2004)

How smooth are the broad lines?NGC 41513C 273

No real fluctuations detected

Bloated stars ruled out- for pure thermal broadening

L5100Å = 7×1042 ergs s-1L5100Å = 6×1045 ergs s-1Dietrich et al. (1999) Arav et al. )1998(

rcloud≈RBLR/)nc(1/2 Observelowest L AGN

What do we see in the smallest AGN?

Rstar~1014 cm - fixed

while RBLR L1/2 Lowest L AGN should

show the largest fluctuations

NGC 4395

In NGC 4395

RBLR ≈ cm Rstar

L5100Å = 6×1039 ergs s-1Laor, Barth, Ho &Filippenko (2006) -eck spectra

No room for bloated stars

Bloated stars are ruled out conclusively

rcloud>1012 cm = thickness of the photoionized layer

BLR gas is in a smooth flow, probably a thick disk

Why are the line profiles not always double peaked ?

What else can we learn from the line profiles?

Barth et al.

S/N~50-400 per pixel (0.26Å)

Keck II ESI spectra

Exponential extended wings in H

Laor (2006)

Probe far wings to 10-3

of peak flux density

Symmetric exponential wings

NGC

What produces exponential wings?

Wing slope set by Te and τe

Thermal electron scattering

Rybicki & Lightman: Radiative Processes in Astrophysics

What are the implied Te and τe?

No wings in NLR

Typical parameters of the BLR gas

A new tool for monitoring Te and τe in the BLR

BLR profiles in low Luminosity AGN

NGC 4395, Pox 52 – very rare objects, MBH~105Msun

What do we expect forMsun?

V2≈GMBH/RBLRMBH/ L1/2

Low luminosity AGN should show broader lines

How broad do the lines get?

Véron-Cetty et al.

The distribution ofHline widths

Vmax~20,000 km/s

1. Real limit. Why does it exist?

2. Detection limit?

L Edd

Implications:

V2MBH L-1/2 +V>25,000 km s-1

BLR disappears at

L>1025.8MBH2 or L/LEdd>10-12.3MBH

True type 2 AGN

upper limit

Explains absence of BLR in FR Is

What controls the existence of the BLR?

V>20,000

BLR

Dusty gas

L/LEdd

Need a BLR survey in very low L AGN

Option 1:

Option 2:

Laor (2003)

)e.g. Nicastro et al(.

NGC 4450, Ho et al. (2000) NGC 4203 Shields et al. (2000)

NGC 4579 Barth et al. (2001)

Low Luminosity AGN with very broad lines

What happens to the NLR at very low L?

Compact BLR compact NLR enters the BH potential well

Example: ]O III] 5007, 4959

Emissivity maximized at ne~106, U~10-3 nvs. n=109 in BLR

R]O III] ~103RBLR (for the most compact region)

BLRMBH1/4(L/LEdd

)-1/4 km/s

What is the critical luminosity for BH dominance?

The bulge contribution is:km/sTremaine et

al.]O III]/*0.15(L/LEdd

)-1/4

BH dominates when L/LEdd<5x10-4

Veilleux (1991)

L/LEdd~1

L/LEdd=5x10-5

BH dominatedBulge dominated

Bulge dominated

NLR in: Liners (low L/LEdd) Seyferts (high L/LEdd)

NLR is BH dominated in low luminosity AGN

Some open questions

What is the threshold parameter for the existence of a BLR? )maximal velocity, L/LEdd(

)is the BLR in a thick disk? how is it supported(?

What is the velocity field of the BLR?

How significant are non-gravitational forces?)explain profile asymmetries(?

Where does the BLR come from, and where does it go to?