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?
