the ubiquitous uv murmurs of sleeping supermassive bhs dani maoz with: neil nagar, heino falcke,...
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The ubiquitous UV murmurs of sleeping supermassive BHs Dani Maoz
With: Neil Nagar, Heino Falcke, Andrew Wilson
Peterson et al. (2004)
High-L accretion physics:
(geometrically ) thin accretion disk
Manners 2002
accretion disk?
Kormendy & Gebhardt 2001
M32; Ho, Terashima, & Ulvestad (2003)
MBH=2.5x106 Msun
LX=1036 erg/s
=3x10-9 LEdd
stellar mass loss:~10-6 Msun/yr
Bondi accretion:~3x10-7 Msun/yr
Lacc=(erg/s
ADAF
CDAF
ADIOS
Outflow
“RIAF” Ho (2003)
if very large or very small, thermal instability,
high T, inefficient cooling, other accretion solutions:
geometrically thick accretion disks
Mç
What is the connection between
active and “normal” galactic nuclei? (AGNs and NGNs):
How can SMBHs sleep so quietly?
One way to progress: study the subtle signs of activity from
“normal” nuclei demographics, accretion physics
SMBH history
The most common manifestation of (possibly)
non-stellar nuclear activity is
LINERs
QSO
Seyfert 1
Seyfert 2
LINER (low ionization nuclear emission-line region)
SDSS; Kaufmann et al. (2003)
LINERs are very common in bulges
Many of our best friends are LINERs…
M87
NGC 4594
At least 1/2 of LINERs have a compact radio source....
Nagar et al. (2002)
...at least 1/2 of which are time variable...
Nagar et al. (2002)
Nagar et al. (2003)
...and at milli-arcsec resolution the cores remain unresolved – TB~108K -- and sometimes have jetlike structures.
Terashima & Wilson (2003)
Unresolved (1”) nuclear X-ray source...
...in about 1/2 of LINERs...
Ho et al. (2001)
Ho et al. (2001)
...with flux falling ~ on AGN L(Ha) vs LX relation.
~1/4 of LINERs have broad (variable) Ha wings
NGC 4579; Barth et al. (2001)
But....
-what about all those “~1/2’s”?
-many LINERs
have not revealed AGN signatures
Do LINERs have anything to do with the BH?
LINERs can be excited by:
Photoionization by an AGN Ferland & Netzer (1983); Halpern & Steiner (1983); Filippenko & Halpern (1984); Ho et al. (1993)
Photoionization by stars – WR stars: Terlevich & Melnick (1985); O-stars: Filippenko & Terlevich (1992); Shields (1992); Schultz & Fritsch (1994) Young starburst: Barth & Shields (2000)
Post-AGB stars: Binnette et al. (1994); Taniguchi et al. (2000)
Shocks Koski & Osterbrock (1976); Heckman (1980); Aldrovandi & Contini (1984); Dopita & Sutherland (1996)
Maybe SMBHs and LINERs are both common in galactic nuclei but an optical LINER spectrum is not directly related to the accretion process.
LINER definition based on optical emission lines;
Excitation determined by far-UV light;
Look in the UV!
Nuclear UV sources in nearby LINER galaxies:
330 nm
250 nm
NGC 404 NGC 3642 NGC 4203
M81 NGC 4258 NGC 4736
Nucleus is obscured by dust in all LINERs w/0 UV nucleus; Probably all LINERs have UV nucleus
Pogge et al. (2000)
UV spectrum of LINERs
NGC 4579; Barth et al. (1996)
Maoz et al. (1998)
NGC 1741B
starburst
So, how to distinguish stellar from nonstellar?
VARIABILITY! (defining characteristic of AGNs)
Monitor in UV a sample of LINERs:
Snapshot Monitoring with HST/ACS/HRC in 2002-2003 at 2500 Ang and 3300 Ang
The sample: (all) 17 LINERs with known UV nuclei
L(UV)~10^(39-41) erg/s
Includes all kinds: LINERs 1 / 2, radio / X-ray detected / undetected, AGN-like / starburst-like, pure / transition types.
Big worry: detector stability
Boffi et al. 2004:
ACS stable in UV to < 1% !
Results:
F330 f250
“historical” (5~10 yr earlier) level
Summary of results:
1. 11/15 vary significantly on short (month) timescales, typical amplitudes ~10%
2. Correlated variations in 2500 A and 3300 A
3. Long timescale (years-decade) variations common, amplitudes factor few
4. Only 3/17 vary neither on long or short timescales, but even these may be due to sparse sampling
5. All LINER types vary
Conclusion: LINERs are indeed genuine signposts of nonstellar activity (i.e., AGNs).
SMBHs in most “normal” galaxies are producing (in one way or another) a LINER spectrum.
Variable UV flux gives lower limit on AGN UV luminosity – can constrain accretion models
Nagar et al. (2001)
ADAFs predict wrong radio slope;
radio emission probably dominated by jets
Also, wrong slope
in X-rays
Terashima & Wilson (2003)
Perhaps UV is also from jets?
NGC 4736: a binary/merging BH?b
nucleus
660 pc
3C 75
7 kpc
NGC 6240
700 pc
Conclusions:
1.Most LINERs are excited by some nonstellar phenomenon near the SMBH (accretion, jets)
2. Sharpens demographic picture and allows probe of accretion process, hence SMBH growth history
3. Possible detection of closest/nearest binary AGN
Ho, Filippenko, & Sargent 1993
radio
loudness
Lbol/LEdd
Ho (2002)