Title: The nuclear activity of late-type galaxies in the Virgo Cluster
1The nuclear activity of late-type galaxies in the
Virgo Cluster
Università degli Studi di Milano
Bicocca Dipartimento di Fisica
Università degli Studi dellInsubria Dipartimento
di Fisica e Matematica
G. GavazziM. ColpiI. Arosio C. BonfantiL.
CorteseA. Boselli
Santiago, September, 6th, 2007
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3The sample
- The Virgo Cluster
- is near us
- is rich
- is widely studied
- We select all spiral galaxies in the Virgo
Cluster Catalogue (Binggeli et al., 1985, 1993)
with mph 15. - Among the complete sample of 237galaxies
- 213 (90) have a spectroscopic classification
fortheir nuclear activity - 216 (91) have NIR imaging
- 199 (84) have r-band imaging
4The AGN unified model
- The SMBH influence radius is defined as the
radius at which potential energies of the galaxy
and of the massive BH are equal - The line emission near the SMBH is Doppler
broadened because of the gas fast motion (gt1000
km/s!) due to the SMBH potential well (Broad Line
Region) - Lines produced outside Rinf are sensitive only of
the galactic potential well (Narrow Line Region)
5Line flux ratios and nuclear activity
- Gas emission line fluxes depend on gas
temperature, density, metallicity and on the
intensity and energy distribution of the incident
radiation field - Comparing line intensities one can infer
information about the ionization source and its
strength
VCC 664
Stasinska, 2006
AGNs
HII-regions
6Spectroscopic datasets
- Fluxes published in Ho, Filippenko Sargent
(1997) 40 (40) - SDSS spectra 84 (73)
- Nuclear spectra 29 (13)
- Modified drift scan spectra 22 (4)
- Drift scan spectra 193 (81)
- Nuclear activity classification in NED 41 (2)
February-March, 2005-2006 observing runs in
Loiano GOLDMine database (http//goldmine.mib.i
nfn.it)
SDSS fiber
Slit
Nuclear spectra
Drift scan spectra
Modified drift scan spectra
7NII /H? and OIII /H?
- AGNs have NII/H? gt 0.6
- OIII/H? gt 3 when a strong ionization field is
present (Seyfert-like AGN or intensely
star-forming region) - 0.4 lt NII /H? lt 0.6 for Transition objects
- The NII/H? ratio provides a nuclear activity
classification without any further information
856 AGNs (23.6)- 9 Seyfert (3.8)- 23
Seyfert/LINERs (9.7)- 24 LINERs (10.1) 21
Transition objects (8.9) 121 HII-Regions
(51.1) 15 No Emission Line Galaxies (6.3) 24 No
spectra available (10.1)
9Dynamical mass andH-band luminosity
- Mdyn dynamical mass up to the optical radius of
the galaxy - Direct measures of Mdyn areobservational time
consuming - For spiral galaxies
- (Gavazzi et al., 1996)
- We use H luminosity as a surrogate of Mdyn. NIR
datawere taken from 2MASS and from GOLDMine
databases
Adapted from Gavazzi et al. (1996)
10Mass distribution
- Only VCC 213 has Mdynlt1010 Mo and hosts an AGN
- AGN fraction changes from 0 up to 100 when
Mdyn changes between ?1010 Mo and ?31011 Mo
(see also Kauffmann et al., 2003)
- Mdyn gt 1010 Mo is a necessary condition for
harbouring an AGN - Mdyn gt 31011 Mo is also a sufficient condition
11The colour-magnitude diagram
- The AGN host galaxies are usually found to be
redder than non-active galaxies. - Some authors (e.g., Obric et al., 2006) suggested
that the AGN feedback may be responsible of this
effect.
AGNs populate the high-mass end of the same
colour-magnitude relation as the one observed for
inactive galaxies!
12The role of bulges
- From NIR light profile we define
- Bulge dominated galaxies have C31gt4
- Pure disks have C31?2.5
- When Mdyngt 1011 Mo, both bulge- and
disk-dominated spiral galaxies are found (see
Gavazzi Pierini Boselli, 1996 Scodeggio et
al., 2002)
Bulge-dominated spiral galaxies
AGNs are found in all the galaxies having
prominent bulges, but even in bulgeless galaxies!
Disk-dominated spiral galaxies
13M100
M61
NGC4535
14Light cusps
- Sensitive to unresolved nuclei and light cusps
- Nuc increases continuously with Mdyn
AGNs are found mainly at highvalues of Nuc
15Are r-band nuclei the due to AGN continuum?
- Nuclear spectra of 4 AGNs in our sample were
observed with HST (Spinelli et al., 2006). All of
them are well fitted with Bruzual Charlot
libraries of star spectra. - AGN continuum light is thus negligible with
respect to the stellar component.
VCC 1110 - Seyfert
VCC 2070 - LINER
VCC 1401 - Seyfert
VCC 1690 - LINER
16Environment I
- We divide our sample in two parts, according to
the angular separation of the galaxies from M87 - High density subsample 114 galaxies, 37 AGNs
(328 ) - Low density subsample 99 galaxies, 40 AGNs
(4010 )
- The mass distribution of the subsamples are
similar. - The observed AGN fractions are consistent.
17Environment II
- We check the NII/Ha dependence on the neutral
gas deficiency (Haynes Giovanelli, 1984). - Even considering the HI deficiency no clear
environmental effect is observed, once the
luminosity dependence is taken into account.
The environment does not significantly influence
thenuclear activity
18What can we argue about the BH-host galaxy joint
evolution?
- At least in spiral galaxies, the nuclear activity
is strongly sensitive to the host galaxy mass,
while the morphology plays a secondary role. - The environment is not relevant in nuclear
activity. - There is no evidence of a strong feedback
mechanism in the galaxy colours. - Low accretion rates are observed.
19- The massive BH may have grown simultaneously with
the galaxy, in an anti-hierarchical way - The dynamical mass is the driver of both the
galaxy and the BH growth, in a top-down scenario - The scale relations inset during the formation
itself of the system - Galaxies do not require any strong feedback later
on, neither strong accretion rates - The fragile morphology of pure disk and
bulgeless galaxies is preserved, since the BH is
already formed
20Bibliography
- Decarli, Gavazzi, Arosio, Cortese, Boselli,
Bonfanti, Colpi, 2007, arXiv0707.0999, accepted
for publication in MNRAS - Ferrarese, 2006, in Series in High Energy
Physics, Cosmology and Gravitation, Joint
Evolution of Black Holes and Galaxies', ed. by M.
Colpi, V. Gorini, F. Haardt, U. Moschella (New
York - London Taylor Francis Group), 1 - Gavazzi, Pierini Boselli, 1996, AA, 312, 397
- Gavazzi, Boselli, Scodeggio, Pierini Belsole,
1999, MNRAS, 304, 595 - Gavazzi, Boselli, Donati, Franzetti Scodeggio,
2003, AA, 400, 451 - Haynes Giovanelli, 1984, AJ, 89, 6
- Kauffmann et al., 2003, MNRAS, 346, 1055
- Kauffmann Heckman, 2005, RSPTA, 363, 621
- Lequeux et al., 1979, AA, 80, 155
- Marconi Hunt, 2003, ApJ, 589, L21
- Obric, et al., 2006, MNRAS, 370, 1677
- Scodeggio, Gavazzi, Franzetti, Boselli, Zibetti,
Pierini, 2002, AA, 384, 812 - Veilleux, et al., 2003, AJ, 126, 2185
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22Correcting for line absorptions
- Balmer lines are usually observed both in
emission and in absorption - When possible, both the emission and absorption
features are fitted. Otherwise, a correction is
applied assuming various templates according to
the galaxy luminosity.
23Spectroscopic datasets
- Fluxes published in Ho, Filippenko Sargent
(1997) 40 (40) - SDSS spectra 84 (73)
- Nuclear spectra 29 (13)
- Modified drift scan spectra 22 (4)
- Drift scan spectra 193 (81)
- Nuclear activity classification in NED 41 (2)
February-March, 2005-2006 observing runs in
Loiano GOLDMine database (http//goldmine.mib.i
nfn.it)
Slit
Drift scan spectra
Nuclear spectra
Modified drift scan spectra
SDSS fiber
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25The NII/Ha ratio along the slit
26The Narrow Line Region size
- For a subsample of AGNs, we extract the NII/Ha
ratio at various apertures, up to some kpc - Only in one galaxy (VCC 73) the ratio
significantly descreases in the first kpc
Veilleux et al., 2003
- Thus, the photoionization of an AGN extends up
some kpc!
27Mass dependence
- The NII/H? ratio increases with the dynamical
mass of the host galaxy - A bimodality is observed
- In low-mass host galaxies, the NII/H? ratio is
a metallicity indicator -
-
- At higher masses, a further contribution to the
NII/Ha ratio is provided by the AGN
28Black hole masses
- Only few tens direct supermassive BH mass
measures are available, mostly in elliptical
galaxies (see Ferrarese, 2006 for a review)
- Following Marconi Hunt (2003), the MBH of our
sample AGNs is estimated from the bulge NIR
luminosity
- All the BHs in our sample have MBHgt105.8 Mo.
29The accretrion rate L/LEdd
- The accretion rate is usually identified with the
ratio between the AGN bolometric luminosity and
the BH Eddington luminosity
Most of our objects have very low accretion rates
- The AGN bolometric luminosity is roughly
proportional to the OIII luminosity (Heckman et
al., 2004).
- We thus have an order-of-magnitude estimate of
L/LEdd for our objects.
30Summarizing
- Mdyngt1010 Mo is a necessary condition to harbour
an AGN - The AGN fraction steeply rises with the dynamical
mass, and it is virtually 1 when Mdyngt31011 Mo - AGNs are found even in a number of bulgeless
galaxies - Nuclear stellar cusps are often found in AGN host
galaxies - The same colour-magnitude relation describes both
active and inactive galaxies - No significant environmental dependence of the
nuclear activity is observed - All the AGNs in our sample have MBHgt105.8 Mo
- Very low accretion rates are found in almost all
our targets