The nuclear activity of late-type galaxies in the Virgo Cluster Università degli Studi di Milano – Bicocca Dipartimento di Fisica Università degli Studi dell’Insubria Dipartimento di Fisica e Matematica Roberto Decarli The nuclear activity of late-type galaxies in the Virgo Cluster G. Gavazzi M. Colpi I. Arosio C. Bonfanti L. Cortese A. Boselli Santiago, September, 6th, 2007

The 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 237 galaxies: 213 (90%) have a spectroscopic classification for their nuclear activity 216 (91%) have NIR imaging 199 (84%) have r-band imaging

The 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 (>1000 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)

Line 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

Spectroscopic 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.infn.it) SDSS fiber Slit Nuclear spectra Drift scan spectra Modified drift scan spectra

[NII] /H and [OIII] /H AGNs have [NII]/H > 0.6 [OIII]/H > 3 when a strong ionization field is present (Seyfert-like AGN or intensely star-forming region) 0.4 < [NII] /H < 0.6 for Transition objects The [NII]/H ratio provides a nuclear activity classification without any further information

56 AGNs (23. 6%): - 9 Seyfert (3. 8%) - 23 Seyfert/LINERs (9 56 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%)

Dynamical mass and H-band luminosity Mdyn = dynamical mass up to the optical radius of the galaxy Direct measures of Mdyn are observational time consuming For spiral galaxies: (Gavazzi et al., 1996) We use H luminosity as a surrogate of Mdyn. NIR data were taken from 2MASS and from GOLDMine databases Adapted from Gavazzi et al. (1996)

Mass distribution Only VCC 213 has Mdyn<1010 Mo and hosts an AGN AGN fraction changes from 0% up to 100% when Mdyn changes between ∽1010 Mo and ∽3·1011 Mo (see also Kauffmann et al., 2003) Mdyn > 1010 Mo is a necessary condition for harbouring an AGN Mdyn > 3·1011 Mo is also a sufficient condition

The 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!

The role of bulges From NIR light profile we define: Bulge dominated galaxies have C31>4 Pure disks have C31∽2.5 When Mdyn> 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

M100 M61 NGC4535

AGNs are found mainly at high values of Nuc Light cusps Sensitive to unresolved nuclei and light cusps Nuc increases continuously with Mdyn AGNs are found mainly at high values of Nuc

Are 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

Environment – 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 (32±8 %) “Low” density subsample: 99 galaxies, 40 AGNs (40±10 %) The mass distribution of the subsamples are similar. The observed AGN fractions are consistent.

The environment does not significantly influence the nuclear activity Environment – 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 the nuclear activity

What 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.

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

Bibliography Decarli, Gavazzi, Arosio, Cortese, Boselli, Bonfanti, Colpi, 2007, arXiv:0707.0999, 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, A&A, 312, 397 Gavazzi, Boselli, Scodeggio, Pierini & Belsole, 1999, MNRAS, 304, 595 Gavazzi, Boselli, Donati, Franzetti & Scodeggio, 2003, A&A, 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, A&A, 80, 155 Marconi & Hunt, 2003, ApJ, 589, L21 Obric, et al., 2006, MNRAS, 370, 1677 Scodeggio, Gavazzi, Franzetti, Boselli, Zibetti, Pierini, 2002, A&A, 384, 812 Veilleux, et al., 2003, AJ, 126, 2185

Correcting 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.

Spectroscopic 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.infn.it) Slit Drift scan spectra Nuclear spectra Modified drift scan spectra SDSS fiber

The [NII]/Ha ratio along the slit

The 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!

Mass 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 AGN metallicity

Black 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 MBH>105.8 Mo.

The 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.

Summarizing… Mdyn>1010 Mo is a necessary condition to harbour an AGN The AGN fraction steeply rises with the dynamical mass, and it is virtually 1 when Mdyn>3·1011 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 MBH>105.8 Mo Very low accretion rates are found in almost all our targets