BULGES NGC 4710 NGC 4594 ESO 498-G5 NGC 4565 NGC 7457 ESO 1129

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2 BULGES NGC 4594 ESO 498-G5 NGC 4710 ESO 1129 NGC 7457 NGC 4565

3 FORMATION AND EVOLUTION OF BULGES Classical bulge Presents in early type galaxies: lenticular, Sa Very similar to elliptical : Mg2 - ; Dn - ; FP; SSP, R (1/4) Some differences: fotometry shows young stellar populations Formation trough dissipative collapse or merger events (theoretical) Pseudobulge Presents in late type galaxies: Sb and later type Luminosity profile is exponential They are flat component, with a disk kinematic Star formation Formed trough secular evolution slow rearrangement of disk material indicate no major merger (theoretical) Boxy/peanuts bulge boxy/peanut bulges are parts of bars seen edge-on, have their origin in vertical instabilities of the disc and are somewhat shorter in extent than bars. Their stellar population is similar to that of the inner part of the disc from which they formed.

4 FORMATION AND EVOLUTION OF BULGES Eggen et al Sandage 1990 Gilmore & Wyse 1998 Classical Bulges Kauffmann 1996 Baugh et al Cole et al Disk-like Bulges Athanassoula 1992 Heller & Shlosman 1994 Shen & Sellwood 2004 Aguerri et al Fu et al Eliche-Moral et al Boxy/Peanut Bulges Raha et al Debattista et al Martínez-Valpuesta et al. 2006

5 FORMATION AND EVOLUTION OF BULGES IN THE CURRENT PARADIGM Dissipative collapse Merging events Secular evolution Presence of metallicity and α/fe gradient (Kobayashi 2004). Presence of metallicity gradient with flat profile of α/fe (Pipino et al. 2008). Classical Bulges Absent (or very shallow) gradients in bulges (Bekki & Shioya 1999) metallicity gradient rarely enhanced by secondary events of star formation (Hopkins et al. 2009). Disk-like Bulges Which is the relative importance of different mecchanism (is one dominant?) Different formation mechanism leave differences in the stellar populations and in their radial profiles Model predictions Gradients eventualy present could either be amplified (change of scalelength) or erased (disc heating) (Moorthy & Holtzman 2006) More constraints from comparison of stellar populations of disk and bulge

6 ENVIRONMENT STELLAR POPULATION RELATED WITH THE ENVIRONMENT WHERE THE GALAXY FORM AND EVOLVE CLUSTER FIELD Potential wheel formation stop the merging in cluster (Z >2) Merging continue (Z < 1) Bought et al 1996 FIELD GALAXIES YOUNGER THAN CLUSTER COUNTERPART OBSERVATION (elliptical and early type): EXTENDED DATA FIELD YOUNGER AND HIGHER METALLICITY De la rosa et al. 2001, Collobert et al 2006 CENTRAL VALUES NO DIFFERENCES BETWEEN CLUSTER AND FIELD GROUP Bernardi et al. 1998

7 Central values and gradients Environment Late type

8 STEP BY STEP GALAXIES SAMPLE SELECTION 14 BRIGHT, NEARBY, CLUSTER, GALAXIES OBSERVATION AND DATA REDUCTION STANDARD REDUCTION FOR LOW RESOLUTION DATA AQUIRED WITH PHOTOMETRIC ANALYSIS 2D PHOTOMETRIC DECOMPOSITION TO DISENTAGNGLE BULGE FROM DISK KINEMATIC AND LINESTRENGTH ANALYSIS 1) ROTATION GALAXY VELOCITY AND ROTATION VELOCITY DISPERSION MEASURED 2) LINE STRENGTH OF LICK INDICES MEASUERED USING WORTHEY ET AL DEFINITION RESULTS

9 Consistency of results Comparison with the lick system.. Comparison with litterature

10 MAJOR AXIS KINEMATICS AND LINE-STRENGTH Rbd Rbd Rbd

11 Nuclear region Bulge dominated region Disc dominated region ANALISYS OF THE STELLAR POPULATIONS

12 RESULTS CENTRAL VALUES AGE METALLICITY AND /ENHANCEMENT RADIAL PROFILES AGE METALLICITY and /ENHANCEMENT PSEUDOBULGES NGC 1292

13 CONCLUSIONS LINE STRENGTH CENTRAL VALUES 1) The value of /<Fe> is for most of the galaxies between solar and 0.3 ( This imply time-scale that can be very short for star formation) 2) More massive bulges are older, more metal rich and characterized by a fast star formation. LINE STRENGTH PROFILES 1) Most of the sample galaxies show no gradient in age (merging events ) but a negative gradient of metallicity. (dissipative collapse) 2) no gradient was measured in the [α/fe] radial profiles for all the galaxies (No inside-out scenario expected from merging) Star formation fast and homogeneus in the bulge

14 CENTRAL VALUES: H, Mg 2, <Fe>- IN ELLIPTICAL GALAXIES STRUCTURAL PROPERTIES CORRELATE CHEMICAL PROPERTIES Mg 2, H, Fe IN LATER TYPE? We found good correlation for <Fe> Mg 2, H still correlate Hint they are steeper

15 AGE AND METALLICITY CENTRAL VALUES Model grids from Thomas et al Gyr 12 Gyr

16 AGE AND METALLICITY CENTRAL VALUES Very young Hint that early type are older and metal richer than later type Young Old Model grids from Thomas et al T 0 T > 0 3 Gyr 12 Gyr

17 AGE AND METALLICITY CENTRAL VALUES Fornax Pegasus NGC 7582 No relation found with morphological type No relation found with the membership Model grids from Thomas et al Gyr 12 Gyr

18 AGE AND METALLICITY CENTRAL VALUES Very young Young No relation found with morphological type No relation found with the membership 3 clear different classes of ages Relation age-metallicity Old Most of objects show solar value of /Fe while few have super solar /Fe Important correlation with the central velocity rotation dispersion More massive bulges are older, more metal rich

19 AGE AND METALLICITY RADIAL PROFILES Bulges Jabloka et al Early-type Mehlert et al Metallicity is decreasing with the radius Age shows no gradient Grad[Z/H] = [Z/H] (center)- [Z/H] (1Rbd) (Mehlert et al. 2003) Grad(Age) = Age (center)-age (1Rbd) (Mehlert et al. 2003) Collapse model produce metallicity gradient

20 AGE AND METALLICITY RADIAL PROFILES No gradient found with the radius Solar to super-solar value (result from central value) Grad( /<Fe>) = /<Fe> (center)- /<Fe> (Rbd) (Mehlert et al. 2003) Merger model do not produce gradient and produce solar /<Fe> Collapse model produce /<Fe> gradient

21 THE GALAXIES SAMPLE BRIGHT (B T < 15.5 Mag) NEARBY GALAXIES (cz<4500 km s -1 ) MORPHOLOGICAL TYPE: SPIRAL GALAXIES 14 CLUSTER GALAXIES ( Ferguson 1989; Garcia 1983) Fornax, Eridanus, Pegasus, N7582

22 SPECTROSCOPIC OBSERVATIONS 2 RUNS AT EFOSC@ESO3.6 TELESCOPE WAVELENGTH RANGE = Å DISPERSION = 1.98 Å/PIXEL INSTRUMENTAL FWHM 6 Å SPATIAL RESOLUTION = ARCSEC Calibration and Observation BASIC CALIBRATION (bias, flat, HeAr calibration lamp) SPECTRA TAKEN ALONG THE MAJOR AXIS TYPICAL EXPOSURE TIME 2x3600 s S/N> LICK/VELOCITY STANDARD STARS (G, K spectral type)

23 KINEMATICS AND LINESTRENGTH KINEMATICAL MEASUREMENTS We measured the profiles along the major axis of the values of the rotation velocity (v), rotation velocity dispersion ( ) LINE STRENGTH MEASUREMENTS We measured the values of the indices defined in the LICK/IDS system for all the those present in our range They are => H, Fe5015, Mg 1, Mg 2, Mg b, Fe5270,Fe, 5335, NaD Worthey et al.1994 Molecular indices 2 1 F I EW 2.5 log 1 d 1 2 F 1 C Atomic indices EW F F I C d

24 LICK INDICES OVERVIEW Lick indices related with age metallicity and /Fe Balmer lines (H, H ) Stellar population age The iron and magnesium lines Metallicity Mg/<Fe> or /<Fe> Timescale of the star formation Possible way to break the degeneracy MgFe Mgb( 0.72 Fe Fe5335 (Whortey et al. 1994, Thomas et al.2003)

25 Secular evolution PSEUDOBULGES - THE CASE OF NGC 1292 Merging/dissipative collapse PSEUDO-BULGES CLASSICAL BULGES Flattened disk like structures, may have secondary bars, rings, and/or spiral structure Dynamically cold rotation dominated Formed from slow rearrangement of disk material indicate no major merger Usually in types Sbc and later In globally blue galaxies resemble little ellipticals whic happen to have a disc dynamically hot - dispersion dominated formed via violent relaxation during major merger in types S0-Sbc in globally red galaxies Kormendy and Kennicut 2004 translate these general concepts in a list cookbook rules (The more apply, the safer the classification becomes)

26 PSEUDOBULGES - THE CASE OF NGC 1292 APPLICATION OF KORMENDY RULES TO OUR SAMPLE S ersic index (n < 2) Most of the sample bulges have it (9/14) Ellipticity compared with Vmax/σ 0 The apparent flattening of the bulge is similar to that of the disc NGC 1292, NGC 1351 PSEUDOBUGES Outsider in the FJ relation NGC 1292 satisfy all the conditions Forbes & Ponman (1999) pseudobulge

27 Radius PSEUDOBULGES - THE CASE OF NGC 1292 STELLAR POPULATION CENTRAL REGIONS ARE: YOUNG AGE (T=3 Gyr) LOW METAL CONTENTS ([Z/H] =-0.7) OVERABUNDANCE [ /Fe]=-0.12

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29 DATING THE FORMATION OF THE COUNTER-ROTATING STELLAR DISC IN THE SPIRAL GALAXY NGC 5719 BY DISENTANGLING ITS STELLAR POPULATIONS COUNTER-ROTATIONS presence of stars/gas counter-rotating with respect to other stars and/or gas NGC 7217

30 FEW GAS LOT OF GAS

31 FORMATION OF GAS COUNTER-ROTATIONS 1) Acquisition of gas external origin gas disk built by retrograde acquisitions internal origin Gas disk built by a bar Subsequent star formation in the acquired gas disk 2) Acquisition of already formed stars and gas external origin merger with other galaxies internal origin secular evolution with disk instability

32 FORMATION OF GAS COUNTER-ROTATIONS NGC 2855

33 FORMATION OF GAS COUNTER-ROTATIONS 1) Acquisition of gas external origin gas disk built by retrograde acquisitions internal origin Gas disk built by a bar Subsequent star formation in the acquired gas disk 2) Acquisition of already formed stars and gas external origin merger with other galaxies internal origin secular evolution with disk instability Expected observables 1) Age of the counter-rotating component is younger 2) Age of the counter rotating component younger in the 50% of case Metallicity of gas and stars possibly different

34 Flux NGC 5719 DISENTANGLING THE SPECTRA wavelength

35 TEST CASE NGC 5719 count-stars co-stars gas

36 NGC 5719 OBSERVATIONS VIMOS - VIsible MultiObject The integral-field spectroscopic observations in service mode We used the 0.67 arcsec per fiber resolution Spectral range Å with a reciprocal dispersion of 0.54 Å/pixel The instrumental spectral resolution measured at 5200 Å was 2.0 Å (FWHM)

37 NGC 5719 DISENTANGLING THE SPECTRA

38 NGC D FIELD kinematic count-stars gas co-stars

39 NGC 5719 INDICES

40 NGC D FIELD STELLAR POPULATION Age Metallicity A/Fe Corotating Counter-Corotating

41 NGC 5719 CONCLUSIONS 5719 is decomposed into the contributions of three distinct kinematic components characterised by a regular disc-like rotation: one main and one secondary stellar component and a ionised-gas component. The ionised gas is detected all over the observed field of view. It is characterised by a strong Hβ emission, which is concentrated in a twin-peaked morphology indicating an edge-on ring The contributions of the 2 components to the total light is F(main) = 56% and F(secondary) = 44% We prove that the mean age of the counter-rotating disc, which is associated to the neutral and ionised gas disc, is indeed younger than the main stellar disc. This result shows that counter-rotating disc has been recently assembled. The scenario proposed by Vergani et al. (2007) that NGC 5719 hosts a counter-rotating stellar disc originated from the gas accreted during the ongoing merging with its companion NGC 5713, is finally confirmed.

42 NGC 4550

43 NGC 3593

44 NGC 4550, NGC 3593 STELLAR POPULATIONS

45 NGC 5719, NGC 3593, NGC 4550 CONCLUSIONS NGC 3593 and NGC 4550 host a counter-rotating stellar disk, which rotates in the same direction as the ionized gas, and which is on average less massive, younger, metal poorer, and more α enhanced than the main stellar galaxy disk. NGC 3593: counter rotating stellar disk is younger than the main disk NGC 4550: counter rotating stellar disk is younger than the main disk Our results support the scenario of external gas acquisition, followed by a subsequent outside-in star formation as the origin of the observed counter-rotation. The merger scenario cannot be completely ruled out, given the low statistics available.

46 Counterotation next step Large survey of the north and south sky to oberve all the galaxy with hints of counter rotations. Candidates for the north are chosen with Asiago telescope. SOUTH NORTH