Structure and dynamics of the central regions of disk galaxies

1. Structure and dynamics of the central regions of disk galaxies Ph.D. Supervisors: José Alfonso López Aguerri (IAC) Enrico Maria Corsini (Univ. Padova) Jairo Méndez Abreu Post-Doc Consolider Estallidos (IAC) Thesis work conducted at Università di Padova Universidad de La Laguna INAF-Osservatorio di Padova

2. Bulges Bars Introduction • What do we mean by “central regions” of disk galaxies?

3. Eggen et al. 1962 Sandage 1990 Gilmore & Wyse 1998 Kauffmann 1996 Baugh et al. 1996 Cole et al. 2000 Classical Bulges Aguerri et al. 2001 Fu et al. 2003 Eliche-Moral et al. 2006 Athanassoula 1992 Heller & Shlosman 1994 Shen & Sellwood 2004 Disk-like Bulges Raha et al. 1991 Debattista et al. 2004 Martínez-Valpuesta et al. 2006 Boxy/Peanut Bulges Introduction Formation Theories for Bulges

4. Introduction • Bars: 1. Quasi-elliptical structures which are present in most of the disk of spiral galaxies.(Marinova & Jogee 2007, Aguerri et al. 2009) 3. Drive gas efficiently from the outer disk to the central regions of galaxies(Kormendy & Kennicutt 2004) 2. The most important internal factor in redistributing the baryonic and dark matter angular momentum(Weinberg 1985, Debattista & Sellwood 2000, Athanassoula 2003)

5. Introduction Aims of this thesis • How and where did bulges form? • How and where did bars form? • Is the formation of bulges and bars intimately linked? Observational point of view

6. GASP2D v1.0: Two components (Bulge + Disk) Méndez-Abreu, J., Aguerri, J. A. L., Corsini, E. M., Simonneau, E., “Structural properties of disk galaxies. I. The intrinsic equatorial ellipticity of bulges”, 2008, A&A, 478 ,353 GASP2D v2.0: Three components (Bulge + Bar + Disk) Méndez-Abreu, J. et al., 2009, in preparation GASP2D (GAlaxy Surface Photometry 2D)A new two-dimensional photometric decomposition code

7. GASP2D(GAlaxy Surface Photometry 2D) • Three independent reference systems (Ellipticity and Position Angle) • Parametric Flux distributions; Bulge - Sérsic Profile (Sérsic 1968) Disk - Exponential profile (Freeman 1970) - Ferrers (Ferrers 1877) Bar - Flat (Prieto et al. 1997) - Elliptical (Freeman 1966)

8. GASP2D (GAlaxy Surface Photometry 2D) Advantages with respect to other codes • Realistic parametric description of the bar SB • Works automatically • Flexibility to create mask

9. GASP2D (GAlaxy Surface Photometry 2D) Outputs : 1. File with the best-fitted parameters + χ2 + B/D 2. Three fits images: Best model + Residuals + Masks

10. GASP2D v2.0

11. GASP2D (GAlaxy Surface Photometry 2D) Already used and tested in different works: • Méndez-Abreu 2008, PhD thesis • Méndez-Abreu et al. 2008, A&A, 478, 353 • Méndez-Abreu et al. 2009, in preparation • Morelli et al. 2008, MNRAS, 389, 341 • Pizzella et al. 2008, MNRAS, 387, 1099 • Beifiori et al. 2008, ApJ, accepted, arXiv0809.5103 • Sánchez-Janssen et al. 2009 in preparation • Ascaso et al. 2009 in preparation

12. Structure of disk galaxiesScaling relation of bulges and disksMéndez-Abreu, J., Aguerri, J. A. L., Corsini, E. M., Simonneau, E., “Structural properties of disk galaxies. I. The intrinsic equatorial ellipticity of bulges”, 2008, A&A, 478,353 Sample selection 2MASS XSC - 148 galaxies • S0 ≤ Hubble type ≤ Sb ; • Unbarred galaxies (RC3) ; • JT < 10 mag ; • i < 65° ; • |bG|< 30° .

13. Faber-Jackson relation Fundamental Plane Classical bulges Structure of disk galaxiesScaling relation of bulges and disks Bulge parameters and correlations

14. Hierarchical merger Secular evolution Structure of disk galaxiesScaling relation of bulges and disks Bulge and disk interplay

15. Structure of disk galaxiesScaling relation of bulges and disks Conclusions: • Scaling relations alone are not able to distinguish between bulges formed by dissipative collapse, hierarchical merging or secular evolution.

16. 3D Shape of BulgesThe intrinsic equatorial ellipticityMéndez-Abreu, J., Aguerri, J. A. L., Corsini, E. M., Simonneau, E.,“Structural properties of disk galaxies. I The intrinsic equatorial ellipticity of bulges”, 2008, A&A, 478,353 1. Bulges consist of a series of concentric, coaxial isodensity ellipsoidal shells ; 2. Equatorial plane of the bulge coincides with the equatorial plane of the disk ; 3. Disk are circular giving us the line of nodes . Hyphotesis :

17. a C b δ B Line of nodes A 3D Shape of BulgesThe intrinsic equatorial ellipticity Projection of triaxial ellipsoids. Direct problem Inverse problem Line of Sight (θ, φ)

18. 3D Shape of BulgesThe intrinsic equatorial ellipticity Projection of triaxial ellipsoids. Inverse problem Simonneau et al. (1998) where

19. IC 4310 3D Shape of BulgesThe intrinsic equatorial ellipticity Individual statistic The PDF of having an intrinsic equatorial ellipticity is given by where

20. About 80% of bulges in unbarred S0-Sb galaxies are triaxial ellipsoids. The mean axial ratio in the equatorial plane is <B/A>=0.85. There is no significant dependence of the PDF on the morphology, light concentration, and luminosity of bulges 3D Shape of BulgesThe intrinsic equatorial ellipticity Global Statistics

21. Properties of Bars in the Nearby UniverseAguerri, J. A. L., Méndez-Abreu, J., Corsini, E. M., “The population of barred galaxies in the local universe. I Detection and characterisation of bars”, 2009, accepted in A&A, arXiv0901.2346 Sample selection SDSS fifth data release (SDSS- DR5) ~3000 galaxies • Redshift between 0.01 < z < 0.04 ; • Absolute magnitude Mr< -20 ; • Inclination i < 60° ; • Exclude disturbed/interacting galaxies .

22. Properties of Bars in the Nearby Universe Methods for detecting and analyzing bars: Ellipse fitting: - Local maximum in the (Δε) - Constant position angle (ΔPA) Fourier analysis: - Local maximum in the Δ(I2/I0) - Constant phase angle (Δφ2)

23. 1. Bar fraction 2. Bar length 3. Bar strength Bar properties : Properties of Bars in the Nearby Universe

24. Properties of Bars in the Nearby Universe Bar fraction Ellipse fitting45% of disk galaxies are barred 32% of lenticular galaxies are barred 55% of early-type spiral galaxies are barred 52% of late-type spiral galaxies are barred

25. Properties of Bars in the Nearby Universe Bar length rbar,ε rbar,PA

26. Properties of Bars in the Nearby Universe Bar strength is the contribution of the bar to the total galaxy potential. Whyte et al. 2002

27. Properties of Bars in the Nearby Universe 1.Galaxy local environment 2. Galaxy central light concentration 3. Galaxy colors Bars and Galaxy properties

28. Properties of Bars in the Nearby Universe We computed the number density of local galaxies using the distance d5 of the galaxy to its fifth nearest neighbor (Balogh et al. 2004). Thus the projected galaxy density could be defined as Galaxy local environment Only galaxies located in a velocity range of ±1000 Km s-1

29. Properties of Bars in the Nearby Universe Central light concentration

30. Properties of Bars in the Nearby Universe Galaxy colors

31. Properties of Bars in the Nearby Universe Conclusions 1. We found that 45% of disk galaxies are barred. The fraction of bars in the three morphological bins are 32%, 55%, and 52% for lenticulars, early and late-type spirals, respectively. 2. Bars of lenticular galaxies were found to be less frequent and weaker than those in spirals 3. No difference between the local galaxy density was found between barred and non-barred galaxies in our sample 4. The fraction of barred galaxies decrease toward more concentrated galaxies 5. Among late-type spiral galaxies bars are hosted by bluer galaxies

32. Peanut Bulges in Face-on GalaxiesA new kinematic approachMéndez-Abreu, J., Corsini, E. M., Debattista, Victor P., De Rijcke, S., Aguerri, J. A. L., Pizzella, A., “Confirmation of a Kinematic Diagnostic for Face-On Box/Peanut-shaped Bulges”, 2008, ApJ, 679, 73 NO PEANUT PEANUT Peanuts studied only inedge-on galaxies Is there a relation between B/P bulges and bars? Debattista et al. 2005

33. Peanut Bulges in Face-on GalaxiesA new kinematic approach Sample selection • Barred galaxies NGC98 and NGC600 bright, undisturbed, with low inclination and resolved bars. • Unbarred galaxy NGC1703control object. Challenging observations • High S/N spectra to measure h4 moment of the LOSVD • High spectral resolution (Face-on disk galaxies) • Time allocated at VLT- FORS2

34. Double minimum Peanut Bulges in Face-on GalaxiesA new kinematic approach Kinematic measurements The stellar kinematics was measured from the galaxy absorption features present in the wavelength range centered on the Ca II triplet (λλ8498, 8542, 8662) using the Penalized Pixel Fitting method(Cappellari & Emsellem 2004).

35. Peanut Bulges in Face-on GalaxiesA new kinematic approach Conclusions 1. We have confirmed the kinematic method developed by Debattista et al. (2005) ; 2. We have identified for the first time a B/P-shaped bulge in a face-on disk galaxy ; 3. Peanuts are always related to bars but not all bars present a peanut structure ; 4. This study open a new window in the study of the relations between Peanut features and bars.

36. Conclusions The conclusions of this thesis can be summarized in three main points: 1) The typical scaling relations for galaxies cannot be used alone to distinguish between the different formation scenarios proposed until now since different models are able nowadays to reproduce these relations. However, measuring the intrinsic structural properties represents an useful step forward in this field and sets new constraints that should be reproduce by simulations. 2) The link between bulges and bars appears to be fundamental to understand the formation of both components. 3) The distinction between disk-like and boxy/peanut pseudo-bulges can be now investigated by a new kinematic diagnostic that can be applied in face-on galaxies. This result opens a new line of research which will help to give a more general scheme of bulge formation and evolution.

37. THANKS !!!

38. Properties of Bars in the Nearby Universe Conclusions 1. We found that 45% of disk galaxies are barred. The fraction of bars in the three morphological bins are 32%, 55%, and 52% for lenticulars, early and late-type spirals, respectively. 2. Bars of lenticular galaxies were found to be weaker than those in spirals 3. No difference between the local galaxy density was found between barred and non-barred galaxies in our sample 4. The fraction of barred galaxies decrease toward more concentrated galaxies 5. Among late-type spiral galaxies bars are hosted by bluer galaxies

39. Structure and SP of Bulges Stellar kinematics The stellar kinematics was measured from the Mg Triplet absoption lines by applying the Fourier Correlation Quotient method (Bender 1990). Line-strength indices The Mg, Fe and Hβ line-strength indices were measured. To address the problem of emission lines we use GANDALF (Gas AND Absorption Line Fitting, Sarzi et al. 2006). [MgFe]’=Mgb(0.72 x Fe5270 + 0.28 x Fe5335) <Fe>=(Fe5270 + Fe5335)/2

40. Structure and SP of Bulges Ages, metallicities and α/Fe ratios: Central values From the central line-strength indices we derived the mean ages, total metallicities, and total α/Fe ratios by using the stellar populations models by Thomas et al. (2003).

41. Structure and SP of Bulges Ages, metallicities and α/Fe ratios: Gradients The gradient were set as the difference between the values at the galaxy center and rbd (the radius where the surface brightness of the bulge is equal to that of the disk)

42. Structure and SP of Bulges Pseudobulges Following the prescriptions given by Kormendy & Kennicutt (2005) • Apparent flattening of the bulge similar to that of the disk • Sérsic index n ≤ 2 • Rotationally dominated in the v/σvsε diagram • Low sigma outlier in the FJ relation NGC 1292 is the most reliable pseudobulge of our sample. Age = 3Gyrs [Z/H] = -0.7 dex [α/Fe] = -0.12 dex

43. Abel-like integral equation 3D Shape of BulgesThe intrinsic equatorial ellipticity Global Statistics

44. Structure of disk galaxies Bulge parameters and correlations

45. Conclusions The aim of this thesis was to shed some light on the formation and evolution scenarios for the bulges in disk galaxies proposed until now: monolithic collapse, hierarchical merger, and secular evolution. Throughout this thesis, we have presented a series of new results spanning the most important issues in extragalactic astronomy of individual galaxies, i.e., their structure, stellar populations, and kinematics. The necessity, in the scientific community, for a new code to photometrically decompose galaxies with three components (bulge, disk, and bar) was our main concern when we started this thesis. To fill this gap, we developed a new quantitative morphological analysis based on the new code GASP2D. The power and utility of GASP2D has been proved throughout this thesis by using the code with different samples of nearby galaxies.