Introduction The interplay between local and global processes in galaxies. C. Jakob Walcher Leibniz Institut für Astrophysik Potsdam (AIP)

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1 Introduction The interplay between local and global processes in galaxies C. Jakob Walcher Leibniz Institut für Astrophysik Potsdam (AIP)

2 Introduction Why this is NOT and IFU conference!! C. Jakob Walcher Leibniz Institut für Astrophysik Potsdam (AIP)

3 Global M-Z local Σ-Z [O/H] [O/H] 12+log (O/H) O3N Stellar mass Tremonti et al., 2004 ) O3N Stellar Mass Surface density Sanchez et al.,

4 20 years ago: [O/H] I am now old enough to see things rediscovered the third time. Kennicutt 2013 [O/H] Surface brightness Ryder

5 Local: Escape velocity and abundances Hβ MgB Fe5015 ATLAS3D, Scott et al., 2013 Vesc 5

6 Star Formation Rate log (O/H) 0 O3N log (O/H) O3N2 Global SF MS local SF MS Galaxy Mass A&A 554, A58 (2013) Star Formation Rate Stellar Mass Surface Density Sanchez et al., 2013, Cano-Diaz, et al., subm. see also Catalan-Torecilla, et al., log (O/H) O3N

7 Global CMD Local Σ - age Colour (Age) Luminosity (Mass) Log(Age) llaboration: The star formation history of CALIFA galaxies Surface mass density Gonzalez-Delgado et al. (2014) 7 Fig. 11. The stellar mass surface density age relationship resulting from fitting the spectra of 107 galaxies. The color total stellar mass. y weighted age of

8 Local IMF-stellar metallicity (M/L)stars / (M/L)Salp a Figure 1. Best-fitting IMF slope b is compared to the local σ (a), Vrms (b), [Mg/Fe] (c), and age (b). Neither the kinematics propertie x=-2.8 or x=-1.5 follow the measured IMF variations ( 0.35, Vrms 0.30, [Mg Fe] 0.21, age 0.50, with ρ being the Spearman correlation coeffi 1.5 represents the IMF slope in terms of F0.5, defined as the fraction (with respect to the total mass) of stars with masses below 0.5 M. 1.0 Kroupa (M/L)stars / (M/L)Salp Salpeter Chabrier no dark-matter halo x=-2.8 or x=-1.5 d Salpeter Kroupa 0.5 Chabrier best general halo Figure Empirical relation between the metallici Figure 2. IMF metallicity relation obtained from CALIFA local measurements Martin-Navarro, et al., 2015 IMF-sensitive TiO2CALIFA features. Index measur (blue). We also show the local IMF and metallicities measurements derived by Martín-Navarro et al. (2015a, 2015b; red, orange) for three of nearby ETGs, as 200 km s 1) are color-coded by their H o value, (M/L)stars (MO /LO ) well as global SDSS measurements (black). We found it to be the strongest metallicity relation is needed to explain the correlation ( [M H] 0.82 ). As in Figure 1, the right vertical axis indicates the weakly depends total metallic TiO2CALIFA Cappellari et on al.,the2012 F0.5 ratio. For reference, the standard Kroupa IMF value is shown as a independent of the IMF. horizontal dotted line. Dashed line correspond to the best-fittingfigure linear relation 2 The systematic variation of the IMF in early-type galax to all the data sets. using dynamical models, and the (M/L)Salp of the stellar populati Cozumel, 812Colour (Spin the minimized set ofof indices The Walcher black solid line isona loess smoothed version the data.

9 This is all well known Star formation law Krumholz et al.,

10 So what do we make of this? A nice conference Can we do even more? 10

11 Can we use this to understand galaxy evolution? There are a few questions that arise: In order of increasing naivety 11

12 What is the right scale? 1) Galaxies are points - they are the entities we study 2) 1 kpc - that is the typical scale we can resolve for large samples (both obs and sim) 3) Probably not one scale to rule them all, but one scale for each process 12

13 Is this emergence??? Emergence: the arising of novel and coherent structures, patterns and properties during the process of self-organization in complex systems. Analytical expressions? Goldstein (1999) The ability to reduce everything to simple fundamental laws does not imply the ability to start from those laws and reconstruct the universe. Anderson (1972) 13

14 What is the right level of complexity??? Due to the highly complex and nonlinear physical processes involved in galaxy formation numerical simulations have become the major tool for theoretical progress in this field. Springel (2016) But: If you built a computer the size of the universe, with every single atom in it, you could recompute the universe, but you would understand nothing! 14

15 On progress in galaxy evolution Use simulations to identify analytical laws Not to reproduce the universe Use observations to understand processes Not to study pet objects We need a revival of analytic formulations of astrophysical processes 15

16 There is more to discuss. What does it mean to understand galaxy evolution? -> Debate on Friday Barbara Catinella, Patricia Sanchez-Blazquez, Klaus Dolag, Vladimir Avila 16