Modelling the Milky Way with TRILEGAL

Transcription

1 Modelling the Milky Way with TRILEGAL Léo Girardi (Oss. Ast. Padova, Italy) And main collaborators in this moment: DES-Brazil (simulation of DES, kinematics) SDSS-III Brazil (target+field selection for APOGEE) VMC team (data analysis of VISTA Magellanic Clouds Survey) Martin Groenewegen, Evelien Vanhollebeke, Marco Gullieuszik (minimization methods) Alexandre Zabot, Antonio Kanaan, Luciana Bianchi, Boryana Efremova (hot white dwarfs from GALEX) Paola Marigo, Alessandro Bressan, Bernhard Aringer, Mauro Barbieri, ANGST + M31-MCTP Teams (testing evolutionary tracks and spectra of cool stars)

2 What is TRILEGAL TRIdimensional model of the GALaxy (or very nice in Southern Brazil) Actually a population synthesis code to simulate resolved stellar populations in general star clusters, background galaxies, and the Milky Way Main particularities: stands on well-tested stellar models / isochrones (m)any photometric system(s)

3 TRILEGAL scheme (v1.3)

4 TRILEGAL web interface

5 TRILEGAL web interface

6 Evolutionary tracks / isochrones Girardi et al. (2000) for most stars 0.2 to 7 Mꙩ Bertelli et al. (1994) for massive stars Marigo & Girardi (2007) for AGB stars Vassiliadis & Wood for PNN + Benvenuto & Althaus for white dwarfs (under revision; Zabot et al. 2010) Chabrier et al. (2000) for very-low mass and brown dwarfs down to 0.01Mꙩ

7 Stellar atmosphere models Mainly ATLAS9 ODFNEW (Castelli & Kurucz 2004), for -2.5<[M/H]<+0.5], 3500<Teff/K<50000, Blackbody for OB stars with Teff>50000 K (replacement planned) Koester et al. for DA white dwarfs (being updated, Zabot et al. 2010) Fluks et al. (1994) for M giants (under revision, Aringer et al. 2010) Either Loidl et al. (2003, v1.3) or Aringer et al. (2009, v1.4+) for C-type giants BDUSTY1999 (Allard et al. 2000) for very-low mass and brown dwarfs down to 500 K (-> Aringer et al. 2010)

8 Stellar atmosphere models Mainly ATLAS9 ODFNEW (Castelli & Kurucz 2004), for 3500<Teff/K<50000 Blackbody for OB stars with Teff>50000 K (replacement planned) Koester et al. for DA white dwarfs (being updated, Zabot et al. 2010) Fluks et al. (1994) for M giants (under revision, Aringer et al. 2010) Either Loidl et al. (2003, v1.3) or Aringer et al. (2009, v1.4+) for C-type giants BDUSTY1999 (Allard et al. 2000) for very-low mass and brown dwarfs down to 500 K

9 Photometric systems Large database being built with filter sets of major surveys, most are contributed by TRILEGAL users Virtually any Vega, AB, and ST system can be included Latest additions: GALEX, HST/WFC3, Megacam, SuprimeCam, Corot, Kepler, WISE, SWIFT/UVOT (list in )

10 Milky Way components Each galaxy component has its geometry ρ(r), star formation rate and age metallicity relation, ψ (t) and Z (t), + the IMF (apparent binaries are included a posteriori) All functions may depend on r and t (but usually do not) Presently included: Triaxial bulge cf. Binney et al. (1997) Oblate spheroidal halo Thick disk (double exponential) Thin disk (double exponential with hz(t) ) Dust layer (exponential in z)

11 Resulting volume-limited samples All disk stars (including white and brown dwarfs) within 80 pc

12 The same code, near and far Underlying isochrones are being widely used and tested the small bugs detected are usually corrected within 1 week The same code is being used to model star clusters and nearby galaxies (from 40 pc to 4 Mpc) the resulting stellar model improvements are almost immediately incorporated in the MW model

13 The same code, near and far 2MASS 180 deg2 LMC data TRILEGAL simulation (no errors, no pulsation) Modelling IR data in the Magellanic Clouds is essential to improve TP-AGB models and a basic step to model PSCs of extended IR surveys (2MASS, UKIDSS, GLIMPSE, SIRIUS, VISTA, AKARI, etc)

14 The same code, near and far 2MASS 180 deg2 LMC data TRILEGAL simulation (no errors, no pulsation) LMC, pre-agb LMC AGB O-rich LMC AGB C-rich MW disk(s) MW halo Modelling IR data in the Magellanic Clouds is essential to improve TP-AGB models and a basic step to model PSCs of extended IR surveys (2MASS, UKIDSS, GLIMPSE, SIRIUS, VISTA, AKARI, etc)

15 The same code, near and far SAGE inner LMC data (Spitzer IRAC+MIPS) TRILEGAL simulation (no errors, no pulsation) Modelling IR data in the Magellanic Clouds is essential to improve TP-AGB models and a basic step to model PSCs of extended IR surveys (2MASS, UKIDSS, GLIMPSE, SIRIUS, VISTA, AKARI, etc)

16 The same code, near and far LMC outer disk (Piatti et al. 1998) TRILEGAL simulation Details of red clump are also best seen in Magellanic Clouds and as wide as 0.5 mag. Considering such structures makes a difference when modelling the star counts in the inner MW disk.

17 TRILEGAL initial calibration In Groenewegen et al. (2002) and Girardi et al. (2005), model parameters were tweaked so as to reproduce as much as possible star counts of: Deep multicolor surveys (EIS-deep, DMS) 2MASS Hipparcos

18 TRILEGAL initial calibration From the 7-passband CDFS stellar catalogue (Groenewegen et al. 2002):

19 TRILEGAL initial calibration 2MASS towards the NGP (Girardi et al. 2005):

20 TRILEGAL initial calibration 2MASS towards the galactic anticenter (Girardi et al. 2005):

21 TRILEGAL initial calibration Hipparcos local sample (Girardi et al. 2005): all stars with V<7 and 1/π < 100 pc

22 Tests to the initial calibration A very detailed modelling of UKIDSS data (Kerber et al. 2009). For a 0.21 sqrdeg area towards l=-220 deg, b=40 deg, first we simulate the images using TRILEGAL output, then perform the photometry exactly as in the real UKIDSS image.

23 Tests to the initial calibration The logg distribution from large spectroscopic surveys (Girardi, Rossetto et al., 2010), or equivalently, the giant/dwarf ratio. Logg distributions from RAVE DR2 giant fraction vs. b

24 Hot wd, sd, binaries: MW structure L. Bianchi, et al. SOUTH NORTH Disk + Weidemann 2000 AA IFMR Marigo &Girardi 2007 IFMR WD #/sq.deg as a func. of magnitude for 10-deg latitude slices TRILEGAL MW models (Girardi et al): black (halo, disk, total) WD counts (elusive at optical colors) ----> constrain IFMR especially at low masses initial-final mass relation from Weidemann. (no better constraints from open clusters) Blue: AIS, Green: MIS (deeper, but less area) Bianchi et al in prep Bianchi, Efremova, Herald, Girardi 2009, AIP conf.proc. Vol 1135, p.326

25 Where TRILEGAL v1.3 fails the most Inner disk and inner halo (less than say 40 deg from GC) Low b in general, this is partially due to bad extinction, partially because not calibrated there Rossetto et al. 2010: comparison between TRILEGAL v1.3 and 2MASS star counts in DES area

26 Calibrating the Bulge Vanhollebeke et al. (2009)

27 Calibrating the Bulge Results: (similar plots for 15 OGLE-II fields) Best-fitting parameters and error estimates

28 Recalibrating disk(s) and halo Vanhollebeke et al. (2009) algorithm adapted to work with many more l.o.s. and input catalogues (2MASS, SDSS, OGLE, UKIDSS) Recalibration is running, but heavy computational work To have acceptable CPU times: presently limited to ~50 l.o.s., most coincide with SEGUE plate pointings, and ugrizjhks filters thin disk is assumed to follow hz(t) α σw(t) isothermal disks with σw(t) taken from Geneva-Copenhagen survey (Nordstrom et al. 2007, Holberg et al. 2009)

29 Recalibrating disk(s) and halo Vanhollebeke et al. (2009) algorithm adapted to work with many more l.o.s. and input catalogues (2MASS, SDSS, OGLE, UKIDSS) Recalibration is running, but heavy computational work To have acceptable CPU times: presently limited to ~50 l.o.s., most coincide with SEGUE plate pointings, and ugrizjhks filters thin disk is assumed to follow hz(t) α σw(t) isothermal disks with σw(t) taken from Geneva-Copenhagen survey (Nordstrom et al. 2007, Holberg et al. 2009)

30 Recalibrating disk(s) and halo Lessons so far: Slow convergence (many parameters!), with a few solutions trapped in local minima (if too many parameters) The more l.o.s. you include, the worst is the solution With <15 l.o.s, it's easy to get 10% errors in star counts binper-bin, in 8 filters! with >50 l.o.s., errors become about 20% > sign of missing MW components, or of more complex geometry More observables needed, rather than more photometry: e.g. M, R and g from asteroseismology, to probe distance and age distributions! kinematics and abundances to disentangle thick disk from oldest thin disk on base of star counts (both converge to hz ~ 650 pc)

31 Including kinematics Simple description based on Schwarzschild's velocity distribution, and velocity ellipsoids taken from literature Initial validation in Rossetto et al. 2010: TRILEGAL vs. UCAC3 l=352.5 deg b=+62.8 deg Vlim=17 mag

32 What TRILEGAL does not No real dynamics, just kinematics. Some good reasons for this: needs a mass distribution for the MW, which we do not know (e.g. what about a dark matter disk?) would increase a lot the CPU times less flexibility in playing with MW geometry No interacting binaries, just detached ones No stellar rotation, termohaline mixing, 3D convection (for the moment!!!)

33 Summary TRILEGAL is quick, versatile, quite good for simulating photometry of MW fields, from the UV to the mid-ir Population synthesis approach: gives more observables than actually observed (useful for understanding biases) Very useful in interpretation and planning of wide-area surveys 2MASS, SAGE, RAVE, GALEX, Corot, Kepler, VMC, PLATO, APOGEE, MARVELS, DES,...!!! Code is being expanded in several sub-projects Very promising method for best-fitting model parameters application to Bulge leads to excellent fits to data application to disk+halo indicates that more complex descriptions of geometry and SFH are needed, having new observables from asteroseismology will definitely help