AstronomischeNachrichten,7January2016 Milky Way chemo-dynamics in the era of Gaia I.Minchev1,⋆,C.Chiappini1,andM.Martig2 1 Leibniz-Institutfu¨rAstrophysikPotsdam(AIP),AnderSternwarte16,D-14482,Potsdam,Germany 2 Max-Planck-Institutfu¨rAstronomie,Ko¨nigstuhl17,D-69117Heidelberg,Germany 6 ReceivedXXXX,acceptedXXXX 1 PublishedonlineXXXX 0 2 Key words Galaxy: abundances – Galaxy: disc – Galaxy: evolution – Galaxy: formation – Galaxy: kinematics and n dynamics a J ThemaingoalofGalacticArchaeologyisunderstandingtheformationandevolutionofthebasicGalacticcomponents. Thisrequiressophisticatedchemo-dynamicalmodeling,wherediscasymmetries(e.g.,perturbationsfromthecentralbar, 6 spirals arms, and infalling satellites) and non-equilibrium processes are taken into account self-consistently. Here we ] discuss thecurrent statusof Galacticchemo-dynamical modeling and focus on a recent hybrid technique, which helps A circumventtraditionalproblemswithchemicalenrichmentandstarformationencounteredinfullyself-consistentcosmo- G logicalsimulations.Weshowthatthismodelcanaccountforanumberofchemo-kinematicrelationsintheMilkyWay.In addition,wedemonstratethat(1)ourmodelmatcheswelltheobservedage-[α/Fe]andage-[Fe/H]relationsand(2)that . h thescatterintheage-[Fe/H] relationcannot besimplyexplained byblurring(starsonapo- and pericentersvisitingthe p solarvicinity)butsignificantradialmigration(starsbornelsewherebutendingupatthesolarvicinitytodaybecauseofa - o changeinguidingradius)isneeded.Weemphasizetheimportanceofaccuratestellarages,suchasthoseobtainedthrough r asteroseismology by the CoRoT and Kepler missions, for breaking the degeneracy among different Galactic evolution t scenarios. s a [ Copyrightlinewillbeprovidedbythepublisher 1 v 1 Introduction (e.g.,Tisseraetal.2012),itisstillachallengeforcosmolog- 3 icalsimulationstomatchthepropertiesoftheMW(e.g.,the 1 3 Important information concerning the dominant mecha- typicalmetallicitiesofthedifferentcomponents–Tisseraet 1 nismsresponsiblefortheformationoftheMilkyWay(MW) al.2012).Additionally,thefractionoflow-metallicitystars 0 is encoded in the chemistry and kinematics of its stars. A areoftenoverestimated(Caluraetal.2012)andreproducing 1. number of Galactic surveys are currently being conducted thepositionofthin-andthick-discstarsinthe[α/Fe]-[Fe/H] 0 with the aim of obtaining chemical and kinematical infor- plane has proved challenging (Brook et al. 2012; Gibson 6 mation for a vast number of stars, e.g., RAVE (Steinmetz etal. 2013).While such issues couldbe dueto unresolved 1 eta.2006),SEGUE(Yannyeta.2009),APOGEE(Majew- metal mixing (Wiersma et al. 2009), none of the above- : v skietal.2010),HERMES(Freemanetal.2010),Gaia-ESO mentionedsimulationsreproducessimultaneouslythemass, Xi (Gilmore et al. 2012),Gaia (Perrymanet al. 2001),LAM- themorphology,andthestarformationhistory(SFH)ofthe OST(Zhaoetal.2006)and4MOST(deJongetal.2012). MW. r a Tobeabletointerpretthelargeamountsofforthcoming dataweneedgalaxyformationmodelstailoredtotheMW. 1.1 SummaryofMWchemo-dynamicalevolution Producingdisc-dominatedgalaxieshastraditionallybeena modelingtechniques challengeforcosmologicalsimulations(e.g.,Navarroetal. 1991;Abadietal.2003).Althoughanincreaseinresolution Amajorconsiderationinadiscchemo-dynamicalmodelis andimprovedmodelingofstarformationandfeedbackhave taking into account the effect of radial migration, i.e., the resultedinMW-massgalaxieswithreducedbulgefractions factthatstarsendupawayfromtheirbirthplaces(see,e.g., (Guedesetal.2011;Martigetal.2012),typicallythesesim- Sellwood and Binney 2002; Roskar et al. 2008, Minchev ulationsdo notinclude chemicalevolution.Galaxy forma- and Famaey 2010). Below we quickly summarize models tionsimulationsincludingsometreatmentofchemicalevo- whichincluderadialmigration. lutionhavebeenperformedbyseveralgroups(e.g.,Scanna- 1. Semi-analytical models tuned to fit the local metal- piecoetal.2005;Fewetal.2012). licity distribution,velocitydispersion,and chemicalgradi- However,while the results are encouragingand global ents,etc.,today(e.g.,SchoenrichandBinney2009;Kubryk, observed relations are reproduced, such as the metal- Prantzos, and Athanssoula 2014) or Extended distribution licity trends between the different galactic components functions(SandersandBinney2015): ⋆ Correspondingauthor:iminchev@aip.de −Easytovaryparameters Copyrightlinewillbeprovidedbythepublisher 2 Minchevetal.:MilkyWaychemo-dynamics − Provide good description of the disc chemo-kinematic To match the MW in terms of dynamics, at the end of statetoday the simulation we downscale the disc radius by a factor −TypicallynotconcernedwiththeMilkyWaypasthistory of 1.67 and adjust the rotational velocity at the solar ra- −Timeandspatialvariationsofmigrationefficiencydueto dius to be 220 km/s, which affects the mass of each par- dynamicsresultingfromnon-axisymmetricdiscstructureis ticle according to the relation GM ∼ v2r, where G is the hardtotakeintoaccount. gravitationalconstant.Thisplacesthe bar’scorotationres- 2. Fully self-consistent cosmologicalsimulations (e.g., onance (CR) and 2:1 outer Lindblad resonance (OLR) at Kawata and Gibson 2003; Scannapieco et al. 2005; ∼ 4.7 and ∼ 7.5 kpc, respectively, consistent with a num- KobayashiandNakasato2011;Brooketal.2012): berofstudies(e.g.,Dehnen2000,Minchev,Nordhaus,and −Dynamicsself-consistentinacosmologicalcontext Quillen 2007, Minchev et al. 2010). At the same time the −Canlearnaboutdiscformationandevolution discscale-length,measuredfromparticlesofallagesinthe −Notmuchcontroloverfinalchemo-kinematicstate range365 MCM13 model 7

Milky Way chemo-dynamics in the era of Gaia

Similar Milky Way chemo-dynamics in the era of Gaia