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The Universe After Gaia Data Release 2

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The Universe after Gaia Data Release 2 Eugene Vasiliev Institute of Astronomy, Cambridge University of Z¨urich 4 October 2019 The Universe after Gaia Data Release 2 Eugene Vasiliev Institute of Astronomy, Cambridge University of Z¨urich 4 October 2019 Alberto Giacometti, \Le Nez" Synopsis Overview of the Gaia mission and DR2: scientific instruments, catalogue contents, measurement uncertainties, caveats and limitations. Scientific highlights: Kinematic complexity of the disk Accretion history of the halo Search for new objects (streams, satellites) Internal kinematics of stellar structures Measurement of Milky Way gravitational potential Astrometry 101 Position on the sky α; δ Parallax $ = 1=distance Proper motion µα; µδ Line-of-sight velocity vlos Binary orbit parameters How Gaia astrometry works Overview of Gaia mission G I Scanning the entire sky every couple of weeks BP RP RVS I Astrometry for sources down to 21 mag I Broad-band photometry/low-res spectra I Line-of-sight velocity down to 15 mag (end-of-mission) ∼ [Source: ESA] Overview of Data Release 2 astrometry I Based on 22 months of data collection 9 I Total number of sources: 1:69 10 RV × I Sources with full astrometry (parallax $, 9 proper motions µα∗; µδ): 1:33 10 × 9 I Colours (GBP ; GRP ): 1:38 10 × I Line-of-sight velocities: 7:2 106 colours × 6 108 I Effective temperature: 160 10 Teff ICRF3 prototype 107 vrad SSO × Variable Gaia DR1 6 Gaia-CRF2 Gaia DR2 n 6 Stellar parameters (R ; L ): 77 10 i 10 b I g × a 105 m 6 1 . Extinction and reddening: 88 10 0 4 I 10 r e p × 6 r 103 e Variable sources: 0:55 10 b I m 2 u 10 × N 101 100 5 10 15 20 25 Mean G [mag] [Brown+ 2018] Measurement uncertainties 10 parallax uncertainty [mas] 5 ] s a m 2 [ Parallax: 0 05 0 1 mas ) $ : : $ & ¾ ( 1 − x a l l Proper motion: 0 1 0 2 mas/yr a 0:5 µ : : r & a p − n i 0:2 y Line-of-sight velocity: 0 5 km/s t V : n & i a t r 0:1 e c n u 0:05 d r a d n a 0 02 t : RV measurements only for stars with S systematic error 0:01 Teff [3500 6900] K and GRVS 12 (G 13) . 0:005 2 ÷ ≤ 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 ] 10 1 G magnitude ¡ r radial velocity uncertainty [km/s] y proper motion uncertainty [mas/yr] 5 s a m [ ) x a 2 m ; m p ¾ 1 ( : m : 0:5 p n i e s p 0:2 i l l e r o 0:1 r r e f o 0:05 s i x a systematic error r o j 0:02 a m ¡ i 0:01 systematic error m e 1 mas/yr = 4:7 km/s × (D=1 Kpc) S 0:005 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 [Katz+ 2018] G magnitude [Lindegren+ 2018] Gaia parallaxes and the absolute distance scale Mean parallax of 5 × 105 quasars [Arenou+2018] 0:10 ¡63 0:08 ¡64 0:06 Compilation of parallax offset measurements [Lindegren+2018b] ¡65 0:04 1.15 ¡66 ] H = s 0 a m ¡67 0:02 [ 1.10 80.5 x 95% a l l ¡68 a 0 r 99% a 1.05 76.9 p ¡69 n a ¡0:02 i d e Declination [deg] 1.00 ¡70 73.2 M ¡0:04 Median parallax[mas] ¡71 0.95 69.5 68% ¡0:06 95% Planck16+RCDM ¡72 rescale local distance 0.90 65.9 99% ¡0:08 ¡73 Red Giants 0.85 ¡0:10 100 95 90 85 80 75 70 65 60 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 Right Ascension [deg] parallax zeropoint (mas) Mean parallax of LMC stars [Lindegren+2018a] Cepheid distances and Planck constant [Riess+2018] The \golden" 6D sample 6 106 stars brighter than G 13 ∼ × ∼ 5 106 with parallax uncertainty $=$ 0:2 ≤ 4 106 3 106 2 106 Number of stars 106 0 0 2 4 6 8 10 Distance [kpc] [Babusiaux+ 2018; Katz+ 2018] Kinematic complexity in the disk I Moving groups in velocity space [Gaia Collaboration: Katz+2018] = more clearly seen in action space.) I Bar pattern speed constraints [Monari+2018] I Perturbations from spiral arms [Trick+2018] [Quillen+2018; Hunt+2018] I Tests of spiral structure theories [Sellwood+2018] [Quillen+2018] [Monari+2018] [Sellwood+2018] Vertical perturbations and the disk seismology Phase-space spiral [Antoja+2018] 10 perturbation from a (2 10) 10 M satellite − × crossing the disk 200 400 Myr ago (Sgr dSph?) − [Laporte+ 2018] [Darling & Widrow 2018] [Binney & Sch¨onrich2018] [Bland-Hawthorn+ 2018] [Li & Shen 2019] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − Dispersion Anisotropy Rotation 200 1.0 80 (kinematics1<|z|<3 + metallicity) 3<|z|<5 [see also Kruijssen+20185<|z|<9 for globular clusters] 0.8 150 60 0.6 > e ` m 100 40 <V 0.4 50 mr 20 0.2 me mq 0 0.0 0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 [Fe/H] [Fe/H] [Fe/H] [Belokurov+ 2018 { SDSS+Gaia DR1] [Mackereth+ 2019 { APOGEE+Gaia DR2] [Helmi+ 2018 { APOGEE+Gaia DR2] [Fattahi+ 2018 { Gaia DR2] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − (kinematics + metallicity) [see also Kruijssen+2018 for globular clusters] [Mackereth+ 2019 { APOGEE+Gaia DR2] Gaia{Enceladus Helmi+ 2018 [Fattahi+ 2018 { Gaia DR2] Radially-anisotropic population in the stellar halo 9 Evidence for a major merger with a 10 M satellite 8 10 Gyr ago & ∼ − Gaia{Enceladus Helmi+ 2018 Belokurov+ 2018 Finding substructures with Gaia 90 ◦ 90 ◦ north south 15 ◦ -15 ◦ 135 45 45 135 ◦ 30 ◦ ◦ ◦ -30 ◦ ◦ 3 45 ◦ -45 ◦ 10 60 ◦ -60 ◦ 75 ◦ -75 ◦ 180 ◦ 90 ◦ 0 ◦ -90 ◦ 180 ◦ Sagittarius stream 102 SMC # of sources per square degree 225 ◦ 315 ◦ 315 ◦ LMC 225 ◦ 101 270 ◦ 270 ◦ Stars with $ < 0:3, 1 < GBP GRP < 1:5, µα < 3:5, µδ < 3:5 (mainly distant halo) − j j j j Finding streams with Gaia Finding streams with Gaia Finding streams with Gaia Finding streams with Gaia GD-1 stream [Grillmair & Dionatos 2006] Finding new streams with Gaia 20 20 Phlegethon stream [Ibata+2018] 15 15 10 10 25 5 5 best fit orbital model ] ] c c p 0 p 0 k 30 k [ [ ] z y 1 30 5 5 ] r y g 10 10 e s d a [ 15 15 m b 35 [ 20 20 20 15 10 5 0 5 10 15 20 0 5 10 15 20 60 x [kpc] R [kpc] proper motion selection 40 15 10 Padova 10Gyr, [Fe/H] = 1.4 best fit orbital model 10 Phlegethon 10 ] 30 1 ] 5 1 r y 0 r ] 12 s 0 y g a e s m [ d 5 a [ ] m b g 10 10 [ a 14 b m 6015 [ 15 0 proper motion selection G 16 20 20 60 30 0 30 ] 1 25 [deg] r y s 30 a 18 m [ 35 40 20 45 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 3 (GBP GRP)0 [mag] 2 1 ] s a 0 m [ 1 2 3 400 ] 1 200 s m 0 k [ o i l e h 200 v 400 60 40 20 0 20 [deg] A census of stellar streams in the Milky Way Stream name Ylgr Sylgr Fj¨orm Fimbulthul Phlegethon Styx Kwando [Ibata+2019] Murrumbidgee Chenab Indus Jhelum Nix Aliqa Uma Willka Yaku Turranburra Orinoco Wambelong GD-1 [C.Mateu, GalStream database] A census of stellar streams in the Milky Way Stream name Ylgr Sylgr Fj¨orm Fimbulthul Phlegethon Styx Kwando Nix [Ibata+2019] Murrumbidgee Chenab Indus Jhelum Nix Aliqa Uma Willka Yaku Turranburra Orinoco Wambelong GD-1 Styx [C.Mateu, GalStream database] Finding new satellite galaxies with Gaia: Antlia 2 Stellar Density CMD Proper Motions 15 8 5 16 6 17 yr) 4 / 400 (deg) 0 18 2 (mas (mag) δ 0 δ 300 r ∆ All Stars 19 0 s) pm / 200 20 2 − -5 21 4 100 -5 0 5 0.5 0.0 0.5 1.0 1.5 − 5 0 − − HRV(km ∆α cos (δ) (deg) (g r)0(mag) pm α cos (δ) (mas/yr) 15 − 8 0 5 16 6 100 − 3 2 1 0 1.0 0.5 0.0 0.5 1.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 17 yr) 4 − − − − − − − / [Fe/H](dex) µα cos δ(mas/yr) µδ(mas/yr) (deg) 0 18 2 (mas LMC δ (mag) 0 δ LMC r ∆ 17.5 17.5 19 0 − − Selected Stars pm 15.0 15.0 20 2 − − − Fornax Sgr dsph Fornax -5 Sgr dsph 12.5 12.5 21 4 − − -5 0 5 0.5 0.0 0.5 1.0 1.5 − 5 0 − − AndXIX ∆α cos (δ) (deg) (g r)0(mag) pm α cos (δ) (mas/yr) 10.0 LeoII 10.0 LeoII AndXIX Draco − − Draco − Sextans 15 40 Sextans 20.56 0.1 ± Cra 2 Ant 2 5 (mag) 7.5 Cra 2 Ant 2 (mag) 7.5 16 V − V − M M 17 30 5.0 5.0 − − 18 2.5 2.5 − − =1 19 20 (deg) 0 M/L (mag) δ MW galaxies 0 r Classical dwarfs ∆ 0.0 0.0 20 M31 galaxies LG galaxies = 100 = 1000 21 10 = 31 = 32 MW GCs 2.5 µ µ 2.5 M/L M/L 0 1 2 3 4 3 4 5 6 7 8 9 22 10 10 10 10 10 10 10 10 10 10 10 10 -5 rh(pc) M(r<rh)(M ) 23 0 ⊙ 0.4 0.2 0.0 19.0 19.5 20.0 20.5 21.0 -5 0 5 − − The most diffuse galaxy [Torrealba+2018] (g r)0(mag) DMBHB ∆α cos (δ) (deg) − Determination of cluster membership CMD sky plane proper motion space Determination of cluster membership Probabilistic membership determination A hard cutoff in PM space is not always possible and is conceptually unsatisfactory.
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    Universita` degli studi di Roma “Tor Vergata” Facolta` di Scienze Matematiche, Fisiche e Naturali Dottorato di Ricerca in Astronomia XIX ciclo (2003-2006) SELF-CONSISTENT DISTANCE SCALES FOR POPULATION II VARIABLES Marcella Di Criscienzo Coordinator: Supervisors: PROF. R. BUONANNO PROF. R. BUONANNO PROF.SSA F. CAPUTO DOTT.SSA M. MARCONI Vedere il mondo in un granello di sabbia e il cielo in un fiore di campo tenere l’infinito nel palmo della tua mano e l'eternita´ in un ora. (William Blake) ii Dedico questa tesi a: Mamma e Papa´ Sarocchia Giuliana Marcella & Vincenzo Massimo Filippina Caputo Massimo Capaccioli Roberto Buonanno che mi aiutarono a trovare la strada, e a Tommaso che su questa strada ha viaggiato con me per quasi tutto il tempo Contents The scientific project xv 1 Population II variables 1 1.1 RR Lyrae stars 3 1.1.1 Observational properties 4 1.1.2 Evolutionary properties 6 1.1.3 RR Lyrae as standard candles 8 1.1.4 RR Lyrae in Globular Clusters 9 1.2 Population II Cepheids 13 1.2.1 Present status of knowledge 13 2 Some remarks on the pulsation theory and the computational methods 15 2.1 The pulsation cycle: observations 15 2.2 Pulsation mechanisms 17 2.3 Theoretical approches to stellar pulsation 19 2.4 Computational methods 23 3 Updated pulsation models of RR Lyrae and BL Herculis stars 25 3.1 RR Lyrae (Di Criscienzo et al. 2004, ApJ, 612; Marconi et al., 2006, MNRAS, 371) 25 3.1.1 The instability strip 30 3.1.2 Pulsational amplitudes 31 3.1.3 Some important relations for RR Lyrae studies 36 3.1.4 New results in the SDSS filters 39 3.2 BL Herculis stars (Marconi & Di Criscienzo, 2006, A&A, in press) 43 iv REFERENCES 3.2.1 Light curves and pulsation amplitudes 46 3.2.2 The instability strip 48 4 Comparison with observed RR Lyrae stars and Population II Cepheids 51 4.1 RR Lyrae 52 4.1.1 Comparison of models in Johnson-Cousin filters with current ob- servations (Di Criscienzo et al.
  • Dynamical Modelling of Stellar Systems in the Gaia Era

    Dynamical Modelling of Stellar Systems in the Gaia Era

    Dynamical modelling of stellar systems in the Gaia era Eugene Vasiliev Institute of Astronomy, Cambridge Synopsis Overview of dynamical modelling Overview of the Gaia mission Examples: Large Magellanic Cloud Globular clusters Measurement of the Milky Way gravitational potential Fred Hoyle vs. the Universe What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). vs. the Universe What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). Fred Hoyle What does \dynamical modelling" mean? It does not refer to a simulation (e.g. N-body) of the evolution of a stellar system. Most often, it means \modelling a stellar system in a dynamical equilibrium" (used interchangeably with \steady state"). Fred Hoyle vs. the Universe 3D Steady-state assumption =) Jeans theorem: f (x; v)= f I(x; v;Φ) observations: 3D { 6D integrals of motion (≤ 3D?), e.g., I = fE; L;::: g Why steady state? Distribution function of stars f (x; v; t) satisfies [sometimes] the collisionless Boltzmann equation: @f (x; v; t) @f (x; v; t) @Φ(x; t) @f (x; v; t) + v − = 0: @t @x @x @v Potential , mass distribution @f (x; v; t) ; t ; t ; t + @t 3D observations: 3D { 6D integrals of motion (≤ 3D?), e.g., I = fE; L;:::