The importance of galactic fountain in galaxy evolution

Transcription

1 The importance of galactic fountain in galaxy evolution Federico Marinacci in collaboration with: L. Armillotta, A. Marasco, F. Fraternali, J. Binney, L. Ciotti & C. Nipoti Sydney, 4 November 214

2 Galactic fountain credit: A. Marasco halo disk Supernovae and stellar winds eject gas from the disk into the halo (Shapiro & Field 1976)

3 Extra-planar gas NGC 891 Hα, optical R, X-rays halo 2 kpc optical (Strickland et al. 24) (Oosterloo, Fraternali & Sancisi 27) Multiphase medium Mass of extra planar HI M

4 How do galaxies get their gas?

5 The need for gas accretion (Fraternali 214) (Marinacci+ 214) SFR[M yr 1 ] Aq A 5 12 z t look [Gyr] z BH in halo accreted total Aq E 5 BH in halo 35 accreted not sufficient to support SF for 3 a Hubble time total 25 Gas consumption time few Gyrs disk formation yr 1 ] 2

6 Visible gas accretion Gas of non-internal origin: mergers, peculiar dynamical state... (Oosterloo et al. 27) Ṁ accr.1 M /yr

7 Hot coronae around disk galaxies Anderson & Bregman (211) NGC Isothermal Adiabatic Bogdán+ (213) Cooling n cor (cm -3 ) Gatto+ (213) R (kpc) MW detected up to 1 kpc T 1 6 K (for MW mass) Mass M b in the disk R (kpc) R (kpc)

8 Hot coronae around disk galaxies Anderson & Bregman (211) NGC Large reservoir but needs cooling Isothermal Adiabatic Bogdán+ (213) Cooling n cor (cm -3 ) Gatto+ (213) R (kpc) MW detected up to 1 kpc T 1 6 K (for MW mass) Mass M b in the disk R (kpc) R (kpc)

9 The role of (stellar) feedback cooling induced by metals ejected by feedback close to galaxies (Van de Voort & Schaye 212) positive feedback feeds cold gas to the galactic disk directly, fuelling SF (Hobbs et al. 213) importance of galactic fountain for enrichment history and angular momentum redistribution in disks (Brook+ 214)

10 Fountain-corona interaction

11 Kinematics of the extra-planar gas NGC 891 Velocity decreases with height (Fraternali et al. 25)

12 Interaction with the ambient medium (Fraternali & Binney 28) 25 Rotation velocity (km/s) Disc Fountain Fountain + Accretion z=3.9 kpc Kinematic is not reproduced by simple fountain models R (kpc) Ṁ accr 1 M /yr credit: F. Fraternali

13 How the gas is accreted

14 The key concept [Fe/H] = -1. [Fe/H] = -.5 Cooling time for n = 1x1-3 cm -3, T = 1.9x1 6 K 1 4 τ cool corona 1 3 τ cool [Myr] t orb t flow D/v Cooling time of the gas is a strong function of the temperature T[K]

15 Simulations of cloud corona interaction ECHO++ code (based on algorithms by Del Zanna et al. 27) 2D hydro simulations of a cloud moving through coronal gas at different velocities Radiative cooling = Sutherland & Dopita (1993) K v Z cl = Z Z cor =.1 Z 1 5 K

16 Temperature maps t = Myr K without cooling 1 5 K v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = Myr (Marinacci et al. 21) K with cooling 1 5 K

17 Temperature maps t = 15 Myr K without cooling 1 5 K v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = 15 Myr (Marinacci et al. 21) K with cooling 1 5 K

18 Temperature maps t = 3 Myr K without cooling 1 5 K v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = 3 Myr (Marinacci et al. 21) K with cooling 1 5 K

19 Temperature maps t = 45 Myr K without cooling 1 5 K v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = 45 Myr (Marinacci et al. 21) K with cooling 1 5 K

20 Temperature maps t = 6 Myr K without cooling 1 5 K v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = 6 Myr (Marinacci et al. 21) K with cooling 1 5 K

21 Temperature maps t = 6 Myr K turbulent wake cloud 1 5 K without cooling v = 1 km s 1, n cor = 1 3 cm 3, r cl = 1 pc t = 6 Myr (Marinacci et al. 21) K with cooling cooling gas K

22 Condensation of coronal gas 5-5 Mass of gas below 1 5 K cooling Mass of gas below 1 5 K 1 8 M(t) - M() [M sun ] M /M [%] M(t) - M() [M sun ] M /M [%] -25 no cooling Time [Myr] Time [Myr] (Marinacci et al. 21) The total mass of cold gas increases for typical conditions

23 Changing the coronal density 25 2 Mass of gas below 1 5 K (Marinacci et al. 21) 1 8 M(t) - M() [M sun ] M /M [%] 2 Mass of gas below 1 5 K ncor = 1 3 reference cm 3 Time [Myr] 12 2 Mass of gas below 1 5 K 1 2 M(t) - M() [M sun ] M /M [%] M(t) - M() [M sun ] M /M [%] low density n cor = cm high density n cor = cm Time [Myr] Time [Myr]

24 Changing the coronal density 25 2 Mass of gas below 1 5 K (Marinacci et al. 21) 1 8 M(t) - M() [M sun ] M /M [%] 2 Mass of gas below 1 5 K ncor = 1 3 reference cm 3 Time [Myr] 12 2 Mass of gas below 1 5 K 1 2 M(t) - M() [M sun ] M /M [%] -4 6 Mass transfer 1 M -6 yr 1 4 low density n cor = cm Time [Myr] Time [Myr] M(t) - M() [M sun ] high density n cor = cm M /M [%]

25 Motion of the cold gas centroid (Marinacci et al. 211) Time [R cl / v ] simulation with cooling simulation without cooling 1 analytic prediction 1. Time [R cl / v ] simulation with cooling 1.5 simulation without cooling analytic prediction v x [km/s] v = 1 km/s v x / v v x [km/s] v x / v v = 75 km/s Time [Myr] Time [Myr] T < K v(t) = v /(1 + t/t drag ), t drag = M cl /(ρ h σv ) Velocity gradient consistent with the observations

26 Implications for galaxy evolution (from Fraternali 214) Disk acts as a refrigerator of the corona by cooling its gas and making it available for star formation