Clump formation through colliding stellar winds in the Galactic - PowerPoint PPT Presentation

Clump formation through colliding stellar winds in the Galactic Center Calderón et al. (2016) Diego Calderón 1 , J. Cuadra 1 , A. Ballone 2,3 , M. Schartmann 3 , A. Burkert 2,3 & S. Gillessen 2 1 Instituto de Astrofísica, Pontificia Universidad Católica de Chile 2 Max-Planck-Institute for Extraterrestrial Physics, Germany 3 Universitätssternwarte der Ludwig-Maximilians-Universität, Germany 4 Center for Astrophysics and Supercomputing, Swinburne University of Technology � “Dynamics and Accretion at the Galactic Center” Aspen winter conference, February 9th 2016 Numerical Hydrodynamics Group IAUC Image of η Carinae by HST

Gas clumps in the Galactic Center Numerical Hydrodynamics Group IAUC Animation from Cuadra et al. (2008)

Gas clumps in the Galactic Center Numerical Hydrodynamics Group IAUC Animation from Cuadra et al. (2008)

Gas clumps in the Galactic Center Are they physical or numerical? ( H o b b s e t a l . 2 0 1 3 ) 
 � Could G2 be one of them? ( S c h a r t m a n n e t a l . 2 0 1 2 , B u r k e r t e t a l . 2 0 1 2 ) Numerical Hydrodynamics Group IAUC Animation from Cuadra et al. (2008)

Non-linear Thin Shell Instability (NTSI) Vishniac (1994) Numerical Hydrodynamics Group IAUC Figure from McLeod & Whitworth (2013)

Non-linear Thin Shell Instability (NTSI) Vishniac (1994) Numerical Hydrodynamics Group IAUC Figure from McLeod & Whitworth (2013)

Non-linear Thin Shell Instability (NTSI) Vishniac (1994) Isothermal case Numerical Hydrodynamics Group IAUC Figure from McLeod & Whitworth (2013)

Colliding Winds From Stevens et al. (1992), v 5 . 4 χ = t cool ≈ 1 8 d 12 ˙ t dyn 2 M − 7 χ ≥ 1 ⇒ adiabatic wind χ < 1 ⇒ radiative wind The NTSI can take place only if winds are radiative, i.e., form a thin shell. Schematic representation of a colliding winds system Numerical Hydrodynamics Group IAUC Figure from Stevens et al. (1992)

Model for a symmetric wind collision Describing the thermal evolution of the slab, we can estimate the unstable wavelength range, and the mass of possible clumps (assuming λ ~ clump size). Numerical Hydrodynamics Group IAUC

Model for a symmetric wind collision M = 10 − 5 M Sun yr − 1 ˙ Describing the thermal evolution of the slab, we can estimate the Minimum Clump Mass Maximum Clump Mass 900 2 unstable wavelength range, and the mass of possible clumps χ = 1 (assuming λ ~ clump size). 0 800 χ = 0 . 5 Stellar Wind Velocity V (km s − 1 ) D D − 2 700 − 4 log ( M/ M Earth ) 600 − 6 500 E B E B − 8 400 − 10 − 12 300 F C A F C A − 14 200 10 − 1 10 0 10 1 10 − 1 10 0 10 1 Stellar Separation d (mpc) Stellar Separation d (mpc) Clumps can be created in a wide range of masses, some of them can even reach ~100 Earth masses. Numerical Hydrodynamics Group IAUC

Model for a symmetric wind collision M = 10 − 5 M Sun yr − 1 ˙ Describing the thermal evolution of the slab, we can estimate the Minimum Clump Mass Maximum Clump Mass 900 2 unstable wavelength range, and the mass of possible clumps χ = 1 (assuming λ ~ clump size). 0 800 χ = 0 . 5 But … Can this happen in the Galactic Centre? Stellar Wind Velocity V (km s − 1 ) D D − 2 700 − 4 log ( M/ M Earth ) 600 − 6 500 E B E B − 8 400 − 10 − 12 300 F C A F C A − 14 200 10 − 1 10 0 10 1 10 − 1 10 0 10 1 Stellar Separation d (mpc) Stellar Separation d (mpc) Clumps can be created in a wide range of masses, some of them can even reach ~100 Earth masses. Numerical Hydrodynamics Group IAUC

Clump formation in the Galactic Centre y-axis shows maximum stellar separations for 10 2 identical winds to be 10 4 radiative, i.e., form thin 10 1 shells. 33E 10 3 Separations of miliparsec 10 0 (mpc) (AU) (~200AU) scales are not 10 2 2 d cool very common. 2 d cool 9W ∗ ∗ 10 − 1 10 1 AFNWNW 10 − 2 13E4 10 0 16SE2 10 − 3 0 . 00 0 . 05 0 . 10 0 . 15 0 . 20 0 . 25 Momentum Flux (M Sun yr − 1 km s − 1 ) Stellar properties from Martins et al. (2007) Numerical Hydrodynamics Group IAUC Animation Pittard (2009)

Clump formation in the Galactic Centre y-axis shows maximum stellar separations for 10 2 identical winds to be 10 4 radiative, i.e., form thin 10 1 shells. 33E 10 3 Separations of miliparsec 10 0 (mpc) (AU) (~200AU) scales are not 10 2 2 d cool very common. 2 d cool 9W ∗ ∗ 10 − 1 10 1 AFNWNW 10 − 2 What about binaries? 13E4 10 0 16SE2 3 systems so far ~ 3 0 % e x p e c t e d 10 − 3 0 . 00 0 . 05 0 . 10 0 . 15 0 . 20 0 . 25 (Pfuhl+2014) Momentum Flux (M Sun yr − 1 km s − 1 ) Stellar properties from Martins et al. (2007) Numerical Hydrodynamics Group IAUC Animation Pittard (2009)

Clump formation in the Galactic Centre y-axis shows maximum stellar separations for 10 2 identical winds to be 10 4 radiative, i.e., form thin W - > b i n a r y s y s t e m - I R S 1 6 S 10 1 shells. 33E 10 3 
 P ~ 1 9 . 5 d & w i n d s p e e d ~ 5 0 0 k m / s - d ~ 1 0 µ p c , Separations of miliparsec 10 0 (mpc) (AU) 
 n t h e c l o c k w i s e d i s c - L o c a t e d i (~200AU) scales are not 10 2 2 d cool very common. 2 d cool 9W i n t h e d i s c ( S c h a r t m a n n e t a l . 2 0 1 5 ) - G 2 o r i g i n ∗ ∗ 10 − 1 10 1 AFNWNW 10 − 2 What about binaries? 13E4 10 0 16SE2 3 systems so far ~ 3 0 % e x p e c t e d 10 − 3 0 . 00 0 . 05 0 . 10 0 . 15 0 . 20 0 . 25 (Pfuhl+2014) Momentum Flux (M Sun yr − 1 km s − 1 ) Stellar properties from Martins et al. (2007) Numerical Hydrodynamics Group IAUC Animation Pittard (2009)

Clump formation in the Galactic Centre y-axis shows maximum stellar separations for 10 2 identical winds to be 10 4 radiative, i.e., form thin W - > b i n a r y s y s t e m - I R S 1 6 S 10 1 shells. 33E 10 3 
 P ~ 1 9 . 5 d & w i n d s p e e d ~ 5 0 0 k m / s - d ~ 1 0 µ p c , Separations of miliparsec 10 0 (mpc) (AU) 
 n t h e c l o c k w i s e d i s c - L o c a t e d i (~200AU) scales are not 10 2 2 d cool very common. 2 d cool 9W i n t h e d i s c ( S c h a r t m a n n e t a l . 2 0 1 5 ) - G 2 o r i g i n ∗ ∗ 10 − 1 10 1 AFNWNW 10 − 2 What about binaries? 13E4 10 0 16SE2 3 systems so far ~ 3 0 % e x p e c t e d 10 − 3 0 . 00 0 . 05 0 . 10 0 . 15 0 . 20 0 . 25 (Pfuhl+2014) Momentum Flux (M Sun yr − 1 km s − 1 ) Stellar properties from Martins et al. (2007) Numerical Hydrodynamics Group IAUC Animation Pittard (2009)

Another option: Mass-losing star encounters Stellar encounters could be clumps sources too! Numerical Hydrodynamics Group IAUC

Another option: Mass-losing star encounters Stellar encounters could be clumps sources too! Numerical Hydrodynamics Group IAUC

Another option: Mass-losing star encounters Stellar encounters could be clumps sources too! We ran Newtonian test particles gravity simulation of the O/WR stars (using orbital data from Paumard et al. 2006) for 10,000 yrs and register close encounters (<2,000AU~10mpc). Numerical Hydrodynamics Group IAUC

Another option: Mass-losing star encounters Stellar encounters could be clumps sources too! n t e r s a r e n o t v e r y W e f o u n d t h e s e e n c o u y r . c o m m o n , a b o u t 1 i n 1 0 , 0 0 0 We ran Newtonian test particles gravity simulation of the O/WR stars (using orbital data from Paumard et al. 2006) for 10,000 yrs and register close encounters (<2,000AU~10mpc). Numerical Hydrodynamics Group IAUC

Conclusions � � - We developed a straight-forward diagnostic for clump formation through NTSI with (M dot , V wind , d) as input. � For stellar separations <2,000AU, clumps can be created in a very wide range of masses reaching 100 Earth masses. � Symmetric colliding wind encounters are an unlikely source of clumps in the Galactic Centre. � Close encounters (<2,000AU) of the known O/WR are not very common events, however some of them might be clump sources. � IRS 16SW is the most promising clump source and deserves future study (currently working on it). Numerical Hydrodynamics Group IAUC

Work in progress Currently, we are running and analysing hydro AMR simulations. Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Numerical Hydrodynamics Group IAUC

Work in progress Currently, we are running and analysing hydro AMR simulations. Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Numerical Hydrodynamics Group IAUC

Work in progress Currently, we are running and analysing hydro AMR simulations. Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Numerical Hydrodynamics Group IAUC

Thanks for your attention! Numerical Hydrodynamics Group IAUC Numerical Hydrodynamics Group IAUC