Quenching and ram pressure stripping of simulated Milky Way - - PowerPoint PPT Presentation

Quenching and ram pressure stripping

• f simulated Milky Way

satellite galaxies

Christine Simpson

HITS

Collaborators: The Auriga Project Rob Grand (HITS) Facundo Gómez (MPA) Federico Marinacci (MIT) Rüdiger Pakmor (HITS) Volker Springel (HITS) Dave Campbell (Durham) Carlos Frenk (Durham)

z=0.07 d=86 kpc z=0.1 d=48 kpc z=0.11 d=61 kpc

Many substructure puzzles in the Local Group

• ‘Missing satellites’
• ‘Too big to fail’
• cores vs. cusps
• planes of satellites

Solution(s)?

Dark matter? Gravity? Baryons? All of the above?

What do we know about baryons in LG dwarfs?

Grecevich & Putman 2009

Few systems with measured H I within ~270 kpc of host Environment Mass

Weisz et al. 2015

Fraction of quenched systems increases with decreasing luminosity

The Set-up & Physics

• Thirty cosmological zoom simulations of 1012 M⊙ halos
• DM particle mass ~ 3 x 105 M⊙; baryon cell/particle mass ~ 5 x 104 M⊙
• Second-order hydrodynamics on a moving mesh (AREPO)
• MHD, SF & stellar feedback, AGN feedback, UV background, atomic & metal line cooling

The Auriga Project

Grand et al. 2017

physical volume: 400 kpc

106 107 108 109 1010 1011 Mstar (M) 100 101 102 Cumulative Number

MW M31 L4

Satellites & Dwarfs in Auriga

• Cumulative number of

luminous satellites match the MW and M31

• Luminosity of systems lie

above predictions for central galaxies from abundance matching extrapolations

systems within 300 kpc systems within 1 Mpc

Simpson et al. 1705.03018

Quenching of Satellites

106 107 108 109 1010 1011 Final Mstar (M) 0.0 0.2 0.4 0.6 0.8 1.0 Fraction of Quenched Satellites

All (672) 0.0 - 0.3 Mpc (356) 0.3 - 0.6 Mpc (191) 0.6 - 1.0 Mpc (125)

0.0 0.2 0.4 0.6 0.8 1.0 Final Distance (Mpc) 0.0 0.2 0.4 0.6 0.8 1.0 Fraction of Quenched Satellites

All (672) 5 × 105 - 107 M (323) 107 - 108 M (203) > 108 M (146)

• All distance bins show

more quenching at lower masses

• The most isolated

systems only quench strongly at Mstar < 107 M⊙

• Above Mstar > 108 M⊙

almost all systems are star-forming

Simpson et al. 1705.03018

Mechanisms? Ram Pressure?

Simpson et al. 1705.03018

Ram pressure is the dominant quenching mechanism

z=0.07 d=86 kpc z=0.1 d=48 kpc z=0.11 d=61 kpc z=0.14 d=118 kpc x 1.0 100 kpc z=0.2 d=207 kpc x 4.0 25 kpc x 16.0 6 kpc x 32.0 3 kpc

• This system is

~ 6.3 x 106 M⊙ in stellar mass

• The half-stellar mass

radius expands by ~45% during this ram pressure stripping event

Simpson et al. 1705.03018

Safarzadeh & Scannapieco 2017

Ram pressure is the dominant quenching mechanism

z=0.07 d=86 kpc z=0.1 d=48 kpc z=0.11 d=61 kpc z=0.14 d=118 kpc x 1.0 100 kpc z=0.2 d=207 kpc x 4.0 25 kpc x 16.0 6 kpc x 32.0 3 kpc

• This system is

~ 6.3 x 106 M⊙ in stellar mass

• The half-stellar mass

radius expands by ~45% during this ram pressure stripping event

Simpson et al. 1705.03018

Safarzadeh & Scannapieco 2017

NGC 3359 Hsyu+ 2017

−18 −16 −14 −12 −10 −8 Final MV 8.6 8.8 9.0 9.2 9.4 9.6 9.8 10.0 log(τ90/yr) 0.0 0.2 0.4 0.6 0.8 1.0 Final Distance (Mpc) 8.6 8.8 9.0 9.2 9.4 9.6 9.8 10.0 log(τ90/yr)

Observed quenching times

휏90 is the time by which 90% of a system’s stellar mass formed (data: Weisz et al. 2015)

Simpson et al. 1705.03018

Backsplash galaxies

106 107 108 109 1010 1011 Final Stellar Mass (M) 0.0 0.2 0.4 0.6 0.8 1.0 Quenched Fraction

d < R200 (276) d > R200 backsplash (165) d > R200 non-backsplash (233)

‘Backsplash’ galaxies: systems that have been within R200 in the past but not at z = 0

Simpson et al. 1705.03018

106 107 108 109 1010 1011 Final Mstar (M) 0.0 0.2 0.4 0.6 0.8 1.0 Fraction of Quenched Satellites

All (672) 0.0 - 0.3 Mpc (356) 0.3 - 0.6 Mpc (191) 0.6 - 1.0 Mpc (125)

0.0 0.2 0.4 0.6 0.8 1.0 Final Distance (Mpc) 0.0 0.2 0.4 0.6 0.8 1.0 Fraction of Quenched Satellites

All (672) 5 × 105 - 107 M (323) 107 - 108 M (203) > 108 M (146)

Conclusions

• Satellites in Auriga match

general trends found in the Local Group (numbers, quenched fractions, distance trends)

• 50% of quenched systems

do so within 1 Gyr of first infall

• Ram pressure stripping

appears to be the dominant quenching mechanism of satellites in Auriga

Weisz et al. 2015 Simpson et al. 1705.03018