Quenching Timescales or, why the green valley is a red herring Kevin Schawinski Institute for Astronomy ETH Zurich ETH black hole group @kevinschawinski (our coffee is radio-loud)
the star formation main sequence log SFR main sequence log stellar mass
the star formation main sequence main sequence log SFR log stellar mass
the star formation main sequence main sequence log SFR log stellar mass
the star formation main sequence log SFR main sequence log stellar mass
the star formation main sequence log SFR main sequence dead galaxies log stellar mass
Quenching time scales ⟺ what happens to the gas Galaxies are on the MS because inflows and outflows balance (Bouche+10,Lilly+13)
Quenching time scales ⟺ what happens to the gas Galaxies are on the MS because inflows and outflows balance (Bouche+10,Lilly+13) gas inflow gas outflow gas reservoir
Quenching time scales ⟺ what happens to the gas Galaxies are on the MS because inflows and outflows balance (Bouche+10,Lilly+13) gas inflow gas outflow gas reservoir
Quenching time scales ⟺ what happens to the gas Galaxies are on the MS because inflows and outflows balance (Bouche+10,Lilly+13) gas inflow gas outflow gas reservoir Once you are no longer connected to cosmic supply of gas... � SFR = ε M gas / τ dyn � > SFR(t) ~ exponential with long tau (~Gyr)
Quenching time scales ⟺ what happens to the gas Galaxies are on the MS because inflows and outflows balance (Bouche+10,Lilly+13) gas inflow gas outflow gas reservoir Once you are no longer connected to cosmic supply of gas... � SFR = ε M gas / τ dyn � > SFR(t) ~ exponential with long tau (~Gyr)
All galaxies Early-type galaxies 3.0 3.0 3.0 3.0 3.0 2.5 2.5 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 1.0 9.0 9.0 9.0 9.5 9.5 9.5 10.0 10.0 10.0 10.5 10.5 10.5 11.0 11.0 11.0 11.5 11.5 11.5 9.0 9.5 10.0 10.5 11.0 11.5 Late-type galaxies 3.0 3.0 3.0 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour Data 2.0 2.0 2.0 SDSS DR7 Galaxy Zoo 1 morphologies 1.5 1.5 1.5 GALEX GR6 MPA-JHU masses & SFRs OSSY emission lines 1.0 1.0 1.0 9.0 9.0 9.0 9.0 9.5 9.5 9.5 9.5 10.0 10.0 10.0 10.0 10.5 10.5 10.5 10.5 11.0 11.0 11.0 11.0 11.5 11.5 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
All galaxies Early-type galaxies 3.0 3.0 3.0 3.0 3.0 2.5 2.5 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 1.0 9.0 9.0 9.0 9.5 9.5 9.5 10.0 10.0 10.0 10.5 10.5 10.5 11.0 11.0 11.0 11.5 11.5 11.5 9.0 9.5 10.0 10.5 11.0 11.5 Late-type galaxies 3.0 3.0 3.0 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour Data 2.0 2.0 2.0 SDSS DR7 Galaxy Zoo 1 morphologies 1.5 1.5 1.5 GALEX GR6 MPA-JHU masses & SFRs OSSY emission lines 1.0 1.0 1.0 9.0 9.0 9.0 9.0 9.5 9.5 9.5 9.5 10.0 10.0 10.0 10.0 10.5 10.5 10.5 10.5 11.0 11.0 11.0 11.0 11.5 11.5 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
All galaxies Early-type galaxies 3.0 3.0 3.0 3.0 3.0 2.5 2.5 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 1.0 9.0 9.0 9.0 9.5 9.5 9.5 10.0 10.0 10.0 10.5 10.5 10.5 11.0 11.0 11.0 11.5 11.5 11.5 9.0 9.5 10.0 10.5 11.0 11.5 Late-type galaxies 3.0 3.0 3.0 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.5 0.0 u-r colour 0.0 u-r colour Data 2.0 2.0 2.0 SDSS DR7 Galaxy Zoo 1 morphologies 1.5 1.5 1.5 GALEX GR6 MPA-JHU masses & SFRs OSSY emission lines 1.0 1.0 1.0 9.0 9.0 9.0 9.0 9.5 9.5 9.5 9.5 10.0 10.0 10.0 10.0 10.5 10.5 10.5 10.5 11.0 11.0 11.0 11.0 11.5 11.5 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
dust-corrected colours! All galaxies Early-type galaxies 3.0 3.0 3.0 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) 2.5 2.5 2.5 2.5 2.5 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.5 9.0 9.0 9.0 9.5 9.5 9.5 10.0 10.0 10.0 10.5 10.5 10.5 11.0 11.0 11.0 11.5 11.5 11.5 9.0 9.5 10.0 10.5 11.0 11.5 Late-type galaxies 3.0 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.5 Data 2.0 2.0 2.0 SDSS DR7 1.5 1.5 1.5 Galaxy Zoo 1 morphologies GALEX GR6 1.0 1.0 1.0 MPA-JHU masses & SFRs OSSY emission lines 0.5 0.5 0.5 9.0 9.0 9.0 9.0 9.5 9.5 9.5 9.5 10.0 10.0 10.0 10.0 10.5 10.5 10.5 10.5 11.0 11.0 11.0 11.0 11.5 11.5 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
dust-corrected colours! All galaxies Early-type galaxies 3.0 3.0 3.0 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) 2.5 2.5 2.5 2.5 2.5 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.5 9.0 9.0 9.0 9.5 9.5 9.5 10.0 10.0 10.0 10.5 10.5 10.5 11.0 11.0 11.0 11.5 11.5 11.5 9.0 9.5 10.0 10.5 11.0 11.5 Late-type galaxies 3.0 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.5 Data 2.0 2.0 2.0 SDSS DR7 1.5 1.5 1.5 Galaxy Zoo 1 morphologies GALEX GR6 1.0 1.0 1.0 MPA-JHU masses & SFRs OSSY emission lines 0.5 0.5 0.5 9.0 9.0 9.0 9.0 9.5 9.5 9.5 9.5 10.0 10.0 10.0 10.0 10.5 10.5 10.5 10.5 11.0 11.0 11.0 11.0 11.5 11.5 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
All galaxies Early-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Late-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.0 2.0 sSFRs in the Green valley: 1.5 1.5 Both early- and late-types show same low sSFR 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
All galaxies Early-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Late-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.0 2.0 sSFRs in the Green valley: 1.5 1.5 Both early- and late-types show same low sSFR 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
All galaxies Early-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Late-type galaxies 3.0 3.0 0.0 u-r colour (dust corrected) 0.0 u-r colour (dust corrected) Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • ) 2.5 2.5 2.0 2.0 sSFRs in the Green valley: 1.5 1.5 Both early- and late-types show same low sSFR 1.0 1.0 0.5 9.0 9.0 9.5 9.5 10.0 10.0 10.5 10.5 11.0 11.0 11.5 11.5 Stellar Mass log M * (M O Stellar Mass log M * (M O • ) • )
Measure* d/dt sSFR(t) of green valley galaxies * really, broadly constrain
UV-optical colours constrain d/dt sSFR(t) 5 5 NUV-u colour (dust-corr.) All Galaxies Early-type Galaxies Green Valley Early-types Green Valley Early-types 4 4 Green Valley Late-types 3 3 2 2 1 1 0 0 -1 NUV-u colour (dust-corr.) Late-type Galaxies 0.5 1.0 1.5 2.0 2.5 Green Valley Late-types u-r colour (dust-corr.) 4 star formation rate 3 t quench τ quench =1 Myr 250 Myr 1 Gyr 2 2.5 Gyr 1 0 8 8 9 9 10 10 11 11 12 12 13 13 Time (Gyr) Time (Gyr) 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 2.5 2.5 3.0 3.0 u-r colour (dust-corr.)
UV-optical colours constrain d/dt sSFR(t) 5 5 NUV-u colour (dust-corr.) All Galaxies Early-type Galaxies Green Valley Early-types Green Valley Early-types 4 4 Green Valley Late-types 3 3 2 2 1 1 0 0 -1 NUV-u colour (dust-corr.) Late-type Galaxies 0.5 1.0 1.5 2.0 2.5 Green Valley Late-types u-r colour (dust-corr.) 4 star formation rate 3 t quench τ quench =1 Myr 250 Myr 1 Gyr 2 2.5 Gyr 1 0 8 8 9 9 10 10 11 11 12 12 13 13 Time (Gyr) Time (Gyr) 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 2.5 2.5 3.0 3.0 u-r colour (dust-corr.)
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