1. Satellite Quenching and Structural Change
Joanna Woo
ETH Zürich
With
M. Carollo
S. Faber
A. Dekel
S. Tacchella
Et al.

2. What we know about quenching so far
Studies in quenching reveal correlations between:
Morphology and quenching

3. What we know about quenching so far
Studies in quenching reveal correlations between:
Morphology and quenching
Morphology and environment

4. What we know about quenching so far
Studies in quenching reveal correlations between:
Morphology and quenching
Morphology and environment
Environment (Mhalo) and quenching
Σ1kpc
Woo et al. (2015)
Mhalo

5. What we know about quenching so far
Studies in quenching reveal correlations between:
Morphology and quenching
Environment (Mhalo) and quenching
Morphology and environment
Question: Does the halo environment
induce morphological/structural change
during satellite quenching?

6. Satellites vs. the Field
Structure/Morphology
- light within circular annuli in 5 bands → M/L (KCORRECT)
- PSFWIDTH < 1kpc
- strongest predictor of quenching → physical scale of mechanism?
Brinchmann et al., (2004)
Entire distribution contains more information than quenched fraction (Woo et al., 2015)

7. Satellites vs. the Field
Woo et al., in preparation

8. Woo et al., in preparation

9. All Masses
Woo et al., in preparation

10. All Masses
Woo et al., in preparation

11. Satellite Quenching Depends on Environment
Woo et al., (2013)

12. Satellite Quenching vs. Environment
Woo et al., in preparation

15. Difficulties with Interpretation: Progenitors
Mass growth after quenching (accretion cut-off)
Cold gas content needs to be significant: high z
High-z progenitors from a lower mass bin will be quenched by now
Mass loss after quenching
Stellar aging and death
For satellites: stripping of mass can be significant
Timing of infall vs quenching
Degeneracy between assembly history of haloes and actual physical quenching
In light of these difficulties, what can we learn about structural change during quenching?

16. Does the Halo Environment Induce Structural Change During Satellite Quenching?
Assumption: GV galaxies are currently quenching and are drawn from the SF population
Currently quenching satellites: drawn from the whole range of Σ1kpc
Currently quenching field galaxies: drawn only from the highest tip of Σ1kpc
Thus the answer seems to be “No” for currently quenching satellites.

17. Physical Mechanisms Current satellite quenching: Independent of Σ1kpc
Driven by massive halo, not group- centric distance
Candidates:
Starvation due to stripping of hot gas or cut-off of accretion
Ram pressure stripping of cold gas

18. Physical Mechanisms Less massive haloes:
less likely to experience ram pressure or starvation; can be affected by tides
Tidally triggered starburst?
But SFR not enhanced
Tidal compression?
But not enough time at pericentre
These do not quench satellites, only change structure
Complete disruption?
But ratios seems not to have changed.

19. Summary of Findings Possible Interpretation
GV “bridge” for satellites has lower Σ1kpc
Main sequence (and quenched seq.) of satellites is lower than the field
Differences between field and satellites disappears at high M*
Differences driven mainly by high Mh
Group-centric distance affects Σ1kpc distribution of SF satellites in low- mass haloes
Currently quenching satellites quench at all Σ1kpc in contrast to currently quenching isolated galaxies
Very little to no change in structure during quenching
Satellite quenching in massive haloes: ram pressure or starvation
Tidal processes: only in less massive haloes, probably don't quench
Possible Interpretation