Harrison+17 (KMOS, $z=1$)

Spiral galaxies $\leftrightarrow$ high $J_\star$: also at high-$z$

$M_\star, J_\star,M_\mathrm{BH}$, morpho, bulge fraction, …

What causes what?

Galaxy formation in cosmology: the role of the environment

Environmental effects:

• source of “pollution” in weak lensing surveys
  ⇒ intrinsic alignment
   
• extra parameters in semi-analytical models
  ⇒ galaxy-halo correlation

Mediated by angular momentum?

$z=0$

$z = 100$

$$\mathbf{L}_\mathrm{lin.} \propto \int\mathrm{d}^3q(\mathbf{q}-\bar{\mathbf{q}})\times \nabla\phi$$

[White 84]

$z=0$

$z = 100$

[Porciani+02]

$z=0$

$z = 100$

[Genetic modifications: Roth+16, see also Rey&Pontzen 18, Stopyra+20]

Predicting angular momentum

Predicting angular momentum

• Angular momentum of individual regions can be predicted accurately.
• AM of halos ⇒ requires boundaries of patch

[On patch boundaries: see Lucie-Smith+18]

Can we control baryonic
angular momentum?

Wechsler & Tinker 18

${\color{red}M_\star} / M_\mathrm{h} \ll \Omega_b / \Omega_m$
⇒ baryons & DM stem from different regions

• AM of stars originates from initial conditions…
• can be controlled…
• $j_\star$ regulate galaxy disk, bulge, $v/\sigma$, $R_{1/2}$
• Negligible AGN/SN global self-regulation

The effect of environment on halo properties

Conclusion & outlook

• angular momentum is predictable
   

• boundary of halos in the ICs is a hard problem
  ⇒ limits practicality of predictions (for now)
   

• baryons can be controlled!
  ⇒ weak lensing predictions easier than expected?
  ⇒ role in setting morphology
   

• environmental effects can have dramatic impact on halo formation
  ⇒ 50% of concentration scatter due to env.
  ⇒ similar impact on galaxy formation?

Conclusion & outlook

Questions?

More infos in Cadiou+21a,b,c (2012.02201, 2107.03407, 2110.05384)

• angular momentum is predictable
   

• boundary of halos in the ICs is a hard problem
  ⇒ limits practicality of predictions (for now)
   

• baryons can be controlled!
  ⇒ weak lensing predictions easier than expected?
  ⇒ role in setting morphology
   

• environmental effects can have dramatic impact on halo formation
  ⇒ 50% of concentration scatter due to env.
  ⇒ similar impact on galaxy formation?

$l_0 \times 1.2$

$l_0 \times 1.5$

$l_0 \times 0.66$

$l_0 \times 0.8$