Corentin Cadiou
CNRS Researcher
Journées Galaxies ATCG | 2026
What flows from the cosmic web into galaxies?
Left: Leclercq+17
Right: Galárraga-Espinosa+23
Bottom left: Ramsøy+21
Cosmic web: a multiscale structure
Mpc to galactic scales
Right: Peng+10
Left: Zooniverse
“Environmental” quenching
Higher density | high mass \(\rightarrow\) redder galaxies
⚠️ cannot explain morphology/orientations!
Cluster-like
Void-like
Right: Peng+10
Left: Romanowsky&Fall 12
“Environmental” quenching
Higher density | high mass \(\rightarrow\) redder galaxies
⚠️ cannot explain angular momentum!
Cluster-like
Void-like
Cosmic web: effects on scalar galaxy properties
Distance to filament changes
- color & sSFR
- rotation-support (\(v/\sigma\))
Left: Kraljic,...CC+18 (GAMA)
Right: Laigle+18 (COSMOS)
See also Kuutma+17, Malavasi+17, Alpaslan+16 or O'Kane+24
Triple effect:
- Bias halo assembly
- Feedback
- Accretion
Cosmic web: effects on halo vector properties
Small \(\perp\) alignment of halo spin/shape with filament axis
Left: Codis+18
Right: Ganeshaiah Veena+18
See e.g. Tempel+13 for measurement in observation
\(\perp\) filament
// filament
🚧 ¼ temporary conclusion 🚧
CW drives 1%-level effects?
Cosmic web: effects on halo vector properties
How can we study this?
Sample \(M\) at fixed cosmic web
or sample cosmic web at fixed \(M\)
Storck, CC+25 / Bot. right: Aragon-Calvo 15
\( \pm 20\% \)!
🚧 ½ temporary conclusion 🚧
Local CW drives 20%-level effects!*
*for DM halos
Cosmic web: effects on galactic vector properties
Small \(\perp\) alignment of halo spin with filament
Genetically modified simulations: CC+22
comical to present at “Journées ATCG”
Environment perturbed on \(>\mathrm{Mpc}\) scales
Cosmic-web-scale information trickles to galactic scale \(\Rightarrow\) what's the messenger?
🚧 ¾ temporary conclusion 🚧
Local CW drives 20%-level effects!*
*for galaxies
So… effects of the CW on galaxy formation. Is it \(\ll 1\%\) or \(\gg 20\%\)?
So… effects of the CW on galaxy formation. Is it \(\ll 1\%\) or \(\gg 20\%\)?
Talk to Sabri Errachdi for more information!
The local cosmic web \(<1\,\mathrm{Mpc}\): theory
2-3 “Cold flows” embedded in local cosmic web pancakes, feeding the galaxy
\(z=2.5, M_\star = 10^{12}\,M_\odot\); Danovich+12
The CGM cosmic web \(\lessapprox 100\,\mathrm{kpc}\): observations
Hints of detection of anisotropic extended cold emission
Excess of Ly\(\alpha\) in stacked images
\(3< z< 4\); Gallego+18
Ly\(\alpha\) radiation between quasar pairs; \( z\sim 3\); Herwig+24
Ly\(\alpha\), CIV and HeII emissions; Vayner+23
The CGM cosmic web \(\lessapprox 100\,\mathrm{kpc}\): theory
Ly\(\alpha\) is great, but hard to interpret
Other lines are great… but are we getting the right predictions?
Movies: from CC+26
Left: Mitchell, ... CC+20
Ly\(\alpha\)
H\(\alpha\)
CIII] 1906Å
[CIV] 1548Å
HeII 1640Å
The CGM cosmic web \(\lessapprox 100\,\mathrm{kpc}\): theory
Ly\(\alpha\) is great, but hard to interpret
Other lines are great… but are we getting the right predictions?
Movies: from CC+26
Left: Mitchell, ... CC+20
H\(\alpha\)
HeII 1640Å
Ly\(\alpha\)
🚧 Temporary conclusion 🚧
Predictions/interpretation of CGM obs.
may not be mature
[CIV] 1548Å
CIII] 1906Å
Connecting the cosmic web through the CGM
Effect of \(>\mathrm{Mpc}\) scale CW on galaxy well-established...
but likely massively underestimated
Corentin Cadiou — cadiou@iap.fr
How this manifest much less so. Theoretical uncertainties
remain on small-scale:
- Effect of feedback/AGNs on CW?
- Survival of cold flows?
- Observational predictions?
- Deblend from outflows?
Prospects of observation of cosmic web/CGM interface:
- VLT/BlueMUSE: \(z\sim 2-4\) (Ly\(\alpha\), CIV)
- ELT/Harmoni: \(z>3\) (Lyα, CIV, HeII, Hβ)
- ALMA: \(z\sim 2-4\) ([CII]158µm)
What flows from the CW into galaxies @ ATCG
By Corentin Cadiou
