Corentin Cadiou @ Heidelberg 2024

Postdoc @ Lund University
Soon “Chargé de recherche ”CNRS @ IAP, Paris

Modelling of high-\(z\) emission lines & kinematics

Today's talk, in a nutshell

(My) route to high-\(z\) kinematics

Effect of cosmo. env. (Musso+19, Kraljic+20,21, Cadiou+21, Storck+24)
Cosmology-galaxy connection (Cadiou+21)
Cosmological accretion (Cadiou+19, Kocjan+24)
But what are we actually observing? This talk

Low grav. tides

Large grav. tides

cosmological environment \(\sim 50-100\,\mathrm{Mpc}\)
resolve Strömgren spheres \(\sim 10\,\mathrm{pc}\)
radiative-transfer
proper multi-phase ISM \(T \lesssim 10^4\,\mathrm{K}\)
Track ion abundances out-of-equilibrium

Wishlist for proper modelling of emission lines + kinematics

Background: Vintage Gordon (follow-up of Vintergatan) simulation
(PI: Cadiou)

\(t_\mathrm{chem} \propto 1/n^2\)

\(t_\mathrm{dyn} \propto 1/\sqrt{n}\)

\(t_\mathrm{burst} \sim 10-100\,\mathrm{Myr}\)

How we typically model emission lines

Lots of assumptions

(equilibrium, geometry, element abundances, …)

See Aniket's talk (I guess?)

\(\rho, T, Z,v\)
sometimes \(n_\mathrm{H}, n_{\mathrm{HI}}, n_\mathrm{HeI}, n_\mathrm{HeII},n_\mathrm{HeIII},\)

Processes that control ion and molecular properties:

Collisional, photo, cosmic-ray ionization
Radiative, dielectronic, dust recombination
Charge exchange

RAMSES-RTZ + PRISM: Non-equilibrium chemistry coupled to on-the-fly radiative transfer

Processes that control gas temperature:

Cosmic-ray, photo, photo-electric, H2, dust heating
Primordial, \(\mathrm{H}_2\), CO, metal, dust* recombination, dust-gas collisional cooling
Adiabatic (expansion), shocks (e.g. SN, turbulence), gravitational, etc.

Image: Cadiou/Katz/Rey+in prep

Model [i]

Based on RAMSES-RT (Rosdahl+13)
Out-of-equilibrium chemistry (Katz 23)
Primordial species: \(\text{H~{\small I}-{\small II}}\), \(\text{He~{\small I}-{\small III}}\), \(e^{-}\)
Metal ions: \(\text{C~{\small I}-{\small VI}}\), \(\text{N~{\small I}-{\small VII}}\), \(\text{O~{\small I}-{\small VIII}}\), \(\text{Ne~{\small I}-{\small X}}\), \(\text{Mg~{\small I}-{\small X}}\), \(\text{Si~{\small I}-{\small XI}}\), \(\text{S~{\small I}-{\small XI}}\) & \(\text{Fe~{\small I}-{\small XI}} \)
Molecules: \(\text{H}_2\) & \(\text{CO}\)
Dust model (Rémy-Ruyer+14)
Assuming dust-to-gass ratio
Heating & Cooling
photoheating, photoelectric heating, excitation/dissociation heating, primordial, dust recombination, dust-gas collisions, metal lines
- \(\text{C~{\small I}}\), \(\text{C~{\small II}}\), \(\text{N~{\small II}}\), \(\text{O~{\small I}}\), \(\text{O~{\small III}}\), \(\text{Ne~{\small II}}\), \(\text{Si~{\small I}}\), \(\text{Si~{\small II}}\), \(\text{S~{\small I}}\), \(\text{Fe~{\small I}}\), \(\text{Fe~{\small II}}\) @ \(T<10^4\,\mathrm{K}\)
- CLOUDY tables @ \(T>10^4\,\mathrm{K}\)

\(\text{O\small{II}}\)

\(\text{O\small{I}}\)

\(\text{N\small{I}}\)

\(\text{Mg\small{II}}\)

\(\text{Ne\small{II}}\)

\(\text{CO}\)

\(\rho\)

\(v_r\)

\(\text{O\small{III}}\)

Model [ii]

Turbulence-based star formation (Padoan & Nordlund 11, Agertz+21)
\(\dot{\rho_\star} = \varepsilon_\star\rho/t_\mathrm{ff}\)
- if \(Z<10^{-6}Z_\odot\) ⇒ Pop. III
- if \(Z\geq10^{-6}Z_\odot\) ⇒ Pop. I & II, Kroupa
\(M_\star = 500\,\mathrm{M}_\odot\)
\(M_{\star,\rm III} \sim 100\,\mathrm{M}_\odot\)
Feedback (Agertz+21; Rey+23)
core-collapse SN, type Ia, winds + HN (Nomoto+06).
Yields (Limongi & Chieffi 18)
AGB winds (Ritter+18)

Model [iii]

MW analogue @ \(z=0\)
Genetically engineered to form earlier
ICs generated with genetIC
2 main runs
- constant physical \(\Delta x_\mathrm{min} \approx 20-40\,\mathrm{pc}\)
- constant comoving \(\Delta x_\mathrm{min}(z=2) = 20\,\mathrm{pc}\)
  \(\Delta x_\mathrm{min}(z=5)=10\,\mathrm{pc}\)
  \(\Delta x_\mathrm{min}(z=14)=4\,\mathrm{pc}\)

fiducial:
few JWST targets

early-forming:
many targets

\(z>8\)

Early forming MW mass galaxy
\(1.6\times 10^{4}\mathrm{M}_\odot\) DM, \(500\, \mathrm{M}_\odot\) Pop. II stars, individual Pop III stars, \(1\, \mathrm{pc}\) resolution at first star formation
IMF sampled chemical enrichment from individual stars for all relevant elements
SN (CC, Ia, HN, PISN), Winds → follows Vintergatan (validated for MW galaxies at z = 0)
82 species chemistry coupled to 8 bin RT
PRISM ISM model
Enhanced resolution in the CGM
Calibration sims with IMF variations and physical model variations

Introducing MEGATRON

Halo-mass—stellar-mass relation

VG: Vintergatan (Agertz+21)
⇒ Well-regulated by \(z=0\)

High-resolution early \(<1\mathrm{pc}\)

Constant resolution \(\sim 20\,\mathrm{pc}\)

Most massive galaxy, edge-on

Most massive galaxy, face-on

Difference \([\mathrm{C{\small{II}}}]\)-weighted vs. \(n_\mathrm{H}\)-weighted

Early results

Stacked profiles

36 galaxies @ \(z=10\)

\(8.3\leq\log(M_\star/\mathrm{M}_\odot)\leq 10.0\)

⚠️ PRELIMINARY ⚠️

Only gas within \(\pm0.5\,\mathrm{kpc}\) height

All gas

Random discussion points:

“All simulations are wrong, but some are useful”
George “Simulation” Box

How should the complex kinematics be modelled at high-\(z\)?
Non-axisymmetric structures → tilted rings not valid? What about inflows/outflows/extra-planar motions?
Do we really need out-of-equilibrium thermochemistry?
If we do in simulation, probably also required in observation
Likely \(z\) dependent (stay tuned!)
How can we help observers and vice versa?
Fairly easy to generate density/velocity maps, but what's needed?