Data Products

Halo catalogs and Merger Trees

The folder Rockstar/CAMELS-SAM/LH_???/Rockstar contains the CAMELS-SAM Rockstar halo catalogs for each simulation. The format of the catalogs is the default of the code, and we refer the user to the Rockstar documentation for further details. Due to storage limitations, we have kept just the out_??.list files and all ROCKSTAR configuration files that were used to run it. Additional files are stored on long-term magnetic tape; please contact the CAMELS team to discuss accessing them.

We also release the merger trees constructed through ConsistentTrees, tree_?_?_?.dat’ for each subvolume created in the simulation within ``Rockstar/CAMELS-SAM/LH_???/ConsistentTrees`. We refer the reader to the consistent trees documentation for details on the format of the files. The SC-SAM can be rerun with new parameters upon these trees.

The Santa Cruz SAM for galaxy formation

We use the Santa Cruz semi-analytic model (SAM) for galaxy formation (Somerville et al. 2008, 2015, 2021) to robustly populate our large N-body simulations with galaxies. SAMs can be thought of an alternative to full hydrodynamic simulations, which apply simplified empirical recipes for physical processes of galaxy formation and evolution within dark matter halo ‘merger trees’ (e.g. from ConsistentTrees our of ROCKSTAR). Like numerical simulations, SAMs include free parameters that are calibrated to galaxy observations (e.g. Yung et al. 2019 for the local universe). The SC-SAM pipeline used in this work is nearly identical to that applied to IllustrisTNG300 in Gabrielpillai et al. (2021); see their work for complete justification and verification for the fiducial set up.

A note: the SC-SAM that was run for CAMELS-SAM did not store the averaged SFR properties for the galaxies, due to our particular needs and priorities, so all those will be equal to zero.

Click to expand/collapse this table describing the SC-SAM *galaxy* outputs at each redshift

Field

Shape

Units

Description

GalpropBirthHaloID

N

ID of host halo from Haloprop

GalpropHaloIndex

N

Index of host halo in Haloprop (recommend usage: when loading whole subvolumes)

GalpropHaloIndex_Snapshot

N

Index of host halo in Haloprop (recommended usage: when loading snapshots)

GalpropMBH

N

10^9 M☉

Black hole mass

GalpropMH2

N

10^9 M☉

Molecular hydrogen cold gas mass

GalpropMHI

N

10^9 M☉

Neutral hydrogen cold gas mass

GalpropMHII

N

10^9 M☉

Singly ionized hydrogen cold gas mass

GalpropMaccdot

N

M☉ / yr

accretion rate onto black hole

GalpropMaccdot_radio

N

M☉ / yr

accretion rate onto black hole in radio mode

GalpropMbulge

N

10^9 M☉

Stellar mass of the bulge

GalpropMcold

N

10^9 M☉

Total cold gas mass

GalpropMvir

N

10^9 M☉

Total dark matter halo mass

GalpropMstar

N

10^9 M☉

Total stellar mass

GalpropMstar_merge

N

10^9 M☉

Stellar mass entering via mergers

GalpropMstrip

N

10^9 M☉

Stripped mass of DM sub-halo |

GalpropMu_merger

N

mass ratio of last merger (see S08)

GalpropOutflowRate_Mass

N

M☉ / yr

rate of outflowing gas from ISM

GalpropOutflowRate_Metal

N

M☉ / yr

rate of outflowing metals from ISM

GalpropPos

N, 3

cMpc

x, y, and z coordinates

GalpropRbulge

N

kpc

3D half-mass Radius of bulge

GalpropRdisk

N

kpc

3D half-mass Radius of disk

GalpropRedshift

N

redshift

GalpropRfric

N

Mpc

distance from halo center

GalpropRhalo

N

Mpc

halo virial radius

GalpropRootHaloID

N

ID of root halo at z = 0 from Haloprop

GalpropSatType

N

0 = central

GalpropSfr

N

M☉ / yr

instantaneous SFR

GalpropSfrave100myr

N

M☉ / yr

SFR averaged over 100 Myr

GalpropSfrave1gyr

N

M☉ / yr

SFR averaged over 1 Gyr

GalpropSfrave20myr

N

M☉ / yr

SFR averaged over 20 Myr

GalpropSigmaBulge

N

km / s

velocity dispersion of bulge

GalpropTmerger

N

Gyr

time since last merger

GalpropTmerger_major

N

Gyr

time since last major merger

GalpropTsat

N

Gyr

time since galaxy became a satellite in this halo

GalpropVdisk

N

km / s

rotation velocity of disk

GalpropVel

N, 3

km / s

x, y, and z components of velocity

GalpropZcold

N

Z☉ * M☉

metal mass in cold gas

GalpropZstar

N

Z☉ * M☉

metal mass in stars


Click to expand/collapse this table describing the SC-SAM *halo* outputs at each redshift

Field

Shape

Units

Description

HalopropC_nfw

N

NFW concentration parameter for DM halo

HalopropHaloID

N

Halo ID given by Consistent-Trees

HalopropIndex

N

Index of halo in the file (recommended usage: when loading whole subvolumes)

HalopropIndex_Snapshot

N

Index of halo in file (recommended usage: when loading snapshots)

HalopropMaccdot_metal

N

M☉ / Z☉ / yr

accretion rate of metals into the halo

HalopropMaccdot_pristine

N

M☉ / yr

accretion rate of pristine gas into the halo

HalopropMaccdot_radio

N

M☉ / yr

accretion rate onto the BH in radio mode

HalopropMaccdot_reaccreate

N

M☉ / yr

accretion rate of “recycled” gas

HalopropMaccdot_reaccreate_metal

N

M☉ / Z☉ / yr

accretion rate of “recycled” metals

HalopropMass_ejected

N

10^9 M☉

total gas mass in “ejected” reservoir

HalopropMcooldot

N

10^9 M☉ / yr

rate of gas cooling/accretion from halo into ISM

HalopropMdot_eject

N

M☉ / yr

rate of ejection of gas from halo

HalopropMdot_eject_metal

N

M☉ / Z☉ / yr

rate of ejection of metals from halo

HalopropMetal_eject

N

Z☉ / yr

total mass of metals in “ejected” reservoir

HalopropMhot

N

10^9 M☉

mass of hot (CGM) gas in halo

HalopropMstar_diffuse

N

10^9 M☉

mass of stars in a diffuse stellar halo (from disrupted satellites)

HalopropMvir

N

10^9 M☉

halo virial mass

HalopropRedshift

N

redshift

HalopropRockstarHaloID

N

Halo ID from the Rockstar run

HalopropRootHaloID

N

Halo ID of the root halo for this merger tree

HalopropSnapNum

N

snapshot file number

HalopropSpin

N

N

spin of DM halo

HalopropSubfindID_DMO

N

Subfind index in TNG DMO simulation of bijective match

HalopropSubfindID_FP

N

Subfind index in TNG FP simulation of bijective match

HalopropZhot

N

10^9 M☉ / Z☉

metal mass in hot halo (CGM)


Identifying each simulation’s parameters

Within each of these data product directories and within each simulation’s folder exists the file CosmoAstro_params.txt. This file includes the exact values of the cosmological and astrophysical parameters that created each CAMELS-SAM N-body simulation and halo/galaxy catalogs. There are six numbers listed, which are:

  1. \(\Omega_{M}\)
    The true value of \(\Omega_{M}\) of the given simulation.
  2. \(\sigma_{8}\)
    The true value of \(\sigma_{8}\) of the given simulation.
  3. \(A_{\rm SN1} \times 1.7\) for SC-SAM
    The value given to the SC-SAM for the \(\epsilon_{\rm SN0}\) free parameter, which is equal to the prefactor \(A_{\rm SN1}\) times 1.7 (the best-fit fiducial value for this SC-SAM free amplitude parameter for local observations.) \(A_{\rm SN1}\) was generated log-uniformly between 0.25 and 4.0.
  4. \(A_{\rm SN2} + 3.0\) for SC-SAM
    The value given to the SC-SAM for the \(\alpha_{\rm rh}\) free parameter, which is equal to the prefactor \(A_{\rm SN2}\) plus 3.0 (the best-fit fiducial value for this SC-SAM free power law slope for local observations.) \(A_{\rm SN2}\) was generated uniformly between -2.0 and 2.0.
  5. \(A_{\rm AGN} \times 0.002\) for SC-SAM
    The value given to the SC-SAM for the \(\kappa_{\rm radio}\) free parameter, which is equal to the prefactor \(A_{\rm AGN}\) times 0.002 (the best-fit fiducial value for this SC-SAM free amplitude parameter for local observations.) \(A_{\rm AGN}\) was generated log-uniformly between 0.25 and 4.0.
  6. 0.005
    This is an unused parameter in CAMELS-SAM for \(\epsilon_{\rm wind, QSO}\) from the SC-SAM. This was originally meant to be the analogous to \(A_{\rm AGN2}\) in CAMELS, but the iteration of the SC-SAM used in this work showed little to no response to varying this parameter beyond its fiducial value.