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Parameters

In the version of RAMSES after RUM 2017 (PR #284 and after), new blocks were introduced instead of one large &PHYSICS_PARAMS:

Parameters#

Cooling parameters#

The block named &COOLING_PARAMS contains the parameters related to cooling / basic chemistry

Variable name

Fortran type

Default value

Description

cooling

boolean

.false.

Enable gas atomic & metal cooling

metal

logical

.false.

Enable metals advection (requires 1 hydro variable)

isothermal

logical

.false.

(deprecated) Enable equation of state for gas (heating and cooling disabled if .true.)

barotropic_eos

logical

.false.

Enable barotropic equation of state for gas (heating and cooling disabled if .true.). Replaced ‘isothermal’

barotropic_eos_form

string

legacy

Type of barotropic EOS. Options: isothermal, polytrope, double_polytrope, custom, legacy

polytrope_rho

real

1.0d50

sets rho0 in EOS (density normalisation or knee-density), in g/cm3

polytrope_index

real

1.0d0

sets gamma in EOS (polytropic index)

T_eos

real

10

sets T0 in EOS (isothermal temperature or temperature normalisation), in K

mu_gas

real

1d0

molecular weight

haardt_madau

logical

.false.

Enable UV background

J21

real

0.0

UV flux at threshold in 10^21 units

a_spec

real

1.0

Slope of the UV spectrum

self_shielding

logical

.false.

Enable self-shielding for densities above 0.01 g.cm^-3

z_ave

real

0.0

Initial average metal abundance

z_reion

real

8.5

Reionization redshift (UV background disabled for higher redshifts)

ind_rsink

real

4.0

Number of cells defining the radius of the sphere where AGN feedback is active

T2max

real

HUGE

Temperature ceiling for gas heating (heating ceiling if isothermal=.false.)

neq_chem

logical

.false.

Enable non-equilibrium chemistry

Star formation parameters#

The block named &SF_PARAMS contains the parameters related to star formation

Variable name

Fortran type

Default value

Description

m_star

real

-1.0

Star particle mass in units of mass_sph

n_star

real

0.1

Star formation density threshold in H/cc

T2_star

real

0.0

Typical ISM polytropic temperature (cooling floor if isothermal=.false.)

g_star

real

1.6

Typical ISM polytropic index (cooling floor if isothermal=.false.)

del_star

real

2D2

Star formation density threshold in critical density (cosmo=.true. only)

eps_star

real

0.0

Star formation efficiency

jeans_ncells

real

-1.0

Jeans polytropic equation of state (cooling floor if isothermal=.false.)

sf_virial

logical

.false.

Enable turbulent star formation prescriptions (requires 1 hydro variable)

sf_trelax

real

0.0

Relaxation time for star formation (cosmo=.false. only)

sf_tdiss

real

0.0

Dissipation timescale for subgrid turbulence in units of turbulent crossing time (sf_virial=.true. only)

sf_model

integer

3

Turbulent star formation model (sf_virial=.true. only)

sf_log_properties

logical

.false.

Output gas properties of cells undergoing a star particle birth or supernova event

sf_compressive

logical

.false.

Store and advect the compressive and solenoidal turbulent field in two different hydro variables (sf_virial=.true. only)

Feedback parameters#

The block named &FEEDBACK_PARAMS contains the parameters related to cooling / basic chemistry

Variable name

Fortran type

Default value

Description

eta_sn

real

0.0

Supernova mass fraction

eta_ssn

real

0.95

Single supernova ejected mass fraction (sf_imf=.true. only)

t_sne

real

10.0

Supernova blast time in Myr

delayed_cooling

logical

.false.

Enable delayed cooling through passive energy scalar advection (requires 1 hydro variable)

t_diss

real

20.0

Dissipation timescale for supernova feedback in Myr (delayed_cooling=.true. only)

yield

real

0.0

Supernova metal yield

mass_gmc

real

0.0

Stochastic exploding GMC mass in solar mass

kappa_IR

real

0.0

IR dust opacity for supernova feedback

f_ek

real

0.0

Supernova kinetic energy fraction (only between 0 and 1)

f_w

real

0.0

Supernova mass loading factor (f_ek>0 only)

rbubble

real

0.0

Supernova superbubble radius in pc (f_ek>0 only)

ndebris

integer

1

Supernova debris particle number (f_ek>0 only)

mass_star_max

real

120.0

Maximum mass of a star to undergo a supernova with eta_ssn efficiency in solar mass (sf_imf=.true. only)

mass_sne_min

real

10.0

Minimum mass of a star to undergo a supernova blast in solar mass (sf_imf=.true. only)

ir_feedback

logical

.false.

Enable IR feedback from accreting sink particles

ir_eff

real

0.75

Efficiency of the IR feedback on sink particles (ir_feedback=.true.only)

Units parameters#

The block named &UNITS_PARAMS contains the parameters related to units that are set “by hand” (cosmo=.false. only!).

Variable name

Fortran type

Default value

Description

units_density

real

1.0

Density unit in cgs (only for cosmo=.false., requires G=1)

units_time

real

1.0

Time unit in cgs (only for cosmo=.false., requires G=1)

units_length

real

1.0

Length unit in cgs (only for cosmo=.false., requires G=1)

GRACKLE parameters#

Additionally, if the code has been compiled with GRACKLE=1 in the Makefile and properly linked against the hdf5 and grackle libraries, it is possible to define a &GRACKLE_PARAMS block to control the grackle parameters. Please visit https://grackle.readthedocs.io/en/grackle-3.0/Parameters.html for a more extensive description of the grackle parameters.

Variable name

Fortran type

Default value

Description

use_grackle

integer

1

Activate Grackle

grackle_with_radiative_cooling

integer

1

Include radiative cooling

grackle_primordial_chemistry

integer

0

Primordial chemistry flag

grackle_metal_cooling

integer

0

Enable metal cooling using Cloudy tables

grackle_UVbackground

integer

0

Enable UV background

grackle_cmb_temperature_floor

integer

1

Enable effective CMB temperature floor

grackle_h2_on_dust

integer

0

Enable H2 formation on dust grains

grackle_photoelectric_heating

integer

0

Enable a spatially uniform heating term approximating photo-electric heating

grackle_use_volumetric_heating_rate

integer

0

Signal that an array of volumetric heating rates is being provided

grackle_use_specific_heating_rate

integer

0

Signal that an array of specific heating rates is being provided

grackle_three_body_rate

integer

0

Flag to control which three-body H2 formation rate is used

grackle_cie_cooling

integer

0

Enable H2 collision-induced emission cooling

grackle_h2_optical_depth_approximation

integer

0

Enable H2 cooling attenuation

grackle_ih2co

integer

1

grackle_ipiht

integer

1

grackle_NumberOfTemperatureBins

integer

600

grackle_CaseBRecombination

integer

0

grackle_Compton_xray_heating

integer

0

Flag to enable Compton heating from an X-ray background

grackle_LWbackground_sawtooth_suppression

integer

0

Flag to enable suppression of Lyman-Werner flux due to Lyman-series absorption

grackle_NumberOfDustTemperatureBins

integer

250

grackle_use_radiative_transfer

integer

0

Signal that arrays of ionization and heating rates from radiative transfer solutions are being provided

grackle_radiative_transfer_coupled_rate_solver

integer

0

Flag that must be enabled to couple the passed radiative transfer fields to the chemistry solver

grackle_radiative_transfer_intermediate_step

integer

0

Flag to enable intermediate stepping in applying radiative transfer fields to chemistry solver

grackle_radiative_transfer_hydrogen_only

integer

0

Flag to only use hydrogen ionization and heating rates from the radiative transfer solutions

grackle_self_shielding_method

integer

0

Switch to enable approximate self-shielding from the UV background

grackle_Gamma

real

5./3.

The ratio of specific heats for an ideal gas

grackle_photoelectric_heating_rate

real

8.5D-26

The heating rate in units of erg cm-3 s-1

grackle_HydrogenFractionByMass

real

0.76

grackle_DeuteriumToHydrogenRatio

real

2.0*3.4e-5

grackle_SolarMetalFractionByMass

real

0.01295

grackle_TemperatureStart

real

1.0

grackle_TemperatureEnd

real

1.0D9

grackle_DustTemperatureStart

real

1.0

grackle_DustTemperatureEnd

real

1500.

grackle_LWbackground_intensity

real

0.0

Intensity of a constant Lyman-Werner H2 photo-dissociating radiation field in units of 10-21 erg s-1 cm-2 Hz-1 sr-1

grackle_UVbackground_redshift_on

real

7.0

grackle_UVbackground_redshift_off

real

0.0

grackle_UVbackground_redshift_fullon

real

6.0

grackle_UVbackground_redshift_drop

real

0.0

grackle_cloudy_electron_fraction_factor

real

9.153959D-3

grackle_data_file

character

Path to the data file containing the metal cooling and UV background HDF5 tables

Physics parameters (LEGACY ONLY)#

The block named &PHYSICS_PARAMS contains the parameters related to physical models.

Variable name

Fortran type

Default value

Description

units_density

real

1.0

Density unit in cgs (only for cosmo=.false., requires G=1)

units_time

real

1.0

Time unit in cgs (only for cosmo=.false., requires G=1)

units_length

real

1.0

Length unit in cgs (only for cosmo=.false., requires G=1)

cooling

boolean

.false.

Enable gas atomic & metal cooling

isothermal

logical

.false.

Enable equation of state for gas (heating and cooling disabled if .true.)

metal

logical

.false.

Enable metals advection (requires 1 hydro variable)

haardt_madau

logical

.false.

Enable UV background

self_shielding

logical

.false.

Enable self-shielding for densities above 0.01 g.cm^-3

smbh

logical

.false.

Enable super massive black holes for sink particles

agn

logical

.false.

Enable AGN feedback from super massive black holes

neq_chem

logical

.false.

Enable non-equilibrium chemistry

ir_feedback

logical

.false.

Enable IR feedback from accreting sink particles

sf_virial

logical

.false.

Enable turbulent star formation prescriptions (requires 1 hydro variable)

sf_compressive

logical

.false.

Store and advect the compressive and solenoidal turbulent field in two different hydro variables (sf_virial=.true. only)

sf_log_properties

logical

.false.

Output gas properties of cells undergoing a star particle birth or supernova event

delayed_cooling

logical

.false.

Enable delayed cooling through passive energy scalar advection (requires 1 hydro variable)

sf_imf

logical

.false.

Model Initial Mass Function during thermal feedback events

T2_star

real

0.0

Typical ISM polytropic temperature (cooling floor if isothermal=.false.)

g_star

real

1.6

Typical ISM polytropic index (cooling floor if isothermal=.false.)

jeans_ncells

real

-1.0

Jeans polytropic equation of state (cooling floor if isothermal=.false.)

T2max

real

1D50

Temperature ceiling for gas heating (heating ceiling if isothermal=.false.)

n_star

real

0.1

Star formation density threshold in H/cc

m_star

real

-1.0

Star particle mass in units of mass_sph

del_star

real

2D2

Star formation density threshold in critical density (cosmo=.true. only)

eps_star

real

0.0

Star formation efficiency

t_star

real

0.0

Star formation time scale in Gyr (only used if eps_star>0)

sf_trelax

real

0.0

Relaxation time for star formation (cosmo=.false. only)

sf_tdiss

real

0.0

Dissipation timescale for subgrid turbulence in units of turbulent crossing time (sf_virial=.true. only)

sf_model

integer

3

Turbulent star formation model (sf_virial=.true. only)

eta_sn

real

0.0

Supernova mass fraction

eta_ssn

real

0.95

Single supernova ejected mass fraction (sf_imf=.true. only)

t_sne

real

10.0

Supernova blast time in Myr

t_diss

real

20.0

Dissipation timescale for supernova feedback in Myr (delayed_cooling=.true. only)

yield

real

0.0

Supernova metal yield

mass_gmc

real

0.0

Stochastic exploding GMC mass in solar mass

kappa_IR

real

0.0

IR dust opacity for supernova feedback

f_ek

real

0.0

Supernova kinetic energy fraction (only between 0 and 1)

f_w

real

0.0

Supernova mass loading factor (f_ek>0 only)

rbubble

real

0.0

Supernova superbubble radius in pc (f_ek>0 only)

ndebris

integer

1

Supernova debris particle number (f_ek>0 only)

mass_star_max

real

120.0

Maximum mass of a star to undergo a supernova with eta_ssn efficiency in solar mass (sf_imf=.true. only)

mass_sne_min

real

10.0

Minimum mass of a star to undergo a supernova blast in solar mass (sf_imf=.true. only)

J21

real

0.0

UV flux at threshold in 10^21 units

a_spec

real

1.0

Slope of the UV spectrum

z_ave

real

0.0

Initial average metal abundance

z_reion

real

8.5

Reionization redshift (UV background disabled for higher redshifts)

ind_rsink

real

4.0

Number of cells defining the radius of the sphere where AGN feedback is active

ir_eff

real

0.75

Efficiency of the IR feedback on sink particles (ir_feedback=.true.only)
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