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Sink particles
The block named &SINK_PARAMS
contains the parameters related to the sink particle implementation, which can be used for
- star formation (most recently Bleuler & Teyssier 2015)
- supermassive black hole evolution and AGN feedback (most recently Biernacki, Teyssier and Bleuler 2017)
Overview of parameters
Variable name | Fortran type | Default value | Description |
---|---|---|---|
smbh |
boolean |
.false. |
Controls if sink behaves as a star or SMBH |
agn |
boolean |
.false. |
Controls if SMBH sink produces feedback |
create_sinks |
boolean |
.false. |
Specifies if sinks are formed with clump finder |
nsinkmax |
integer |
2000 |
Maximum number of sinks allowed to form |
mass_sink_direct_force |
float |
-1 |
Mass in Msun above which sinks are treated with direct N-body solver |
ir_cloud |
integer |
4 |
Radius of cloud region in unit of grid spacing |
ir_cloud_massive |
integer |
3 |
Radius of massive cloud region in unit of grid spacing |
sink_soft |
integer |
2 |
Gravitational softening length in dx at levelmax for "direct force" sinks |
n_sink |
float |
.false. |
Sink (as a star) formation density threshold in H/cc |
rho_sink |
float |
.false. |
Sink (as a star) formation density threshold in g/cc |
d_sink |
float |
.false. |
Sink (as a star) formation density threshold in code units |
clump_core |
boolean |
.false. |
Trims the clump (for sinks as stars only) |
mass_sink_seed |
float |
0.0 |
Dynamical mass of sink seed in Msun |
mass_smbh_seed |
float |
0.0 |
Accretion mass of sink seed in Msun, if 0, then dynamical and accretion masses are equivalent |
mass_halo_AGN |
float |
1e10 |
Mass of a halo in which AGN sinks are seeded |
mass_clump_AGN |
float |
1e10 |
Mass of a clump in which AGN sinks are seeded |
accretion_scheme |
string |
none |
Accretion scheme: none, bondi |
eddington_limit |
boolean |
.false. |
Controls if accretion rate should be limited by Eddington rate |
acc_sink_boost |
float |
1 |
Value of boost factor in Bondi velocity (-1 to depend on density) |
boost_threshold_density |
float |
0.1 |
Threshold density for boosting, typically the same as n_star; in H/cc |
bondi_use_vrel |
boolean |
.false. |
Excludes relative velocity between gas and sink from the accretion calculations |
mass_merger_vel_check_AGN |
float |
-1 |
Mass above which the check for two sinks' binding energy is applied, in Msun |
merging_timescale |
float |
-1 |
Time during which sinks are considered for merging (non-SMBH only) |
verbose_AGN |
boolean |
.false. |
Controls verbosity of AGN in the log file |
AGN_fbk_mode_switch_threshold |
float |
0.1 |
Controls the AGN feedback switching |
AGN_fbk_frac_ener |
float |
1.0 |
Controls what fraction of energy goes into thermal feedback |
T2_min |
float |
1e7 |
Minimum temperature to which AGN blast should heat the gas in K |
T2_AGN |
float |
1e12 |
Temperature of AGN blasts in K - feedback efficiency |
AGN_fbk_frac_mom |
float |
1.0 |
Controls what fraction of energy goes into kinetic feedback |
epsilon_kin |
float |
1.0 |
Kinetic feedback coupling efficiency |
kin_mass_loading |
float |
100. |
Kinetic feedback mass loading |
cone_opening |
float |
180. |
Opening angle of the cone through which momentum feedback proceeds |
Example set of parameters for cosmological simulations with AGN feedback
The example listed below by no means can fit everyone's needs, but can serve as a minimum starting example.
#!fortran &SINK_PARAMS ! General switches smbh=.true. ! turns sinks into SMBH agn=.true. ! enables AGN feedback create_sinks=.true. ! enables formation of new sink particles mass_sink_direct_force=1.0 ! minimum mass of sink to treat it with direct solver, in M_sun ! Seeding masses mass_sink_seed=1.0d6 ! dynamical mass of sink particle mass_smbh_seed=1.0d6 ! accretion mass of sink particle mass_halo_AGN=5.d10 ! minimum mass of PHEW halo in which a sink is seeded mass_clump_AGN=1.d9 ! minimum mass of PHEW clump in which a sink is seeded ! Accretion accretion_scheme='bondi' ! selects Bondi accretion as accretion mode eddington_limit=.true. ! enables Eddington limit on accretion acc_sink_boost=-1 ! boosts accretion according to Booth&Schaye 2009 boost_threshold_density=0.1 ! threshold density for boosting, typically the same as n_star; in H/cc bondi_use_vrel=.false. ! excludes relative velocity between gas and sink from the accretion calculations ! Merging mass_merger_vel_check=1e8 ! sum of sinks' masses for which velocities are checked upon merging to determine if the system is bound ! Feedback T2_min=0 ! if feedback can heat the gas to this temperature then deposit it; here deposits at every fine step T2_AGN=0.15d12 ! thermal feedback efficiency AGN_fbk_frac_ener=1.0 ! controls what fraction of energy goes into thermal feedback, here 100% AGN_fbk_frac_mom=0.0 ! controls what fraction of energy goes into momentum feedback, here 0% AGN_fbk_mode_switch_threshold=1d-2 ! switches between thermal (above) and momentum modes for this ratio of Bondi-to-Eddington epsilon_kin=1. ! momentum feedback efficiency kin_mass_loading=100. ! mass loading factor of momentum feedback cone_opening=90. ! opening angle of the cone in which momentum feedback is deposited (180. means full sphere) /
Notes:
- if
agn=.false.
all feedback settings are disregarded - in order to seed the sink both
mass_halo_AGN
andmass_clump_AGN
have to be satisfied (as well as condition of only one sink per halo and minimum density of the halo - at least star forming) - currently the only other accretion mode besides
bondi
isnone
; please feel free to add more - to not boost accretion, set
acc_sink_boost=0.0
- it is highly advised to use
T2_min=0.0
in order to have all feedback modes on the finest timestep - if
chi_switch=0.0
, then the initial values ofAGN_fbk_frac_*
will be used throughout the simulation
Updated