snapshot (version 0.1.2)

addhead: Add header information to particle data

Description

Function to add required header information to a Gadget read particle dataframe. This has sensible defaults for a small galaxy merger style simulation

Usage

addhead(part, Npart = 2, Massarr = 0, Time = 0, z = 0, FlagSfr = 0,
FlagFeedback = 0, FlagCooling = 0, BoxSize = 0, OmegaM = 0, OmegaL = 0,
h = 1, FlagAge = 0, FlagMetals = 0, NallHW = 0, flag_entr_ics = 0)

Arguments

part

Strictly speaking 'part' is passed through the function, but to make this a useful object 'part' should be a data.frame containing the main particle level information. Columns required are: ll{ ID particle ID x x position in units of

Npart

The index on the Npart vector that should contain the particle number, where: gas [1] / collisionless particles [2:6]. The actual value is calculated based on the part data.frame provided with 'part', Nall is also calculated based on this number and not g

Massarr

The mass of the particles in the particle index provided to Npart

Time

Time of snapshot in units of km/s and kpc so 1 unit is ~10 Gyrs

z

Redshift of snapshot

FlagSfr

Star formation turned on/off

FlagFeedback

Feedback turned on/off

FlagCooling

Cooling turned on/off

BoxSize

Size of simulation box edge length in units of kpc

OmegaM

Omega matter of the simulation

OmegaL

Omega lambda of the simulation

h

Hubble constant divided by 100 used in the simulation

FlagAge

Stellar ages on/off

FlagMetals

Stellar metallacities on/off

NallHW

Tell Gadget to use large integers in the particle index provided to Npart- not usually necessary

flag_entr_ics

Entropy for gas on/off

Value

• part
  Strictly speaking 'part' is passed through the function, but to make this a useful object 'part' should be a data.frame containing the main particle level information. Assuming 'part' has been given a sensible input, columns provided are: ll{ ID particle ID x x position in units of Mpc y y position in units of Mpc z z position in units of Mpc vx x velocity in units of km/s vy y velocity in units of km/s vz z velocity in units of km/s Mass particle mass in units of Msun }
• head
  A list containing various header information as list elements. These are: ll{ Npart Vector of length 6 containing the number of particles in this snapshot file, where: gas [1] / collisionless particles [2:6] Massarr Vector of length 6 containing the particle masses for the respective particle types in Npart Time Time of snapshot in units of km/s and kpc so 1 unit is ~10 Gyrs z Redshift of snapshot FlagSfr Star formation turned on/off Nall Vector of length 6 containing the number of particles in all snapshot files, where: gas [1] / collisionless particles [2:6] FlagFeedback Feedback turned on/off FlagCooling Cooling turned on/off NumFiles Number of files per snapshot- usually 1 BoxSize Size of simulation box edge length in units of kpc OmegaM Omega matter of the simulation OmegaL Omega lambda of the simulation h Hubble constant divided by 100 used in the simulation FlagAge Stellar ages on/off FlagMetals Stellar metallacities on/off NallHW Tell Gadget to use large integers for the respective particle types in Npart - not usually necessary flag_entr_ics Entropy for gas on/off }

Details

Nall is calculated based on Npart, and therfore it cannot be specified via an input argument. This increases the likelihood that a legal Gadget header will be produced.

See Also

snapwrite,snapread,genparam

Examples

tempadd=addhead(temp$part)