Describing the output of COSMIC/BSE: Columns names/Values/Units

Evolutionary states of stars/binaries

Since COSMIC uses BSE as it’s core binary evolution algorithm, the output of COSMIC follows most of the same conventions as BSE. The kstar values and evolution stages are nearly identical to their BSE counterparts.

The kstar value specifies the evolutionary state of the star:

Evolutionary State of the Star

kstar

evolutionary state

0

Main Sequence (MS), < 0.7 {\mathrm{M}_\odot}

1

MS, > 0.7 {\mathrm{M}_\odot}

2

Hertzsprung Gap

3

First Giant Branch

4

Core Helium Burning

5

Early Asymptotic Giant Branch (AGB)

6

Thermally Pulsing AGB

7

Naked Helium Star MS

8

Naked Helium Star Hertzsprung Gap

9

Naked Helium Star Giant Branch

10

Helium White Dwarf

11

Carbon/Oxygen White Dwarf

12

Oxygen/Neon White Dwarf

13

Neutron Star

14

Black Hole

15

Massless Remnant

The evolutionary changes of the binary are logged in the evol_type column, which is filled with integer values. The key for each integer is listed below:

Evolve Type

evol_type

evolutionary change

1

initial state

2

kstar change

3

begin Roche lobe overflow

4

end Roche lobe overflow

5

contact

6

coalescence

7

begin common envelope

8

end common envelope

9

no remnant leftover

10

max evolution time

11

binary disruption

12

begin symbiotic phase

13

end symbiotic phase

14

blue straggler

15

supernova of primary

16

supernova of secondary

100

RLOF interpolation timeout error

bpp

This pandas.DataFrame tracks a selection of binary parameters at key evolutionary changes. Entries are added with changes in the Evolve Type. All values with a _1 label refer to the primary (i.e., the initially more massive component); the bpp DataFrame also includes the same column for the secondary with _1 replaced by _2

tphys

Evolution time [{\rm{Myr}}]

mass_1

Primary mass [{\mathrm{M}_\odot}]

kstar_1

Evolutionary state of primary (see Evolutionary State of the Star)

sep

Semimajor axis [{\mathrm{R}_\odot}]

porb

Orbital period [{\rm{days}}]

ecc

Eccentricity

RRLO_1

Primary radius in units of Roche lobe radii

evol_type

Key moment in evolution (see Evolve Type)

aj_1

Effective age of the primary [{\rm{Myr}}]

tms_1

Primary main sequence lifetime [{\rm{Myr}}]

massc_1

Primary core mass [{\mathrm{M}_\odot}]

rad_1

Primary radius [{\mathrm{R}_\odot}]

mass0_1

Previous epoch mass [{\mathrm{M}_\odot}]

lum_1

Luminosity of the primary [{\mathrm{L}_\odot}]

teff_1

Effective temperature of the primary [{\mathrm{K}}]

radc_1

Primary core radius [{\mathrm{R}_\odot}]

menv_1

Mass of the envelope of the primary [{\mathrm{M}_\odot}]

renv_1

Radius of the envelope of the primary [{\mathrm{R}_\odot}]

omega_spin_1

Angular velocity of the primary [{\rm{yr}}^{-1}]

B_1

Neutron star magnetic field [{\rm{G}}]

bacc_1

(only for pulsars) \delta{\mathrm{M}_\odot} during accretion, see Equation 7 in COSMIC paper

tacc_1

Accretion duration (used for magnetic field decay) [{\rm{Myr}}]

epoch_1

Time spent in current evolutionary epoch [{\rm{Myr}}]

bhspin_1

Black hole spin magnitude [dimensionless]

bin_num

Unique binary index that is consistent across initial conditions, bcm, bpp, and kick_info DataFrames

bcm

This pandas.DataFrame provides several binary parameters at user-specified timesteps in the evolution. By default, COSMIC saves only the first and last timestep in the bcm DataFrame. All values with a _1 label refer to the primary; the bcm DataFrame also includes the same column for the secondary with _1 replaced by _2

tphys

Evolution time [\rm{Myr}]

kstar_1

Evolutionary state of primary (see Evolutionary State of the Star)

mass0_1

Previous evolutionary stage primary mass [{\mathrm{M}_\odot}]

mass_1

Primary mass [{\mathrm{M}_\odot}]

lumin_1

Primary luminosity [{\mathrm{L}_\odot}]

rad_1

Primary radius [{\mathrm{R}_\odot}]

teff_1

Primary effective temperature [{\rm{K}}]

massc_1

Primary core mass [{\mathrm{M}_\odot}]

radc_1

Primary core radius [{\mathrm{R}_\odot}]

menv_1

Primary envelope mass [{\mathrm{M}_\odot}]

renv_1

Primary envelope radius [{\mathrm{R}_\odot}]

epoch_1

Primary epoch [\rm{Myr}]

omega_spin_1

Primary spin [\rm{rad/yr}]

deltam_1

Primary mass transfer rate [{\mathrm{M}_\odot/\rm{yr}}]

RRLO_1

Primary radius in units of Roche lobe radii

porb

Orbital period [\rm{days}]

sep

Semimajor axis [\mathrm{R}_{\odot}]

ecc

Eccentricity

B_1

Neutron star magnetic field [{\rm{G}}]

SN_1

Supernova type:

1: Iron core-collapse supernova

2: Electron capture supernova

3: Ultra-stripped supernova (these happen whenever a He-star undergoes a common envelope with a compact companion)

4: Accretion induced collapse supernova

5: Merger induced collapse

6: Pulsational pair instability

7: Pair instability supernova

bin_state

State of the binary: 0 [binary], 1 [merged], 2 [disrupted]

merger_type

String of the kstar’s in the merger. For example, two neutron stars that merged will be ‘1313’. Set to ‘-001’ if binary has not merged.

bin_num

Unique binary index that is consistent across initial conditions, bcm. bpp, and kick_info DataFrames

kick_info

kick_info is a (2,17) array that tracks information about supernova kicks. This allows us to track the total change to the systemic velocity and the total change in the orbital plane tilt after both supernovae, as well as reproduce systems. The first row contains information about the first supernova that occurs, the second row the second supernova. Note that some values the second row will take into account the effect of the first SN (e.g., kick_info[2,10] is the total systemic velocity after both supernovae).

kick_info[i,1]: star

whether the exploding star is the primary (1) or secondary (2)

kick_info[i,2]: disrupted

whether the system was disrupted from the SN (0=no, 1=yes)

kick_info[i,3]: natal_kick

magnitude of the natal kick [{\rm{km/s}}]

kick_info[i,4]: phi

polar angle of explosion (in the frame of the exploding star) [{\rm{degrees}}]

kick_info[i,5]: theta

azimuthal angle of explosion (in the frame of the exploding star) [{\rm{degrees}}]

kick_info[i,6]: mean anomaly

mean anomaly at time of explosion [{\rm{degrees}}]

kick_info[i,7]: delta_vsysx_1

change in 3D systemic velocity of the binary, or the change in 3D velocity of star=1 if the system is disrupted (x-component)

kick_info[i,8]: delta_vsysy_1

change in 3D systemic velocity of the binary, or the change in 3D velocity of star=1 if the system is disrupted (y-component)

kick_info[i,9]: delta_vsysz_1

change in 3D systemic velocity of the binary, or the change in 3D velocity of star=1 if the system is disrupted (z-component)

kick_info[i,10]: vsys_1_total

magnitude of systemic velocity of the binary if bound, or magnitude of total velocity of star=1 if disrupted, accounting for both SNe

kick_info[i,11]: delta_vsysx_2

change in 3D velocity of the star=2 if system is disrupted (x-component)

kick_info[i,12]: delta_vsysy_2

change in 3D velocity of the star=2 if system is disrupted (y-component)

kick_info[i,13]: delta_vsysz_2

change in 3D velocity of the star=2 if system is disrupted (z-component)

kick_info[i,14]: vsys_2_total

magnitude of velocity of star=2 if disrupted, accounting for both SNe [{\rm{km/s}}]

kick_info[i,15]: delta_theta_total

angular change in orbital plane due to supernovae, relative to the pre-SN1 orbital plane [{\rm{degrees}}]

kick_info[i,16]: omega

azimuthal angle of the orbital plane w.r.t. spins [{\rm{degrees}}]

kick_info[i,17]: randomseed

random seed at the start of call to kick.f