Review of
Binary Population Synthesis
Silvia Toonen - toonen@strw.leidenuniv.nl
Simon Portegies Zwart, Gijs Nelemans
Joke Claeys, Nicki Mennekens, Ashley Ruiter
March 26th 2014
donderdag 27 maart 2014
Outline
✤
Review of binary population synthesis (BPS)
✤
✤
Including applications of CE-studies
Population synthesis comparison (PopCORN)
donderdag 27 maart 2014
BPS approach:
✤
Simulate the evolution of a large number of binaries
✤
From ZAMS to remnant formation (or any desired evolutionary phase)
✤
At each timestep for each binary take into account relevant physics,
e.g. processes as stellar winds, mass transfer (stability), mass accretion,
angular momentum loss, tidal evolution
✤
Folding with:
✤ Initial distribution of:
✤ mass of (primary stars)
✤ mass ratio
✤ orbital separation
✤ eccentricity
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Binary evolution
✤
✤
✤
✤
✤
✤
✤
✤
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Stellar evolution
Stellar winds
Stellar dynamics
Stability of mass transfer
Physics of mass transfer
Mass loss and accretion
Angular momentum loss
✤ mass loss
✤ gravitational waves
✤ magnetic braking
Tidal effects
Stellar and binary evolution
✤
✤
✤
✤
✤
✤
✤
✤
donderdag 27 maart 2014
Stellar evolution
Stellar winds
Stellar dynamics
Stability of mass transfer
Physics of mass transfer
Mass loss and accretion
Angular momentum loss
✤ mass loss
✤ gravitational waves
✤ magnetic braking
Tidal effects
Stellar and binary evolution
✤
✤
✤
✤
✤
✤
✤
✤
donderdag 27 maart 2014
Stellar evolution
Stellar winds
Stellar dynamics
Stability of mass transfer
Physics of mass transfer
Mass loss and accretion
Angular momentum loss
✤ mass loss
✤ gravitational waves
✤ magnetic braking
Tidal effects
Stellar and binary evolution
✤
✤
✤
✤
✤
✤
✤
✤
donderdag 27 maart 2014
Stellar evolution
Stellar winds
Stellar dynamics
Stability of mass transfer
Physics of mass transfer
Mass loss and accretion
Angular momentum loss
✤ Mass loss
✤ Gravitational waves
✤ Magnetic braking
Tidal effects
BPS approach:
✤
✤
✤
✤
Simulate the evolution of a large number of binaries
From ZAMS to remnant formation (or any desired evolutionary phase)
At each timestep for each binary take into account relevant physics,
e.g. processes as stellar winds, mass transfer (stability), mass accretion,
angular momentum loss, tidal evolution
Folding with:
✤ Initial distribution of:
✤ mass of primary star
✤ mass ratio
✤ orbital separation
✤ eccentricity
✤ Star formation history
donderdag 27 maart 2014
:
s
t
n
e
i
BPS approach: ingred
S
P
B
✤
✤
✤
✤
Simulate the evolution of a large number of binaries
From ZAMS to remnant formation (or any desired evolutionary phase
At each timestep for each binary take into account relevant physics,
e.g. processes as stellar winds, mass transfer (stability), mass
accretion, angular momentum loss, tidal evolution
Folding with:
✤ Initial distribution of: M1, M2, a, e
✤ mass of primary star
✤ mass ratio
✤ orbital separation
✤ eccentricity
✤ Star formation history
donderdag 27 maart 2014
Binary population synthesis codes
✤
Rapid calculation:
✤ Not feasible to use a detailed code for BPS
✤ Simplifying assumptions (e.g. straightforward prescriptions for the
stability and rate of mass transfer)
donderdag 27 maart 2014
Binary population synthesis
✤
Study e.g.
✤ characteristics of a binary population (e.g. mass ratio distribution,
period distribution)
✤ frequency of an astrophysical event
✤ chemical enrichment of a region
✤
because
✤ study the effect of uncertain phases of evolution on macroscopic
properties of binary populations
✤ study evolutionary phases that cannot be studied yet in much
detail
donderdag 27 maart 2014
Binary population synthesis
✤
Study e.g.
✤ characteristics of a binary population (e.g. mass ratio distribution,
period distribution)
✤ frequency of an astrophysical event
✤ chemical enrichment of a region
✤
because
✤ study the effect of uncertain phases of evolution on macroscopic
properties of binary populations
✤ study evolutionary phases that cannot be studied yet in much
detail
donderdag 27 maart 2014
Binary population synthesis
Separation (Rsun)
WD+MS
M1,wd (Msun)
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Binary population synthesis
✤
WD+MS
Initial population WDMS
M1,zams (Msun)
Separation (Rsun)
Separation (Rsun)
progenitors of WD+MS
M1,wd (Msun)
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Binary population synthesis
✤
WD+MS
Initial population WDMS
M1,zams (Msun)
Separation (Rsun)
Separation (Rsun)
progenitors of WD+MS
No interaction
Stable mass transfer
Common-Envelope
M1,wd (Msun)
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Binary population synthesis
✤
WD+MS
Initial population WDMS
M1,zams (Msun)
No contact
MS donor
HG donor
GB donor
AGB donor
Separation (Rsun)
Separation (Rsun)
progenitors of WD+MS
M1,wd (Msun)
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Populations under investigation
Supernova type Ia progenitors
See next slides
Double white dwarfs
Iben et al. 1997, Han 1998, Nelemans et al. 2001, Toonen et
al. 2012
AM CVn
Tutukov & Yungelson 1996, Nelemans et al. 2001
White dwarf - main sequence
de Kool & Ritter 1993, Willems & Kolb 2004, Politano &
Weiler 2007, Davis et al. 2009, Toonen & Nelemans 2013
Cataclysmic variables
de Kool 1992, Kolb 1993, Kolb & Stehle 1996, Howell et al.
2001, Podsiadlowski et al 2003, Willems et al. 2007, Davis et
al. 2008
SdB stars
Han et al 2002, 2003, Yungelson & Tutukov 2005, Nelemans
2010, Chen et al. 2013
Gravitational wave sources
Lipunov et al 1987, Portegies Zwart & Spreeuw 1996,
Nelemans et al. 2001, Belczynski et al. 2002, Voss & Tauris
2003, Dewi et al. 2006, O’Shaughnessy et al. 2008, Dominik
et al. 2012, 2013, see also: Abadie et al. 2010 for a review
Chemically peculiar stars
e.g. de Kool & Green 1995, Izzard et al. 2009, 2010, Pols et
al. 2012, Abate et al. 2013
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Double white dwarfs
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Double white dwarfs
✤
Observed double white dwarf population
α-CE
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1.3.1
α-formalism
Common-envelope evolution
The classical ce prescription dates back to 1976 [Paczynski, 1976] and st
servation of energy while it implicitly assumes conservation of angular m
binding energy of the ce is equated with a fraction α of the change o
energy between the initial and final state of the binary. When the differ
energy equals the binding energy of the common envelope, the latter i
equations:
α-CE (Webbink 1984)
✤ based on energy balance
∆Ebind = α∆Eorb
! GM m GM m "
GMg Me
c
g
=α
−
λRg
2af
2ai
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The subscripts g, e and c refer to giant, envelope and core respectively; m
γ-CE
(Nelemans et al. 2000, van der Sluys et al
companion mass which is 2006)
assumed not to vary during the common enve
and af are the initial and final
separation of the binary. Here λ is a struct
✤ based on angular momentum
of the envelope and is in general taken to be a constant, e.g. λ = 0.5. T
balance
stems from the fact that it takes too much time and computing power t
∆J
∆M
tot
binding energy of every binary individually
and
into detail during a popul
=γ
(in which millions of binaries may Jneed to M
betot
simulated). The uncertaint
into one parameter, the product αλ.
Double white dwarfs
✤
✤
Mass ratio distribution is better reproduced by modelling with γ-CE
However, stable non-conservative mass transfer might work as well
(Woods et al. 2012)
α-CE
γ-CE
ref: Nelemans et al. 2001, Toonen et al. 2012
donderdag 27 maart 2014
Post-common-envelope binaries
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Post-common-envelope binaries
✤
White dwarf main-sequence binaries
✤
✤
SDSS - homogeneously selected post-common-envelope binaries
(PCEBs)
✤
✤
Detached & close
Rebassa-Mansergas et al. 2007; Nebot Gómez-Morán et al. 2011, Zorotovic et al. 2011.
Observed period distribution: few hours - few days
✤
BPS codes predict periods up to hundreds of days
donderdag 27 maart 2014
Post-common-envelope binaries
g-r
donderdag 27 maart 2014
r-i
g-r
Selection effects - Which systems are visible ?
u-g
✤
r-i
i-z
Post-common-envelope binaries
r-i
g-r
donderdag 27 maart 2014
i-z
r-i
g-r
u-g
g-r
r-i
g-r
Selection effects - Which systems are visible ?
u-g
✤
r-i
i-z
Post-common-envelope binaries
Period (d)
Mwd (Msun)
donderdag 27 maart 2014
γ-CE
Period (d)
α-CE
Mwd (Msun)
Post-common-envelope binaries
γ-CE
Period (d)
Period (d)
Period (d)
α-CE
Mwd (Msun)
Mwd (Msun)
Mwd (Msun)
ref: Toonen & Nelemans 2013
donderdag 27 maart 2014
α-CE
with low CE-efficiency
Overview
Progenitors
Orbit
CE-prescription
DWDs
first phase of mass
transfer
DWDs
second phase of mass
transfer
Modest
widening
γ-CE (γ ≈1.75)
Modest
contraction
PCEBs
Strong
contraction
CV
Strong
contraction
(Nelemans ea 2000, 2001, but
see also Woods ea 2012)
α-CE (αλ ≈2)
(Nelemans ea 2000, 2001)
α-CE (αλ ≈0.25)
(Zorotovic ea 2010, this work *)
α-CE (αλ =0.45±0.17)
(Portegies Zwart 2013)
Mass ratio
at start of mass
transfer
q≈1
q ≈ 0.2 − 0.5
q ≈ 0.2 − 0.5
q ≈ 0.3
ref: Toonen & Nelemans 2013
donderdag 27 maart 2014
De Marco et al. 2011
Overview
✤
α decreases with
Progenitors
Orbit
CE-prescription
DWDs
first phase of mass
transfer
DWDs
second phase of mass
transfer
Modest
widening
γ-CE (γ ≈1.75)
Modest
contraction
PCEBs
Strong
contraction
CV
Strong
contraction
q = Ma /Md
(Nelemans ea 2000, 2001, but
see also Woods ea 2012)
α-CE (αλ ≈2)
(Nelemans ea 2000, 2001)
α-CE (αλ ≈0.25)
(Zorotovic ea 2010, this work *)
α-CE (αλ =0.45±0.17)
(Portegies Zwart 2013)
Mass ratio
at start of mass
transfer
q≈1
q ≈ 0.2 − 0.5
q ≈ 0.2 − 0.5
q ≈ 0.3
ref: Toonen & Nelemans 2013
donderdag 27 maart 2014
Supernova Type Ia progenitors
donderdag 27 maart 2014
Supernova Type Ia progenitors
✤
BPS studies:
✤
Yungelson et al. 1994
Han et al. 1995
Jorgensen et al. 1997
Yungelson & Livio 2000
Nelemans et al. 2001
DeDonder & Vanbeveren 2004
Han & Podsiadlowski 2004
Yungelson 2005
Bogomazov & Tutukov 2009
Meng et al. 2009
Ruiter et al. 2009
Wang et al. 2009 (2x)
Claeys et al. 2010
Meng & Yang 2010 (3x)
Mennekens et al. 2010
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
donderdag 27 maart 2014
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
Wang et al. 2010
Wang & Han 2010 (2x)
Yungelson 2010
Bogomazov & Tutukov 2011
Meng et al. 2011
Ruiter et al. 2011
Chen et al. 2012
Meng & Yang 2012
Toonen et al. 2012
Bours et al. 2013
Claeys et al. 2013
Mennekens et al. 2013
Ruiter et al. 2013
Wang et al. 2013
Ruiter et al. 2014
Supernova Type Ia progenitors
Progenitor systems:
✤
Single degenerate channel
(Whelan & Iben ’73)
donderdag 27 maart 2014
✤
Double degenerate channel
(Iben & Tutukov ’84, Webbink ’84)
%:S
/A0"
&/
)
8#/.#03/0
Supernova Type Ia progenitors
SNIa
rate (#/Msun/yr)
,00.-
dashed line single degenerate channel
solid line double degenerate channel
Review:
Wang & Han 2012
,.Delay
time (Myr)
ref: Nelemans, Toonen, Bours 2011
donderdag 27 maart 2014
Theoretical uncertainties
from BPS:
Claeys et al. 2014
Retention efficiency of
mass accretion
Retention efficiency
Based on Nomoto et al. 2007
Based on Ruiter et al. 2009
Based on Yungelson et al. 2010
Mass accretion rate (Msun/yr)
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Retention efficiency of
mass accretion
Retention efficiency
stable burning
wind
novae
Mass accretion rate (Msun/yr)
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Based on Nomoto et al. 2007
Based on Ruiter et al. 2009
Based on Yungelson et al. 2010
Based on Nomoto et al. 2007
Based on Ruiter et al. 2009
Based on Yungelson et al. 2010
SNIa rate (#/Msun/yr)
Retention efficiency of
mass accretion
ref: Bours, Toonen, Nelemans 2013
donderdag 27 maart 2014
Delay time (Myr)
Populations under investigation
Supernova type Ia progenitors
Double white dwarfs
mass accretion, merger
common-envelope, stable mass transfer
AM CVn
stable mass transfer
White dwarf - main sequence
common-envelope
Cataclysmic variables
magnetic braking, stable mass transfer
SdB stars
common-envelope, stable mass transfer
Gravitational wave sources
Chemically peculiar stars e.g. barium
stars, carbon enhanced metal poor stars
donderdag 27 maart 2014
evolution of massive stars
(wind) accretion, circularization
Population synthesis comparison
(PopCORN)
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Population synthesis comparison
(PopCORN)
Are different results caused by
accuracy or assumptions?
donderdag 27 maart 2014
PopCORN
Binary population synthesis
codes:
✤ Binary_c (Izzard et al. 2004, 2006,
2009, Claeys et al. 2014. Based on Hurley
et al.2000 & 2002)
✤
Brussels code (De Donder & Van
Beveren et al. 2004, Mennekens et al.
2010 )
✤
SeBa (Portegies Zwart & Verbunt 1996,
Nelemans et al. 2001, Toonen et al. 2012,
2013)
✤
StarTrack (Belczynski et al. 2008,
Ruiter et al. 2009)
ref: Toonen et al. 2014
donderdag 27 maart 2014
PopCORN
Binary population synthesis
codes:
✤ Binary_c (Izzard et al. 2004, 2006,
Most simple comparison:
✤
✤
Equalize assumptions where possible
Study inherent differences in codes
2009, Claeys et al. 2014. Based on Hurley
et al.2000 & 2002)
✤
✤
Brussels code (De Donder & Van
Focus on two populations:
Beveren et al. 2004, Mennekens et al.
2010 )
✤
Single white dwarf + non-degenerate
companion
✤
Double white dwarf systems
SeBa (Portegies Zwart & Verbunt 1996,
Nelemans et al. 2001, Toonen et al. 2012,
2013)
✤
StarTrack (Belczynski et al. 2008,
Ruiter et al. 2009)
ref: Toonen et al. 2014
donderdag 27 maart 2014
WD + non-degenerate companion
SeBa
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
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StarTrack
WD + non-degenerate companion
SeBa
StarTrack
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
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No interaction
Common-Envelope
Stable mass transfer
WD + non-degenerate companion
SeBa
StarTrack
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
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No interaction
Common-Envelope
Stable mass transfer
WD + non-degenerate companion
SeBa
StarTrack
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
donderdag 27 maart 2014
No interaction
Common-Envelope
Stable mass transfer
Brussels code
SeBa
StarTrack
log a (Rsun)
log a (Rsun)
Binary_c
Mwd (Msun)
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Mwd (Msun)
(for M1,i > 3 Msun)
Brussels code
SeBa
StarTrack
log a (Rsun)
log a (Rsun)
Binary_c
(for M1,i > 3 Msun)
No contact
CommonEnvelope
Stable mass
transfer
Mwd (Msun)
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Mwd (Msun)
Double white dwarfs
SeBa
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
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StarTrack
Double white dwarfs
SeBa
StarTrack
log a (Rsun)
Binary_c
Mwd (Msun)
Similar simulated populations
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No interaction
RLOF
Single-degenerate
Popcorn
✤
When input assumptions are equalized: different BPS
codes give similar populations.
✤
Differences are not caused by numerical differences, but
can be explained by differences in the input physics
donderdag 27 maart 2014
ref: Toonen, Claeys, Mennekens, Ruiter 2014
Popcorn
see also: www.astro.ru.nl/~silviato/popcorn
Small differences due to input physics:
Inherent to the codes:
✤ Initial-Final mass relation
✤ Stability criterion
✤ Survival of mass transfer
✤ He star evolution
donderdag 27 maart 2014
ref: Toonen, Claeys, Mennekens, Ruiter 2014
Popcorn
see also: www.astro.ru.nl/~silviato/popcorn
Small differences due to input physics:
Inherent to the codes:
✤ Initial-Final mass relation
✤ Stability criterion
✤ Survival of mass transfer
✤ He star evolution
donderdag 27 maart 2014
Assumptions of this study:
✤ Same initial distributions (primary
mass, mass ratio, separation)
✤ Conservative mass transfer to all
types of stars
✤ Common envelope evolution
prescription
✤ No tides, magnetic braking, wind
accretion, eccentricities
www.amusecode.org
✤
✤
AMUSE - Astrophysical Multipurpose Software Environment
✤
software framework astrophysical simulations,
✤
existing codes from different domains (stellar dynamics, stellar evolution,
hydrodynamics and radiative transfer)
✤
easy coupling between the codes
BPS codes
✤
✤
✤
BSE (Hurley et al. 2000 & 2002)
SeBa (Portegies Zwart & Verbunt 1996, Nelemans et al. 2001, Toonen et al. 2012, 2013)
Stellar evolution codes
✤
fast: SSE (Hurley et al. 2000), SeBa
✤
detailed: EVtwin (Eggleton 1971, 1972, 1973, Glebbeek et al. 2008), MESA (Paxton et al. 2010)
donderdag 27 maart 2014
Future
✤
Observations
Large-scale surveys as the SDSS and Gaia
• Gravitational wave astronomy with advanced LIGO
•
✤
Computationally
Mix of BPS and detailed stellar evolution codes (Wang, Han)
• Triples (Hamers et al. 2013)
•
donderdag 27 maart 2014
Conclusion
✤
Binary population synthesis
Differences in BPS results are not caused by numerical effects, but by different
assumptions of input physics
• Large-scale surveys as the SDSS and Gaia will be providing unprecedented large
and homogeneously selected sample of binaries
•
✤
Common-envelope evolution
1st (CE)-phase in DWDs progenitors leads to a modest widening of the orbit
• 2nd CE-phase in DWDs progenitors leads to a modest contraction of the orbit
• CE-phase in PCEB progenitors leads to a strong contraction of the orbit
•
donderdag 27 maart 2014
Questions?
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Populations under investigation
Supernova type Ia progenitors
See previous slide
Double white dwarfs
Iben et al. 1997, Han 1998, Nelemans et al. 2001, Toonen et
al. 2012
AM CVn
Tutukov & Yungelson 1996, Nelemans et al. 2001
White dwarf - main sequence
de Kool & Ritter 1993, Willems & Kolb 2004, Politano &
Weiler 2007, Davis et al. 2009, Toonen & Nelemans 2013
Cataclysmic variables
de Kool 1992, Kolb 1993, Kolb & Stehle 1996, Howell et al.
2001, Podsiadlowski et al 2003, Willems et al. 2007, Davis et
al. 2008
SdB stars
Han et al 2002, 2003, Yungelson & Tutukov 2005, Nelemans
2010, Chen et al. 2013
Gravitational wave sources
Lipunov et al 1987, Portegies Zwart & Spreeuw 1996,
Nelemans et al. 2001, Belczynski et al. 2002, Voss & Tauris
2003, Dewi et al. 2006, O’Shaughnessy et al. 2008, Dominik
et al. 2012, 2013, see also: Abadie et al. 2010 for a review
Chemically peculiar stars
e.g. de Kool & Green 1995, Izzard et al. 2009, 2010, Pols et
al. 2012, Abate et al. 2013
donderdag 27 maart 2014
Binary population synthesis codes
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
✤
In alphabetical order:
Binary_c/nucsyn (Izzard et al. 2004, 2006, 2009, Claeys et al. 2013, based on Hurley et al. 2000, 2002
Brussels code (De Donder & Vanbeveren 2004, Mennekens et al. 2010)
BSE (Hurley et al. 2000, 2002)
Eggleton’s BPS code (Eggleton 1989)
Han’s BPS code (Han et al 1995, Han et al. 2003)
Moe’s BPS code (Moe & De Marco 2006)
Pols’s BPS code (Pols & Marinus 1994)
Scenario Machine (Kornilov & Lupinov 1983, Lupinov et al 2007)
SeBa (Portegies Zwart & Verbunt 1996, Nelemans et al. 2001, Toonen et al. 2012, 2013)
Startrack (Belczynski et al. 2008, Ruiter et al. 2009)
Tutukov & Yungelson’s BPS code (Tutukov & Yungelson 1992, 2002, Yungelson & Tutukov
2005, Yungelson 2010)
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Supernova Type Ia progenitors
donderdag 27 maart 2014
Binding energy
FIGURE 2. Two-dimensional histogram displaying λenv versus M1 for primary stars at the onset of a CE. Darker pixels indicate
more donors in the bin, as indicated by the legend at the left. See Sect. 4.2 for more details. Note that the pattern looks like a λ !
4.2. The envelope-structure
ref:parameter
Van derλenv
Sluys
donderdag 27 maart 2014
et al. 2010
In population-synthesis codes, where the evolution of millions of binaries must be computed, detailed stellar-