(What) Can We Learn about the Lives & Deaths of Massive Stars from Gravitational Wave Mergers?
Floor Broekgaarden
Center for Astrophysics | Harvard & Smithsonian
Aspen 2022
@FloorAstro
Cover images credit: pngegg (diver) – LIGO/T. Pyle (GW merger) – adjusted by FB
With contributions from: Edo Berger, Simon Stevenson, Lieke van Son, Tom Wagg, Alejandro Vigna-Gomez, Martyna Chruslinska, Debatri Chattopadhyay, Ilya Mandel, Stephen Justham, Selma de Mink, Coen Neijssel, Will Farr, TEAM COMPAS, and many others
A “flipped” talk
Full pptx & PDF for accessibility available on my website
“Flipped” Talk
Flipped:
~15-20 min: talk (me + you!!)
~2 min: Quick (v. urgent) Questions (you)
15 min: ”Break out Discussion rooms” (we)
20 min: reconvene + discussion with everyone (we)
~2 min: closing�
Use your Post-it notes!
Let’s practice: How are you feeling today?
Dynamic!
(a bit) tired
Confused
Excited
Other
We are at the tipping point of entering
“The Big Data Era for NS/BH binaries”
Illustration by Jon Krause
BH-BH
NS-NS
BH-NS
We are here! ~100 detections (GWTC-3)
Figure: Baibhav+19
Cosmic Explorer Einstein Telescope
3G
2G
We are at the tipping point of entering
“The Big Data Era for NS/BH mergers:”
Floor Broekgaarden
Higher redshifts
BH/NS systems spiral in over Myr-Gyr timescales
Images credit: pngegg (diver) – NASA (GW merger) – adjusted by FB
-> GW detections probe Massive Stars throughout “Cosmic History”!
Floor Broekgaarden
Higher redshifts
BH/NS systems spiral in over Myr-Gyr timescales
Images credit: pngegg (diver) – NASA (GW merger) – adjusted by FB
-> GW detections probe Massive Stars throughout “Cosmic History”!
Floor Broekgaarden
Higher redshifts
BH/NS systems spiral in over Myr-Gyr timescales
Mix of Myr-Gyr gravitational-wave inspiral times makes GW detections unique probes to study the lives & deaths of massive stars throughout Cosmic History
LIGO,
Virgo,
KAGRA
-> GW detections probe Massive Stars throughout “Cosmic History”!
Images credit: pngegg (diver) – NASA (GW merger) – adjusted by FB
Floor Broekgaarden
Higher redshifts
BH/NS systems spiral in over Myr-Gyr timescales
Mix of Myr-Gyr gravitational-wave inspiral times makes GW detections unique probes to study the lives & deaths of massive stars throughout Cosmic History
3G GW networks (CE & ET)
3G GW networks will enable to probe mergers at higher redshift where we might observe different properties, species and/or formation channels
Images credit: pngegg (diver) – NASA (GW merger) – adjusted by FB
-> GW detections probe Massive Stars throughout “Cosmic History”!
We are at the tipping point of the “Big Data” era of GWs.
3G detectors will uniquely enable us to study the “stellar graveyard” of BHs/NSs as a function of redshift
How do these BH/NS systems form?� What can we learn from their detections?
Images credit: pngegg (diver) – LIGO/T. Pyle (GW merger) – adjusted by FB
Floor Broekgaarden
How do BH/NS mergers form?
See also review by Mandel & Broekgaarden (subm. to LRR), Mapelli (2021), Gerosa & Fishbach (2021)
Isolated Binaries
�
Population-III stars
�
Chemically homogeneous evolution
Mandel & de Mink+16, de Mink & Mandel+16, Marchant+16, Riley+16, du Buisson+16
Kinugawa+14, Belczynski+17, Hijikawa+21,Liu & Bromm+21, Tanikawa+21
Isolated Triples/Multiples�
e.g. Silsbee & Tremaine+17, Antonini+17, Rodriguez & Antonini+18, Martinez+20 Hamers & Thompson+19
Smarr & Blandford+76, Dominik+15, Kruckow+18, Artale+19,Neijssel+19, Spera+19,
Mapelli+20, Shao & Li+21
Globular Clusters
Young/Open Star Clusters
Nuclear star clusters
e.g. Clausen+13, Rodriguez+15
Antonini & Rasio+16, Askar+17, Hong+18, Kremer+20 Ye+20
e.g. Ziosi+14,Mapelli+16+20, Di Carlo+20, Kumamoto+20, Rastello+20, Santoliquido+20 Banerjee+21
e.g. Miller & Lauburg+09, Antonini & Perets+12, Petrovich & Antonini+17, Stephan+19, Arca-Sedda+20, McKernan+20
In the “field”
stars born in isolated binary/triple systems
“Dynamical”
stars born in dense stellar environments
Primordial
�
“Other”
e.g. Bird+16, Ali-Haimoud+18, Raidal+19
Floor Broekgaarden
Which channel below contributes > 20% of current GW detections?
See also review by Mandel & Broekgaarden (subm. to LRR), Mapelli (2021), Gerosa & Fishbach (2021)
Isolated Binaries
�
Population-III stars
�
Chemically homogeneous evolution
Mandel & de Mink+16, de Mink & Mandel+16, Marchant+16, Riley+16, du Buisson+16
Kinugawa+14, Belczynski+17, Hijikawa+21,Liu & Bromm+21, Tanikawa+21
Isolated Triples/Multiples�
e.g. Silsbee & Tremaine+17, Antonini+17, Rodriguez & Antonini+18, Martinez+20 Hamers & Thompson+19
Smarr & Blandford+76, Dominik+15, Kruckow+18, Artale+19,Neijssel+19, Spera+19,
Mapelli+20, Shao & Li+21
In the “field”
stars born in isolated binary/triple systems
“Dynamical”
stars born in dense stellar environments
Primordial
�
“Other”
e.g. Bird+16, Ali-Haimoud+18, Raidal+19
Globular Clusters
Young/Open Star Clusters
Nuclear star clusters
e.g. Clausen+13, Rodriguez+15
Antonini & Rasio+16, Askar+17, Hong+18, Kremer+20 Ye+20
e.g. Ziosi+14,Mapelli+16+20, Di Carlo+20, Kumamoto+20, Rastello+20, Santoliquido+20 Banerjee+21
e.g. Miller & Lauburg+09, Antonini & Perets+12, Petrovich & Antonini+17, Stephan+19, Arca-Sedda+20, McKernan+20
Floor Broekgaarden
How do BH/NS mergers form?
See also review by Mandel & Broekgaarden (subm. to LRR), Mapelli (2021), Gerosa & Fishbach (2021)
Isolated Binaries
�
Population-III stars
�
Chemically homogeneous evolution
Mandel & de Mink+16, de Mink & Mandel+16, Marchant+16, Riley+16, du Buisson+16
Kinugawa+14, Belczynski+17, Hijikawa+21,Liu & Bromm+21, Tanikawa+21
Isolated Triples/Multiples�
e.g. Silsbee & Tremaine+17, Antonini+17, Rodriguez & Antonini+18, Martinez+20 Hamers & Thompson+19
Smarr & Blandford+76, Dominik+15, Kruckow+18, Artale+19,Neijssel+19, Spera+19,
Mapelli+20, Shao & Li+21
In the “field”
stars born in isolated binary/triple systems
“Dynamical”
stars born in dense stellar environments
Primordial
�
“Other”
e.g. Bird+16, Ali-Haimoud+18, Raidal+19
Globular Clusters
Young/Open Star Clusters
Nuclear star clusters
e.g. Clausen+13, Rodriguez+15
Antonini & Rasio+16, Askar+17, Hong+18, Kremer+20 Ye+20
e.g. Ziosi+14,Mapelli+16+20, Di Carlo+20, Kumamoto+20, Rastello+20, Santoliquido+20 Banerjee+21
e.g. Miller & Lauburg+09, Antonini & Perets+12, Petrovich & Antonini+17, Stephan+19, Arca-Sedda+20, McKernan+20
Compare population synthesis simulations to observed rates and properties (masses, mass ratio) of BH/NS mergers to learn about massive stars!
Floor Broekgaarden
Does this sound familiar?
Yes!
No!
Floor Broekgaarden
What I work on lately / my message of tonight:
Gravitational waves will teach us everything!!!!
(the hope of) Population Synthesis modellers
Floor Broekgaarden
What I work on lately / my message of tonight:
Gravitational waves will teach us everything!!!!
model uncertainties
(the hope of) Population Synthesis modellers
Not so fast..
See also:
Chruslinska et al. (2019)
Belczynski et al. (2021),
the discussion in Zevin et al. (2021),
Broekgaarden et al. (2021a, 2021b)
What Can We Learn from GW Merger Rates…�
Images credit: pngegg (diver) – LIGO/T. Pyle (GW merger) – adjusted by FB
Floor Broekgaarden
1. Comparing to Observations: Merger Rates
Ping us if your paper is missing!
Publicly available code/data:
Mandel & Broekgaarden (2021) Living Review in Relativity
1. Only very few formation channels can be “ruled out”
2. Population Synthesis predicted BH/NS merger rates span enormous ranges
Floor Broekgaarden
Common envelope physics
e.g. Dominik+12, Ivanova+20, Marchant+21
Muhammad & Noam+21
Stellar Winds
e.g. Renzo+17, Vink+18a,18b
Initial conditions (e.g. IMF)
e.g. de Mink & Belczynski+15, Klencki+17
Fraction of Binaries
e.g. Sana+12, Moe & di Stefano+17,
Stellar tracks of Massive Stars
e.g. Laplace+20, Agrawal+20
Supernova kicks
e.g. Belczynski & Bulik+99, Shao & Li+18
Pair instability Supernovae
e.g. Farmer+19, Marchant+19, Stevenson+19
Electron-capture supernovae
e.g. Giacobbo & Mapelli+18
AGN disk density and lifetime
e.g. Mckernan+19
Sampling (Poisson) uncertainties
e.g. Andrews+19, Broekgaarden+19
Initial cluster properties
e.g. Fragione & Kocsis+18
Ultra-stripped supernovae?
e.g. Tauris+15, Mandel & Muller+20
Mass transfer stability criteria
e.g. Soberman+97 , Ge+05, Claeys+14
Depth of convective envelope
e.g. Klencki+20
Over Contact Binaries?
e.g. Marchant+16, du Buisson+20, Riley+20
Expansion of Pop III stars
e.g. Marigo+01, Kinugawa+21
Escape velocities cluster
e.g. Rodriguez+18,19, Gerosa&Fishbach+21
What are key uncertainties in population synthesis?
Floor Broekgaarden
Floor Broekgaarden
Common envelope physics
e.g. Dominik+12, Ivanova+20, Marchant+21
Muhammad & Noam+21
Stellar Winds
e.g. Renzo+17, Vink+18a,18b
Initial conditions (e.g. IMF)
e.g. de Mink & Belczynski+15, Klencki+17
Fraction of Binaries
e.g. Sana+12, Moe & di Stefano+17,
Stellar tracks of Massive Stars
e.g. Laplace+20, Agrawal+20
Supernova kicks
e.g. Belczynski & Bulik+99, Shao & Li+18
Pair instability Supernovae
e.g. Farmer+19, Marchant+19, Stevenson+19
Electron-capture supernovae
e.g. Giacobbo & Mapelli+18
AGN disk density and lifetime
e.g. Mckernan+19
Sampling (Poisson) uncertainties
e.g. Andrews+19, Broekgaarden+19
Initial cluster properties
e.g. Fragione & Kocsis+18
Ultra-stripped supernovae?
e.g. Tauris+15, Mandel & Muller+20
Mass transfer stability criteria
e.g. Soberman+97 , Ge+05, Claeys+14
Depth of convective envelope
e.g. Klencki+20
Over Contact Binaries?
e.g. Marchant+16, du Buisson+20, Riley+20
Expansion of Pop III stars
e.g. Marigo+01, Kinugawa+21
Escape velocities cluster
e.g. Rodriguez+18,19, Gerosa&Fishbach+21
What are key uncertainties in population synthesis?
On top of this many uncertainties in the metallicity-dependent star formation history
Floor Broekgaarden
Floor Broekgaarden
With so many uncertainties, can we learn anything from Gravitational Waves?
Cartoon: xkcd
Floor Broekgaarden
Floor Broekgaarden
Method
Isolated Binaries
Figure from Broekgaarden et al. (2021a)
Broekgaarden et al. (2021a, 2021b)
Floor Broekgaarden
Floor Broekgaarden
1. Simulate Cosmic star formation:
based on models from Neijssel et al., incl. FSB (2019)
28x variations
Method
Isolated Binaries
“Cosmic History”
When & Where
do stars form? (metallicity)
Figure from Broekgaarden et al. (2021a)
Floor Broekgaarden
Floor Broekgaarden
1. Simulate Cosmic star formation:
based on models from Neijssel et al., incl. FSB (2019)
28x variations
Method
Isolated Binaries
“Cosmic History”
When & Where
do stars form? (metallicity)
2. Simulate binaries:
FSB+19 (“STROOPWAFEL”), FSB+21, Team COMPAS; Riley et al., incl. FSB, (2021).
How do stars
live & die?
20x variations
Figure from Broekgaarden et al. (2021a)
Floor Broekgaarden
Floor Broekgaarden
1. Simulate Cosmic star formation:
based on models from Neijssel et al., incl. FSB (2019)
Method
Isolated Binaries
“Cosmic History”
When & Where
do stars form? (metallicity)
2. Simulate binaries:
FSB+19 (“STROOPWAFEL”), FSB+21, Team COMPAS; Riley et al., incl. FSB, (2021).
How do stars
live & die?
20x variations
560 publicly available model realizations
Broekgaarden (2021a, 2021b)
Figure from Broekgaarden et al. (2021a)
28x variations
Floor Broekgaarden
Floor Broekgaarden
Both uncertainties in stellar evolution & cosmic history can impact the BHNS merger rates with factors > 10-100x
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021); Broekgaarden et al. (2021b)
Stellar Evolution models
Floor Broekgaarden
Both uncertainties in stellar evolution & cosmic history can impact the BHNS merger rates with factors > 10-100x
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021); Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Floor Broekgaarden
Both uncertainties in stellar evolution & cosmic history can impact the BHNS merger rates with factors > 10-100x
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021); Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Floor Broekgaarden
Both uncertainties in stellar evolution & cosmic history can impact the BHNS merger rates with factors > 10-100x
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021); Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Both stellar evolution & cosmic history uncertainties can impact the BHNS rate >10x
Floor Broekgaarden
BHBH rates dominated by “cosmic history”
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021);Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Floor Broekgaarden
BHBH rates dominated by “cosmic history”
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021);Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Particularly cosmic history uncertainties can impact the BHBH rate >10x
Floor Broekgaarden
NSNS rates dominated by “stellar evolution”
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021);Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Floor Broekgaarden
NSNS rates dominated by “stellar evolution”
cf. Chruslinska+19, Boco+19, Neijssel+19, Santoliquido+21
Broekgaarden & Berger (2021);Broekgaarden et al. (2021b)
Stellar Evolution models
Cosmic models
Particularly stellar evolution uncertainties can impact the NSNS rate >10x
Floor Broekgaarden
What can we learn from the distribution shapes?
Stellar
Evolution
models
Broekgaarden et al. (2021b)
BH-NS:
Cosmic
models
Floor Broekgaarden
What can we learn from the distribution shapes?
Stellar
Evolution
models
Cosmic
models
Broekgaarden et al. (2021b)
BH-NS:
stellar evolution uncertainties dominantly impacts the BHNS distribution shape
Floor Broekgaarden
What can we learn from the distribution shapes?
Stellar
Evolution
models
Cosmic
models
Broekgaarden et al. (2021b)
BH-NS:
Detections
stellar evolution uncertainties dominantly impacts the BHNS distribution shape
Floor Broekgaarden
What can we learn from the distribution shapes?
Stellar
Evolution
models
Cosmic
models
Broekgaarden et al. (2021b)
BH-NS:
BH-BH:
Both cosmic history & stellar evolution uncertainties significantly impact the BHBH distribution shape
Floor Broekgaarden
Particularly the SNe assumptions affect the BBH mass distributions
Broekgaarden et al. (2021b)
Floor Broekgaarden
Particularly the SNe assumptions affect the BBH mass distributions
Broekgaarden et al. (2021b)
Floor Broekgaarden
Particularly the SNe assumptions affect the BBH mass distributions
Broekgaarden et al. (2021b)
Floor Broekgaarden
Particularly the SNe assumptions affect the BBH mass distributions
Broekgaarden et al. (2021b)
Floor Broekgaarden
Particularly the SNe assumptions affect the BBH mass distributions
Population synthesis urgently requires better supernova remnant models
Broekgaarden et al. (2021b)
Can current population synthesis models “resolve” the remnant mass function with resolution < 2 Msun?
Yes!
No!
Other…
As also discussed in Jessica Lu’s talk (and questions by Chris Belczynski, Saavik Ford)
Can current population synthesis models “resolve” the remnant mass function with resolution < 5 Msun?
Yes!
No!
Other…
As also discussed in Jessica Lu’s talk (and questions by Chris Belczynski, Saavik Ford)
So what now?�
Some thoughts
Floor Broekgaarden
Mandel & Broekgaarden (2021) Living Review in Relativity
Ping us if your paper is missing!
Publicly available code/data:
Floor Broekgaarden
Mandel & Broekgaarden (2021) invited Living Review in Relativity
Ping us if your paper is missing!
Publicly available code/data:
Most dynamical channels seem not efficient in making NS-BH
Floor Broekgaarden
Mandel & Broekgaarden (2021) invited Living Review in Relativity
Ping us if your paper is missing!
Publicly available code/data:
Most dynamical channels might not seem efficient in making NS-NS?
Floor Broekgaarden
Matching BHBH, BHNS and NSNS rates
Broekgaarden et al. (2021b)
Floor Broekgaarden
Do all three flavors of GW mergers have the same dominant formation channel?
Yes!
No!
Floor Broekgaarden
What will we learn from looking at redshift dependent rates?
And redshift dependent distribution functions?
Redshift dependent BHBH merger rate for different formation channels. From Ng et al. (2021)
See also van Son et al. (2021, incl FSB)
But….
Floor Broekgaarden
What will we learn from looking at redshift dependent rates?
And redshift dependent distribution functions?
The 3 models used in Ng et al. (2021)
But….
Floor Broekgaarden
What will we learn from looking at redshift dependent rates?
And redshift dependent distribution functions?
The 3 models used in Ng et al. (2021)
But….
+ more isolated models
Floor Broekgaarden
What will we learn from looking at redshift dependent rates?
And redshift dependent distribution functions?
The 3 models used in Ng et al. (2021)
But….
+ more isolated models�+ other models
Floor Broekgaarden
Other observational constraints?
See talks Jessica Lu, Katie Breivik
Detecting BH-NS in our Milky Way
1. Pulsars binaries
e.g. BH-PSR: Debatri Chattopadhyay, Simon Stevenson, Jarrod Hurley, Matthew Bailes & FSB (2021), ArXiv:2011.13503
2. BH/NS binaries in LISA
Thomas Wagg, FSB, Selma de Mink et al. (2021)
Floor Broekgaarden
We need to improve many
things in our models…
Floor Broekgaarden
Population Synthesis
BSE code that
Hurley’s SSE/BSE code from 2000/2002
e.g. Laplace+20, Agrawal+20,21, Klencki+20
Original: xkcd
See, for example, the Aspen talk about POSYDON by Jeff Andrews
BH-BH
NS-NS
BH-NS
We are here! (GWTC-3)
Figure: Baibhav+19
Cosmic Explorer Einstein Telescope
3G
2G
We are at the tipping point of entering
“The Big Data Era for NS/BH mergers:”
Floor Broekgaarden
What I work on lately / my message of tonight:
Gravitational waves will teach us everything!!!!
model uncertainties
(the hope of) Population Synthesis modellers
Not so fast..
See also:
Chruslinska et al. (2019)
Belczynski et al. (2021),
the discussion in Zevin et al. (2021),
)
Going forward I believe it will be vital to understand and quantify the model uncertainties in population synthesis (& observations)�e.g. Broekgaarden et al. (2021a, 2021b)
How are you feeling today?
We are
doomed
More
pessimistic
Confused
More
optimistic
other
Questions
Discussion Questions
�
What’s next?:
Flipped: 15 min: ”Break out Discussion rooms” (we)
�
Find the number on your
yellow post-it note
1
Go to the place for your number and find your fellow group members
In the coming 15 min:� - Introduce yourself quickly
- Discuss the questions (or other related questions)� - Assign 1 person* who report back from the group / pose a question on behalf of the group.
*aim for the person who so far has spoken the fewest
Final Poll: write down your answers & I’ll collect them
1. The dominant formation channel(s) of LIGOs (z<1) detections are:
� BH-BH: ………………………………………………………………..…………………..…….…………………….�
BH-NS: …………………………………………………………………………………………………………………..�
NS-NS: ……………………………………………………………………………………………………………………�
2. Once we have 1000 GW detections we will
�…………………….…………………..…….…………………….…………………….…………………..…….…………………….�
3. Once we have 1000 GW detections we will not
�…………………….…………………..…….…………………….…………………….…………………..…….…………………….�
Name (optional): …………………………………………………………..