Massive runaway stars: probes for stellar physics and dynamics - - PowerPoint PPT Presentation
Massive runaway stars: probes for stellar physics and dynamics Mathieu Renzo Collaborators: E. Zapartas, S. E. de Mink, Y. G otberg, S. Justham, R. J. Farmer, R. G. Izzard, S. Toonen, D. J. Lennon, H. Sana, E. Laplace, S. N. Shore, F .
probes for stellar physics and dynamics
Collaborators:
. Evans ...
What is a runaway star?
2
Hipparcos velocity distribution for young ( 50 Myr) stars, Tetzlaff et al. 11, see also Zwicky 57, Blaauw, 93, Gies & Bolton 86, Leonard 91, Renzo et al. 19a, 19b
v3D [km s−1] Runaway stars Tail of the velocity distribution
Blaauw 61
What is a runaway star?
2
Hipparcos velocity distribution for young ( 50 Myr) stars, Tetzlaff et al. 11, see also Zwicky 57, Blaauw, 93, Gies & Bolton 86, Leonard 91, Renzo et al. 19a, 19b
v3D [km s−1] Runaway stars Tail of the velocity distribution
Blaauw 61
Fraction per type O: ∼ 10 − 20% Be: ∼ 13%
Two ways to produce fast massive stars
Binary supernova disruption Dynamical ejection from cluster Massive runaway origins ... ... is there a problem?
3
Most common massive binary evolution
4
Credits: ESO, L. Calc ¸ada, M. Kornmesser, S.E. de Mink
Spin up, pollution, and rejuvenation
Spin up: Packet ’81, Cantiello et al. ’07, de Mink et al. ’13 Pollution: Blaauw ’93 Rejuvenation: Hellings ’83, Schneider et al. ’15
What exactly disrupts the binary?
6
Ejecta impact
(Tauris & Takens 98, Liu et al. 15)
Loss of SN ejecta
(Blaauw ’61)
Renzo et al. 19b, Kochanek et al. 19, Eldridge et al. 11, De Donder et al. 97
What exactly disrupts the binary?
6
SN Natal kick
(Shklovskii 70, Katz 75, Janka 13, 17)
Ejecta impact
(Tauris & Takens 98, Liu et al. 15)
Loss of SN ejecta
(Blaauw ’61)
Renzo et al. 19b, Kochanek et al. 19, Eldridge et al. 11, De Donder et al. 97
Do BHs receive kicks ?
⇒ most remain together with their widowed companion
⇒ most are single and we can’t see them...
7
Do BHs receive kicks ?
⇒ most remain together with their widowed companion
⇒ most are single and we can’t see them...
7
A way to constrain BH kicks with Gaia
8
0.0 1.0 0.0 1.0 Probability×105 10 20 30 40 50 60 70 Mdis [M⊙] 0.0 1.0
Mass # stars
Massive runaways mass function (v ≥ 30 km s−1, M ≥ 7.5 M⊙)
Renzo et al. 19b Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
A way to constrain BH kicks with Gaia
8
0.0 1.0 0.0 1.0 Probability×105 10 20 30 40 50 60 70 Mdis [M⊙] 0.0 1.0
BH momentum kick (σkick = 265 km s−1, fiducial)
Mass # stars
Massive runaways mass function (v ≥ 30 km s−1, M ≥ 7.5 M⊙)
Renzo et al. 19b Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
A way to constrain BH kicks with Gaia
8
0.0 1.0 0.0 1.0 Probability×105
BH: σkick = 100 km s−1 NS: σkick = 265 km s−1 (no fallback for BH)
10 20 30 40 50 60 70 Mdis [M⊙] 0.0 1.0
BH momentum kick (σkick = 265 km s−1, fiducial)
Mass # stars
Massive runaways mass function (v ≥ 30 km s−1, M ≥ 7.5 M⊙)
Renzo et al. 19b Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
A way to constrain BH kicks with Gaia
8
0.0 1.0
BH kick=NS kick (σkick = 265 km s−1) (no fallback)
0.0 1.0 Probability×105
BH: σkick = 100 km s−1 NS: σkick = 265 km s−1 (no fallback for BH)
10 20 30 40 50 60 70 Mdis [M⊙] 0.0 1.0
BH momentum kick (σkick = 265 km s−1, fiducial)
Mass # stars
Massive runaways mass function (v ≥ 30 km s−1, M ≥ 7.5 M⊙)
Renzo et al. 19b Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
Kicks do not change companion velocity
9
SN Natal kick
(Shklovskii 70, Katz 75, Janka 13, 17)
before the SN
Renzo et al. 19b, Kochanek et al. 19, Eldridge et al. 11, De Donder et al. 97
Velocity distribution: Runaways
10
Renzo et al. 19b
Velocity respect to the pre-explosion binary center of mass
Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
Velocity distribution: Walkaways
11
Renzo et al. 19b
Velocity respect to the pre-explosion binary center of mass
Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
Velocity distribution: Walkaways
11
Renzo et al. 19b
Velocity respect to the pre-explosion binary center of mass
Numerical results publicly available at: http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A66
Summary of ejection mechanisms
12
Binary SN disruption
2
fast rotation, He/N enrichment, lower apparent age
Outline
Binary supernova disruption Dynamical ejection from cluster Massive runaway origins ... ... is there a problem?
13
N-body interactions (typically) least massive thrown out. Binaries matter...
∗
Poveda et al. 67
...but don’t necessarily leave imprints!
Credits: C. Rodriguez
Typical outcome of dynamical interactions
15
(the least massive of the three)
e.g., Fujii & Portegies-Zwart 11
The most massive runaways known
5h37m00s 30s 38m00s 30s 39m00s Right Ascension (J2000) 08′ 06′ 04′ 02′ −69◦00′ Declination (J2000) R136 VFTS16 VFTS72 VFTS682
16
Renzo et al. 19a Lennon et al. (incl. MR), 18
M = 91.6+11.5
−10.5 M⊙
M = 97.6+22.2
−23.1 M⊙
M = 137.8+27.5
−15.9 M⊙
The most massive runaways known
5h37m00s 30s 38m00s 30s 39m00s Right Ascension (J2000) 08′ 06′ 04′ 02′ −69◦00′ Declination (J2000) R136 VFTS16 VFTS72 VFTS682
16
Renzo et al. 19a Lennon et al. (incl. MR), 18
M = 91.6+11.5
−10.5 M⊙
M = 97.6+22.2
−23.1 M⊙
M = 137.8+27.5
−15.9 M⊙
The most massive runaways known
5h37m00s 30s 38m00s 30s 39m00s Right Ascension (J2000) 08′ 06′ 04′ 02′ −69◦00′ Declination (J2000) R136 VFTS16 VFTS72 VFTS682
16
Renzo et al. 19a Lennon et al. (incl. MR), 18
M = 91.6+11.5
−10.5 M⊙
v2D = 80 ± 11 km s−1 M = 97.6+22.2
−23.1 M⊙
v2D = 93 ± 15 km s−1 M = 137.8+27.5
−15.9 M⊙
The most massive runaways known
5h37m00s 30s 38m00s 30s 39m00s Right Ascension (J2000) 08′ 06′ 04′ 02′ −69◦00′ Declination (J2000) R136 VFTS16 VFTS72 VFTS682
16
Renzo et al. 19a Lennon et al. (incl. MR), 18
M = 91.6+11.5
−10.5 M⊙
v2D = 80 ± 11 km s−1 M = 97.6+22.2
−23.1 M⊙
v2D = 93 ± 15 km s−1 M = 137.8+27.5
−15.9 M⊙
v2D = 38 ± 17 km s−1
Outline
Binary supernova disruption Dynamical ejection from cluster Massive runaway origins ... ... is there a problem?
17
Known ejection mechanisms
18
Binary SN disruption
2
fast rotation, He/N enrichment, lower apparent age
Cluster ejections
dynamical ejection
...Binaries are still important! but might not leave signature
Known ejection mechanisms
18
Binary SN disruption
2
fast rotation, He/N enrichment, lower apparent age
Cluster ejections
dynamical ejection
...Binaries are still important! but might not leave signature
Relative efficiency ? ∼ 2
3 of runaways from binaries
Hoogerwerf et al. 01
O type stars runaway fraction
19
Observational claims: (regardless of origin)
∼ 2
3 from binaries
Hoogerwerf et al. 01
Theoretical consensus from binaries:
Renzo et al. 19b, De Donder et al. 97, Eldridge et al. 11, Kochanek et al. 19
O type stars runaway fraction
19
Observational claims: (regardless of origin)
∼ 2
3 from binaries
Hoogerwerf et al. 01
J i l i n s k i e t a l . 1
Is it really a problem? Theoretical consensus from binaries:
Renzo et al. 19b, De Donder et al. 97, Eldridge et al. 11, Kochanek et al. 19
Summary of ejection mechanisms
20
Binary SN disruption
2
fast rotation, He/N enrichment, lower apparent age
Cluster ejections
dynamical ejection
...Binaries are still important! but might not leave signature
VFTS682: Concordant Picture?
0.0 0.1 0.2 0.3 0.4 0.5 µrel [mas yr−1] 5 10 15 20 25 30 35 40 # stars VFTS682 VFTS16 VFTS72 Expected if ejected from R136 ∆µrel ≤ 0.1 [mas yr−1] ∆µrel ≤ 0.05 [mas yr−1] 20 40 60 80 100 120 vrel [km s−1] −π −π/2 π/2 π θ [radians] 5 10 15 20 25 30 35 40 # stars VFTS682 VFTS72 VFTS16 π π/2 π/2 π dummy
Large error bars compatible with no motion, but best values fit with expectations for dynamical ejection
Renzo et al. 19a
Methods: Population Synthesis
Fast ⇒ Allows statistical tests of the inputs & assumptions
SN kicks Stellar Winds Initial Distributions
Synthetic Population
(available online)
RLOF & Common Envelope Tidal Interactions Mass Transfer
Star forming region velocity dispersion
10 20 30 40 50 60 70 vdis [km s−1] 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Normalized Probability R15 =26.8 RSFH
15
=14.1 ≥ 15 M⊙ Convolved −40−20 0 20 40
vSFH [km s−1]
0.00 0.01 0.02 0.03 0.04 0.05
Renzo et al. 19b
Mass-velocity varying the natal kick
Fiducial σkick = 265 km s−1
20 40 60 80 100 120 vdis [km s−1] 10 20 30 40 50 60 70 80 90 100 Mdis [M⊙] BH momentum kick (σkick = 265 km s−1, fiducial) −10 −9 −8 −7 −6 log10(Pdis)
Intermediate BH kick σkick = 100 km s−1
20 40 60 80 100 120 vdis [km s−1] 10 20 30 40 50 60 70 80 90 100 Mdis [M⊙] BH: σkick = 100 km s−1 NS: σkick = 265 km s−1 (no fallback for BH) −10 −9 −8 −7 −6 log10(Pdis)
Large BH kicks (no fallback)
20 40 60 80 100 120 vdis [km s−1] 10 20 30 40 50 60 70 80 90 100 Mdis [M⊙] BH kick=NS kick (σkick = 265 km s−1, no fallback) −10 −9 −8 −7 −6 log10(Pdis)
Renzo et al. 19b
How far do they get?
(No potential well)
Renzo et al. 19b
Where do they die?
for M ≥ 7.5 M⊙: D = 128 pc Drun = 525 pc Dwalk = 103 pc I Zw18
Credits: ESA/Hubble & Nasa, A. Aloisi
SN natal kick
Observationally: vpulsar ≫ vOB−stars
Credits: C. D. Ott, S. Drasco
Timing of ejection
from Oh & Kroupa 16, see also, Poveda et al. 64, Fujii & Portegies-Zwart 11, Banerjee et al. 12, 14
Most ejections happen early Before the first stellar core-collapse Very sensitive to initial conditions