Black Holes Dark Dress The impact of local Dark Matter halos on the - - PowerPoint PPT Presentation

Bradley J Kavanagh GRAPPA, University of Amsterdam 27th September 2018 DESY Theory Workshop

@BradleyKavanagh b.j.kavanagh@uva.nl

Black Holes’ Dark Dress

The impact of local Dark Matter halos on the mergers of primordial black hole binaries Powered by

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs 2

Could the observed LIGO events be due to merging Primordial Black Holes (PBHs)? How do local Dark Matter (DM) halos affect the merger rate of PBHs?

arXiv:1805.09034, PRD 98, 023536 (2018) BJK, Daniele Gaggero & Gianfranco Bertone Movies at tinyurl.com/DESYDarkDress

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Primordial Black Holes

3

[BJK, Gaggero & Bertone,1805.09034]

LIGO sensitive here

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

104 105

Redshift, z

−0.015 −0.010 −0.005 0.000 0.005 0.010 0.015

PBH separation, x [pc]

Hubble flow Binary Decoupling 10−1 100 101 102 103 −0.015 −0.010 −0.005 0.000 0.005 0.010 0.015 GW Inspiral PBH-PBH Merger

Life of a PBH binary

4

PBH binaries form predominantly from ‘nearby’ PBH pairs in the Early Universe:

[Sasaki et al., 1603.08338 and others, but see also Bird et al., 1603.00464]

a = 0.01 e = 0.995

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

PBH Binary Population

5

e > 0.9999

[Ali-Haïmoud et al., 1709.06576, BJK, Gaggero & Bertone, 1805.09034]

tmerge = 3 c5 170 G3

N

a4j7 M 3

PBH

Randomly distributed (unclustered) PBHs Angular momentum set by torques from smooth density perturbations and all other PBHs Close, eccentric binaries merge today: j =

• 1 − e2

R(tmerge) = 1 2nPBHP(tmerge)

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Merger rate estimate

6

[Ali-Haïmoud et al., 1709.06576, BJK, Gaggero & Bertone, 1805.09034]

LIGO merger rate estimate Solar mass PBHs should only be a sub-dominant (%-level) contribution to the DM density in the Universe

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

• Survival
• Clustering
• Baryons
• Dark Matter

Caveats

7

[Ali-Haïmoud et al., 1709.06576]

Do these binaries survive for the age of the Universe? Smooth density perturbations and close encounters are unlikely to disrupt the binaries

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

• Survival
• Clustering
• Baryons
• Dark Matter

Caveats

8

[1805.05912, 1807.02084, 1808.05910 and others]

See Paul Depta’s talk (which we just watched) How does the distribution of PBHs affect the merger rate?

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Caveats

9

• Survival
• Clustering
• Baryons
• Dark Matter

Does baryonic accretion disrupt the binary? Some simulations have been performed, but the effects are still unclear (especially for highly eccentric binaries)

[0909.1738, 0805.3408, astro-ph/0607467, 1703.03913]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

• Survival
• Clustering
• Baryons
• Dark Matter

Caveats

10

Do local Dark Matter halos disrupt PBH binaries? Dynamical friction as the PBHs move through DM halos may affect the orbital properties…

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Dark Dresses

11

[astro-ph/0608642, 0706.0864,1712.05421]

large redshift large background density low background density small redshift (later time)

PBHs seed the formation of `local’ DM halos:

Slide shamelessly ripped off from Daniele Gaggero

Rtr(z) = 0.0063 MPBH M 1 + zeq 1 + z

• pc

ρ(r) ∝ r−3/2

By matter-radiation equality, Mhalo ∼ MPBH

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

12

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

13

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

14

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

15

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

16

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

17

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

18

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

19

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

20

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

21

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulations

22

Use GADGET-2 as a pure N-body solver and follow the binary from decoupling:

[Springel, astro-ph/0505010]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

ai = 0.01 ei = 0.995

Life of a dressed PBH binary

23

104 105

Redshift, z

−0.015 −0.010 −0.005 0.000 0.005 0.010 0.015

PBH separation, x [pc]

Hubble flow Growth of DM Halo Binary Decoupling Unbinding

• f halo

N-BODY SIM.

10−1 100 101 102 103 −0.015 −0.010 −0.005 0.000 0.005 0.010 0.015 GW Inspiral PBH-PBH Merger

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Interpreting the simulations

24

Conservation of energy Conservation of angular momentum Eorb

i

+ 2 U bind = Eorb

f

LPBH

i

= LPBH

f

Lhalo

i

= Lhalo

f

j =

• 1 − e2

Binaries shrink… …and circularise

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Interpreting the simulations

25

103 102 101 100 Initial angular momentum, ji 104 103 102 101 Final semi-major axis, af [pc]

Merging today

1000 M; ai = 0.063 pc 30 M; ai = 0.01 pc 1 M; ai = 0.002 pc 0.9 0.99 0.999 0.9999 0.99999 Initial eccentricity, e

Conservation of energy Conservation of angular momentum Eorb

i

+ 2 U bind = Eorb

f

LPBH

i

= LPBH

f

Lhalo

i

= Lhalo

f

fixes semi-major axis, a

Binaries shrink… …and circularise

j =

• 1 − e2

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Interpreting the simulations

26

103 102 101 100 Initial angular momentum, ji 104 103 102 101 Final semi-major axis, af [pc]

Merging today

1000 M; ai = 0.063 pc 30 M; ai = 0.01 pc 1 M; ai = 0.002 pc 0.9 0.99 0.999 0.9999 0.99999 Initial eccentricity, e 10−3 10−2 10−1 100 Initial angular momentum, ji 10−2 10−1 100 Final angular momentum, jf

Merging today

0.9 0.99 0.999 0.9999 0.99999 Initial eccentricity, e

Conservation of energy Conservation of angular momentum Eorb

i

+ 2 U bind = Eorb

f

LPBH

i

= LPBH

f

Lhalo

i

= Lhalo

f

fixes semi-major axis, a fixes jf = ji

• ai/af

Binaries shrink… …and circularise

j =

• 1 − e2

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Calculating the final merger rate

27

Draw PBH binaries from the distribution of (a, e)

Guided by the simulations, map (ai, ei) → (af, ef)

Merger time is almost conserved: tf = ai af ti

tmerge = 3 c5 170 G3

N

a4j7 M 3

PBH

j =

• 1 − e2

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

100 101 102 103

MPBH [M]

104 103 102 101 100

DM fraction fPBH = ΩPBH/ΩDM

LIGO

EROS+MACHO Eridanus II Accretion - radio Accretion - X-ray CMB - PLANCK CMB - FIRAS

Limits from LIGO

28

[BJK, Gaggero & Bertone,1805.09034]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Caveats (once again)

29

• Survival
• Clustering
• Baryons
• Dark Matter

[See Paul Depta’s talk] [More (tough) simulation needed]

Bounds from merging PBHs are being placed on a more and more solid footing!

[Ali-Haïmoud et al., 1709.06576] [BJK, Gaggero & Bertone, 1805.09034]

A little more work is still needed…

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Conclusions

30

Movies and code available at github.com/bradkav/BlackHolesDarkDress

Many PBH binaries can be formed in the early Universe Their mergers could be observable by LIGO today Local DM halos affect the size and shape of PBH binaries but (surprisingly) have only a small effect on their merger rate LIGO bounds set the strongest constraints on 10 - 300 Solar Mass PBHs, at the sub-percent level Can Dark Matter influence other systems and their GW signals?

arXiv:1805.09034, PRD 98, 023536 (2018) BJK, Daniele Gaggero & Gianfranco Bertone

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs 31

Backup Slides

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Primordial Black Holes

32

[Y. B. Zel’dovich and I. D. Novikov, Soviet Astronomy 10, 602 (1967)] [S. Hawking, Mon. Not. R. Astron. Soc. 152, 75 (1971)] [Carr and Hawking, MNRAS 168 (1974)] [Garcia-Bellido, Linde & Wands, astro-ph/9605094] [Green, 1403.1198] [Sasaki et al, 1801.05235]

Primordial Black Holes (PBHs) could form at from:

• Collapse of large density perturbations
• Cosmic String Loops
• Bubble collisions
• …

z 106

A sign of New Physics and a probe of the early universe. A possible contribution to Dark Matter?

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Decoupling and Halo Mass

33

MPBH = 30 M

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Binary Evolution

34

5 10 15 20 Simulation time [kyr] 0.000 0.005 0.010 0.015 0.020 0.025 0.030 PBH separation [pc] MPBH = 30 M, ai = 0.01 pc, ei = 0.995 0.0 0.2 0.4 0.6 0.8 1.0 1.2 DM mass enclosed within 0.1 Rtr [M] 5 10 15 20 Simulation time [kyr] 0.00 0.02 0.04 0.06 0.08 0.10 Angular momentum, L [M pc km/s] MPBH = 30 M, ai = 0.01 pc, ei = 0.995

PBH DM

jf = ai af ji for j 1

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Remapping the semi-major axis

35

104 103 102 101 Initial semi-major axis, ai [pc] 104 103 102 101 Final semi-major axis, af [pc] 1000 M 30 M 1 M

tf = ai af ti

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Extended mass functions

36

[See also 1801.10327]

LIGO O1 Limit

[1707.01480]

“Old” merger rate calculation à la Sasaki et al., but picture doesn’t change too much…

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Astrophysical BH binaries

37

Astrophysical BH binaries could be formed dynamically, or through e.g. common envelope evolution:

[Banerjee, 1611.09357, LIGO-Virgo, 1602.03846, Elbert et al., 1703.02551, Stevenson et al., 1704.01352, and many others…] [1602.04531]

Bradley J. Kavanagh (GRAPPA, Amsterdam) Black Holes’ Dark Dress: Dark Matter & Merging PBHs

Simulation Details

38

For ‘high-resolution’ simulations, we use a multi-mass scheme in which the DM halo is composed of 4 different masses of pseudo-particles. Each simulation takes ~ 3000 CPU-hours, with very poor scaling with NCPU

Part II: A closer look to merger rates

A) Binaries formed in the early Universe B) Binaries formed after close encounters within a DM halo

Hubble flow

• If most of the DM is made of PBHs, most pairs

decouple from the Hubble flow and form a binary deep in the radiation era.

• If f < 0.01, only rare pairs with small

separation form binary systems.

Sasaki+ PRL 2017 Ali-Haimoud+ 2017 Bird+ PRL 2017

σ = π ✓85 π 3 ◆2/7 R2

s

⇣vpbh c ⌘18/7 = 1.37 ⇥ 1014 M 2

30 v18/7 pbh200 pc2,

R = 4π Z Rvir r2 1 2 ✓ρnfw(r) Mpbh ◆2 hσvpbhi dr

• PBHs become bound if GW

emission exceeds initial kinetic energy

[Daniele Gaggero, UCI 20/02/2018]