Simeon Bird JHU I Cholis J Munoz Y AliHaimoud M Kamionkowski E Kovetz A Raccanelli A Riess PRL 116 201301 arXiv 160300464 LIGO detected Gravitational Waves LIGO Detection Two merging 30 solar mass BHs ID: 787548
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Slide1
Did LIGO detect dark matter?
Simeon Bird (JHU)
I. Cholis, J. Munoz, Y. Ali-Haimoud, M. Kamionkowski, E. Kovetz, A. Raccanelli, A. Riess
PRL 116 201301
arXiv: 1603.00464
Slide2LIGO detected Gravitational Waves
Slide3LIGO Detection
Two merging 30 solar mass BHs
Slide4LIGO Detection
How did this binary form?Two 100 solar mass stars → Black Holes
Slide5LIGO Detection
How did this binary form?Two 100 solar mass stars → Black Holes
Other options?
Primordial Black Holes
Slide6Primordial Black Holes
Primordial Black Holes form after inflationForm from density perturbation, or inflaton, not stars
Slide7Primordial Black Holes
Mass inside horizon > Schwarzchild mass:
Very small scales
Mass, abundance free parametersForget about formation
Slide8Primordial Black Holes
Dark matter candidate.
But black holes are luminous:
Slide9Primordial Black Holes
Dark matter candidate.
PBHs have no gas → Low accretion
Slide10Are PBHs at 30 Solar MassRuled Out?
Slide11CMB Spectral Distortions
An indirect limit: radiative feedback from PBH accretion affects CMB
Ricotti+07
30
Slide12CMB limits
Strong assumptions:Bondi Accretion
Radiative feedback does not damp accretion
Limit weaker than published (Ali-Haimoud, in prep)
Slide13Are PBHs at 30 Solar MassRuled Out?
NO
Slide14The Model
DM of 30 Msun PBHs in halosStandard dark matter assumptions
Close BHs emit gravity waves, form binary, and merge.
Does the merger rate match LIGO?
Slide15PBH Merger in Halos
Binary!
GW
Halo object
Halo object
Slide16Cross-Section
(Quinlan & Shapiro 1989)
PBH Velocity like halo velocity dispersion:
- most mergers in smallest halosForms close binary, fast merger by GW emission.
Slide17Merger Rate
Two-body encounter, so merger rate is:
Convolve with halo mass function:
Slide18Total Merger Rate
Different halo mass functions and concentrations.
Slide19Merger Rate
Integrated:LIGO:
Slide20Merger Rate
Total mergers:Uncertainties:
- 50 % halo profile (Einasto increases)
- 50 % cosmological parameters
- 50 % different concentrations
- 50 % different halo mass functions
Total: multiplicative factor of 3
Slide21Merger Rate
Total mergers:This number could have been 10
±10INTERESTING
Did LIGO Detect Dark Matter?Possibly.