Welcome to our Session!

New Constraints on

as Dark Matter

work in particular withBernard Carr

Katherine FreeseJens Jasche

Pavel NaselskyTommy OhlssonGlenn Starkman

Talk at 13. KosmologietagBielefeld, 4th of May 2018

Primordial Black Holes

Florian Kühnel

PBH Generalities

Black-hole (BH) formation for .

Astrophysical: From down to , but not lower.

Have a look at the density

To form smaller black holes we need higher density

Formation at early times; primordial black holes (PBHs)

Compare to cosmological density

Masses of primordial black holes:

PBH Formation Mechanisms

Formation of primordial black holes

http://www.damtp.cam.ac.uk/research/gr/public/cs_top.html

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes by

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes

Bubble collisions

by

http://www.damtp.cam.ac.uk/research/gr/public/cs_phase.html

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes

Pressure reduction

Bubble collisions

0.0 0.5 1.0 1.5 2.0

0.34

0.36

0.38

0.40

0.42

0.44

M/M⊙11

δc

by

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes

Pressure reduction

Bubble collisions

0.0 0.5 1.0 1.5 2.0

0.34

0.36

0.38

0.40

0.42

0.44

M/M⊙11

δc

by

More in Chris' talk

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes

Pressure reduction

Bubble collisions

by

Cosmic string loops

PBH Formation Mechanisms

Formation of primordial black holes

Pressure reduction

Large density perturbations

Bubble collisions

https://ned.ipac.caltech.edu/level5/Sept12/Kravtsov/Kravtsov3.htmlby

[Carr 1975]Simple estimate:

Jeans lengthscale of the over density

PBH —Probes of Scales

Probe a huge range of scales:Planck relics, Extra dimensions and higher-dimensional black holes, …

Quantum Gravity:

Early Universe: Baryogenesis, Nucleosynthesis, Reionisation, …

High-Energy Physics: Cosmological and galactic gamma-rays, …

Critical phenomena, Cold dark matter, Dynamical effects, Lensing effects, Gravitational waves, Black holes in galactic nuclei, …

Gravity:

PBH —Some Numbers

Mass range:

Size:

Number in our Galaxy:

Distance:

Consider an example of primordial black holes constituting all of the dark matter:

PBH Constraints at Formation

[Carr et al. 2010]

10-30

10-25

10-20

10-15

10-10

10-5

100

0 10 20 30 40 50

`’

log10(M/g)

Planck

LSP

Entropy

BBN

CMB

Galactic aEGB

21cm

1PBH

GRB

GW

WMAP3FIRAS

MACHOQSO

WBDF

LSS

Note that

and hence

PBH & Particle Dark Matter

If PBHs do not constitute the entirety of the dark matter, the latter must necessarily contain something else.

One possibility: a combined scenario, e.g. DM = PBHs + Particles

Halo profile does matter; enhancement of in density spikes.The annihilation rate .

�

� / n2

Let us now study WIMP annihilations in PBH halos:

PBH & Particle Dark Matter

Halo profile does matter; enhancement of in density spikes.The annihilation rate .

�

� / n2Let us now study WIMP annihilations in PBH halos:

Halo profile does matter; enhancement of in density spikes.

PBH & Particle Dark Matter

The annihilation rate . �

� / n2

1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

Let us now study WIMP annihilations in PBH halos:

-� � � �� ��-��

-��

-��

-��

-�

�

�

��

[Boucenna, FK, Ohlsson, Visinelli 2018]

PBH & Particle Dark Matter

1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

The annihilation rate . � / n2

Halo profile does matter; enhancement of in density spikes.�

Let us now study WIMP annihilations in PBH halos:

-�� -�� -�� -�� -�� -� -� -�-��

�

��

��

��

��

h�vi = 3⇥ 10�26 cm3/s

[Boucenna, FK, Ohlsson, Visinelli 2018]

��-�� ��-�� ��-� �����-��

��-�

��-�

��-�

��-�

������� ���� ���� ����

KEG F NS

HSC

ML E WB

PBH & Particle Dark Matter

Let us now study WIMP annihilations in PBH halos:

Halo profile does matter; enhancement of in density spikes.1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

The annihilation rate . � / n2

�

[Boucenna, FK, Ohlsson, Visinelli 2018]

PBH & Particle Dark Matter

��-�� ��-�� ��-� �����-��

��-�

��-�

��-�

��-�

������� ���� ���� ����

KEG F NS

HSC

ML E WB

1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

[Boucenna, FK, Ohlsson, Visinelli 2018]

��-�� ��-�� ��-� �����-��

��-�

��-�

��-�

��-�

������� ���� ���� ����

KEG F NS

HSC

ML E WB

h�vi = 3⇥ 10�26 cm3/s

PBH & Particle Dark Matter

1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

[Boucenna, FK, Ohlsson, Visinelli 2018]

��-�� ��-�� ��-� �����-��

��-�

��-�

��-�

��-�

������� ���� ���� ����

KEG F NS

HSC

ML E WB

h�vi = 3⇥ 10�26 cm3/s

PBH & Particle Dark Matter

1) We derive the density profile of the captured WIMPs, 2) calculate the annihilation rate, 3) and compare to data:

[Boucenna, FK, Ohlsson, Visinelli 2018]

Primordial black holes are very interesting!

Conclusion

They are unique probes of their formation scenarios.

These scenarios (also those with sterile neutrinos) have distinct signatures and might be falsified or confirmed in the near future.

If PBHs do not constitute the entirety of the dark matter, the latter must necessarily contain something else, with combined dark-matter scenarios (PBHs + WIMPs) are amongst the most plausible ones.