How we did not find the Black Hole Dark Matter

How we did not find the Black Hole Dark Matter

Fedor Bezrukov

2017Christmas!

Real achievement!

Particle TheoryJournal Club

http://www.hep.manchester.ac.uk/u/bezrukov/journalclub.html

Fedor Bezrukov No BH DM 2017 Christmas! 2 / 12

http://www.hep.manchester.ac.uk/u/bezrukov/journalclub.html

Journal club summary:

2017-09-21 Thu: Chris Shepherd – arXiv:1709.04925

2017-09-28 Thu: Kieran Finn – arXiv:1709.04891

2017-10-05 Thu: Jack Holguin – arXiv:1707.02550

2017-10-12 Thu: Sotirios Karamitsos – arXiv:1709.09671

2017-10-19 Thu: Kiran Ostrolenk – arXiv.org:1710.01515

2017-11-09 Thu: Matthew De Angelis – arXiv.org:1710.06722

2017-11-16 Thu: Fedor Bezrukov – Phys.Rev. 133 (1964) B1549

2017-11-23 Thu: Baptiste Cabouat – arXiv:1705.04365, arXiv:1709.08655

2017-11-30 Thu: Jack Holguin - Phys.Rev. D20 (1979) 2619


2017-12-14 Thu: Kieran Finn – Commun. math. Phys. 43, 199(1975), Phys. Rev. D14 (1976) 870









































And now – back to the darkrealms of astrophysics


Black Holes = Dark Matter?

Planck

Evaporation

FL

WD K

HSC

NS

EROS

M

WB

SegI

Eri II

-15 -10 -5 0

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

log10(Mc /M⊙)

log 10f PBH

monochromatic

Carr, Raidal et al.’07LIGO – merges of ∼ 30M BH


https://arxiv.org/abs/1705.05567

Black Holes = Dark Matter?

Planck

Evaporation

FL

WD K

HSC

NS

EROS

M

WB

SegI

Eri II

-15 -10 -5 0

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

log10(Mc /M⊙)

log 10f PBH

monochromatic

Carr, Raidal et al.’07LIGO – merges of ∼ 30M BH



Inflation can make them!

Dark matter – BH should be primordial (i.e. not baryonic)Forming primordial BH – large density perturbations of somesmall scale required

Large perturbations – very flat potential PR = V 3/2

4π2M3PV ′2

Inflection point inflation may give this0 1 2 3 4 5 6 7 8

0

0.5

1

1.5

2

xc

x65

x

V(x)/V0

Ezquiaga, Garcia-Bellido, Morales’17



Can it? Bezrukov, Pauly, Rubio’17My favourite model – Higgs inflation with radiative correctionsleading to small self coupling λ at high scales!

10-3 101 105 109 1013 1017 1021

k[Mpc−1 ]

10-10

10-9

10-8

10-7

P Rns =0.968, r=0.065

ns =0.968, r=0.027

ns =0.968, r=0.015

ns =0.968, r=0.007

ns =0.968, r=0.004

0102030405060N

But PR & 10−3 is required for BH production. . .


http://arxiv.org/abs/arXiv:1706.05007

Experiment says:

No LIGO MACHO∗: Primordial Black Holes,Dark Matter and Gravitational Lensing of Type Ia Supernovae

Miguel Zumalacarregui1, 2, 3, † and Uros Seljak1, 4, ‡

1Berkeley Center for Cosmological Physics, LBNL and University of California at Berkeley,Berkeley, California 94720, USA

2Institut de Physique Theorique, Universite Paris Saclay CEA, CNRS, 91191 Gif-sur-Yvette, France3Nordita, KTH Royal Institute of Technology and Stockholm University,

Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden4Physics and Astronomy Department, LBNL, University of California at Berkeley,

Berkeley, California 94720, USA(Dated: December 7, 2017)

Black hole merger events detected by the Laser Interferometer Gravitational-Wave Observatory(LIGO) have revived dark matter models based on primordial black holes (PBH) or other massivecompact halo objects (MACHO). This macroscopic dark matter paradigm can be distinguished fromparticle physics models through their gravitational lensing predictions: compact objects cause mostlines of sight to be demagnified relative to the mean, with a long tail of higher magnifications. Wetest the PBH model using the lack of lensing signatures on type Ia supernovae (SNe), modelingthe effects of large scale structure, allowing for a non-gaussian model for the intrinsic SNe luminos-ity distribution and addressing potential systematic errors. Using current JLA (Union) SNe data,we derive bounds ΩPBH/ΩM < 0.346 (0.405) at 95% confidence, ruling out the hypothesis of MA-CHO/PBH comprising the totality of the dark matter at 5.01σ(4.28σ) significance. The finite sizeof SNe limits the validity of the results to MPBH & 10−2M, fully covering the black hole mergersdetected by LIGO and closing that previously open PBH mass range.

I. INTRODUCTION

A major goal of cosmology is to characterize the darkcomponents of the universe. The nature of Dark Mat-ter (DM), the component sourcing the formation of largescale structure (LSS) and contributing 27% of the energybudget of the universe, remains highly elusive. The stan-dard DM scenario postulates a new elementary particle,abundantly produced in the early universe and with asmall cross section that makes it difficult to detect bycurrent experiments or be produced in particle colliders.Although cosmology is insensitive to most microscopicdetails of DM scenarios, observations prefer cold darkmatter (CDM) models in which DM behaves as a non-relativistic fluid.

An alternative to microscopic dark matter scenariospostulates that CDM is formed by Primordial BlackHoles (PBH) or other macroscopic entities, genericallyknown as massive compact halo objects (MACHO), thatwould have formed in the early universe [1–4]. PBHsbehave as non-relativistic matter on sufficiently largescales, making them viable CDM candidates for cosmol-ogy. They leave no trace on particle searches, but can beprobed by a series of small-scale effects that depend onthe mass and other properties of the object (see Fig. 1and [5, 6] for recent reviews).

Interestingly, the weakest constraints on PBHs (M ∼

∗This is funnier in Spanish†Electronic address: [email protected]‡Electronic address: [email protected]

10− 100M) coincide with the masses of black holes de-tected by the Laser Interferometer Gravitational Obser-vatory (LIGO) [7–9]. This intriguing possibility lead to arevival of PBH models [10–12] (see [13] for pre-detectionwork) that could simultaneously provide the right darkmatter abundance, explain the high merger rate and pro-genitor masses inferred by the first LIGO detections whilebeing compatible with other bounds. Unfortunately, un-certainties in the small-scale distribution of PBHs remainan obstacle to constrain their abundance on the basis ofcurrent gravitational wave (GW) observations (althoughsee [14]). Other methods are needed to reliably test thePBH-DM hypothesis.

Given the dark nature of PBHs, a promising techniqueis to probe their gravitational influence on the propaga-tion of light. Microlensing observations, based on moni-toring a field of stars and search for magnification causedby compact objects moving near the line of sight, yieldsone of the most powerful constraints in the range of masesM . M, right below the LIGO band. The character-istic timescale for microlensing-induced variations growsas√M and this technique becomes ineffective for PBH

over M & 10M [15].

In this paper we will derive lensing constraints on thePBH abundance using Supernovae as standard candlesof known luminosity. This measurement is different fromtraditional microlensing of stars in a number of ways.Instead of comparing the same star at different times,this method compares different type Ia supernovae, someof which will be highly magnified by a PBH. The mainadvantage of this method is that it does not rely on themovement of the PBHs, making SNe lensing sensitive tolarger PBH masses than stellar microlensing. Instead,

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10−4 10−3 10−2 10−1 100 101 102 103 104

MPBH [M]

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

α≡

ΩP

BH/Ω

M(9

5%c.

l.)

LIG

OB

Hs

EROS

Eri

dan

osII

SNe lensing(this work)

Pla

nck

(col

l)

Pla

nck

(ph

oto)


Power of theory

Prediction confirmed!


Also happened

Found some more ways to prevent sterile neutrino fromdestroying the UniverseStill trying to understand how GeV scalar decays to pions. . .new – Early Universe coursenew – Standard Model course on HEP Supper school in LancasterMPhys students – QFT, inflation, dark matter – lot’s of fun!Climbed Weisshorn (to repeat – have yet to climb it down)


Next year

More predictions to make and test!Something else I don’t know yet!

Merry Christmas!


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How we did not find the Black Hole Dark Matter