Primordial black holes as a dark matter candidate
Ranjan Laha Theoretical Physics Department, CERN Contents • Primordial black hole introduction
• Primordial black hole constraints (a) from evaporation (b) from lensing (c) from gravitational waves (d) from dynamical effects (e) from accretion
• Future of primordial black hole detection
• Conclusions
Ranjan Laha
Primordial black holes Primordial Black Holes What are primordial black holes? Primordial black holes are exotic compact objects which can form in the early Universe due to large density perturbations (numerous formation models) and/ or due to new physics (Zel’dovich and Novikov PrimordialAstron. Zhu, 1966, HawkingBlack MNRAS Holes 1971, Carr (PBHs) and Hawking could MNRAS 1974, form Chapline in Nat.the 1975 early and many others; Shandera, Jeong, and Gebhardt 1802.08206 PRL and Kouvaris, Tinyakov, and8 Tytgat 1804.06740 PRL )
Universe ( z
M 17 15 13 11 9 7 5 3 1 1 3 5 10 10 10 10 10 10 10 10 10 10 10 10
30g 57 1018 1020 10122M 1024 2 101026 10kg28 110.301 101032 GeV1034 1036 1038 ⇡ ⇥ ⇡ ⇥ Primordial black holes can have a log-normaleV mass function or a power law mass function1051 10and53 can1055 have10 a57 wide1059 range1061 of spins1063 1065 1067 1069 1071
Ranjan Laha
[Zel’dovich & Novikov (1967), Hawking (1971), Carr & Hawking (1974), Carr (1975)]
Bradley J. Kavanagh (GRAPPA, Amsterdam) Hearing the sirens of the early Universe: PBHs & GWs 3 Primordial black hole (PBH)dark matter MPBH/M⊙ 10-17 10-15 10-13 10-11 10-9 10-7 10-5 10-3 10-1 101 103 100 SN Kepler Mass range where PBHs can lensing K - form the entire dark matter density MACHO/EROS/OGLE
-1 10 SUPER
Subaru O2 result INTEGRAL O1 result 10-2
PBH UF dwarf f
fPBH = fraction of the dark matter in the form of PBHs Planck 10-3 (collisional ionization)
IGRB VOYAGER Global constraints on primordial black hole dark matter Dasgupta, Laha, and Ray 1912.01014 10-4 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 MPBH [g] Multiple constraints exist over wide range of masses (all of these are not shown for clarity)
I will discuss some of these constraints in the following slides (individual references later)
Ranjan Laha Microlensing Dynamical effects stars, supernovae, quasars dwarf galaxies, wide binary stars
Accretion Evaporation CMB, radio & X-ray Primordialgamma-rays black holes constraints from evaporation Constraints
Emission of particles
PBH
Pic. courtesy: Green 2019 talk
Ranjan Laha Effects on stars Mergers white dwarf explosions gravitational waves
[Initially all constraints assume a delta-function PBH mass function.] Evaporation of low-mass primordial black holes
Black holes evaporate to produce Standard Model particles and can have observable consequences S. W. Hawking, Nature 248 10 (1974) 30–31.
Temperature of 10 kg S. W. Hawking,, Commun. Math. the black hole T =1.06 GeV Phys. 43 (1975) 199–220. BH M
The isotropic gamma-ray background and the cosmic MeV background has been used to constrain the density of primordial black holes
The constraint can be derived by either assuming astrophysical contribution(s) to the photon background or by assuming no modeling (to derive a more conservative limit)
100 FERMI Dirac 1 FERMI =0.1 10 FERMI =0.5 10 2 FERMI =1.0 3 10 DM 4 / ⇢ 10 Auffinger, Arbey,
PBH and Silk 1906.04750 Ballesteros etal.
⇢ 5 10 + = Bulge e Dirac 1906.10113 f 6 Bulge e+ =0.1 10 Bulge e+ =0.5 7 Voyager 1 e+ Dirac 10 Voyager 1 e+ =0.1 10 8 Voyager 1 e+ =0.5 Voyager 1 e+ =1.0 10 9 1015 1016 1017 1018 M (g) Low-mass primordial black holes and Galactic Center 511 keV line
0 Low-mass primordial black holes can 10
evaporate to produce e
Cosmic rays rays − CMB Iso 1.5 kpc −1 10 NFW 1.5 kpc gamma The positrons will lose energy, become non- Iso 3 kpc NFW 3 kpc relativistic, and annihilate with the ambient Cosmic rays DM electrons to produce photons f
10−2 Galactic Center observations reveal an Laha 1906.09994 PRL intense flux of 511 keV photons produced Monochromatic by unknown source(s) (talk to R. Crocker and J. Knodlseder for more details about modeling and observation) 10−3 1013 1014 MPBH (kg) Requiring that the positrons from primordial Similar results in DeRocco and Graham 1906.07740 PRL black hole evaporation do not overshoot the positron luminosity produces the strongest These positron measurements can limit on their abundance with masses also be used to constrain spinning between ~ 1013 kg to 1014 kg primordial black hole dark matter (Dasgupta, Laha, and Ray 1912.01014) Microlensing Dynamical effects stars, supernovae, quasars dwarf galaxies, wide binary stars Primordial black holes constraints from lensing
Source
Pic. courtesy: Green 2019 talk
Exotic compact object
Observer
Ranjan Laha Accretion Evaporation CMB, radio & X-ray gamma-rays Constraints
Effects on stars Mergers white dwarf explosions gravitational waves
[Initially all constraints assume a delta-function PBH mass function.] Constraint from supernova lensing
Gravitational lensing of type Ia supernova can be used to constrain compact objects near the line of sight
Some caveats regarding these constraints were also put forward in the literature (Garcia-Bellido, Cleese, and Fleury 1712.06574 Phys. Dark Univ.) 0.9 100 0.8
0.7 SNe lensing 80
(this work) Eridanos II 0.6 (95% c.l.) 0.5 60 M
⌦ 0.4 / 40 0.3 PBH EROS
⌦ Planck (photo) 0.2 Dark Matter fraction [%] ⌘ 20 See earlier study in ↵ 0.1 Planck (coll) Metcalf and Silk astro-ph/0612253 PRL LIGO BHs 0.0 0 4 3 2 1 0 1 2 3 4 10 10 10 10 10 10 10 10 10 MPBH [M ] Zumalacarregui and Seljak 1712.02240 PRL Ranjan Laha Constraint from Subaru HSC observations of M31
Microlensing of stars in M31 can constrain low-mass compact objects (Niikura etal. 1701.02151 Nat. Astron., Montero-Camacho etal. 1906.05950 JCAP, Katz etal. 1807.11495 JCAP, and Smyth etal. 1910.01285)
Important to take into account the finite size of the source and wave optics effect
1 Smyth etal. 1910.01285 0.500 Kepler MACHO
BH Evaporation 0.100 DM / 0.050
1000 500 Constratints
rcinPBH fraction 100 0.010 50 10 See related papers in 5 Niikura etal. 1701.02151 Nat. 0.005 Astron. 1 Old Constraints (R⊙) 1022 1024 1026 1028 Sugiyama etal. 1905.06066 Updated Constraints M (g) Montero-Camacho etal. rcinlCag in Change Fractional PBH 1906.05950 JCAP Katz etal. 1807.11495 JCAP 0.001 1018 1020 1022 1024 1026 1028
MPBH (g) Ranjan Laha 150
EROS−1+EROS−2 ) 7 −
100 EROS−2−LMC = 4.7 10 τ (
50 EROS−1−Plates
N events EROS−2−SMC
EROS−1−CCD Constraint from microlensing0 of stars in the −8 −6 −4 −2 02 Magellanic Clouds logM= 2log(tE /70d) 0.6 Tisserand etal. astro-ph/0607207 Various collaborations have observed Astron. Astrophys. microlensing of stars in the Magellanic Clouds in order to discover massive 0.4 7 astrophysical compact halo objects − MACHO (Tisserand etal. astro-ph/0607207 A&A, 95% cl Wyrzykowski 1106.2925 MNRAS, / 4.7 10 Alcock etal. astro-ph/0011506 ApJL) τ 0.2 EROS−2 + EROS−1
f = upper limit (95% cl)
Wyrzykowski 1106.2925 MNRAS
0.0 −8 −6 −40−2 2 logM= 2log(tE /70d) Signal events have been determined to be due to due to non-dark matter astrophysical objects
-5 Hint of ~ 10 M¤ primordial black hole at fPBH ~ 1%? (Niikura etal. 1901.07120 PRD)
Ranjan Laha Microlensing Dynamical effects stars, supernovae, quasars dwarf galaxies, wide binary stars
Accretion Evaporation CMB, radio & X-ray gamma-rays Constraints
Primordial black holes constraints Effects on stars from gravitationalMergers waves white dwarf explosions gravitational waves
Exotic compact object
Pic. courtesy: Green 2019 talk
Exotic compact object
[Initially all constraints assume a delta-function PBH mass function.] Ranjan Laha Constraint from gravitational waves Gravitational waves from sub-solar ultracompact binaries can be detected by the LIGO Scientific and Virgo collaboration Two recent models of sub-solar mass dark black holes: Shandera, Jeong, and Gebhardt 1802.08206 PRL and Kouvaris, Tinyakov, and Tytgat 1804.06740 PRL
LIGO Scientific and Virgo 1904.08976 PRL
LIGO Scientific and Virgo 1904.08976 PRL
Earlier studies in LIGO Scientific and Virgo 1808.04771 PRL and Magee etal. 1808.04772 PRD
Ranjan Laha
Constraint from gravitational waves Constraint from non-observation of the stochastic gravitational wave background Solid line: mc = 30 M Dashed line: mc = 10 M monochromatic -6 Dot-dashed line: mc = 100 M lognormal, σ=1 LIGO O1 O2 O5 merger rate in the LIGO sensitivity range today C1 -3 -1 -3 -1 = 12 Gpc yr (lower lines) and 213 Gpc yr (upper lines) LISA C2 -8 C3 C4 GW Ω
10 -10 log
0.0 -12 Planck O1 M O1 M -0.5 Eri II WB Raidal, VaskonenWB, and O2 Veermae 1707.01480 JCAP -14 O2 -1.0 -4 -2 0 2 EROS EROS O5 log10(ν/Hz) O5 PBH 1.5 f - Eri II 10
log See other studies in -2.0 Bird etal. 1603.00464 PRL Raidal, Vaskonen, and Sasaki etal. 1603.08338 PRL
Planck -2.5 Veermae 1707.01480 JCAP Raidal, Spethmann, Vaskonen, and Veermae 1812.01930Seg I JCAP Seg I Kavanagh, Gaggero, and Bertone monochromatic lognormal, σ=1 -3.0 1805.09034 PRD -3 -2 -1 0 1 2 3 -3 -2 -1 0 1 2 3
log10(mc /M⊙) Ranjan Laha log10(mc /M⊙) Primordial black holes constraints Microlensing Dynamicalfrom dynamical eff ectseffects stars, supernovae, quasars dwarf galaxies, wide binary stars
Pic. courtesy: Green 2019 talk star star
Primordial black hole
Accretion Evaporation CMB, radio & X-ray gamma-rays Constraints
Effects on stars Mergers white dwarf explosions gravitational waves
[Initially all constraints assume a delta-function PBH mass function.] Constraint from Eridanus II and ultra-faint dwarf galaxies Dynamical heating of the central star cluster of Eridanus II and stars in compact ultra-faint galaxies can constrain massive compact halo objects (MACHOs)/ PBHs
Various astrophysical uncertainties exist, however, the constraints are robust
Further studies in Zhu etal. 1710.05032 MNRAS and Stegmann etal. 1910.04793 MNRAS
Brandt 1605.03665 ApJL Ranjan Laha Constraint from Segue 1 Dynamical heating will cause a lack of stars at the center of the galaxy: observed stellar density constrain massive compact halo objects (MACHOs)/ PBHs
Further studies in Zhu etal. 1710.05032 MNRAS and Stegmann etal. Koushiappas and Loeb 1704.01668 PRL 1910.04793 MNRAS
Ranjan Laha Constraint from wide binaries Gravitational perturbations will cause a disruption in wide binary stars: observations constrain massive compact halo objects (MACHOs)/ PBHs
Monroy-Rodriguez and Allen 1406.5169 ApJ
Earlier studies in Yoo etal. astro-ph/ 0307437 ApJ and Quinn etal. 0903.1644 MNRAS Lett.
Ranjan Laha Primordial black holes constraints from accretion
Pic. courtesy: Green 2019 talk
Ranjan Laha Constraint from cosmic microwave background Accretion of primordial gas on PBHs leads to emission of photons which can be detected via cosmic microwave background
Significant uncertainties in accretion
“Collisional ionization”: radiation from the PBH does not ionize the local gas
� “Photoionization”: wide binaries local gas is ionized ����� micro-lensing due to the PBH Planckultra-faint dwarfs radiation Planck ) ����� (collisional ionization) ��� � (photoionization) ( Other related works: Horowitz ����� ROM 1612.07264 Outdated Aloni, Blum and Flauger ��� constraints 1612.06811 JCAP -� Poulin etal. 1707.04206 PRD �� Abe, Tashiro, and Tanaka 1901.06089 PRD Ali-Haimoud and Kamionkowski 1612.05644 Nakama, Carr, and Silk ��-� PRD 1710.06945 PRD ��� � �� ��� ���� ��� / ���� �Ranjan⊙ Laha Constraint from X-ray and radio point sources Accretion of interstellar gas on PBHs leads to emission of photons which can be detected as point sources in the X-ray and radio sky
Significant uncertainties in accretion 100 Radio 5 X-ray 5 These type of Radio 3 X-ray 3 constraints have been Radio 2 X-ray 2 disputed Hektor, Hutsi, and 1 Raidal 1805.06513 AA
DM 10 f
2 10
PBH DM fraction 3 10 Other related works: Gaggero etal. 1612.00457 PRL Inoue and Kusenko 1705.00791 JCAP Manshanden etal. 1812.07967 JCAP 10 4 20 40 60 80 100 PBH mass [M ] Ranjan Laha Extended mass functions of primordial black holes
Ranjan Laha
Impact of the primordial black hole mass function All the constraints presented earlier are for monochromatic mass function of primordial black holes Many techniques have been proposed in order to convert the monochromatic mass function constraints into constraints on the extended mass functions (Carr etal. 1705.05567 PRD, Green 1609.01143 PRD, Kuhnel & Freese 1701.07223 PRD, Bellomo etal. 1709.07467 JCAP)
Primordial black holes with extended mass functions can also form the entire dark matter density (Bhaumik & Jain 1907.04125 JCAP and many others) EROS-2 MACHO Ultra-Faint Dwarf Galaxies CMB (Spherical Accretion) Bellomo etal. 1709.07467 JCAP fˆCMB 0 0 PBH 10 ˆCMB 10 ˆEROS2 =0.5 Bellomo etal. 1709.07467 JCAP =1.0 f fPBH 0 PBH fˆMACHO 10 ˆUFDG PBH fPBH ˆUFDG ˆMACHO fPBH fPBH ˆEROS2 fPBH
10 1 10 1
PBH 1 f 10
PBH f
fˆPBH fˆPBH EROS-2 EROS-2 MACHO MACHO UFDG UFDG 2 2 10 10 EROS2 MACHO CMB CMB Meq Meq 10 2 100 100 101 102 103 101 102 103 CMB Meq 1 µ [M ] µ [M ] 10 2 10 UFDG 2 Meq 2 2 10 [ln (MPBH/µ)]/2 /dM 3 CMB d e MACHO Meq PBH 10 Meq UFDG d Meq 3 = 10 10 4 EROS2 Meq dMPBH p2⇡ MPBH 5 10
10 6 10 4 Log-normal mass function 100 101 102 103 100 101 102 103 M [M ] M [M ] Ranjan Laha Future probes
Ranjan Laha Future of primordial black hole detection
Detection of primordial black holes at any cosmic density will give us a probe of one of the earliest cosmological era
Important to probe the smallest fPBH value possible
Various near future probes proposed: lensing of fast radio bursts (Munoz etal. 1605.00008 PRL, Laha 1812.11810), lensing of X-ray bursts (Bai and Orlofsky 1812.01427 PRD), lensing of gamma-ray bursts (Katz etal. 1807.11495 JCAP), GRB lensing parallax (Jung and Kim 1908.00078), pulsar timing (Schutz and Liu 1610.04234 PRD & Dror etal. 1901.04490 PRD), and many others Laha 1812.11810 0 0 10 10 WB CMB Laha 1812.11810 UFDG
MACHO MACHO
CMB UFDG
∆ ∆
∆ ∆ ∆ t = 0.1 ms t = 0.3 ms t = 3 ms EROS t = 1 ms t = 3 ms ∆ −1
t = 1 ms −2 10 −1 EROS DM DM 10 f f
∆t = 0.3 ms Monochromatic
Mmin = 1 MO· γ = − 0.5 10−2 constant− SFR density ∆ t = 0.1 ms −2 10 0 1 2 3 100 101 102 103 10 10 10 10
M (M ) Ranjan Laha M (M ) max O· L O· Conclusions Primordial black hole (PBH) is a well motivated dark matter candidate
There are large regions of the parameter space where PBHs can make up the entire dark matter density or a substantial portion of it
It is important to probe this entire parameter space to as small a cosmic densityPrimordial as possible black hole (PBH)dark matter Questions & comments: [email protected] MPBH/M⊙ 10-17 10-15 10-13 10-11 10-9 10-7 10-5 10-3 10-1 101 103 100 SN Kepler Mass range where PBHs can lensing K - form the entire dark matter density MACHO/EROS/OGLE
-1 10 SUPER
Subaru O2 result INTEGRAL O1 result 10-2
PBH UF dwarf f
fPBH = fraction of the dark matter in the form of PBHs Planck 10-3 (collisional ionization)
IGRB VOYAGER Global constraints on primordial black hole dark matter Dasgupta, Laha, and Ray 1912.01014 10-4 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
MPBH [g]Ranjan Laha Multiple constraints exist over wide range of masses (all of these are not shown for clarity)
I will discuss some of these constraints in the following slides (individual references later)
Ranjan Laha