A strong bound on the dark matter fraction in primordial black holes - - PowerPoint PPT Presentation

A strong bound on the dark matter fraction in primordial black holes from astronomical data.

Daniele Gaggero

Flic-en-Flac 03/05/2017 10-22 eV 1 eV 1 TeV 1 GeV 1019 GeV (10-5 g) 1057 GeV (1033 g)

“Fuzzy” Dark Matter

λdB ~ 1 kpc ~ size of a dSph Galaxy [Hui, Ostriker, Tremaine, Witten 2016]

Axion-like particles

Primordial black holes (PBHs)

Weakly interacting massive particles (WIMPS) e.g. lightest neutralino state in MSSM

DM candidates: 90 orders of magnitude in mass

Padova 22/06/2017

[Zeld’ovich and Novikov 1966, Hawking 1971]

many constraints from lensing, wide binaries, Galactic disk stability became less popular after MACHO and EROS results [Alcock 2001] now reconsidered in the DM community, as we will see Berlin 30/08/2018

logP(k)

1/2

logk

10

−5

ΛCDM

GBLW ('96)

10

−1

CGB('15) CMB reion LSS

Power spectrum

The PBH - DM connection

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

Garcia-Bellido 1702.08275

• Primordial black holes can collapse in the early Universe out of small-scale large

density fluctuations formed during the inflation era, as soon as the over-densities re- enter the horizon [Y. B. Zel’dovich and I. D. Novikov, Soviet Astronomy 10, 602 (1967); S. Hawking, MNRAS

152, 75 (1971); Carr and Hawking, MNRAS 168 (1974); recent review: Sasaki et al. arXiv:1801.05235]

• Do massive PBHs constitute a significant fraction of the Dark Matter in the Universe?

[Chapline, Nature, vol. 253, Jan. 24, 1975]

• Are the massive PBHs observed by LIGO and Virgo of primordial origin? Is the

merger rate inferred by LIGO and Virgo compatible with this hypothesis? [Bird et al. arXiv:

1603.00464; Sasaki et al. arXiv:1603.08338; Ali-Haïmoud et al. arXiv:1709.06576; Kavanagh et al. arXiv: 1805.09034]

logP(k)

1/2

logk

10

−5

ΛCDM

GBLW ('96)

10

−1

CGB('15) CMB reion LSS

Power spectrum

The PBH - DM connection

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

Garcia-Bellido 1702.08275

• Primordial black holes can collapse in the early Universe out of small-scale

large density fluctuations formed during the inflation era, as soon as the over- densities re-enter the horizon [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); recent review: Sasaki et al. arXiv:1801.05235]

• Do massive PBHs constitute a significant fraction of the Dark Matter in the

Universe? [Chapline, Nature, vol. 253, Jan. 24, 1975]

• Can PBHs be the seeds of IMBHs and SMBHs?

log M logn(M) SBH PBH IMBH SMBH 50MΘ 1MΘ 103MΘ 109MΘ

Black Hole Mass Distribution

Garcia-Bellido 1702.08275

Current constraints

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

The region under the spotlight

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

wide binaries ultra-faint dwarfs micro-lensing

R O M

P l a n c k ( s t r

• n

g f e e d b a c k )

• /⊙

()

Planck (no feedback)

Ali-Haimoud and Kamionkowski, 1612.05644

Our idea: Look at radio and X-ray data

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• If ~30M⊙ PBHs are the DM: ~1011 objects in the Milky Way, ~108 in the Galactic bulge.
• Given the large amount of gas in the inner Galaxy, how easy is it to hide such a population of

PBHs?

• Given conservative estimates of the accretion rate and radiative efficiency, is this population of

PBHs compatible with current radio (VLA) and X-ray (NuStar, Chandra) observations? Our approach: A MC simulation

• We populated the Galaxy with PBHs, and computed the predicted X-ray and radio luminosity
• We produced simulated maps of predicted bright X-ray and radio sources and compared to

data The crucial ingredient: Physics of gas accretion onto PBHs

• What is a conservative estimate of the accretion rate?
• We chose a conservative, small fraction λ ~ 0.02 of the Bondi-Hoyle-Lyttleton rate, compatible with

recent data-driven analyses

˙ M = 4πλ(GMBH)2ρ

• v2

BH + c2 s

3/2

[see e.g. isolated neutron star population estimates and studies of active galactic nuclei accretion R. Perna, et al., ApJ 598, 545 (2003), astro-ph/ 0308081; S. Pellegrini, ApJ 624, 155 (2005), astro-ph/050203]

Results

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

102 101 100 101 102 103 104 105 MPBH [M] 103 102 101 100 DM fraction fPBH = ΩPBH/ΩDM

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

20 40 60 80 100

PBH mass [M]

102 101 100

PBH DM fraction fDM

Radio 5σ Radio 3σ Radio 2σ X-ray 5σ X-ray 3σ X-ray 2σ

X-rays:

[10-40 keV band; ROI: -0.9° < l < 0.3°; -0.1° < b < 0.4°]

• Prediction: more than 3000 bright X-ray sources
• Observed sources in the ROI by Chandra: ~400

(40% are cataclysmic variables)

Radio:

[1 GHz; ROI: -0.5° < l < 0.5°; |b| < 0.4°]

• Prediction 40±6 bright radio sources in the ROI
• Observed radio sources in the ROI: 170
• Number of candidate black holes in the ROI: 0

assuming BHs obey the Fundamental Plane relation

A strong bound in the 10 - 100 Msun range! The constraining power mainly comes from BHs in the low-velocity tail of the BH distribution (v < 10 km/s) accreting gas in the Central Molecular Zone See B. Kavanagh’s poster for a complimentary approach and a stronger bound based on the merger rate of PBH binaries formed in the early universe!

The role of the mass function

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

10 18 10 13 10 8 0.001 100 107 10 5 10 4 0.001 0.01 0.1 1

MPBH M

PBH DM

femtolensing EGB NS capture MACHO EROS FIRAS WMAP3 PBH

Clesse & Garcia-Bellido 1501.07565 Deng&Vilenkin 1710.02865

• Primordial black holes can originate from a variety of mechanisms and can

exhibit broad mass functions of different shapes.

The role of the mass function

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• It is crucial to re-evaluate the constraints depending of the shape of the expected

mass function!

• A remapping method has been proposed in Bellomo+ 1709.07467

102 101 100

fPBH

ˆ f EROS2

PBH

ˆ f MACHO

PBH

ˆ f UFDG

PBH

ˆ f CMB

PBH

102 101 100 ˆ f EROS2

PBH

ˆ f MACHO

PBH

ˆ f UFDG

PBH

ˆ f CMB

PBH

100 101 102 103

M [M]

106 105 104 103 102 101 100

dΦ/dM

MEROS2

eq

MMACHO

eq

MUFDG

eq

MCMB

eq

100 101 102 103

M [M]

104 103 102 MEROS2

eq

MMACHO

eq

MUFDG

eq

MCMB

eq

EROS-2 MACHO Ultra-Faint Dwarf Galaxies CMB (Spherical Accretion)

fMMD

PBH g(Meq, {pj}) = fEMD PBH

Z dM dΦEMD dM g(M, {pj}),

• The method is based on the calculation
• f the equivalent mass
• The equivalent mass is, by definition,

the effective mass associated with a monochromatic PBHs population such that the observable effects produced by the latter are equivalent to the ones produced by the EMD

The role of the mass function

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• We analyzed the impact of different mass distribution functions on our results

via dedicated numerical simulations, and compared to the remapping method proposed in Bellomo+ 1709.07467

Results for log-normal EMDs:

20 40 60 80 100

PBH mass [M]

102 101 100

PBH DM fraction fDM

Delta LN σ = 0.25 LN σ = 0.50 LN σ = 0.75 LN σ = 0.90 LN σ = 1.00

20 40 60 80 100

PBH mass [M]

102 101 100

PBH DM fraction fDM

Delta LN σ = 0.25 LN σ = 0.50 LN σ = 0.75 LN σ = 0.90 LN σ = 1.00

• J. Manshanden, D. Gaggero, G. Bertone et al., in preparation

Radio X-ray

Preliminary! Preliminary!

• J. Manshanden, “Black Hole Dark Matter”, M.Sc. thesis,

University of Amsterdam

The role of the mass function

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

Results for power-law EMDs:

• J. Manshanden, D. Gaggero, G. Bertone et al., in preparation

20 40 60 80 100

Mmax [M]

20 40 60 80 100

Mmin [M]

γ = 0.5

Mmin > Mmax 20 40 60 80 100 Mmax [M]

γ = 0.5

Mmin > Mmax 0.05 0.1 0.2 0.4 0.6 0.8 1.0 fDM

20 40 60 80 100

Mmax [M]

20 40 60 80 100

Mmin [M]

γ = 0

Mmin > Mmax 20 40 60 80 100 Mmax [M]

γ = 0

Mmin > Mmax 0.05 0.1 0.2 0.4 0.6 0.8 1.0 fDM

Radio X-ray

• For each mass

distribution, represented by a point in the (Mmax, Mmin)-space, the color represents the DM fraction fDM that is excluded with a 5σ significance

Radio X-ray

The role of the mass function

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

Comparison with the semi-analytical remapping method

• J. Manshanden, D. Gaggero, G. Bertone et al., in preparation

20 40 60 80 100

µ [M]

102 101 100

PBH DM fraction fDM

LN σ = 1

• Sim. Radio
• Conv. Radio
• Sim. X-ray
• Conv. X-ray

20 40 60 80 100

Mmin [M]

102 101 100

PBH DM fraction fDM

PL γ = 0

• Sim. Radio
• Conv. Radio
• Sim. X-ray
• Conv. X-ray
• We find a good match of the 5σ EMD constraints in the simulations (solid,

radio: dark red, X-ray: blue) with 5σ EMD constraints obtained from the semi-analytical conversion!

Radio X-ray

Log-normal EMD Power-law EMD

A closer look at the physics of accretion

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• MHD numerical simulations are a precious tool to understand the physics of

accretion

• Park&Ricotti 2013 — series of 3 papers presenting state-of-the-art simulations.

Radiation feedback has a crucial role: The accretion rate increases with speed due to the formation of a D-type (dense) ionization front preceded by a bow shock

With increasing Mach number, the density of the shell in the upstream direction increases, and the density behind the dense shell also increases

A closer look at the physics of accretion

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

10 20 30 40 50

vBH [km/s]

10−6 10−5 10−4 10−3 10−2 10−1 100 101

˙ M/ ˙ MEdd

Park&Ricotti (2013) λ = 0.02, unionized λ = 0.02, ionized

˙ MBHL = 4⇡ (GM)2⇢∞ (v2 + c2

∞)3/2

• Park&Ricotti 2013 — series of 3 papers presenting state-of-the-art simulations.

Radiation feedback has a crucial role.

• At large Mach numbers, the Bondi-Hoyle-Littleton formula provides a good

approximation of the accretion rate

• At low Mach number, non-trivial behavior of the accretion rate with the speed due to

the radiation feedback mechanisms (formation of a D-type I-front increases the rate in the supersonic regime)

Our results following Park&Ricotti

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

20 40 60 80 100

PBH mass [M]

104 103 102 101 100

PBH DM fraction fDM

Radio 5σ Radio 3σ Radio 2σ X-ray 5σ X-ray 3σ X-ray 2σ

• The bound was recomputed

adopting the formalism from MHD simulations and an improved modeling of the velocity distribution based on the Eddington formula

• Both the X-ray and radio

bounds get stronger: Given the peak in the accretion rate at high mach numbers, the constraining power does not come from the low-v tail only

• The constraints get either

stronger or weaker with inreasing mass: Trade-off between threshold effect (due to limited sensitivity of the instruments) and population of PBHs getting smaller with increasing mass

• J. Manshanden, D. Gaggero, G. Bertone et al., in preparation

Preliminary!

• J. Manshanden, “Black Hole Dark Matter”, M.Sc. thesis,

University of Amsterdam

0.4 0.2 0.0 0.2 0.4

` []

0.4 0.3 0.2 0.1 0.0 0.1 0.2 0.3 0.4

b []

21.4 21.2 21.0 20.8 20.6 20.4 20.2 20.0

log10(Σgas[g/cm2])

Future prospects: Radio searches with SKA

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• With the SKA1-MID (band 2, 0.95-1.76 GHz) point-source sensitivity, we predict to detect

~2000 sources in the Galactic Ridge ROI (<1° away from the GC) for 1 hour of exposure, if PBHs are the DM and λ ~ 0.02.

• Assuming no candidate BH sources, with SKA data we can place a stringent bound

If a subdominant population of PBHs is present, SKA can detect it (even for a DM fraction at the percent level)

• PBHs seem a testable DM candidate!

0.4 0.2 0.0 0.2 0.4

` []

0.4 0.3 0.2 0.1 0.0 0.1 0.2 0.3 0.4

b []

0.60 0.75 0.90 1.05 1.20 1.35 1.50

log10(Σgas[g/cm2])

Preliminary!

Conclusions

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

• Radio and X-ray data offer the opportunity to strongly constrain the

abundance of DM in PBHs in the 1 - 100 Msun range

• A MC simulations based on conservative assumptions on the physics of

accretion allowed to place a robust bound on the abundance of PBHs

• The impact of an extended mass distribution function (EMD), and of the

assumptions on the accretion physics has been discussed in detail

• Extended EMDs — expected in several formation scenarios — and a

more realistic treatment of the accretion physics, based on numerical simulations that capture the phenomenon of radiative feedback, imply a much stronger bound

• Future radio facilities such as SKA will allow to either place an even

stronger bound or detect a sub-dominant population of PBHs that constitute a small fraction of the DM in the Universe

Pisa 12/01/2017 LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting Berlin 30/08/2018

Thank you!

Backup Slides

Part 1: LIGO, PBHs and DM

Pisa 12/01/2017

In general, PBHs can span an extremely large mass range

• collapse at Planck time (10−43 s) -> Planck mass (10−5 g),
• collapse at ~1 s -> 105 M⊙

if the mass is too low, the PBHs have enough time to evaporate (Hawking-Bekenstein radiation)

• Chapline was among the first to suggest PBHs as a DM candidate [G. F. Chapline, Nature 253,

251 (1975)]

typical ranges for a PBH as DM candidate: M ~ 1016 g (10-17 M⊙) — 1039 g (105 M⊙) size ~ 10-13 cm — 1010 cm number in our Galaxy ~ 1029 — 106

Brief summary on primordial black holes as DM candidate

LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

LIGO, PBHs and DM

Flic-en-Flac 03/05/2017 CAPS meeting SLAP meeting

An argument based on rates: the predicted merger rate is (roughly) compatible with the one inferred by

• LIGO. We’ll go back to this

at the end of the talk!

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

V = Z (dn/dM)(M) R(M) dM. V = 2 f(Mc/400 M)11/21 Gpc3 yr1

• FIG. 2.

The total PBH merger rate as a function of halo

• mass. Dashed and dotted lines show different prescriptions

for the concentration-mass relation and halo mass function.

Simeon Bird, Ilias Cholis, Julian B. Muñoz, Yacine Ali-Haïmoud, Marc Kamionkowski, Ely D. Kovetz, Alvise Raccanelli, Adam G. Riess, Phys. Rev.

• Lett. 116, 201301 (2016)

UCI meeting UCI 20/02/2018

is DM made of PBHs? existing constraints

Pisa 12/01/2017

Existing constraints on DM as PBHs

wide binaries ultra-faint dwarfs micro-lensing

R O M

Planck (strong feedback)

• /⊙

()

Planck (no feedback)

• Lensing constraints

blue line: MACHO project [Alcock et al. 2000]: search for micro-lensing events towards the Large Magellanic Cloud. 13-17 short-duration events reported no long-duration (> 150 days) events

• > constraints up to 30 Msun.

Hints from Andromeda? This channel offers opportunity of detection! purple line: EROS project [Tisserand et al. 2007]; similar strategy, based on a 7-year monitoring of ~106 bright stars in the LMC and SMC

• Dynamical constraints

green line: disruption of wide binaries [1406.5169] red line: ultra-faint dwarf [Brandt 1605.03665], constraint based on a recently discovered star cluster near the center

• f the ultra-faint dwarf galaxy Eridanus II. MACHO dark

matter would lead it to higher velocity dispersions until it dissolves into its host galaxy

LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017

Ali-Haimoud and Kamionkowski, 1612.05644

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

wide binaries ultra-faint dwarfs micro-lensing

R O M

Planck (strong feedback)

• /⊙

()

Planck (no feedback)

Pisa 12/01/2017

Existing constraints on DM as PBHs

• Early universe constraints:

PBHs, if present in the early Universe, would accrete, radiate, heat up and partially reionize the Universe (strong-feedback case assumes that the local gas is entirely ionized due to the PBH radiation) Current bounds are under debate, and based

• n WMAP and PLANCK data.

SKA has the opportunity to probe the altered reionization history induced by PBHs looking at 21 cm brightness temperature fluctuations

xe(z)

z

without PBHs instantaneous asymmetric

Chen et al. 1608.02174

LPTHE 14/02/2017 Padova 22/02/2017 Flic-en-Flac 03/05/2017

is DM made of PBHs? existing constraints

Ali-Haimoud and Kamionkowski, 1612.05644

20 10

• 10

îTb [mK] z = 30

1 0.01

comoving radius [Mpc] comoving radius [Mpc]

0.001 0.1

102Mì 10 Mì 103Mì 105M 104Mì 106Mì 107Mì

10

Tashiro et al. 1207.6405

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

Our idea: why not looking at radio and X-ray data?

Flic-en-Flac 03/05/2017 based on: D. Gaggero, G. Bertone, F. Calore, R. Connors, M. Lovell, S. Markoff, E. Storm, “Searching for Primordial Black Holes in the radio and X-ray sky”, arXiv:1612.00457, PRL 2017

• 0.10
• 0.20
• 68

• If ~30M⊙ PBHs are the DM —> ~1011 objects of this kind in the Milky

Way, and ~108 in the Galactic bulge. (compare to ~108 astrophysical stellar-mass black holes in our Galaxy, Fender et al. arXiv:1301.1341)

• Given the large amount of gas in the inner Galaxy, how easy is it to

hide such a large population of black holes?

• Given conservative estimates of the accretion rate and radiative

efficiency, is this population of PBHs compatible with current radio (VLA) and X-ray (NuStar, Chandra) observations?

• Will SKA have the capability to detect a population of PBHs in our

Galaxy if they are all the DM, or maybe a subdominant population of them?

1.4 GHz, VLA, Lazio & Cordes 2008

10-40 keV, NuStar catalog, Hong et al. 2016

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

1.5 1.0 0.5 0.0 0.5 1.0 1.5

` []

0.4 0.2 0.0 0.2 0.4

b []

Astronomical constraints: our simulation

Flic-en-Flac 03/05/2017

— We set up a MC simulation — We populate the Galaxy with PBHs, and compute the predicted X-ray and radio luminosity — We produce simulated maps of predicted bright X-ray and radio sources

Spatial distribution of PBHs: We consider as a benchmark the NFW distribution. We also consider other variations, based on numerical simulations with baryons (see F. Calore et al., arXiv: 1509.02164)

black line: NFW from Navarro et al. 2004

Velocity distribution: we consider, for each radius R, a Maxwell-Boltzmann distribution centered on v = We use a spherical average of a mass model of the Milky Way M(R) from McMillian 1608.00971

(2016), including DM halo and baryonic

structures (bulge, thin and thick stellar disk, gas distribution).

he GC is a Maxwell ) = p (G M(< R)/R).

1

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

Astronomical constraints: physics of BH accretion

Flic-en-Flac 03/05/2017

• A crucial ingredient is the physics of gas accretion on BHs

—> what is a conservative estimate of the accretion rate? —> what is a conservative estimate of the radio and X-ray emission?

1) Accretion rate: a small fraction of the Bondi-Hoyle rate:

• λ ~ 0.02 (conservative value)

isolated neutron star population estimates and studies of active galactic nuclei accretion

• R. Perna, et al., ApJ 598, 545 (2003), astro-ph/0308081
• S. Pellegrini, ApJ 624, 155 (2005), astro-ph/050203

2) We assume radiative inefficiency

• Physical picture: advection-dominated accretion in which the gas cooling timescales greatly exceed

the dynamical timescales

Narayan and Yi 1994, “Advection-Dominated Accretion: A Self-Similar Solution” Blanford and Begelman 1998: “On the Fate of Gas Accreting at a Low Rate onto a Black Hole”

˙ M = 4πλ(GMBH)2ρ

• v2

BH + c2 s

3/2

η, defined by y LB = η ˙ Mc2,

relation for the bolometric lumi η = 0.1 ˙ M/ ˙ M crit for ˙ M < ˙ Mcrit

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

Astronomical constraints: comparison with data

Flic-en-Flac 03/05/2017

30 35 40 log Lradio (erg s−1) 35 40 45 50 55 log Lxray − ξM log MBH (erg s−1)

Beamed BL Lacs GBH (10 MΟ

• )

Sgr A* (106 MΟ

• )

LLAGN (107−8 MΟ

• )

FR I (108−9 MΟ

• )

SDSS HBLs (108−9 MΟ

• )

X-rays:

• 30% of the bolometric luminosity in the 2-10 keV band [Fender 2013]
• We extrapolate to the 10-40 keV band assuming a hard power-law (index 1.6)
• We compare to the NuStar catalog [Hong et al. 2016] data in the 10-40 keV band

(threshold: 8 * 10 32 erg/s; ROI: -0.9° < l < 0.3°; -0.1° < b < 0.4°) and to the Chandra catalog

in the 0.5-8 keV band Radio:

• We use fundamental plane relation between soft X-ray and radio luminosity [Plotkin et al.

2013]

• We are assuming that the BH launches a jet, and is in the “hard state”
• We convert X-ray fluxes into radio fluxes (1 GHz) and compare to the VLA catalog

(threshold ~1 mJy; ROI: -0.5° < l < 0.5°; |b| < 0.4°)

• We also compute the number of point sources detectable by SKA1-MID.

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

Astronomical constraints: our results

Flic-en-Flac 03/05/2017

wide binaries ultra-faint dwarfs micro-lensing

ROM

Planck (strong feedback)

• /⊙

()

Planck (no feedback)

X-rays:

• Prediction: more than 3000 bright

X-ray sources

• Observed sources in the ROI by

Chandra: ~400

(40% are cataclysmic variables)

Radio:

• Prediction 40±6 bright radio

sources in the ROI

• Observed radio sources in the ROI:

170

• Number of candidate black holes in

the ROI: 0 assuming BHs obey the Fundamental Plane relation

(i.e. no radio source in the ROI have a X-ray counterpart compatible with the FP relation they cannot be BHs accreting in the hard state)

30 100 M [M] 102 101 100 DM fraction fDM

Radio constraint (2σ, 3σ, 5σ); λ = 0.02 X-ray constraint (2σ, 3σ, 5σ); λ = 0.02

CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

Astronomical constraints: our results

Flic-en-Flac 03/05/2017 X-rays:

• Prediction: 160±12 bright X-ray

sources

• Observed sources in the ROI: 70

(40% of those are cataclysmic variables)

Radio:

• Prediction 40±6 bright radio

sources in the ROI

• Observed radio sources in the ROI:

170

• Number of candidate black holes in

the ROI: 0, assuming that BHs obey the Fundamental Plane relation

(i.e. no radio source in the ROI have a X-ray counterpart compatible with the FP relation they cannot be BHs accreting in the hard state)

0.4 0.2 0.0 0.2 0.4

` []

0.4 0.3 0.2 0.1 0.0 0.1 0.2 0.3 0.4

b []

21.4 21.2 21.0 20.8 20.6 20.4 20.2 20.0

log10(Σgas[g/cm2]) The constraining power mainly comes from BHs in the low-velocity tail of the BH distribution (v < 10 km/s) accreting gas in the Central Molecular Zone (a compact, very dense region in the inner Galactic bulge) CAPS meeting SLAP meeting UCI meeting UCI 20/02/2018

102 M [M] 104 103 102 101 100 DM fraction fDM

Projected SKA radio constraint (1000 hours, 5σ); λ = 0.001

Our predictions for SKA (very optimistic scenario)

Flic-en-Flac 03/05/2017

It is possible to get a strong bound (or detect a population of sources) even for much lower values of λ (as low as 10-3), but a much larger integration time is needed: O(1000 h)

compare to other projected bounds (e.g. pulsar timing, 21 cm fluctuations)

Very preliminary!

1 10 100 1000 1 0.1 0.01 M [M⊙] fPBH Limits on PBH DM Abundance

EROS Known Pulsars Ultra-faint Dwarfs FRB Lensing Eridanus II W i d e B i n a r i e s SKA Pulsars

Schutz et al. 2017

10-6 10-5 10-4 10-3 10-2 10-1 100 10-3 10-2 10-1 100 101 102 103 104 fPBH MPBH/M ML WMAP SKA FIRAS

Gong et al. 2017

CAPS meeting SLAP meeting UCI 20/02/2018