Quantum Insights on. as Dark Matter

Transcription

1 Quantum Insights on Primordial Black Holes as Dark Matter UPV/EHU - Bilbao 2ND WORLD SUMMIT ON EXPLORING THE DARK SIDE OF THE UNIVERSE Guadalupe Island - June 29 th, 2018

2 THE DARK SIDE OF GRAVITY Caution: not a complete list! DARK ENERGY Cosmological Constant (or more complicated GR modification) Gravitational Backreaction see Buchert s talk Quantum Gravity: Spacetime Discreteness Perez, Sudarsky, Bjorken DARK MATTER Mond, Mimetic Gravity and other classical modification of GR Bimetric Gravity see Henry-Couannier s talk N-body Equivalence Principle Quantum Gravity: Minimal Acceleration Emergent Gravity Primordial Black Holes see also Garcia-Bellido s talk Alexander, Smolin Smolin Verlinde

3 PRIMORDIAL BLACK HOLES PBHs are the least exotic beast in the dark universe zoo of theories PBHs are a viable DARK MATTER candidate * careful with old constraints in the literature! PBHs are interesting even if they are not all DARK MATTER * PBHs can be used to test QUANTUM GRAVITY

4 IN THIS TALK: QUANTUM GRAVITY 1. QG makes PBH remnants stable * Quantum Gravity: minimal aerea 2. QG cures GR singularities * NO central BH singularity, NO cosmological singularity: instead a bounce 3. QG allows for Black-to-White tunnelling * Decay happens faster than the Hawking evaporation: new phenomenology 3 different scenarios discussed in this talk

5 QUANTUM EFFECTS MAKE REMNANTS STABLE WHITE HOLES AS REMNANTS 1 LARGE INTERNAL VOLUME ~ Mo 4 It depends only on the original mass Mo at the BH formation Christodoulou, Rovelli Christodoulou, De Lorenzo Bianchi, Cristodoulou, D Ambrosio, Haggard, Rovelli REMNANT LIFETIME ~ Mo 4 Time for information to leak out from such a large volume trough the small WH surface. PROCESSES 1. BH volume increase & WH volume decrease 2. White to black instability 3. Hawking evaporation 4. Black to white tunnelling Rovelli, Vidotto From the outside, at a finite time, no distinction between black and white holes STABILITY The minimal area yields a minimal mass! Ri = p a b B,µi W, µi p 1+ a b oscillation between black and white hole states

6 Scenario 1 REHEATING Remnants Quantum Black Holes

7 REMNANTS FORMED AFTER INFLATION Rovelli, Vidotto PBHs form at the reheating, evaporates and evolve in a long-living remnant REMNANT LIFETIME COMPATIBLE WITH FORMATION AT REHEATING Mo 4 thubble Mo 3 < thubble gr apple mmo 3 o < gr cm apple R o < cm NUCLEOSYNTHESIS BH evaporation should not modify D/H, Li6/Li7, and He3/D ratio

8 Scenario 2 BIG BOUNCE Remnants Quantum Black Holes

9 BIG BOUNCE REMNANTS Rovelli, Vidotto BOUNCING BLACK HOLES IN A BOUNCING UNIVERSE Planckian PBH remands from a previous eon (Penrose s EREBONS) Planck size particles can pass trough the bounce. Quintin, Brandenberger Carr, Clifton, Coley PAST LOW ENTROPY Matter near thermal equilibrium: geometry has low entropy A volume of the universe outside BH as low as only 1/TH could have been outside the remnants at the bounce! of the total DARK MATTER We want Mo 4 thubble for them to survive till today. Inflation dilutes PBH: 1 T 2 H ȧ a 2 M, b T 3 H T H V int = b V WH >T 2 H. MATTER BOUNCE: PBH as pressureless component

10 QUANTUM BOUNCE Quantum Tunneling superposition Effective repulsive force Planck density expanding solution Size Planck length V b m `3P cm 3 m P Phenomenology signature in the CMB pre-big-bang accessible see Ashtekar,Barrau for a review contracting solution

11 BH EXPLOSION quantum region Planck Star Vidotto, Rovelli Black -to- White tunnelling Quantum Black Holes

12 Scenario 3 FAST EXPLOSION Quantum Black Holes

13 QUANTUM EFFECTS SHORTEN BH LIFETIME Black Hole Lifetime Quantum Gravity effects should manifest before the Page time (firewalls!) the hole lifetime must be shorter or of the order of ~ m 3 Vidotto, Rovelli Black-to-White Tunnelling Minimal time for quantum effects to appear on the horizon: Curvature (time) ~ (L P ) -1 the hole lifetime must be longer or of the order of ~ m 2 1m r 3 m 2 T b 1 See also Quantum Break Time Dvali, Gomez Other BH instabilities? From large extra dimensions? From infinite branes? Gubser 2002, Kol 2002 Emparan, Garcıa-Bellido, Kaloper 2003

14 (QUANTUM) PBH DARK MATTER Today, black holes smaller than m(t) t=th have already exploded. It decreases with time. ( but for later accretion/merging ) Caution with constraints! Raccanelli, Vidotto, Verde Constraints from Hawking evaporation do not apply any more. G 04 +BCA B B 1 A 8 B Effects on late cosmology 92,0 G Galaxy clusters surveys G 3/ BCA6 CB DBC8A 45 8 B 2A8 DB BCA6 CB G G G G G G 1 1 H

15 EFFECT ON GALAXY CLUSTERS Raccanelli, Vidotto, Verde C XY ` (z i,z j )= Da X`m(z E i ) a Y `m(z j ) angular positions and redshifts perturbed by peculiar velocities, gravitational lensing and potentials Choice of redshift distribution: ) ,,4 1 0,,4 1 0,, ( ), ,

16 Characterisation of the signal Quantum Black Holes

17 PBH EXPLOSIONS Barrau, Rovelli, Vidotto fast process ( few milliseconds? ) the source disappears with the burst very compact object: big flux E = mc erg exploding today: m = r th 4k kg R = 2Gm c 2.02 cm LOW ENERGY: size of the source wavelength predicted &. 2 cm (?) HIGH ENERGY: energy of the particle liberated Tev SYNCHROTRON EMISSION Kavic &al GRAVITATIONAL WAVES Quantum Gravity Phenomenology

18 FAST RADIO BURSTS fast process ( few milliseconds ) compact object: big flux E = mc erg HIGH ENERGY Tev REES MECHANISM Kavic &al Electron-positron pairs traveling trough a magnetic field Repetition can be due to: reflection of the signal due to plasm walls region dense of PBH LOW ENERGY: size of the source wavelength predicted &. 2 cm We may have missed a factor in our rough calculation! We may be seeing only the a window in a distribution of event Barrau &al Quantum Gravity Phenomenology

19 MAXIMAL DISTANCE Barrau, Bolliet, Vidotto, Weimer shorter lifetime smaller wavelength Low energy channel High energy channel Hubble radius Galactic scale R [m] Galactic scale R [m] Hadron decay Direct emission k E [ev] k E [ev] detection of arbitrarily far signals better single-event detection PBH: mass - temperature relation different scaling

20 THE SMOKING GUN: DISTANCE/ENERGY RELATION distant signals originated in younger, smaller&hotter sources

21 THE SMOKING GUN: DISTANCE/ENERGY RELATION distant signals originated in younger, smaller&hotter sources

22 THE SMOKING GUN: DISTANCE/ENERGY RELATION other obs =(1+z) other emitted. obs 2Gm c 2 (1 + z) v u t H k 1/2 sinh 1 " M 1/2 (z + 1) 3/2 # distance 1/wave length l taking into account the redshift the resulting function is very slowly varying Barrau, Rovelli, Vidotto z

23 INTEGRATED EMISSION m 2 Barrau, Bolliet, Vidotto, Weimer Low energy channel High energy channel k=0.05 direct decayed k=0.05 direct+decayed enlarged dn mes dedtds = Z ind((1+z)e,r) n(r) ) Acc Abs(E,R)dR, characteristic shape: distorted black body depends on how much DM are PBL

24 ues of k, i.e. for longer black-hole lifetimes. Z mordial black holes are directly formed by t M (t+ t) worth considering the n(r) term a bit more in of density dn fluctuations with a high-enough d n(r) = dm, (8) dn for the smaller the lowpbh energy channel, values rawn: If one denotes by the initial di erential MASS SPECTRUM indv the early Universe, the initial mass s dm dmspectrum dv M (t) trast PBH MASS, a single bounce canblack be detected arbitrary far ectrum of primordial holes per unit volume, directly related to the equation of state of th to a better singley in the Universe. ssible to define n(r) as:leading to at the formation epoch. It is given by [18, 19 h energy channel. s cases, the signal a t)are large enough and exall the distances ZinM (t+ dn t dn dn being hopeless w d, thisn(r) e ect is overmental detection is far from 1+w, n(r), (9) M = = dm, (8) dm dv 8k dm dv dm dv unt of photons.m (t) tances the where the mass spectrum is where evaluated the mass w =forp/. In a cormatter-dominated u III. between INTEGRATED EMISSION to 1+3w Low decreases forenergy higher channel responding to a time (th R ). If one assumes that priexponent 1 c 1+w takes the value k-hole lifetimes. mordial black holes are directly by the coefficient collapse will be kep The formed normalization dn t tion to the instantaneous emitted by(9) awith a high-enough density conn(r), ofspectrum density fluctuations as it depends on the details of the black hole dm dv 8k uncing black hole, it is interesting to consider the the smaller values compotrast in the early Universe, the initial mass is amount of primo mechanism. Forspectrum a sizeable di use background to the integrated emistected far due directly llowing arbitrary related to thecorequation state of the he mass spectrum is evaluated for the mass holesof to form, the Universe powermass spectrum normali Different spectra population of bouncing black holes. Formally, epoch. given needs by [18,to19]: ing to a time (th Rc ).atifthe oneformation assumes that pri-it iscmb be boosted at small scales. gives qualitatively same er of measured photons detected per unit time, black holesand are exdirectly formed by the collapse be achieved, for example, through Staobinsk rge enough diffuse emission singlegy and unit surface, can be written as: dn 1+3w 1 invariance tybeing fluctuations nel. Al- hopeless.with a high-enough density con-= M scale (BSI) (10) scenario. The idea m 1+w, Z althe in early a dm dv is mass spectrum takes a high enough value in t Universe, the initial mass spectrum = ((1+z)E, R) n(r) Acc Abs(E, R)dR, isrelated over-indto the equation of state of the Universe range whereas it is naturally suppressed at sm where = 19]: p/. In(7) a matter-dominated universe the ons. MISSION ormation epoch. It is given by w[18, by inflation and at large masses by the BSI 1+3w exponent 1 takes thenot value = 5/2. 1+w We will study those questions here and ju flux emitted nd (E, een ther) denotes the individual The normalization coefficient shape will be keptresulting unknown 1+3w dn the of the emission, nor its no 1 ectrum emitted by=a M gle bouncing black hole at 1+w distance R and (10) at higher, as it depends on the details which of the depends black holesensitively formationon the bounds o dm dv sting the acceptance of the detector, Acctoisconsider the angular mes. mechanism. For a sizeable spectrum, amount of that primordial black are highly model-dependent. A he integrated emisd by its efficiency (in principle this is also a holes to form, the power spectrum normalized on to thethe investigation o w = p/. In a matter-dominated universe the values of the study is devoted ck holes. Formally, of E but this will be ignored here), Abs(E, R) 1+3w CMB needs to = be boosted atthe small scales. This can rary far nt 1 takes the value 5/2. of signal, the y axis on the figures are not n 1+w ected per unit time, sorption function, and n(r) is the number of be will achieved, for example, Staobinsky s broken FIG. 5: Low energy channel signal calculatedthrough for di erent rmalization coefficient be kept unknown Quantum Gravity Phenomenology written as: es bouncing at distance R per unit time and

25 to conclude Quantum Black Holes

26 SUMMARY ON REMNANTS 1. REMNANTS AS DARK MATTER * compatible with PBH formation at reheating * stability via minimal area/mass 2. BOUNCE 2 : Bouncing BH in a Bouncing Universe - their presence in the contracting phase yields ns scale invariance - large old volume inside remnants make sense of the Past Hypothesis 3. FAST EXPLODING PBH - phenomenology depends on the lifetime as short as m 2 - new experimental window for quantum gravity - signals in the sub-mm, radio & TeV direct detection & diffuse emission peculiar energy distance relation also late-universe observations what else can change if black holes explode this way?

27 MAIN REFERENCES Planck Stars Cosmic Rays Late Cosmo. Remnants Planck stars Carlo Rovelli, Int. J. Mod. Phys. D23 (2014) 12, Planck star phenomenology Aurelien Barrau, Carlo Rovelli. Phys. Lett. B739 (2014) 405 Fast Radio Bursts and White Hole Signals Aurélien Barrau, Carlo Rovelli,. Phys. Rev. D90 (2014) 12, Quantum effects of Primordial Black Holes on Galaxy Clustering Alvise Raccanelli, Licia Verde, to appear in JCAP, e-print: arxiv: Planck stars as observational probes of quantum gravity Carlo Rovelli Nature Astronomy, March 17, comment Phenomenology of bouncing black holes in quantum gravity: a closer look Aurélien Barrau, Boris Bolliet,, Celine Weimer JCAP 1602 (2016) no.02, 022 Fast radio bursts and the stochastic lifetime of black holes in quantum gravity Aurélien Barrau, Flora Moulin, Killian Martineau Phys.Rev. D97 (2018) no.6, White Holes as Remnants: A Surprising Scenario for the End of a Black Hole Eugenio Bianchi, Marios Christodoulou, Fabio D Ambrosio, Hal Haggard, Carlo Rovelli e-print: arxiv: Erebons Small black/white hole stability and dark matter Carlo Rovelli,. e-print: arxiv: Pre-big-bang black-hole remnants and the past low entropy Carlo Rovelli,. e-print: arxiv: