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Fast Radio Bursts and White Hole Signals Aurélien Barrau, CR, Francesca Vidotto

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Fast Radio Bursts and White Hole Signals Aurélien Barrau, CR, Francesca Vidotto Planck Stars: Black-to-white hole tunnelling and Fast Radio Bursts Carlo Rovelli Collaborators Main idea: Francesca Vidotto Classical solution: Hal Haggard Phenomenology: Aurélien Barrau, Francesca Vidotto, Boris Bolliet, Celine Weimer A clear theme emerges from these spacetime diagrams: ⌥ build a time symmetric model (cfr intro talk Akim Kempf) Two deep puzzles we have all wondered about: → → A brief (very incomplete) history of ideas What is the final fate What does actually happen of a black hole? at the classical singularity? What do we miss? Quantum gravity Quantum gravity is not quantum field theory on a geometry! Quantum gravity is the quantum theory of the geometry Difficulties remain until we keep thinking about a classical spacetime and qft over it 3WCPVWOTGIKQP What happens here? General relativity does not teach us that there is a singularity General relativity does teaches us that there is new physics there What happens to the matter falling into black holes? - It disappears (?) - It creates“another universe” (Smolin) - It stays there forever (nothing is forever) - It comes out. At MG2 and in a paper ’79-’81 Valeri Frolov Grigori A. Vilkovisky (left) 1992: remnants Steve Giddings In ’93 Cristopher R. Stephens Gerard ’t Hooft Bernard F. Whiting In ’05 Abhay Ashtekar Martin Bojowald Sean A. Hayward in ’06 cfr Sven Koppel Also: P. Nicolini B. Carr L. Modesto I. Premont-Schwarz S. Hossenfelder J. M. Bardeen G. Ellis … (cfr G Ellis) (cfr Bernard Carr: [see M. Smerlak’s talk] Loop Black Holes) Quantum mechanics is still missing Singularity avoidance by collapsing The Hajicek-Kiefer bounce shells in quantum gravity Petr Hájíček, Clauss Kiefer. IJMP D, (2001), 775. I - Spherical symmetry - Null shell of matter - Classically: Finite dimensional phase space (v,p) separated in two disconnected components: I - p>0: shell collapsing into white hole (future singularity) I - p<0: shell emerging from a white hole (past singularity) - Formal quantization: transition between the two components p I v - Can a black hole truly tunnel into a white hole? Intriguing aspects: I - Classical stable objects often unstable via quantum effects (cfr. nuclear decay). - Hawking radiation takes a huge amount of time (t~m3) and is not a full quantum gravitational phenomenon. I I Difficulties: - Two distinct asymptotic regions. I - A quantum jump involving the entire universe. - What could determine the tunneling time? A clear theme emerges from these spacetime diagrams: ⌥ build a time symmetric model 3WCPVWOTGIKQP What happens here? How big is a black hole? Marios Christodoulou, Carlo Rovelli. V Phys.Rev. D91 (2015) 6, 064046 r =2m V 3p3 ⇡m2v ⇠ v The inside of a black hole is very large What happens near r = 0? From Loop Quantum Cosmology: Inspired by LQC we imagine an effective quantum pressure that avoids a singularity a˙ 2 8⇡G ⇢ = ⇢ 1 a 3 − ⇢ ✓ ◆ Could this✓ “pressure”Pl◆ push matter back out? Would be like a cosmological bounce. a˙ 2 8fiG fl = fl 1 Pressure developsa when3 ≠ fl matter density3 4 reaches 3 Pl 4 The Planck density Planck density does not mean Planck size ! (cfr Bernard Carr) -12 Example: if a star collapses (M ~ M☉), Planck density is reached at 10 cm Planck black Planck star length star hole 10-33 10-12 105 1013 cm 1 R 1 R = m 3 R =2m R m ⇠ 1 There is a relevant intermediate scale between the M 3 L LP Schwarzschild radius LS and the Planck scale LP ⇠ M ✓ P ◆ Does a star bounces at that scale? Planck Stars CR, Francesca Vidotto. IJMP D23 (2014), 1442026 Is this compatible with external classical GR? I I The spacetime The metric of the black-to-white hole transition I Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling Hal M. Haggard, CR arXiv:1407.0989 III II ds2 = F (u, v)dudv + r2(u, v)(d✓2 + sin2✓dφ2) − I vI uI Region I (Flat): F (u ,v )=1,r(u ,v )= − . I I I I I 2 vI < 0. 3 32m r r r Region II F (u, v)= e 2m 1 e 2m = uv. (Schwarzschild): r − 2m ⇣ ⌘ 1 uI uI Matching: rI (uI ,vI )=r(u, v) u(uI )= 1+ e 4m . vo 4m ⇣ ⌘ 3 32m rq Region III (Effective): F (uq,vq)= e 2m ,rq = vq uq. rq − Minkowski region I Outgoing (null) shell Past trapped horizon White hole Quantum region III II Schwarzschild region Conventional black hole Future trapped horizon I Incoming (null) shell Minkowski region The metric of the black-to-white hole transition: parameters The external metric is determined by two constants: 0 = - m is the mass of the collapsing shell. r - δ is the radius at which the two shells meet in the u Schwarzschild metric t = 0 τ v R a = = r The full metric is determined by four constants:r 1 m 3 ✏ 3 lP . Shell enters in quantum region ⇠ m So, cut it up... ✓ P ◆ δ ∆ > δ Maximal extension of quantum region What does δ represent and what determines it? ... and resew to get... Time dilation ⌧ =2R m ln(δ/m) R − T: bounce time (very large) 0 = r u t = 0 2 9 ⌧ m 1ms ⌧external m 10 years internal ⇠τ ⇠ ⇠ ⇠ v R a = = r r “A black hole is a short cut to the future” Time inside: 1 ms Time outside: 10 billions years ! white hole black hole What determines δ ? Quantum gravity Covariant loop quantum gravity. Full definition. n0 l 2 L N hl State space Γ = L [SU(2) /SU(2) ]Γ (h ) =lim Γ n H l H Γ H 3 !1 Kinematics Operators [cfr: Steve]: Boundary Γ spin network (nodes, links) Transition amplitudes W (hl)=N dhvf δ(hf ) A(hvf ) hf = hvf C C SU(2) v v Z Yf Y Y Bulk Dynamics j γ(j+1) j 1 Vertex amplitude A(h )= dg0 (2j + 1) D (h )D (g g− ) vf e mn vf jmjn e e0 SL(2,C) j Z Yf X e Γ v spinfoam W =limW 8⇡~G =1 f C (vertices, edges, faces) C!1 C How non perturbative quantum gravity works Quantum system Boundary = ➜ Hamilton function: S(q,t,q’,t’) Spacetime region States: associated to 3d boundaries of spacetime regions. ➜ Boundary formalism Transition amplitudes: associated to 4d regions Covariant loop quantum gravity. Full definition. n0 l 2 L N hl State space Γ = L [SU(2) /SU(2) ]Γ (h ) =lim Γ n H l H Γ H 3 !1 Kinematics Operators [cfr: Steve]: Boundary Γ spin network (nodes, links) Transition amplitudes W (hl)=N dhvf δ(hf ) A(hvf ) hf = hvf C C SU(2) v v Z Yf Y Y Bulk Dynamics j γ(j+1) j 1 Vertex amplitude A(h )= dg0 (2j + 1) D (h )D (g g− ) vf e mn vf jmjn e e0 SL(2,C) j Z Yf X e Γ v spinfoam W =limW 8⇡~G =1 f C (vertices, edges, faces) C!1 C Covariant loop quantum gravity. Calculation of T(m). j, -k j, k j,k 2 2 (j+ j) (j+ j) A(j, k)= dg dh dh+ e− − e− − SL(2C) SU2 − SU2 Z Z Z j+j X− kσ3 kσ3 n n Trj+ [e Y †gY ]Trj [e Y †gY ] v − j,-k A(j, k) 2 1 ➜ ➜ | | ⇠ relation j-k relation m-time Can we estimate T(m) ? (cfr Gia Dvali, Roberto Casadio, Andrea Giugno) 2M a 2M ·R = 1 R a 2M ln ≠ Û ≠ R 3 ≠ ≠ R 2M 4 ≠ 0 = r Classicality parameter q = ¸ · , u PlR R t =0 here M measures strength of R ≥ R3 ⌧ curvature & q << 1 means classical v R a = r q 1 for a 2M and ·R large enough. = ≥ ≥ 7 r It has a maximum at Rq = 6 (2M ) (outside horizon!) and requiring q 1 ≥ gives · M 2. q ≥ Quantum effect leak out the horizon T m2 ⇠ Observable ? Already observed? Primordial black holes! (cfr Bernard Carr) A real-time FRB 5 Figure 2. The full-Stokes parameters of FRB 140514 recorded in the centre beam of the multibeam receiver with BPSR. Total intensity, and Stokes Q, U,andV are represented in black, red, green, and blue, respectively. FRB 140514 has 21 7% (3-σ)circularpolarisation ± averaged over the pulse, and a 1-σ upper limit on linear polarisation of L<10%. On the leading edge of the pulse the circular polarisation is 42 9% (5-σ)ofthetotalintensity.Thedatahavebeensmoothedfromaninitialsamplingof64µsusingaGaussianfilteroffull-width ± half-maximum 90 µs. source given the temporal proximity of the GMRT observa- 4.5 Gamma-Ray Burst Optical/Near-Infrared tion and the FRB detection. The other two sources, GMRT2 Detector and GMRT3, correlated well with positions for known ra- After 13 hours, a trigger was sent to the Gamma-Ray Burst dio sources in the NVSS catalog with consistent flux densi- Optical/Near-Infrared Detector (GROND) operating on the ties. Subsequent observations were taken through the GMRT 2.2-m MPI/ESO telescope on La Silla in Chile (Greiner et al. ToO queue on 20 May, 3 June, and 8 June in the 325 MHz, 2008). GROND is able to observe simultaneously in J, H, 1390 MHz, and 610 MHz bands, respectively. The second and K near-infrared (NIR) bands with a 100 100 field of epoch was largely unusable due to technical difficulties. The ⇥ view (FOV) and the optical g0, r0, i0,andz0 bands with a search for variablility focused on monitoring each source for 60 60 FOV. A 2 2 tiling observation was done, providing flux variations across observing epochs. All sources from the ⇥ ⇥ 61% (JHK)and22%(g0r0i0z0) coverage of the inner part first epoch appeared in the third and fourth epochs with no of the FRB error circle.
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