Moriond 2015 Gravitation Highlights (first part)

Transcription

1 Rencontres de Moriond Gravitation: 100 years after GR Moriond 2015 Gravitation Highlights (first part) Luc Blanchet Gravitation et Cosmologie (GRεCO) Institut d Astrophysique de Paris 28 mars 2015 Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 1 / 37

2 Gravitation: 100 years after GR 1 Gravitational waves General relativity is the correct tool for the future GW astronomy Direct observations of GW will put bounds on deviations of GR in the strong field regime, e.g. by checking the no-hair theorems for black holes 2 Modified gravity & alternatives We do not expect GR to be valid above the Planck scale GR faces a crisis in cosmology (dark matter and dark energy) which may be evidence for a modification in the IR At small galactic scales, for very weak accelerations, there is evidence that new physics happens in the distribution of dark matter Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 2 / 37

3 Gravitation: 100 years after GR 1 Gravitational waves General relativity is the correct tool for the future GW astronomy Direct observations of GW will put bounds on deviations of GR in the strong field regime, e.g. by checking the no-hair theorems for black holes 2 Modified gravity & alternatives We do not expect GR to be valid above the Planck scale GR faces a crisis in cosmology (dark matter and dark energy) which may be evidence for a modification in the IR At small galactic scales, for very weak accelerations, there is evidence that new physics happens in the distribution of dark matter Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 2 / 37

4 Gravitation: 100 years after GR 1 Gravitational waves General relativity is the correct tool for the future GW astronomy Direct observations of GW will put bounds on deviations of GR in the strong field regime, e.g. by checking the no-hair theorems for black holes 2 Modified gravity & alternatives We do not expect GR to be valid above the Planck scale GR faces a crisis in cosmology (dark matter and dark energy) which may be evidence for a modification in the IR At small galactic scales, for very weak accelerations, there is evidence that new physics happens in the distribution of dark matter Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 2 / 37

5 Gravitational waves GRAVITATIONAL WAVES Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 3 / 37

6 Binary pulsars Gravitational waves Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 4 / 37

7 Binary pulsars Gravitational waves Measurement of relativistic orbital effects ω: relativistic advance of periastron γ: gravitational red-shift and second-order Doppler effect r and s: amplitude and shape of Shapiro time delay P : secular decrease of orbital period Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 4 / 37

8 Binary pulsars Gravitational waves Paulo Freire: Tests of GR & alternative theories of gravity with binary pulsars Three independent tests of GR with the double pulsar PSR J Constraints on the emission of dipolar radiation with PSR Several alternative theories like TEVES are ruled out Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 5 / 37

9 Binary pulsars Gravitational waves Paulo Freire: Tests of GR & alternative theories of gravity with binary pulsars Three independent tests of GR with the double pulsar PSR J Constraints on the emission of dipolar radiation with PSR Several alternative theories like TEVES are ruled out Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 5 / 37

10 Gravitational waves World-wide network of interferometric detectors A Global Network of Interferometers LIGO Hanford 4 & 2 km GEO Hannover 600 m Kagra Japan 3 km LIGO Livingston 4 km Virgo Cascina 3 km LIGO South Indigo Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 6 / 37

11 Gravitational waves Binary neutron star merger localisation 90% localization ellipses for face-on BNS 160 Mpc Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 7 / 37

12 Gravitational waves Binary neutron star merger localisation 90% localization ellipses for face-on BNS 160 Mpc Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 7 / 37

13 Gravitational waves Ground-based advanced detectors Chris Van Den Broeck: Gravitational wave searches with advanced LIGO/Virgo 1 Advanced gravitational wave observatories are getting ready to make first direct detections in the next few years 2 Wealth of possible sources: Coalescing binaries composed of neutron stars or black holes Burst events: supernovae, cosmic strings,..., and the unknown! Continuous waves from fast-spinning neutron stars Stochastic backgrounds Fundamental, cosmological Confusion backgrounds (e.g. weak signals from coalescing binaries out to large distances) 3 Robust data analysis techniques are in place Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 8 / 37

14 Gravitational waves Ground-based advanced detectors Andrea Viceré: What advanced detectors will be able to do 1 Range for BNS or BBH expanded by 10 = rate by Amplitude sensitivity improved by 10 = same factor improvement of upper limit (or detection) of signals from galactic distorted NS: allow to probe ellipticities down to Detection of impulsive events in our Galaxy with energies as small as 10 9 M c 2 = possible detection of next supernova 4 Limits on stochastic background, e.g. on Ω GW, improved by a factor Localization of BNS events improved as sensitivity progresses and all detectors come on line Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 9 / 37

15 Gravitational waves Neutron stars in GR Dorota Gondek-Rosińska: A new view on differentially rotating NS in GR Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 10 / 37

16 Gravitational waves Ground-based advanced detectors Chris Belczynski: Theoretical Predictions for Mergers of BH-BH Binaries STANDARD EVOLUTION: LIGO/VIRGO UPPER LIMITS MODELS A MODELS B Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 11 / 37

17 Gravitational waves Ground-based advanced detectors Chris Belczynski: Theoretical Predictions for Mergers of BH-BH Binaries Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 11 / 37

18 Gravitational waves Some interesting event Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 12 / 37

19 Gravitational waves Some interesting event short GRB in Andromeda? Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 12 / 37

20 Gravitational waves Short GRB in Andromeda? Giulia Stratta: Multi-messenger past searches and future program The gamma-ray observatory SVOM will be in operation on line with LIGO/VIRGO Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 13 / 37

21 Gravitational waves Space-based laser interferometric detector Ed Porter: Exploring the mhz Gravitational Wave Universe with elisa Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 14 / 37

22 Gravitational waves Supermassive black-holes detected by elisa Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 15 / 37

23 Gravitational waves The gravitational chirp of compact binaries inspiralling phase merger phase ringdown phase innermost circular orbit r = 6M Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 16 / 37

24 Gravitational waves The gravitational chirp of compact binaries inspiralling phase post-newtonian theory merger phase numerical relativity ringdown phase perturbation theory innermost circular orbit r = 6M Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 16 / 37

25 Gravitational waves Post-Newtonian calculation of compact binaries S 1 J = L + S + S m 1 S 2 CM 1 2 L m 2 Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 17 / 37

26 Gravitational waves Post-Newtonian calculation of compact binaries S 1 J = L + S + S m 1 S 2 CM 1 2 L m 2 Sylvain Marsat: PN higher-order spin effects in inspiraling compact binaries Spin effects in equations of motion SO to 3.5PN SS to 4PN SSS to 3.5PN Spin effects in radiation field SO to 3.5PN+4PN SS to 3PN SSS to 3.5PN Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 17 / 37

27 Gravitational waves Matching numerical relativity to the PN Alejandro Bohé: Comparaison between NR and PN waveforms PN and NR waveforms are combined into hybrid waveforms provided that they overlap over the late inspiral The construction of hybrids and comparison over the overlapping portion has been studied in details in the case of the dominant (2,2) and (3,3) modes Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 18 / 37

28 Gravitational waves Matching numerical relativity to the PN Alejandro Bohé: Comparaison between NR and PN waveforms (2,2) mode at 3.5PN order r2, MΩ 0 (3,3) mode at 3PN order 1.20 r3, MΩ 0 PN and NR waveforms are combined into hybrid waveforms provided that they overlap over the late inspiral The construction of hybrids and comparison over the overlapping portion has been studied in details in the case of the dominant (2,2) and (3,3) modes Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 18 / 37

29 Gravitational waves Matching numerical relativity to the PN Alejandro Bohé: Comparaison between NR and PN waveforms (2,2) mode at 3.5PN order r2, MΩ 0 (3,3) mode at 3.5PN order r3, MΩ 0 PN and NR waveforms are combined into hybrid waveforms provided that they overlap over the late inspiral The construction of hybrids and comparison over the overlapping portion has been studied in details in the case of the dominant (2,2) and (3,3) modes Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 18 / 37

30 Gravitational waves Synergy between PN and perturbative SF The motion of the particle deviates from a geodesic of the background because of its own stress-energy hence the appearance of a SF a µ = F µ SF = O ( m M a = 0 a = F F ) m SF M SF Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 19 / 37

31 Gravitational waves Synergy between PN and perturbative SF The motion of the particle deviates from a geodesic of the background because of its own stress-energy hence the appearance of a SF a µ = F µ SF = O ( m M a = 0 a = F F ) m SF M SF Guillaume Faye: High-order comparisons between PN and perturbative SF A comparison between PN and SF conservative parts of the dynamics Computation of high-order half-integral PN terms in Detweiler s observable a 5.5PN = π, a 6.5PN = π, a 7.5PN = π Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 19 / 37

32 Gravitational waves Synergy between PN and perturbative SF I + u µ k µ k µ light ring I Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 20 / 37

33 Gravitational waves Synergy between PN and perturbative SF Alexandre Le Tiec: Gravitational SF correction to the ISCO of a Kerr BH method (i) method (ii) 1.32 C Ω χ = S / M 2 [ Ω ISCO = Ω Kerr ISCO(χ) 1 + q C Ω (χ) + O ( q 2)] }{{} self-force correction Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 21 / 37

34 Gravitational waves Synergy between PN and perturbative SF Alexandre Le Tiec: Gravitational SF correction to the ISCO of a Kerr BH PN (ISCO) PN (MECO) EOB (ISCO) δc Ω /C Ω χ = S / M 2 [ Ω ISCO = Ω Kerr ISCO(χ) 1 + q C Ω (χ) + O ( q 2)] }{{} self-force correction Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 21 / 37

35 Gravitational waves Synergy between PN and perturbative SF Alexandre Le Tiec: Gravitational SF correction to the ISCO of a Kerr BH PN (ISCO) PN (MECO) EOB (ISCO) δc Ω /C Ω χ = S / M 2 Tal Alexander: Relativistic stellar dynamics around a massive black hole Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 21 / 37

36 Modified gravity & alternatives MODIFIED GRAVITY & ALTERNATIVES Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 22 / 37

37 Modified gravity & alternatives Massive gravity theory? Fierz & Pauli [1939] action: Unique linear theory for massive spin-2 gravity without ghosts S FP = 1 16π [ d 4 x µ h νρ µ h νρ H µ H µ }{{} Einstein-Hilbert action for gµν = ηµν + hµν The massive graviton has 5 defrees of freedom + m 2 ( g hµν h µν h 2) ] }{{} mass term Discontinuity of Van Dam, Veltman & Zhakharov [1970]: Massless limit of massive gravity differs from GR and is invalidated by Solar System tests (deflection of light by the Sun) γ PPN = 1 2 (?) Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 23 / 37

38 Modified gravity & alternatives Massive gravity theory? Fierz & Pauli [1939] action: Unique linear theory for massive spin-2 gravity without ghosts S FP = 1 16π [ d 4 x µ h νρ µ h νρ H µ H µ }{{} Einstein-Hilbert action for gµν = ηµν + hµν The massive graviton has 5 defrees of freedom + m 2 ( g hµν h µν h 2) ] }{{} mass term Discontinuity of Van Dam, Veltman & Zhakharov [1970]: Massless limit of massive gravity differs from GR and is invalidated by Solar System tests (deflection of light by the Sun) γ PPN = 1 2 (?) Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 23 / 37

39 Modified gravity & alternatives Massive gravity theory? Vainshtein [1972] mechanism: Nonlinear terms may restore the continuity of the massless limit and GR is recovered for ( M r < r Vainshtein = m 4 g ) 1/5 Explicit proof given by Babichev, Deffayet & Ziour [2009] Boulware-Deser [1972] ghost: An instability appears at quadratic order due to a 6-th degree of freedom for the massive spin-2 field instead of 5 Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 24 / 37

40 Modified gravity & alternatives Massive gravity theory? Vainshtein [1972] mechanism: Nonlinear terms may restore the continuity of the massless limit and GR is recovered for ( M r < r Vainshtein = m 4 g ) 1/5 Explicit proof given by Babichev, Deffayet & Ziour [2009] Boulware-Deser [1972] ghost: An instability appears at quadratic order due to a 6-th degree of freedom for the massive spin-2 field instead of 5 Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 24 / 37

41 Modified gravity & alternatives Ghost-free massive gravity theory [de Rham, Gabadadze & Tolley 2010] The theory is defined non-perturbatively as S = c3 16πG d 4 x [ g R[g] + m 2 g where the matrix K 1 g 1 f and we pose L 2 = 1 [ ] (TrK) 2 Tr(K 2 ) 2 L 3 = 1 [ ] (TrK) 3 3TrKTr(K 2 ) + 2Tr(K 3 ) 6 L 4 = 1 24 )] (L 2 + α 3 L 3 + α 4 L 4 } {{ } mass term [ (TrK) 4 6(TrK) 2 Tr(K 2 ) + 8TrKTr(K 3 ) 6Tr(K 4 ) The second metric f µν can be made dynamical by adding another Einstein-Hilbert term yielding a bimetric theory of gravity [Hassan & Rosen 2012] ] Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 25 / 37

42 Modified gravity & alternatives Bounding the mass of the graviton [Will 1998] 1 Most obvious way is to compare the arrival times of GW and EM wave from the same event, e.g. a supernova or a short GRB 2 However this can be measured directly from GW emitted by inspiralling compact binaries, without need of a GRB The frequency of GW sweeps from low to high frequency during the inspiral and the speed of GW varies from lower to higher (close to c) speed at the end This results in a distortion of the observed phasing of the GW and a shorter overall time of passage for a given number of cycles 3 For a stellar-size inspiral (NS or BH) at 200 Mpc in LIGO/VIRGO band λ g 1 light year or m g 10 4 ev Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 26 / 37

43 Modified gravity & alternatives Massive gravity on a de Sitter background Sébastien Renaux-Petel: Aspects of massive gravity 1 Embed d-dimensional de Sitter into (d + 1)-dimensional Minkowski 2 Perform the Stückelberg covariantization in (d + 1)-Minkowski before projecting out on de Sitter 3 The helicity-0 mode disappears completely in the decoupling limit Unique candidate theory for massive gravity Link with galileon theory Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 27 / 37

44 Modified gravity & alternatives Explicit solutions of massive gravity Eugeny Babichev: Black holes in massive gravity Look for BH solutions in the form of double Eddington-Finkelstein metric ( ds 2 g = 1 r ) g dv 2 + 2dvdr + r 2 dω 2 [ ( r ds 2 f = C 2 1 r ) f dv 2 + 2dvdr + r 2 dω 2] r Solutions are either bidiagonal (r g = r f ) or not (constraint on C) It is possible to construct non-bidiagonal black hole solutions in massive gravity, that are the analogue of the corresponding GR solutions (Schwarzschild, charged, rotating) The non-bidiagonal BHs are stable against radial perturbations Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 28 / 37

45 Modified gravity & alternatives Degrees of freedom of massive gravity Laura Bernard: Consistent massive graviton on arbitrary background Linearization of the field equations on a general reference background metric [ ] δe µν δg µν + m 2 δv µν Eµν ρσ + m 2 Mµν ρσ h ρσ = 0 Explicit counting of the 5 degrees of freedom of the massive spin-2 graviton Is a linearization around an arbitrary background completely equivalent to a perturbation expansion around Minkowski to any order? Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 29 / 37

46 Modified gravity & alternatives Beyond Horndeski? Most general scalar-tensor action leading to at most second order equations of motion for the scalar field and metric [Horndeski 1974] David Langlois: A unifying description of Dark Energy & Modified Gravity 1 Unified treatment of DE and MG based on a scalar field φ 2 Use of the ADM formalism on the preferred three dimensional φ-slicing 3 Yields a class of theories which go beyond Horndeski without Ostrogradski (i.e. ghost) instabilities Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 30 / 37

47 Modified gravity & alternatives Dilatonic type couplings Olivier Minazzoli: Pressuron s phenomenology Scalar field non-minimally coupled to curvature and matter whose source is matter fluid s pressure Same PPN parameters as GR & cosmological solutions converge toward GR in matter area (so what are the observational consequences?) Aurélien Hees: EP violation in electromagnetic sector Dilatonic scalar coupling to the electromagnetic Lagrangian variation of fine structure constant α violation of distance duality relation in cosmology distorsion of the CMB temperature spectrum These effects are phenomenologically related and constrained by the best tests of the variation of α in the laboratory Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 31 / 37

48 Modified gravity & alternatives Other alternative approaches Alexander Vikman: Imperfect dark matter Model of dark matter built out of Effective Field theory Does this model produce non-primordial non gaussianities in the CMB? David Mota: Nonlinear cosmological probes of screening mechanisms in MG Where to look for testing modified gravity and screening mechanisms in cosmology? Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 32 / 37

49 Modified gravity & alternatives Problems of Λ-CDM at galaxy scales Benoit Famaey: Phenomenology of MOND Minor problems Large disks with low ratio between bulge and disk Missing satellites problem DM cusp problem Bigger problems Tightness of the baryonic Tully-Fisher relation Mass discrepancy vs Surface density Satellite phase-space correlation The MOND paradigm solves these problems but keep in mind 1 Cosmology (e.g. the CMB) 2 Strong field tests (e.g. in the Solar System) Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 33 / 37

50 Modified gravity & alternatives Baryonic Tully-Fisher relation [Tully & Fisher 1977, McGaugh 2011] Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 34 / 37

51 Modified gravity & alternatives Dual aspect of dark matter Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 35 / 37

52 Modified gravity & alternatives Hybrids between Dark matter and MOND Justin Khoury: MOND phenomenology from DM superfluidity 1 Two conditions for DM condensation Overlapping de Broglie wavelength (λ db l) Thermal equilibrium 2 Conjecture: DM superfluid phonons are governed by MOND action 3 Phonons are coupled to baryons P MOND (X) = 2Λ(2m)3/2 X X 3 where X = µ V + φ ( φ)2 2m Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 36 / 37

53 Modified gravity & alternatives Hybrids between Dark matter and MOND Luc Blanchet: Phenomenology of DM via a bimetric extension of GR 1 Model of dipolar dark matter (DDM) based on a bimetric theory with derivative coupling between the two metrics 2 Good phenomenological model MOND Λ-CDM including CMB PPN 3 Nonviable as a fundamental theory (presence of ghosts) Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 37 / 37

54 Modified gravity & alternatives Hybrids between Dark matter and MOND Luc Blanchet: Phenomenology of DM via a bimetric extension of GR 1 Model of dipolar dark matter (DDM) based on a bimetric theory with derivative coupling between the two metrics 2 Good phenomenological model MOND Λ-CDM including CMB PPN 3 Nonviable as a fundamental theory (presence of ghosts) Luc Blanchet (IAP) Gravitation highlights Rencontres de Moriond 37 / 37