Searching for Intermediate Mass Black Holes mergers

Transcription

1 Searching for Intermediate Mass Black Holes mergers G. A. Prodi, Università di Trento and INFN for the LIGO Scientific collaboration and the Virgo collaboration special credits to Giulio Mazzolo and Chris Pankow MG-13, July 2, 2012 LIGO-G

2 OUTLINE IMBHs Intermediate Mass Black Holes (IMBHs) Inspiral Merger and Ring-down (IMR) waveforms Results from the LSC-Virgo collaborations Un-modeled search for IMBHs mergers IMR-template search for Binary Black Hole mergers Methodological studies on simulated data Advanced detectors Search range on simulated data IMBHs detection chances 2

3 IMBHs STELLAR MASS BLACK HOLES < TENS of SOLAR MASSES? SUPER MASSIVE BLACK HOLES 5 > 10 SOLAR MASSES 3

4 INTERMEDIATE MASS BLACK HOLES (IMBHs) IMBHs : from tens to 105 solar masses[1] HINTS: Possible engine of the ultraluminous X-ray sources (ULXs, L>1041 ergs) Globular clusters (GCs) are the most likely hosts of IMBHs[2] Formation mechanism under debate collapse of population III stars progressive growth from smaller objects (direct capture, binary mergers) Their discovery could shed light on: evolutionary process from stellar to super-massive black holes evolution of Globular Clusters they might reside in 4 Artist's view of ULXs[3]

5 OBSERVATION OF IMBHs In Globular Clusters, IMBHs interacting with: Black holes Neutron stars White dwarfs Main sequence (MS) stars Decreasing interaction probability (due to mass segregation) IMBHs expected to be observable via: Dynamical effects on nearby objects (measurements with large systematics) Photons emission (negligible, significant only for MS star companion, ULXs) Gravitational waves (GWs) when in binary with another black hole[4] Upper limit on IMBH coalescence rate[5]: 2 * 10-5 Mpc-3 Myr GC-1 Gyr -1 5 Inspiralling black holes[6]

6 GW WAVEFORMS FOR IMBH COALESCENCE EOBNRv2[7] Effective One Body Hamiltonian used to evolve the binary system up to merger Numerical Relativity information guide to higher order Post Newtonian approximation Superposition of ring-down frequency modes matched to the end of the merger Non spinning components IMRPhenomB[8] Hybrid waveforms: analytical PN inspiral waveform stitched to numerical merger waveform Aligned and anti aligned spin configurations IMRPhenomB IMRPhenomB 6

7 LIGO-Virgo results 7

8 LIGO AND VIRGO DETECTORS In the frequency band of the LIGO-Virgo detectors: SNR dominated by merger and ring-down phases IMBH expected to be visible for < 500 Msun total LIGO-Virgo joint runs: S5-VSR1 (Nov Oct. 2007), S6-VSR2/3 (Jul Oct. 2010) Comparable sensitivities between these runs S5-VSR1 H1 L1 H2 V1 S6-VSR2/3 H1 L1 VSR2 VSR3 8

9 UN-MODELED TRANSIENT SIGNAL SEARCH Coherent WaveBurst (cwb)[9] algorithm: targets GW transients of duration up to a second un-modeled and weakly modeled coherent searches on networks of GW detectors constrained Maximum Likelihood approach (maximization over h+ hx, sky position...) Can be used to search for signals from compact binaries coalescence for total masses > 10 Msun with no significant SNR loss wrt optimally matched template searches BLACK: injected RED: reconstructed simulated advanced LIGO-Virgo net 9

10 RANGES FOR IMBH MERGERS ON S5-VSR1 DATA Paper on un-modeled cwb results recently published by PRD[10] Two networks considered: H1H2L1V1 (58 days) and H1H2L1 (237 days) Simulations performed by injecting EOBNR waveforms, checked with IMRPhenom Search range estimated for total mass values Msun, no BH spin Mpc Mpc L1H1H2V1 MAX RANGE: 241 Mpc AVERAGED RANGE: 87 Mpc L1H1H2 MAX RANGE: 192 Mpc AVERAGED RANGE: 72 Mpc 10

11 UPPER LIMITS FROM S5-VSR1 ANALYSIS no gravitational wave candidates were found merger rate upper limits R90% combining H1H2L1V1 and H1H2L1 in terms of productivity v (loudest event statistic[11]) upper limits a few orders of magnitude larger than expected rates BEST UPPER LIMIT: 0.13 Mpc-3 Myr-1 AVERAGED UL: 0.9 Mpc-3 Myr-1 conservative corrections for systematics are included (mainly due to waveforms) 11

12 SEARCH FOR IMBHS ON S6-VSR2/3 DATA cwb search for IMBH binaries in S6-VSR2/3 close to completion differences with respect to the S5-VSR1 search: No four detectors network (no H2) S6-VSR2/3 total live time ~ ½ of S5-VSR1 one EOBNRv2, EOBNRv2 with higher modes[12] and IMRPhenomB injected Investigated total mass spectrum extended down to 50 solar masses If no GW event will be found, S5-VSR1 and S6-VSR2/3 combined upper limits will be set S5-VSR1 S6-VSR2/3 12

13 TEMPLATE MATCHED SEARCH for MSUN The first search for IMR waveforms performed by LSC-Virgo[12] 0.78 yr of data (LIGO only, ) total mass range: Msun, component masses 1-99 Msun, no spin Innermost Stable Circular Orbit (ISCO) frequency 100 Hz template bank of EOBNRv1 waveforms Coincidence search with signal consistency checks Range measured with EOBNR and IMRPhenom waveforms MAX RANGE for 100 Msun, equal masses consistent result wrt un-modeled search 13 UPPER LIMITS ON MERGER RATE ARE OVER-CONSERVATIVE

14 EXTENSION TO LIGO-VIRGO DATA Similar template matched search extended comparison with EOBNRv2 & IMRPhenomB tests on some spinning waveforms (co-aligned with orbital angular momentum) LIGO and Virgo data adds 0.43 yr of observation time (+55%) range of search is improved by a fraction results under final internal review 14

15 Methodological studies by CWB group 15

16 ADVANCED DETECTORS Advanced LIGO-Virgo[14,15] detectors and KAGRA[16] will start operating from 2015 Design sensitivities 10 times better => 1000 times larger visible volume (after 2018) Improve sensitivity at low frequencies => more massive IMBH detectable LHO, S6 Virgo, VSR3 Advanced LIGO Advanced Virgo KAGRA For IMBHs binaries more massive than ~ 50 solar masses, networks sensitivities dominated by LIGO observatories 16

17 SEARCH RANGE ON SIMULATED DATA EOBNRv2 injected in advanced H1L1V1, H1L1 and H1J1L1V1 simulated data half of max. search range up to 1100 total solar masses comparable performances from the different networks (sensitivity dominated by LIGO) H1L1V1 Gpc MAX RANGE: 3.1 Gpc AVERAGED RANGE: 1.9 Gpc Search more sensitive to equal mass components and total mass ~ Msun 17

18 IMBHs DETECTION CHANCES Productivity v with advanced detectors can be estimated MAX RANGE: 3.1 Gpc AVERAGED RANGE: 1.9 Gpc vh1l1v1 ~ 1.2 * 105 (T/yr) Mpc3 Myr vh1l1v1 ~ 2.9 * 104 (T/yr) Mpc3 Myr WITH SUCH IMPROVEMENT IN PRODUCTIVITY, GOOD CHANCE TO DETECT IMBHS WITH ADVANCED DETECTORS In the no detection scenario, for T = 1 yr, upper limits are: MAX RANGE: ULH1L1V1 ~ 10-5 Mpc-3 Myr-1 AVERAGED RANGE: ULH1L1V1 ~ 3.5 * 10-5 Mpc-3 Myr-1 projected Upper Limits then will become comparable with expected rates 18

19 CONCLUSIONS Intermediate mass black holes are very exciting astrophysical objects Evolutionary process of black holes and dynamics of globular clusters could coalescing IMBHs expected to be visible within the interferometers bandwiths Un-modeled approaches (e.g, cwb) have been used to search for IMBHs mergers First cwb IMBH search performed on S5-VSR1 data, no GW found Merger rate upper limits cwb IMBH search on S6-VSR2/3 data close to completion Template matched searches used for high-stellar-mass BH mergers First Inspiral-Merger-Ringdown search by LSC-Virgo on S5 LIGO data Results comparable wrt un-modeled searches in the overlapping range Extension to S6-VSR2/3 data close to finalize internal review Advanced GW detectors will start operating in the next years Improved sensitivity, larger visible volume, more massive IMBH binaries accessible On simulated data, performances dominated by L1 and H1 design sensitivities Maximum range of search for ~ total solar masses At ~ 1 Gpc, systems with total mass ~ 1000 solar masses still visible Redundant search methods can improve the overall search range[18] 19 GOOD CHANCES TO DETECT IMBHs WITH ADVANCED DETECTORS

20 REFERENCES [1] M. Coleman Miller, E.J.M Colbert, Int.J.Mod.Phys. D13 (2004) 1-64 [2a] M. C. Miller and D. P. Hamilton, Mon. Not. Roy. Astron.Soc. 330 (2002) [2b] K. Gebhardt et al., Astrophys.J.634: ,2005 [3] [4] Tatsushi Matsubayashi et al., 2004, ApJ 614, 864 [5] J. Abadie et al., Class. Quant. Grav. 27, (2010) [6] [7] A. Buonanno et at., Phys. Rev. D 76, (2007) [8] P. Ajith et al., Phys. Rev. D 77, (2008). [9] S. Klimenko et al., Phys. Rev. D 72, (2005) [10] J. Abadie et al., Phys. Rev. D 85, (2012) [11] R. Biswas et al., Class. Quant. Grav. 26, (2009) [12] J. Abadie et al., Phys. Rev. D 83, (2011) [13] Y. Pan et al., arxiv: v2 [gr-qc] [14] [15] [16] [17] E. Komatsu et al., The Astrophysical Journal Supplement, Volume 192, Issue 2, article id. 18 (2011) [18] R. Biswas et al. Phys. Rev. D 85, (2012) 20

21 EXTRA 21

22 IMPACT OF RED SHIFT With advanced detectors, IMBH visible by cwb up to O(few Gpc) Red shift effects not negligible anymore Astrophysical objects observed as heavier and farther than they are ΛCDM cosmological model[17] assumed 22