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Searching for Intermediate Mass Black Holes mergers

MG-13, July 2, 2012LIGO-G1200704

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

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OUTLINE

IMBHs

Results from the LSC-Virgo collaborations

Methodological studies on simulated data

➢ Intermediate Mass Black Holes (IMBHs) ➢ Inspiral Merger and Ring-down (IMR) waveforms

➢ Un-modeled search for IMBHs mergers ➢ IMR-template search for Binary Black Hole mergers

➢ Advanced detectors➢ Search range on simulated data➢ IMBHs detection chances

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IMBHs?STELLAR MASS BLACK HOLES

< TENS of SOLAR MASSESSUPER MASSIVE BLACK HOLES> 105 SOLAR MASSES

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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

Their discovery could shed light on:➢ evolutionary process from stellar to super-massive black holes

➢ evolution of Globular Clusters they might reside in

➢ collapse of population III stars➢ progressive growth from smaller objects (direct capture, binary mergers)

Artist's view of ULXs[3]

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OBSERVATION OF IMBHs

➢ Black holes➢ Neutron stars➢ White dwarfs➢ Main sequence (MS) stars

Decreasing interaction probability(due to mass segregation)

● In Globular Clusters, IMBHs interacting with:

● 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]:

Inspiralling black holes[6]

2 * 10-5 Mpc-3 Myr -1

10-2 GC-1 Gyr -1

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GW WAVEFORMS FOR IMBH COALESCENCE ● EOBNRv2[7]

● IMRPhenomB[8]

➢ 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

➢ Hybrid waveforms: analytical PN inspiral waveform stitched to numerical merger waveform➢ Aligned and anti – aligned spin configurations

IMRPhenomB IMRPhenomB

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LIGO-Virgo results

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LIGO AND VIRGO DETECTORS● In the frequency band of the LIGO-Virgo detectors:

SNR dominated by merger and ring-down phasesIMBH expected to be visible for < 500 Msun total

● LIGO-Virgo joint runs: S5-VSR1 (Nov. 2005 - Oct. 2007), S6-VSR2/3 (Jul. 2009 - Oct. 2010)Comparable sensitivities between these runs

S5-VSR1 H1 L1 H2 V1 S6-VSR2/3 H1 L1 VSR2 VSR3

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UN-MODELED TRANSIENT SIGNAL SEARCHCoherent 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.....)

BLACK: injectedRED: reconstructedsimulated advanced LIGO-Virgo net

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

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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 100 - 450 Msun, no BH spin

L1H1H2V1 L1H1H2 Mpc Mpc

MAX RANGE: 241 MpcAVERAGED RANGE: 87 Mpc

MAX RANGE: 192 MpcAVERAGED RANGE: 72 Mpc

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● 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

UPPER LIMITS FROM S5-VSR1 ANALYSIS

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)

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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:

● If no GW event will be found, S5-VSR1 and S6-VSR2/3 combined upper limits will be set

➢ 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

S5-VSR1 S6-VSR2/3

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TEMPLATE MATCHED SEARCH for 25-100 MSUN

● 0.78 yr of data (LIGO only, 2005-2007)● total mass range: 25-100 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

UPPER LIMITS ON MERGER RATEARE OVER-CONSERVATIVE

MAX RANGE for 100 Msun, ≈ equal massesconsistent result wrt un-modeled search

The first search for IMR waveforms performed by LSC-Virgo[12]

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EXTENSION TO 2009-2010 LIGO-VIRGO DATA

● 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

Similar template matched search

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Methodological studiesby CWB group

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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, S6Virgo, VSR3Advanced LIGOAdvanced VirgoKAGRA

For IMBHs binaries more massive than ~ 50 solar

masses, networkssensitivities dominatedby LIGO observatories

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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)

MAX RANGE: 3.1 GpcAVERAGED RANGE: 1.9 Gpc

Gpc

Search more sensitive toequal mass components and

total mass ~ 150-600 Msun

H1L1V1

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IMBHs DETECTION CHANCES

● Productivity v with advanced detectors can be estimated

● In the no detection scenario, for T = 1 yr, upper limits are:

● projected Upper Limits then will become comparable with expected rates

➢ MAX RANGE: ULH1L1V1 ~ 10-5 Mpc-3 Myr-1

➢ AVERAGED RANGE: ULH1L1V1 ~ 3.5 * 10-5 Mpc-3 Myr-1

MAX RANGE: 3.1 Gpc vH1L1V1 ~ 1.2 * 105 (T/yr) Mpc3 MyrAVERAGED RANGE: 1.9 Gpc vH1L1V1 ~ 2.9 * 104 (T/yr) Mpc3 Myr

WITH SUCH IMPROVEMENT IN PRODUCTIVITY, GOOD CHANCE TO DETECT IMBHS WITH ADVANCED DETECTORS

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CONCLUSIONS

● Intermediate mass black holes are very exciting astrophysical objects

● Un-modeled approaches (e.g, cWB) have been used to search for IMBHs mergers

● Template matched searches used for high-stellar-mass BH mergers

● Advanced GW detectors will start operating in the next years

➢ Evolutionary process of black holes and dynamics of globular clusters could ➢ coalescing IMBHs expected to be visible within the interferometers bandwiths

➢ 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

➢ 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

➢ 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 ~ 150-600 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]

GOOD CHANCES TO DETECT IMBHs WITH ADVANCED DETECTORS

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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.634:1093-1102,2005[3] http://www.yalescientific.org/2008/04/observation-of-stellar-mass-black-holes-and-the-discovery-of-m33-x-7/[4] Tatsushi Matsubayashi et al., 2004, ApJ 614, 864[5] J. Abadie et al., Class. Quant. Grav. 27, 173001 (2010)[6] http://www.scidacreview.org/0802/html/astro.html[7] A. Buonanno et at., Phys. Rev. D 76, 104049 (2007)[8] P. Ajith et al., Phys. Rev. D 77, 104017 (2008).[9] S. Klimenko et al., Phys. Rev. D 72, 122002 (2005) [10] J. Abadie et al., Phys. Rev. D 85, 102004 (2012)[11] R. Biswas et al., Class. Quant. Grav. 26, 175009 (2009)[12] J. Abadie et al., Phys. Rev. D 83, 122005 (2011)[13] Y. Pan et al., arXiv:1106.1021v2 [gr-qc][14] https://www.advancedligo.mit.edu/[15] https://wwwcascina.virgo.infn.it/advirgo/[16] http://gwcenter.icrr.u-tokyo.ac.jp/en/researcher/parameter[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, 122009 (2012)

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EXTRA

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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