Astrophysics to be learned from observations of intermediate mass black hole in-spiral events. Alberto Vecchio

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1 Astrophysics to be learned from observations of intermediate mass black hole in-spiral events Alberto Vecchio Making Waves with Intermediate Mass Black Holes

2 Three classes of sources IMBH BH(IMBH) IMBH IMBH SMBH IMBH

3 Some questions Do IMBHs exist? Demographics of IMBHs: Masses Spins. Mass vs redshift distribution Hierarchical clustering Structure formation IMBHs and their environment Dynamical processes in clusters BH and SMBHs studies

4 Outline Some jargon and fundamental scales Sensitivity Astronomy with laser interferometers Information extraction: astrophysics and cosmology Conclusions

5 Observational window Advanced resonant M sun

6 Coalescence of binary systems f = 4 [ M (1+z) /10 3 M ] -1 Hz f = 32 [ M (1+z) /10 3 M ] -1 Hz [Kip s cartoon] Long lived Short lived

7 Sensitivity (low redshift) Optimal filtering is assumed Whole coalescence LISA Advanced LIGO In-spiral Merger: Flanagan and Hughes parameters (optimistic!); Ring-down: a/m = 0.98

8 Sensitivity (low redshift) Optimal filtering is assumed LIGO-I Whole coalescence Merger: Flanagan and Hughes parameters (optimistic!); Ring-down: a/m = 0.98

9 Sensitivity (high redshift) m1 = m2 m2 = 0.01 m1 z = 0.5 z = 5 z = 0.5 z = 5 z = 30 z = 30

10 ESA/NASA joint mission (launch: 2012) ESA cornerstone mission NASA Beyond Einstein Initiative mission with ConX Space-borne laser interferometers with 5 million km arms, 30 cm diameter telescopes and 1 W lasers Powerful GW telescope: thousands of signals at anyone time LISA Pathfinder: technology demonstrator

11 Binary systems L S2 S1 m2 m1 D_L N The most general system is described by 17 parameters: Masses [2] and spins [6] Orbit [4] Sky position and distance [3] Arbitrary initial time and phese [2] Penn State, 20 th 22 nd May 2004

12 Michelson observables i = II (Cutler, 1998; i=i PennState, 20th 22nd May 2004 Tinto et al, 2000)

13 Signal at detector output Chirp mass and distance Physical parameters: masses and spins

14 Wave cycles Newt. 1PN tail spin-orbit 2PN spin-spin Penn State, 20 th 22 nd May 2004

15 Signal at detector output

16 LISA: the orbit

17 LISA motion Two key (and distinct) motions: 1. LISA orbits the Sun: the signal frequency is Doppler shifted 2. Spacecraft constellation rotates around the normal to the detector plane: the response of the detector is not fixed, that is the antenna pattern is time dependent The signal is therefore phase and amplitude modulated The LISA motion is essentially what provides the detector pointing capability

18 Induced frequency shifts _f _f ~f GW (v LISA /c) ~ 10-7 (f GW /1 mhz) Hz orientation motion _f ~ 2/T LISA ~ 7 _ 10-8 Hz ~1 mhz Frequency/ Hz

19 Simple precession S = S 1 + S 2 J = L + S L -N (Apostolatos et at, 94; Kidder, 95)

20 Signal at detector output Location, orientation Sky location and spins and masses

21 Signal modulations m 1 = 10 7 M sun m 2 = 10 5 M sun SdotL = 0.5 S/m 2 = 0.95 m 1 = 10 6 M sun m 2 = 10 6 M sun SdotL = 0.9 S/m 2 = 0.3 (AV astroph/ )

22 Low redshift IMBHs (cont d)

23 Low redshift IMBHs (cont d)

24 Low redshift IMBHs (cont d) Confirm existence of IMBH Demographics and properties Identify time of possible EM burst due to collision for follow-on observations but error box larger than 1 sq. degree Studies of IMBHs and their environment are not likely

25 High redshift IMBHs

26 High redshift IMBHs (cont d)

27 High redshift IMBHs (cont d) Confirm existence of IMBH at high redshift Demographics and properties Distance known to ~1%-30% Redshift can (in principle) be reconstructed with a fractional error ~ 10%-20% (or better, as errors on cosmological parameters decrease; Hughes, 2002) However, weak lensing will degrade our ability of reconstructing D(z) (Markovic, 1993; Holz and Hughes, 2003) Concrete chance of studying structure formation

28 Some caveats Circular orbits Only leading quadrupole included in the amplitude: other harmonics can refine information extraction (Sintes and AV, 2000; Hellings and Moore, 2001) For radiation at f > 5 mhz, LISA transfer function behaviour (not taken into account here) will improve parameter estimation, angular resolution in particular (Seto, 2003; AV and Wickham, 2004) Estimate of the errors are based on Cramer-Rao bound, which is a tight lower bound for high SNR (Finn, 1992; Dhurandhar et al, 1998; Nicholson and AV, 1998)

29 IMBH + SMBH [D = 1 Gpc; circular orbit and spinning SMBH] (Finn and Thorne, 2000)

30 IMBH + SMBH (cont d) [D = 1 Gpc; eccentric orbit and non-spinning SMBH] (Barack and Cutler, gr-qc/ )

31 IMBH + SMBH (cont d) [D = 1 Gpc; eccentric orbit and non-spinning SMBH] (Barack and Cutler, gr-qc/ )

32 IMBH + SMBH (cont d) [D = 1 Gpc; eccentric orbit and non-spinning SMBH] (Barack and Cutler, gr-qc/ )

33 IMBH + SMBH (cont d) For binary systems at D ~ 1 Gpc: IMBH and SMBH mass with fractional error < 1 part in 10,000 Distance with fractional error < 10% Location of the source in the sky within an error box < srad Spin of SMBH better than 10-4

34 Conclusions GW observations: confirmation of existence of IMBH Mass vs z(d) distribution of IMBH Demographics of IMBH IMBH can also provide a census of SMBHs up to z ~ a few and possibly close-by BHs (Advanced) LIGO has a fighting chance of detecting IMBHs and measuring at least the mass