1. and the quest for gravitational waves
A.Viceré – INFN Firenze/Urbino
for the Virgo Collaboration

2. Plan of the talk Few words about gravitational waves
Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 2/63

3. Ripples in the Cosmic Sea
Linearized Einstein eqs. (far from big masses) admit wave solutions (perturbations to the background geometry)
GW: transverse space-time distortions propagating at the speed of light, 2 independent polarization
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 3/63

4. Coupling constants Ideal information carrier,
strong
e.m.
weak
gravity
0.1
1/137
10-5
10-39
GW emission: very energetic events but almost no interaction
In SN collapse n withstand 103 interactions before leaving the star, the gravitational waves instead leave the core undisturbed
Very early GW decoupling after Big Bang
GW ~ s (T ~ 1019 GeV)
n ~ s (T ~ 1 MeV)
γ ~ s (T ~ eV)
Ideal information carrier,
Universe transparent to GW all the way back to the Big Bang!!
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 4/63

5. Nobel Prize 1993: Hulse and Taylor
PSR : GW do exist
Pulsar bound to a “dark companion”, 7 kpc from Earth.
Relativistic clock: vmax/c ~10-3
GR predicts such a system to loose energy via GW emission: orbital period decrease
Radiative prediction of general relativity verified at 0.2% level
Nobel Prize 1993: Hulse and Taylor
P (s)
(9)
dP/dt
-2.425(10)·10-12
dw/dt (º/yr)
(18) Mp
1.442 ± M Mc
1.386 ± M
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 5/63

6. Plausible target GW amplitude
Luminosity:
Amplitude:
Compactness C
1 for BH
0.3 for NS
10-4 for WD
Efficient sources of GW must be asymmetric, compact and fast
GW detectors sensitivity expressed in amplitude h : 1/r attenuation
Example target amplitude:
coalescing NS/NS in the Virgo cluster
(r ~10 Mpc)
h ~ 10-21
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 6/63

7. Synopsis of sources LONG DURATION SHORT DURATION MATCHED FILTERING
Rotating NS
Coalescing compact binaries
TEMPLATE-LESS
METHODS
Stochastic GW
Supernovae
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 7/63

8. Few words about gravitational waves Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 8/63

9. Principle of Detection
GW induce space-time
deformation
Measure space-time
strain using light
Interference fringes
Target h ~ 10-21
Cluster)
Feasible L ~ 103 m
Credit: M.Lorenzini
Need to measure: DL ~ m
Big challenge for experimentalists!
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze 9/63

10. How much is 10-18 m? log10 r Virgo sensitivity Size of the Universe
Virgo cluster
Galactic center
1 Light-year
Target GW wavelengths
Neutron star radius
Wavelength of YAG laser
Size of an atom
Proton radius
Virgo sensitivity
log10 r
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

11. A real detector scheme Virgo optical scheme Input Mode Cleaner
Output Mode Cleaner
3 km long Fabry-Perot cavities:
to lengthen the optical path to
100 km
Input Mode Cleaner
Laser 20 W
Power recycling mirror:
to increase the light power
to 1 kW
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

12. Laser Master laser, 1W F.I. F.I. E.O. F.I. Main Beam Path
Slave laser, 22W
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

13. Super mirrors Fused silica mirrors 35 cm diam, 10 cm thick, 21 kg
Scattering losses: a few ppm
Substrate losses: ppm
Coating losses: <5 ppm
Surface deformation: l/100
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

14. VIBRATION ISOLATION
Thermal noise
Superattenuator: filters off the seismic vibrations.
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

15. Vacuum enclosure 7000 m3 Requirements 10-9 mbar for total pressure
10-14 mbar for hydrocarbons
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

16. Plan of the talk Few words about gravitational waves
Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

17. The GW detectors network
A network of 4 (5) GW detectors
LIGO – Hanford, WA
GEO600, Hannover, D
LIGO – Livingston, LA
VIRGO, Pisa, Italy
Virgo and the LIGO Scientific Collaboration have signed a MoA for
full data exchange and joint data analysis and publication policy
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

18. Virgo: 3km arms LAPP – Annecy OCA - Nice NIKHEF – Amsterdam
GPG - Birmingham
RMKI - Budapest
INFN – Firenze-Urbino
INFN – Frascati
INFN – Genoa
LMA – Lyon
INFN – Napoli
OCA - Nice
LAL – Orsay
APC – Paris
INFN – Padova-Trento
INFN – Perugia
INFN – Pisa
INFN – Roma 1
INFN – Roma 2
POLGRAV – Warsav
Virgo: 3km arms
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

19. Design sensitivity curves10
-24
-23
-22
-21
-20
-19
-18 1
100
1000 4
h (Hz-1/2)‏
Virgo
LIGO
Resonant
antennas Hz
GEO
Core Collapse
@ 10 Mpc
BH-BH Merger
Oscillations
@ 100 Mpc
Pulsars
hmax – 1 yr integration
BH-BH Inspiral,
z = 0.4
BH-BH Inspiral, 100 Mpc
QNM from BH Collisions,
Msun, z=1
NS, 
=10 -6
, 10 kpc
Msun, 150 Mpc
NS-NS Inspiral, 300 Mpc
NS-NS Merger
1st generation detectors
Credit: P.Rapagnani
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

20. Detector technology demonstrated ! LIGO Scientific Collaboration
Commissioning started in 1999.
Design sensitivity achieved end 2005
Detector technology demonstrated !
S1 - Aug 23, 2002 – Sep 9, 2002
S2 - Feb 14, 2003 – Apr 14, 2003
S3 - Oct 31, 2003 – Jan 9, 2004
S4 - Feb 22, 2005 – March 23, 2005
S5 - November 2005 – Fall year of 3 det. coincident data
LIGO Scientific Collaboration
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

21. Virgo sensitivity evolution
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

22. FIRST SCIENCE RUN (VSR1)
From May 18 to Oct
Joined LIGO S5
The detector demonstrated excellent stability
Sensitivity improved during the run, exploiting short interruptions
BNS Inspiral Range (Mpc)
Duty cycle: 84%
Longest lock: 94 hours
Avg. Lock Duration: hrs
Lock Recovering Time: ~30 min
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

23. Recent progress
Reaching the design sensitivity and being limited by fundamental noises is all but simple
One has to fight with many little technical noises, often unpredicted and unmodelled
Most relevant: scattered light triggered by environmental noise, eddy currents, magnetic couplings, thermal transients
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

24. VIRGO vs LIGOs & GEO600 Same HF sensitivity
LIGO slightly better in the mid range
Virgo much better at LF
GEO600 not competitive
A factor 2-3 still missing
at low frequency. WHY?
The big step forward in the last decade has been the demonstration of the
interferometers technology. The design sensitivity has been (almost) reached
and stability is so good (unexpectedly) that an efficient network could be created.
Virgo, now, has opened the road to very low frequency region.
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

25. Few words about gravitational waves Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

26. 368 days of triple-coincident LIGO data
Science Runs So Far
368 days of triple-coincident LIGO data
2002
2003
2004
2005
2006
2007
LIGO:
S1 S2 S3 S4 S5
GEO:
Since end of S5 / VSR1 :
► Upgrading LIGO 4-km interferometers and Virgo
► GEO and LIGO 2-km interferometer taking data whenever possible for “AstroWatch” vigil
Virgo:
VSR1
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

27. Unmodeled burst searches
Supernova collapse: dynamics and waveform badly predictable
Estimated rate: several /yr in the VIRGO cluster, but the efficiency of GW emission is strongly model dependent
Simulations suggest EGW~10-6 Mʘc2, but NS kick velocities suggest possible strong asymmetries
GW emitted
secs
hrs
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63
[Zwerger, Muller]

28. All-Sky Burst Searches
The most-recent published results use S4 data
LIGO-only search[ Classical and Quantum Gravity 24, 5343 (2007) ]
► Searched days of triple-coincidence data (H1+H2+L1) for short (<1 sec) signals with frequency content in range Hz
► No event candidates observed
► Upper limit on rate of detectable events: per day (at 90% C.L.)
► Sensitive to GW energy emission as small as ~10-7 M at 10 kpc, or ~0.25 M at the distance of the Virgo Cluster
LIGO-GEO joint search [ CQG 25, (2008) ]
First use of fully-coherent network analysis for burst signals
S5 / VSR1 all-sky search is currently under internal review
Factor of ~2 better amplitude sensitivity, and much longer observation time
Doing coherent network analysis using LIGO and Virgo data
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

29. Gravitational Waves from Soft Gamma Repeaters
SGRs are believed to be magnetars
Occasional flares of soft gamma rays
May be associated with cracking of the crust that excites vibrational f-modes of the neutron star
LIGO searched for GW signals associated with SGR flares
Dec “giant” flare of SGR 1806–20
190 flares from SGR 1806–20 and SGR during first year of S5
Placed upper limits on GW signal energy for each flare
[ PRL 101, (2008) ]
Within the energy range predicted by some models
LIGO also searched for GW signals matching the quasiperiodic oscillations seen in X-rays in the tail of the Dec giant flare
Placed upper limits [ PRD 76, (2007) ]
Smallest gamma: 30
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

30. Coalescing binaries chirp
[Campanelli et al., PRL, 2006]
Coalescing binaries
chirp
Pairs of compact stars, like PSR , but close to the final “coalescence”
PBH: Primordial Black Holes (in the galactic halo): M in [0.2, 0.9]
BNS: Binary neutron stars: M in [0.9, 3.0]
BBH: Binary black holes: M in [3, 20]
Inspiral signal accurately predictable
Newtonian dynamics
Post-Newtonian corrections (3PN, (v/c)11/2) [L.Blanchet et al., 1996]
Recent big progress in merger 3D simulation [Baker et al 2006, Praetorious 2006]
Crucial to extract physics, mostly encoded in the merger phase
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

31. Binary Inspiral Searches
New result from first year of S5 data
No inspiral signals detected
Using population models, calculated 90% confidence limits on coalescence rates:
For binary neutron stars: ×10–2 per year per L10
For 5+5 M binary black holes: ×10–3
For BH-NS systems: ×10–2
(Slightly tighter limits if BHs are assumed to have no spin)
100 Mpc
Milky way is 1.7 L10
Rates could plausibly be as high as 5e-4 for BNS, 6e-5 for BBH or BHNS
i.e. about two orders of magnitude away from plausible rates
Also, S4 ringdown search paper in preparation
[ Preprint arXiv: ]
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

32. GRB 070201 Short, hard gamma-ray burst
Leading model for short GRBs: binary merger involving a neutron star
Position (IPN) consistent with being in M31
LIGO Hanford detectors were operating
Searched for inspiral & burst signals
Result from LIGO data analysis: No plausible GW signal found; therefore very unlikely to be from a binary merger in M31
[ ApJ 681, 1419 (2008) ]
Hundreds of GRB occurred during the live time of LIGO and Virgo detectors: still under analysis
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

33. Spinning Neutron Stars
Non-axisymmetric rotating NS emit periodic GW at f=2fspin but…weak
SNR can be increased by integrating the signal for long time (months)‏
109 NS in the galaxy, 163 known in LIGO/Virgo band
Doppler correction of Earth motion needed (f/f  10-4): blind search limited by computing power
Data from ATNF Pulsar Catalogue (
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

34. Searches for Periodic Signals from Known Radio/X-ray Pulsars
Demodulate data, correcting for motion of detector
Doppler frequency shift, amplitude modulation from antenna pattern
For a triaxial star, expect GW signal at twice the spin frequency
S5 preliminary results (using first 13 months of data):
Place limits on strain h0 and equatorial ellipticity e
► e limits as low as ~10–7
It’s plausible that an ordinary neutron star could sustain an ellipticity as large as ~10–6 ; Some models allow larger
Crab
Plot from Greg Mendell’s talk at Amaldi in July 2007
Lowest epsilon limit presented by Matt in April 2007 APS meeting; note that there was a correction after that, but in both cases the value was less than 1e-7.
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

35. Searches for a Stochastic Background of Gravitational Waves
Weak, random gravitational waves should be bathing the Earth
Left over from the early universe, analogous to CMBR ; or due to overlapping signals from many astrophysical objects / events
Results from LIGO S5 data analysis
Searched for isotropic stochastic signal with power-law spectrum
For flat spectrum, set upper limit on energy density in gravitational waves:
Preliminary result from ~half of S5 data: 0 < 1.3 × 10–5
Starts to constrain cosmic (super)string and “pre-Big-Bang” models
Final S5 result to be released soon, with factor of ~2 better sensitivity – will dip below Big Bang Nucleosynthesis bound
Or look for anisotropic signal: [ PRD 76, (2007) ] (S4 data)
BBN bound is 1.1e-5
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

36. A broader look at the stochastic background
Credit: B.Sathyaprakash
LIGO S1, 2 wk data
h1002 < 23 PRD (2004)
LIGO S3, 2 wk data
h1002 < 8 x 10-4 PRL (2005)‏
Laser Interferometer
Space Antenna - LISA -2
CMB
Pulsar
Nucleosynthesis
(0h1002 )‏ -4
Cosmic strings
Initial LIGO, 1 yr data
Expected h1002 < 2x10-6 -6
Log -8
Advanced IFOs, 1 yr data
Expected h1002 < 7x10-10
Pre-big bang
model
-10
EW or SUSY
Phase transition
Inflation
-12
-14
Slow-roll
Cyclic model
-18
-16
-14
-12
-10 -8 -6 -4 -2 2 4 6 8 10
Log
( f [Hz])‏
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

37. Few words about gravitational waves Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

38. 1st generation detection chances
1ST GENERATION INTERFEROMETERS CAN
DETECT A NS-NS COALESCENCE
AS FAR AS VIRGO CLUSTER (15 MPc)
LOW EXPECTED EVENT RATE:
ev/yr (NS-NS)
FIRST DETECTION:
POSSIBLE BUT UNLIKELY
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

39. First step to improve: Virgo+
Important technology progress achieved in the last years. It is possible to upgrade Virgo now, enhancing the sensitivity by 2-3 (and the rate by one order of magnitude)
The Virgo+ package:
more laser power (20  50 W)
compensation of mirror thermal lensing
better electronics
change of input mode cleaner mirror
monolithic suspensions
LIGO also undergoing similar upgrades, towards Enhanced LIGO
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

40. 2nd generation detectors
Virgo and LIGO have achieved the design sensitivity. Data still under analysis, but the expected event rate is low ( ev/yr)
To increase the chance of first detection and to open the way to GW astronomy we want to enhance the amplitude sensitivity by x10 (hence the detection rate by x1000!)
Advanced LIGO (USA): funded by NSF. In construction
Advanced Virgo: Conceptual Design e Preliminary Project Execution Plan submitted to funding agencies (INFN and CNRS). Facing a project review process to get approved.
108 ly
Enhanced LIGO/Virgo+
2009
Virgo/LIGO
Credit: R.Powell, B.Berger
Adv. Virgo/Adv. LIGO
2014
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

41. Advanced LIGO Projected Sensitivity
Factor of ~10 in amplitude sensitivity
Factor of ~1000 in volume
10–21
–22
10–23
10–24 10
100
1000 Hz
Advanced LIGO is approved and funded; construction has begun
Expect to be operational starting in 2014 or 2015
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

42. Adv design features better vacuum environmental noise reduction
tilt control
heavier mirrors
low dissipation coating
larger spot
high finesse cavity
compensation of
thermal lensing
moreover…
better vacuum
environmental noise reduction
low noise electronics …
signal recycling
fused silica
suspension fibers
DC detection
high power
laser (200 W)
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

43. Binary NS sight distance in AdV
AdV: ~150 Mpc
Advanced LIGO: ~170 Mpc each detector

44. Virgo upgrade plans Advanced Virgo Virgo+ Advanced Virgo Science Run 108 10 12 14 16 18
100
101
102
103 yr
Mpc
BNS inpiral range – expected progress
Advanced Virgo
Advanced Virgo Science Run 1
Advanced Virgo commissioning 08 09 10 11 12 13 14 15 16
Advanced Virgo installation
Virgo Science Run 3
Virgo+
Installation of monolithic suspensions (?)
Virgo Science Run 2
Virgo+ commissioning
Virgo+ installation
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

45. Benefits by the LIGO-Virgo network
False alarm rejection thanks to coincidence
Triangulation allowing to pinpoint the source
A network allows to deconvolve detector response and regress signal waveform --> measure signal parameters, including source distance for BNS signals
Joint operation yields a longer observation time, and a better sky coverage
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63 45

46. BNS events: will we ever see them?
Empirical models
Use observed (4) galactic binary systems coalescing on timescales comparable to Universe age
Infer # of events/Milky Way Equivalent Galaxy
Assume galactic density 0.01 Mpc-3
Population synthesis models
Use galactic luminosity to deduce star formation rate
Alternatively, use supernova events to calibrate the number of massive stars
Model binary formation and evolution to deduce # of systems coalescing in less than Hubble time

47. BNS: AdV predictions Empirical model rather uncertain
Small number of systems observed, little statistic
Population synthesis still unconclusive
Strong dependence on models
AdV alone sees from O(1) to O(10) events/year
AdV to operate together with Advanced LIGO!
Combined sight distance may exceed 300 Mpc
Network will see from O(10) to O(100) events/year

48. BBH sight distance
AdV: ~ 700 Mpc

49. BBH: pop. synth. predictions
Notes
Sight distance is effective: takes into account the distribution of masses in the population synthesis
Only masses < 10 M are simulated
BBH population synthesis very uncertain
Merger rates vary by factors of hundreds
If model A is true, prospects of detection are dim!
However ...

50. BBH: empirical prediction
IC10 X-1
Binary system in local group (~ 700 kpc)‏
Includes a BH, m~24 Mo, and a massive Wolf-Rayet star, m~ 35 Mo
Allows to predict a rate (Bulik et al.)‏
The WR will evolve in BH, without disrupting the binary system
The resulting system should have Mchirp~14Mo
Such systems are detectable by AdV up to 1.1 Gpc ...
Rate for AdV should be ~ 250 /year
Rate for combined Advanced LIGO – AdV ~ 2500/year

51. Known pulsars: AdV limits on h
Dots: spin down limits.
Beaten by AdV for about 40 known objects

52. Stochastic background limits with AdV
H1 - L1
H1 - V1
One year of operation of AdV – AdLIGO
Will improve over nucleosynthesis bounds by several orders
For comparison, LIGO S5 results should be just below BBN limit
AdV contribution depends on the exponent n of the stochastic background model, and is more relevant for larger n

53. Astrophysical backgrounds
A network can locate point sources of random GW signals
Such could be objects of astrophysical interests, for instance very large black holes in active galaxies
LIGO – Virgo network, with multiple baselines, improves sensitivity by 25% at equator and by 42% at poles, over LIGO only
Source localization is improved by a factor O(10)‏

54. Advanced Detectors will see GWs
The technology of interferometric detectors has been demonstrated
A further step in sensitivity appears necessary to open the way to physics and astronomy. Some sources appear certain, unless astrophysical assumptions are wrong
To make science, a multimessenger approach will be mandatory
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

55. Few words about gravitational waves Working principles of GW detectors
The large interferometers in the world, and Virgo
A personal choice of science results
LSC-Virgo joint observation perspectives
Towards GW astronomy: multimessenger opportunities
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

56. Targeting SNe; low energy 's ...
Boost detection confidence
Neutrino and GW expected within a few ms delay
Very tight coincidence can be required
Constrain  mass strongly
1ms accuracy: m < 1eV constrain

57. High energy 's KM3Net and IceCube will see  with E up to 100's GeV
Coverage of Southern and Northern sky
Reconstruction capabilities in the 1° range
Common targets: GRB's, SGR giant flares, etc...

58. Targeting GRB events
Swift now, Fermi (GLAST) keep looking at  rays from GRB
GRB powered by accretion disks on newly formed objects
Neutrino and GW expected within a few ms delay
Short GRB (< 2s) potentially related to BNS, BH-NS
Long GRB (>2s, average 30s) related to (classes of) SNe
Again, boost detection confidence
Provide insight in the fireball mechanism

59. Other messengers ... Radiotelescopes
Crucial, f.i. to “lock” on pulsar signals
(Automated) Optical telescopes
To alert GW detectors of interesting events
To follow up triple coincidences observed in GW detectors
X-ray telescopes
Privileged eyes on the hot material falling into compact objects
For instance, in LMXB
Another eye at GRB events ..

60. Beyond the 2° generation?
Where and how can we reduce the detector noise?
Thermal
Seismic
Shot
Underground detectors
New materials
Cryogenic interferometers
High power laser
Better optics
New optical configuration
QND techniques
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

61. ET, THE “ULTIMATE” DETECTOR
Underground facility to minimize seismic noise
Mirrors held at cryogenic temperature
Longer arms, new geometry
E.T. - Einstein gravitational-wave Telescope
Design Study Proposal funded by EU within FP7
Large part of the European GW community involved (EGO, INFN, MPI, CNRS, NIKHEF, Univ. Birmingham, Cardiff, Glasgow)
Credit: H.Lück
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

62. frequency f / binary black hole mass whose freq at merger=f
Credit: B.Sathyaprakash
h (1/√Hz)‏
10-22
10-23
10-24
10-25
Current detectors
LISA
2008
2015
Adv detectors
2013
3rd generation
2020
0.1m m Hz k
frequency f / binary black hole mass whose freq at merger=f
4x x x103 M
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63

63. Conclusions?
I recall lessons at a summer school in theoretical physics in Parma in 1997: detectors still mostly on paper. General skepticism
This seminar in 2009: 1° generation detectors demonstrated! LIGO and Virgo upgrading towards 2° generation
We hope that 2° generation will allow to start GW ASTRONOMY!
To make the most science of it, close cooperation with the astrophysical community will be a must.
Bologna – February 19th, A.Viceré – Università di Urbino & INFN Firenze /63