Title:
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2 Contents1.Introduction2.Setup
construction3.Objectives for observation4.Rece
nt results5.Cold damping spring.6.Advanced
instrument at SQL
3 Global network of
Detectors
Coherent Analysis why? -Sensitivity increase
-Source direction determination from time of
flight differences
-Polarizations measurement -Test of GW Theory
and GW Physical properties Astrophysical
targets - Far Universe expansion rate
Measurement -GW energy density in the
Universe -Knowledge of Universe at times close
to Plancks time
TAMA 300
Nautilus Auriga
Explorer
GEO 600
VIRGO
L LIGO
4Ligo interferometrs
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6 1915 Theory of G.R. 1916 Einstein predicts
gravitational waves (g.w.) 1960 Weber operates
the first detector 1970 Construction of
cryogenic detectors begins 1984 Taylor and
Hulse find the first indirect evidence of g.w.
(Nobel Prize 1993) 2003 First light in the large
interferometer 2005-2009 First meaninful results
(upper limits) 2015 Start upgraded machines
first
7Gravitational Waves (GW) Gravitational waves
give fundamental informations on the Universe.
The four fundamental interactions coupling
constants are Strong E.M.
Weak Gravitational
?s1 e21/137 GFM210-5
GM210-39 Some consequences of G smallness
1)In stellar collapses Neutrinos undergo
103interactions before leaving the collapsing
star, GWltlt1. 2)After Big-Bang ,
electromagnetic waves decouple from hot matter
after 13000 years, neutrinos after 1s, GW only
after Plancks Time (10-43s) . 3) It is
extremely difficult to detect them.
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9Displacement sensitivity can reach 10-19-10-20
m, then, for measuring ?L/L10-22 LA and LB
should be km long.
10Astrophysical sources, expected amplitudes
GW- luminosity
only relativistic stars are effective radiators
GW amplitude estimate for NS
frequency
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13 GW DETECTORS SENSITIVITY
14Frequency Range (50 1500) Hz Blind All
Sky Searching Sources - compact
binary systems evolution
(inspiral, merging, ring down) -
supernova collapse events - continuous GW
radiation (Pulsars) - stochastic GW background
- Triggered Search ( Astro-gravity
associations)
15Bursts
- Classical sources supernovae
- Waveform poorly known
- Several events/year in the Virgo cluster
- Possibly detectable only within our Galaxy
- Generally, whatever can cause short ( lt 1s ) GW
impulses - Include exotic things (strings) or classical
things (NS, BH ringdowns)
16Coalescing Binaries
- Source coalescence of compact binary stars (BNS,
BBH, NS/BH)? - Waveform accurately modeled in the first and last
phase - Allows matched filtering
- Less known in the merger phase
- Interesting physics here, for instance for BNS
- Rate very uncertain
- A few events/year could be accessible to the
LSC-Virgo network
17Pulsars
- Distorted NS, emitting lines of GW radiation
- Things greatly complicated by the Doppler effect
- Contrary to intuition, by the far the most
computing intensive search - Thousands of known potential sources in our
Galaxy - Most probably below detection threshold
- Many more yet unknown NS could generate a
detectable signal
18Cosmological Stochastic Background
- Potential access to very early Universe
19 LIGO Scientific Runs (2000
2007) S1 (08-09) 2000 y. (
noise 100 times projected level)
S2 , S3 - during 2003 y (bad seismic
isolation) S4 - (02-03) 2005 y ( duty cycle
70, but selected 15,5 days data !)
joint operation of 3 interferometers
S5 - (06. 2006 - 10.2007) main
results
20Basic searching algorithms
Non modeled Bursts outputs of two GW
detectors vectors a , b total
energy E normalized and integrated at the
it is reduced to variables Bursts Excess
Power Bursts Cross Power
21S.Klimenko, GWDAW14, January 26, 2010, Rome,
LIGO-G1000033-v8
Results of the all-sky search for gravitational
wave burst signals are presented for the first
joint LIGO (S5) and Virgo VSR1 runs in
2006-2007. ?The analysis has been performed with
three different search algorithms in a wide
frequency band between 50-6000 Hz. No plausible
GW candidates have been identified. ?As a result,
a limit on the rate of burst GW signals (combined
with the LIGO results from the first S5 year) has
been established less than 2 events per year at
90 confidence level with sensitivity in the
range 6-20 10-22 Hz-1/2 ? This rate limit is
increased by more than an order of magnitude
compared to the previous LIGO runs.
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24What we known about SBGW from BBN bound
? ?gw(1/?c)d?gw/dlog(f) h0 ?gw ,
h00.73(3) Â ?gw ? d log(f) d?gw/dlog(f)
from the balance of H and G at
nucleosynthesis, (H2 (8pG/3) ?) is a bound on
the total energy density, integrated over all
frequencies. fmin 10-10 Hz fixed by the
horizon size at BBN
N? effective number of neutrino species,
parametrizes any extra energy contribution in
the SM, N? (4.4 3.046) (due to residual
interaction ? with e QED effects). So in
order of magnitude at time of NS there were no
more GWs than photons it can be translated into
a bound on the integrand
?gw lt 6.9 10-6
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27Results S4 , S5 , last run S6 (04.09
09.10) Unmodeled bursts upper limit ?
lt 0.15 day -1 , h rss lt 10-20 Hz ½
Inspiral Bursts upper limit ?
Event Rate R
R (Number of events/ year. galaxy)
1 event per 20-300 years for NS binary
for dH 60 Mpc 1 event per
20-2000 years for binary 5 M0
1 event per 3
30 years for binary 10 M0 Pulsars f
150 Hz , h 10-25 , e lt 10-5
Stochastic background f (50 100) Hz,
O lt 6.5 10-5
28???????????? ?????????? LIGO
1. ????? (????????) ??????? ?????? ?? ??-??????
?? ?????-?????????. ?? ????? ????? S5 ????? ?????
??????? GRB 070201 ???????? ?-??????? (lt 2
???), ????????? ????????? ????????????? ? ?31
(770 ???) (reg. Integral, Messenger, Swift)
fl.10-5erg/cm2. ? ???? 180 ???. ??????
tarv ?????? ?????????????? ??-???????. ?
???????????? 95 ?? ?????? ?? ?????????. ??????
?? ??? ????????????? ? ?????? NS, BH binary
coalescence ?????? ??? E lt 4.4 10-4 M0c2
(1M0ltm1lt3M0 , 3M0ltm2lt40M0) f150 Hz (????.
p????? ??? ?? NS ????????? E 10-2 !) 2.
?????????? ??????? ?????????? ?? ?? ?????????
????????? PSR BO53121, PSR JO534-22, Crab Neb.
(?30 Hz, d?/dt-3 10-10 Hz/s ) ????. ??????
?? spin-down rate ???? hgw 1.4 10-24.
?????????? S5, 3 ???.(200 ??.) ?? ??????? ?
60 Hz ???? hgwlt3.4 10-25 ??? ??? ???????
????????????? e lt 1.8 10-4 3. ??????????
??????? ??????????????? ??-???? ?? ???????????? ?
?????? ????????? ?????? ????????????? ????
??????????? ?? ???????????? (?? ???????)
????????? ?? ???? ?? ?????????????, ???
?????????? ???? ?? ??????, ??? ??????? ??? ????
??? ??????????? ???????????? ????????? ?? ????
?gw 9.7 10-6. ???????????????? ?? ?????
?????????? 200 ???? ?? ?????????? H1, L1
???????? ?????? ?gw 6.9 10-6 ?
?????????????? 95
29Cold Spring Damping of Thermal Noise in the LIGO
setup
New Journal of Physics 11 (2009) 073032, B
Abbott1 et.al. (LSC)
- Observation of quantum effects such as ground
state cooling, quantum jumps, optical squeezing,
and entanglement that involve macroscopic
mechanical systems are the subject of intense
experimental effort. - The first step toward engineering a non-classical
state of a mechanical oscillator is to cool it,
minimizing the thermal occupation number of the
mode. Any mechanical coupling to the environment
admits thermal noise that randomly drives the
systems motion, as dictated by the
fluctuationdissipation theorem, but cold
frictionless forces, such as optical or
electronic feedback, can suppress this motion,
hence cooling the oscillator.
30Thermal standard
T?0 , Q ?? , (H?0)
Quantum standard
LIGO displacement sensitivity S5 scientific run
31Quantum behaviour of macroscopic test body
(?) V.B.Braginskii. Physics Uspekhi, v.48, 595,
2005 a pendulum in gravity field, mode of
acoustical resonator etc. can demonstrate
quantum features under the following requirement
instead of usual condition
- Dodonov V.V., Manko V.I., Rudenko V.N., Quantum
Electronics, v.7 (?10), p.2124, 1980 - Quantum properties of macroscopic resonator with
a high quality factor - a) classical calculation mean values and a system
evolution corresponds to quantum calculation with
the accuracy O(1/n) - b) transition probability requires only the
quantum calculation - c) observation of energy steps requires
unrealistic measurement accuracy (Q 1018 )
Realistic objective is a preparation of
macroscopic system (oscillator) in the ground
energetic state, i.e. with n 1. procedure of
super cooling in expectation of macroscopic
quantum effects
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34LIGOs Hanford Observatory. The detector shown
comprises a Michelson interferometer with a 4 km
long FabryPerot cavity of finesse 220 placed in
each arm to increase the sensitivity of the
detector. Each mirror of the interferometer has
mass M 10.8 kg, and is suspended from a
vibration-isolated platform on a fine wire to
form a pendulum with frequency 0.74 Hz, to
shield it from external forces
To minimize the effects of laser shot noise, the
interferometer operates with high power levels
approximately 400W of laser power of wavelength
1064 nm is incident on the beam splitter,
resulting in over 15kW of laser power circulating
in each arm cavity. The present detectors are
sensitive to changes in relative mirror
displacements of about 10-18 m in a 100 Hz band
centered around 150 Hz (figure 2).
Differential arm cavity motion, which is the
degree of freedom excited by a passing
gravitational wave, and hence also the most
sensitive to mirror displacements. This mode
corresponds to the differential motion of the
centers of mass of the four mirrors, xc (x1
-x2)-(x3 -x4), and has a reduced mass of Mr 2.7
kg.
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38?????????? ????????? ?? ?????????????? ?1
Advanced LIGO (2015) ????????? ????????
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43GW-experiment News
Fig. 1. Advanced Virgo sensitivity curve compared
with Virgo and LIGO design and current bar
sensitivity. Violin modes are not displayed for
clarity
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