st thomas, virgin islandsbcbact/talks06/st... · 17-march-06 confronting gravity - st thomas 4...

Status and Prospects for

LIGO

Barry C. BarishCaltech

17-March-06St Thomas, Virgin Islands

Crab Pulsar

17-March-06 Confronting Gravity - St Thomas 2

LIGOLivingston, Louisiana

4 km


LIGO

Hanford Washington

4 km

2 km


Interferometer optical layout

laser various optics

6-7 W 150-200 W10 W 4-5 W 9-12 kW

vacuum

photodetector

suspended, seismically isolated test masses

GW channel

200 mW

modecleaner

4 km


LIGO Beam Tube

• 1.2 m diameter - 3mm stainless 50 km of weld

• 65 ft spiral welded sections

• Girth welded in portable clean room in the field

• Minimal enclosure

• Reinforced concrete

• No services


LIGOvacuum equipment


Core Opticsinstallation and

alignment


LIGO Opticsfused silica

Caltech data CSIRO data

Surface uniformity < 1 nm rmsScatter < 50 ppmAbsorption < 2 ppmROC matched < 3%Internal mode Q’s > 2 x 106


Interferometer Noise Limits

Thermal (Brownian)

Noise

LASER

test mass (mirror)

Beamsplitter

Residual gas scattering

Wavelength & amplitude fluctuations photodiode

Seismic Noise

Quantum Noise

"Shot" noiseRadiation pressure


What Limits LIGO Sensitivity?Seismic noise limits low frequencies

Thermal Noise limits middle frequencies

Quantum nature of light (Shot Noise) limits high frequencies

Technical issues -alignment, electronics, acoustics, etc limit us before we reach these design goals


Commissioning /Running Time Line

NowInauguration

1999 2000 2001 2002 20033 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

E2Engineering E3 E5 E9 E10E7 E8 E11

First Lock Full Lock all IFO

10-17 10-18 10-20 10-21

2004 20051 2 3 4 1 2 3 4 1 2 3 4

2006

First Science Data

S1 S4Science S2 RunsS3 S5

10-224K strain noise at 150 Hz [Hz-1/2]4x10-23


Evolution of LIGO SensitivityS1: 23 Aug – 9 Sep ‘02S2: 14 Feb – 14 Apr ‘03S3: 31 Oct ‘03 – 9 Jan ‘04S4: 22 Feb – 23 Mar ‘05S5: 4 Nov ‘05 -


Initial LIGO - Design Sensitivity


102 10310-23

10-22

10-21

10-20

10-19

10-18

Frequency (Hz)

Equi

vale

nt s

trai

n no

ise

(Hz-1

/2)

H1, 20 Oct 05L1, 30 Oct 05SRD curve

Rms strain in 100 Hz BW: 0.4x10-21

Sensitivity Entering S5 …


S5 Run Plan and Outlook

Goal is to “collect at least a year’s data of coincident operation at the science goal sensitivity”

Expect S5 to last about 1.5 yrs

S5 is not completely ‘hands-off’

Run S2 S3 S4

22% 75%

81%

H2 58% 63% 81% 85% 90%

57%

69%

16%

37%

74%

22%

S5 Target

SRDgoal

L1 85% 90%

H1 85% 90%

3-way 70% 75%

Interferometer duty cycles


Sensitivity Entering S5 …Hydraulic External Pre-Isolator


Locking Problem is Solved


What’s after S5?


“Modest” Improvements

Now – 14 Mpc

Then – 30 Mpc


Astrophysical Sources

Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates

Supernovae / GRBs: “bursts”» burst signals in coincidence with signals in

electromagnetic radiation » prompt alarm (~ one hour) with neutrino

detectors

Pulsars in our galaxy: “periodic”» search for observed neutron stars

(frequency, doppler shift)» all sky search (computing challenge)» r-modes

Cosmological Signal “stochastic background”


Our Searches

BNS

PBH

Spin is important

“High mass ratio”Coming soon

1

3

100.1

Mass

Mass0.1 1 3

10

Inspiral-Burst S4

Several inspiralsearches are performed currently:» Primordial black holes

binaries (PBHB)» Binary Neutron Stars (BNS)» Binary Black Holes (BBH)

Other searches in progress» Spinning Black Holes» Coincidences with GRB» Black Hole Ringdown» Inspiral-Burst

BBH


Template Bank

Covers desiredregion of massparam spaceCalculatedbased on L1noise curveTemplatesplaced formax mismatchof δ = 0.03

2110 templatesSecond-orderpost-Newtonian


Binary Neutron Star Search Results (S2)

cum

ulat

ive

num

ber o

f eve

nts

signal-to-noise ratio squared

Rate < 47 per year perMilky-Way-like galaxy

Physical Review D


Binary Black Hole Search


From Limit Setting to Detections


Improving Sensitivities

Effective distance of L1 improved – S3 S4

8 Mpc to 40 Mpc


Binary Inspiral Search: LIGO Ranges

Image: R. Powell

binary neutron star range

binary black hole range






detectors





‘Unmodeled’ Burstssearch for waveforms from sources for which we cannot currently make an accurate prediction of the waveform shape.

GOAL

METHODS

Time-Frequency Plane Search‘TFCLUSTERS’

Pure Time-Domain Search‘SLOPE’

freq

uenc

y

time

‘Raw Data’ Time-domain high pass filter

0.125s

8Hz


Burst Search ResultsBlind procedure gives one event candidate» Event immediately

found to be correlated with airplane over-flight


Burst Source - Upper Limit


Astrophysical Sourcessignatures




detectors





Detection of Periodic Sources

Pulsars in our galaxy: “periodic”» search for observed neutron stars » all sky search (computing challenge)» r-modes

Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes.

Amplitude modulation due to the detector’s antenna pattern.


Directed Pulsar Search

28 Radio Sources


Einstein@Home

LIGO Pulsar Search using home pc’s

BRUCE ALLENProject Leader

Univ of Wisconsin Milwaukee

LIGO, UWM, AEI, APS

http://einstein.phys.uwm.edu

ALL SKY SEARCHenormous

computing challenge


All Sky Search – Final S3 Data

NO Events

Observed






detectors





Signals from the Early UniverseStrength specified by ratio of energy density in GWs to total energy density needed to close the universe:

Detect by cross-correlating output of two GW detectors:

d(lnf)dρ

ρ1(f)Ω GW

criticalGW =

Overlap Reduction Function


Stochastic Background Search (S3)

Fraction of Universe’senergy in gravitational waves:

(LIGO band)


Results – Stochastic Backgrounds


ConclusionsLIGO works! Data Analysis also works for broad range of science goals. Now making transition from limit setting to detection based analysisData taking run (S5) to exploit Initial LIGO is well underway and will be complete within ~ 1.5 yearsIncremental improvements to follow S5 are being developed. (improve sensitivity ~ x2)Advanced LIGO fully approved by NSF and NSB and funding planned to commence in 2008. (design will improve sensitivity ~ x20)R&D on third generation detectors is underway

st thomas, virgin islandsbcbact/talks06/st... · 17-march-06 confronting gravity - st thomas 4...

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