Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://zebu.uoregon.edu/~uochep/talks/talks07/Frey_c2cr07.pdf Äàòà èçìåíåíèÿ: Tue Mar 13 02:40:45 2007 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 11:42:01 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: merging galaxies

LIGO: The Search for the Gravitational Wave Sky
- status, physics, results, prospects
Ray Frey, University of Oregon for the

LIGO Scientific Collaboration
C2CR07, Granlibakken

· Introduction (brief) · Current status · Observational results, selected
No detections can be reported (yet).

· Prospects: enhanced and Advanced LIGO; toward a worldwide network of GW observatories


Laser Interferometer Gravitational-wave Observatory

4 km & 2 km

WA Caltech
· Managed and operated by

30 (± 30 10 k mm s)

MIT

Caltech & MIT with funding from NSF · Ground breaking 1995 · 1st interferometer lock 2000 · LIGO Scientific collaboration: 45 institutions, world-wide
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4 km

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Required GW Sensitivity

· ·

GW emission requires time varying quadrupole moment of mass distribution Strain estimate (h = L/ L) :

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GW Interferometer Principle

GW strain: h = L/ L
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Interferometer parameters
· · · Long baseline 4 km ( h = L/ L ) - For h 10-21, L 1 km, then L 10 10-9 rad required phase sensitivity Fabry-Perot Cavity storage time 1 ms (100 bounces) High laser power ( = 1 m) Power recycling (x30) Cavities: Few watts in; few kW in arms
-18

m

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What Limits Sensitivity of the Interferometers?
· Seismic noise & vibration limit at low frequencies Thermal noise of suspensions and test masses Quantum nature of light (Shot Noise) limits at high frequencies Limitations of facilities much lower

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S5 Science Run: LIGO at Design Sensitivity

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Science runs and sensitivity

Run
S1
Sept `02

# days 17 59 70 30 ongoing

S2
Feb 03-Apr 03

S3
Nov 03-Jan 04

S4
Feb- March 05

S5
Nov 05 -- ?

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Astrophysical Signal Types
· Compact binary inspiral: "chirps" NS-NS, BH-BH waveforms are well described search technique: matched templates Supernovae / GRBs: "bursts" "unmodelled" search triggered searches
SN 1987 A

·

·

Pulsars in our galaxy: "periodic" observe known neutron stars (frequency, doppler shift) all sky search (computing challenge) Low-mass X-ray binaries Cosmological "stochastic background" GWs neutrinos photons
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now

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Coalescing Compact Binaries
NS-NS, BH-BH, (BH-NS) binary systems

Matched filter

Template-less

Matched filter

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Binary Black Holes Early S5:

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Mass-dependent horizon

NS/BH
3
Component mass m2 [M] Binary Neutron Stars Early S5 BNS horizon: Hanford-4km: 25 Mpc Livingston-4km: 21 Mpc Hanford-2km: 10Mpc Was 1.5 Mpc in S2 Primordial Black Hole Binaries / MACHOs S4 reach: 3 Milky Way-like halos S5 in progress

Peak for H1: 130Mpc ~ 25M



NS/BH

1

BNS horizon: distance of optimally oriented and located 1.4-1.4 M binary at SNR=8

0.1

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S4 upper limits-compact binary coalescence
Rate/year/L
10

vs. binary total mass (L

10

= 10

10

L

sun

(1 Milky Way = 1.7 L10)

Excluded at 90% CL

Preliminary
10 / yr / L10 1 / yr / L 1.4-1.4 Mo 0.1 / yr / L10
10

0.8-6.0 Msun

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S5 search for compact binary signals ·
· ·

3 months of data analyzed- no signals seen
For 1.4-1.4 Mo binaries, ~ 200 MWEGs in range For 5-5 Mo binaries, ~ 1000 MWEGs in range

Inspiral horizon for equal mass binaries vs. total mass

(horizon=range at peak of antenna pattern; ~2.3 x antenna pattern average)


Burst Search (All-sky) Results and Prospects
PRD 72 (2005) 042002

d de clu Ex % 90 CL

S1 S2

S4

projected

S5

projected

(assumes no detections)

S5 sensitivity: EGW > 1 Mc2 at 75Mpc EGW > 0.05 Mc2 at 15Mpc
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Gravitational Radiation and Gamma-ray Bursts
BATSE Long-duration GRBs · Stronger afterglows z · SNe or "hypernovae" · mean z 2.5
GSFC

Short-duration GRBs · Until 2005, no measured z's enter Swift · Now: a few z's "compact binary mergers" · mergers are efficient GW radiators · much smaller z's (mean 0.4)
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GRB030329 HETE-2

Oct 6, 2005

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Search Method: GWs associated with GRBs
trigger time counts/sec

sample GRB lightcurve
(Swift)

use 180-second LIGO on-source data surrounding GRB trigger

180 seconds
LIGO IFO 1 crosscorrelate output of two IFOs over 100 ms

LIGO IFO 2

look for largest on-source crosscorrelation and compare to nearby off-source segments
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GRB-GW Results
No significant detections in S2, S3, S4 strain (hrss ) limits
to be submitted to PRD

preliminary

S5 Run · Expect 200 GRBs · LIGO at design sens. · Typical GRB sensitivity: EGW 0.3 M c2 (merger at 20 Mpc,250 Hz)

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Search for known pulsars - preliminary
95% upper limits for 97 pulsars using ~10 months of the S5 run
For 32 of the pulsars we give the expected sensitivity upper limit (red stars) due to uncertainties in the pulsar parameters .

Pulsar timings provided by the Jodrell Bank pulsar group Lowest GW strain upper limit: PSR J1802-2124 (fgw = 158.1 Hz, r = 3.3 kpc) h0 < 4.9â10-26

inary m Preli

Lowest ellipticity upper limit: PSR J2124-3358 (fgw = 405.6 Hz, r = 0.25 kpc) < 1.1â10-7


Relic GWs: Results and Prospects
LIGO S1: 0 < 44 0 Pulsar CMB+galaxy+Ly- Timing -4 adiabatic homogeneous -6 -2 Log (0) Log(GW) -8 CMB Inflation Slow-roll Pre-BB model
PRD 69 122004 (2004)

LIGO S3: 0 < 8.4x10-
PRL 95 221101 (2005)

4

BB Nucleosynthesis

LIGO S4: 0 < 6.5x10-
(newest)

5

Cosmic strings

Initial LIGO, 1 yr data Expected Sensitivity ~ 4x10-6 Adv. LIGO, 1 yr data Expected Sensitivity ~ 1x10-9

-10 -12 -14

EW or SUSY Phase transition -18 -16 -14 -12 -10 -8 -6 -4 -2 Log (f [Hz])
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Cyclic model 0 2 4 6 8 10

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Global network of interferometers LIGO
4 km & 2 km

GEO
600m

VIRGO
3 km

TAMA
300m

News flash (1/18/07) LSC (LIGO and GEO) have reached a collaborative agreement with Virgo · Detection confidence

AIGOR&D facility

LIGO
4 km

· · · ·
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The Future: Enhanced and Advanced LIGO
S5 Run
2006 2007 2008

S6
2009 2010 2011 2012 2013

S7
2014

LIGO News flash: Advanced LIGO is in the FY08 President's budget

enhanced LIGO Advanced LIGO build hardware installation science

Enhanced LIGO (S6) · readout noise; laser power · Commission AdLIGO readout with real IFOs · reduce AdLIGO startup time Advanced LIGO · Major upgrades: optics, lasers, suspensions, ... · â10 better sensitivity

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Advanced LIGO reach (example)
NS-NS inspiral search

NS-NS sources (h sensitivity)2.7

h sensitivity will improve by 10, with improved bandwidth

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Observational Publications
Bursts · All-sky untriggered searches: · S1 - PRD 69, 102001 (2004)
· S2 - PRD 72, 062001 (2005) ; LIGO+TAMA - PRD 72, 122004 (2005) · S3 - CQG 23, S29-S39 (2006) · S4 - to be submitted 3/07 · GRB-GW searches: · GRB030329 ­ PRD 72, 042002 (2005) ; · S2,S3,S4 ­ to be submitted to PRD 3/07 · Search for quasi-periodic GWs from SGR 1806-20 following record gamma-ray flare of Dec 27, 2004 - to be submitted 3/07 · Cosmic (super-)string GW search (S5) ­ in preparation

Stochastic · S1 - PRD 69, 122004 (2004)
· S3 - PRL 95, 221101 (2005) · S4 ­ submitted to ApJ

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Projects and Publications (contd)
Pulsars · Searches: S1 - PRD 69, 082004 (2004) ;
· S2 known pulsar search - PRL 94, 181103 (2005) · S2 coherent search ­ submitted to PRD · S2 Hough transform search - PRD 72, 102004 (2005) · S3/S4 known pulsar search ­ to be submitted 3/07

Inspirals/coalescences · NS-NS searches:
· S1 - PRD 69, 122001 (2004) · S2 - PRD 72, 082001 (2005) · S3/S4 ­ in preparation · S2 MACHO search - PRD 72, 082002 (2005) · S2 LIGO+ TAMA - PRD 73, 102002 (2006) · S2 BH-BH search - PRD 73, 062001 (2006)

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Summary
· LIGO is now a powerful scientific instrument with "reasonable" sensitivity to astrophysical GW sources Analysis groups and methods have reached a mature level with a good publication record Now it is up to nature...

·

·

The scientific collaboration (LSC) is strong and prospects are excellent for advancing GW science through the next decade Advanced LIGO is on track Future ground-based GW science will be based on a global network of sensitive interferometers (LIGO, GEO, Virgo, ...)

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