status of advanced ligo: we are listening! · michelson interferometer ... currently engaged in o1!...
TRANSCRIPT
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LIGO-G1501517
Status of Advanced LIGO: We are listening!
Johannes Eichholzfor the
LIGO Scientific Collaboration
16th December 2015Miami 2015 CGC Conference in Ft Lauderdale, FL
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Overview
2 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Gravitational waves and laser interferometers
● Advanced LIGO topology
● Current status
● Data challenge
● Future efforts
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99 Years of Gravitational Waves
3 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Perturbed Einstein equations
● Quadrupole pattern
● Two polarizations
● Precise measurement of change in orbital period● Energy loss mechanism: Gravitational Waves!
Best indicator this far: PSR B1913+16 (Hulse-Taylor)
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GW Strain and Detector Sensitivities
4 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Supernovae
BinaryInspirals
Pulsar Timing
Long BaselineSpace Interferometers
SupermassiveBinaries
PrimordialGWs
Extreme Mass-Ratio Inspirals
BinarySystems
LIGO
aLIG
O
Ground-basedInterferometers
Spinning NS
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Interferometric Detectors
5 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Changing distance affects laser phase● Michelson topology suppresses laser noise● Passing waves modulate IFO output● Interferometers are antennas
● Little to no directional resolution● Polarization and direction dependance
Antenna patterns
Several enhancing key technologies
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First Generation Detector Sites
6 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
LIGO Hanford (x2)
Virgo (Italy)
GEO600 (Germany)
LIGO Livingston
● Large Scientific Collaboration● Technology transfer● Joint science runs● Coordinated upgrade schedule● Advanced LIGO approved in 2004
● Transition to second generation
List of publications: https://www.lsc-group.phys.uwm.edu/ppcomm/Papers.html
4 km + 2 km
4 km3 km
1.2 km (folded 600 m)
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Duty Cycle Over the past 10 Years
7 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
https://losc.ligo.org/timeline/
Maintains up-time in case of events
Decommissioned
Beginning ofConstruction
Beginning ofinstallation
Installation complete;Commissioning starts
Advanced Virgois approved
Beginning ofconstruction
GEO
H1
H2
L1
V1
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From Enhanced to Advanced LIGO
8 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Detectors sense amplitude of GW● Range scales with strain sensitivity● 10x sensitivity: 1000x volume
● Boosts event rates
● Better seismic isolation● Lower mechanical loss
● Increased laser power● Need to be aware:
● Thermal noise● Radiation pressure
Suspensions Laser Power
RadiationPressure Coating Brownian
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Advanced LIGO Optical Layout
9 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Cavity-enhanced dual-recycledMichelson interferometer
● High input power
Pre-Stabilized Laser
Phase Modulator
Input Mode Cleaner
Output Mode Cleaner
Faraday Isolator
Faraday Isolator
End Test Mass X-Arm
End Test Mass Y-Arm
Detector Readout
4 km
4 km
Beamsplitter
125 W
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Pre-Stabilized Laser
Phase Modulator
Input Mode Cleaner
Output Mode Cleaner
Faraday Isolator
Faraday Isolator
Input Test Mass X-Arm
End Test Mass X-Arm
End Test Mass Y-Arm
Input Test Mass Y-Arm
Detector Readout
4 km
4 km
Beamsplitter
125 W
18 kW
18 kW
Advanced LIGO Optical Layout
10 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Cavity-enhanced dual-recycledMichelson interferometer
● High input power● Arm cavities increase interaction time
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Advanced LIGO Optical Layout
11 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Cavity-enhanced dual-recycledMichelson interferometer
● High input power● Arm cavities increase interaction time● Power recycling traps light in IFO
Pre-Stabilized Laser
Phase Modulator
Input Mode Cleaner
Output Mode Cleaner
Faraday Isolator
Faraday Isolator
Input Test Mass X-Arm
End Test Mass X-Arm
End Test Mass Y-Arm
Input Test Mass Y-Arm
Detector Readout
Power Recycling Mirror
4 km
4 km
Beamsplitter
125 W
5.2 kW
750 kW
750 kW
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Advanced LIGO Optical Layout
12 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Cavity-enhanced dual-recycledMichelson interferometer
● High input power● Arm cavities increase interaction time● Power recycling traps light in IFO● Signal recycling enhances GW signals
● New in Advanced LIGO
Pre-Stabilized Laser
Phase Modulator
Input Mode Cleaner
Output Mode Cleaner
Faraday Isolator
Faraday Isolator
Input Test Mass X-Arm
End Test Mass X-Arm
End Test Mass Y-Arm
Input Test Mass Y-Arm
Detector Readout
Power Recycling Mirror
Signal Recycling Mirror
4 km
4 km
Beamsplitter
125 W
5.2 kW
750 kW
750 kW
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Key Upgrades: Suspensions
13 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● External hydraulic pre-isolation● Internal active stabilization● Quadruple suspensions for arm
cavity optics● Monolithic last stage
● Triple suspensions for other core optics
● Over ten orders of magnitude seismic isolation above 10 Hz
Picture credit: https://www.advancedligo.mit.edu
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Key Upgrades: Laser and Optics
14 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Picture credit: https://www.advancedligo.mit.eduP. Kwee et al.: Opt. Express 20 10 (2012)
● More laser power● Additional amplification stage
● New test masses● 4x heavier (40 kg each)● High purity fused silica substrates● Ti:Ta2O5-SiO2 multilayer coatings
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Commissioning
15 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Installation complete as of August 2014● Formally accepted in March 2015
● Both detectors full lock capability● Since then: Commissioning
● Gradually improve sensitivity
● Detector characterization● 100k+ auxiliary channels
● Identify problems● Stray light● Channel cross-talk, feedback controls● ???
● Gradually increase laser powerAasi et al. (2013)
LIGO Document G1401390
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Advanced LIGO Timeline
16 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Timeline as of December 2014 (presented at last year's CGC conference)● Intermittent engineering runs
● Extended periods of detector up-time for testing● First observation run (O1) started with only a few days delay
● Will lasts until mid-January● Second observation run planned for second half of 2016
We are here, according to plan!
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Currently Engaged in O1!
17 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● ~70 Mpc at beginning of O1● For binary neutron star inspirals
● Larger for heavier binaries● Merger frequency decreases
● Uncertain for SN or spinning NS
Laser power
Detector calibration
Brownian noise?
● Shot noise limit reached● Further increase laser power● Squeezed light
● Detector noise characterization● Coupling to environmental noise
● Brownian noise levels● First-time limitation
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The Data Challenge
18 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Main channel: differential arm● Projection into plane of detector● GW signals will be weak
● Only few cycles for integration● Buried in noise● Require complex extraction techniques
How exactly do we look for gravitational waves in the data stream?
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Modeled Searches
19 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Continuous wave
Inspiral
Ringdown
● Simulate waveforms with GR and PN methods● Create template bank
● Large parameter space for binary inspirals● Masses, separation, spins● Orientation, distance and sky location
● Correlate datastream with template bank
Example: Matched Filtering
Compact BinaryCoalescences
● Online or offline searches● Can be turned into a test of GR!
● Merger and ringdown modeled with numerical relativity
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Unmodeled Searches
20 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
Example: Coherent Wave Burst (CWB)
LIGO Livingston
LIGO Hanford
Reconstructed waveform
● Trigger from excess power in frequency bins● Coincident in different detectors?● Find timing offsets
● Identical phase progression● Correlate detector data for waveform
INJE
CTED
EVE
NT
Time-frequency traces
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Problems with blind searches
21 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Ground-based detector sources are all transient in nature● Cannot simply “look again”
● Detectors can glitch and produce output that looks like a GW● Detection statistics for ranking of significance● Vetos from auxiliary channels
● Glitches are caused locally● Uncorrelated between different detectors● Can still be coincident
● The more independent data streams, the better!!!
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More detectors are coming!
22 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
LIGO Hanford
Virgo (Italy)
GEO600 (Germany)
LIGO Livingston
KAGRA
LIGO-India
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Advanced Virgo
23 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Advanced Virgo approved in 2009 ● Construction began in fall 2011● Installation expected to finish soon● Joint observation run with LIGO
planned for 2016
● Input laser noise to specs● Input test masses suspensions installed
● Quads were pioneered by Virgo● All large mirrors have been produced
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LIGO-India
24 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Awaiting “in principal” approval from government (very soon)● Will use parts of decommissioned Hanford-2 LIGO detector● Far into site selection process (from 20 down to 2-3)
Cooperation between LIGO and Indigo(Indian Initiative in Gravitational-wave Observations)
Would improve sky localization immensely!
Without LIGO India With LIGO IndiaAasi et al. (2013)
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KAGRA
25 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Third large Japanese detector● TAMA 300, CLIO
● First underground observatory● Located in Kamioka mine with other experiments
(Super-Kamiokande, XMASS, KamLand)● Pioneering cryogenics in interferometric detectors
● May start observing as early as 2018!
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Summary
26 Johannes Eichholz for the LIGO Scientific Collaboration Dec 16 2015, CGC Conference in Ft. Lauderdale, FL
● Advanced LIGO completed upgrades● Outperforms previous sensitivity by factor of 3 and improving
● Currently engaged in first observation run● Advanced Virgo is expected to join observations in 2016● KAGRA may start observing as early as 2018● LIGO-India could reach astrophysical sensitivities by 2022
● Six 2nd generation interferometric detectors on the horizon● LISA Pathfinder launched successfully
In the meantime,LIGO is staying tuned
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LIGO Scientific Collaboration