Transcript INDIGO-KR_plancomm_pI_v3

IndIGO
Indian Initiative in Gravitational-wave Observations
Detecting Einstein’s Elusive Waves
Opening a New Window to the Universe
Inaugurating Gravitational wave Astronomy
LIGO-India: An Indo-US joint mega-project concept proposal
IndIGO Consortium
www.gw-indigo.org
Version: pI_v3 Jun 21, 2011 : BI
What are Gravitational waves and
how best to detect them??
Beauty & Precision
Einstein’s General theory of
relativity is considered the most
beautiful, as well as,
theory of modern physics.
It has matched all experimental tests
of Gravitation in the solar system
remarkably well…
Einstein’s Gravity predicts
• Matter in motion Space-time ripples; fluctuations in
space-time curvature that propagate as waves
Gravitational waves (GW)
• In GR, as in EM, GW travel at the speed of light ,
are transverse and have two states of polarization.
• A major qualitatively unique prediction
beyond Newton’s gravitation
Indirect evidence for Gravitational waves
Binary pulsar systems emit gravitational waves
•
leads to loss of orbital energy
•
period speeds up 14 sec from
1975-94
Pulsar Timing
•
measured to ~50 msec accuracy
•
Nobel prize
in 1993 !!!
deviation grows quadratically
with time
Pulsar
companion
Hulse and Taylor
Results for PSR1913+16
Astrophysical Sources for Terrestrial GW
Detectors
• Compact binary inspiral:
– NS-NS, NS-BH, BH-BH
“chirps”
• Supernovas or GRBs: “bursts”
– GW signals observed in coincidence
with EM or neutrino detectors
• Pulsars in our galaxy: “periodic waves”
– Rapidly rotating neutron stars
– Modes of NS vibration
• Cosmological: “stochastic background” ?
– Probe back to the Planck time (10-43 s)
– Probe phase transitions : window to force
unification
Courtesy;:
Stan Whitcomb distribution of Primordial black holes
– Cosmological
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Oscillatory Tidal Effect of GW on a ring of test masses
If Interferometer mirrors are the test masses
Difference in Path length due to tidal distortion  Interference of laser light at the(Photodiode)
Current Status of World-wide
GW detection efforts
Laser Interferometer Gravitational-wave
Observatory (LIGO)
IndIGO - ACIGA meeting
9
Virgo detector (near Pisa, Italy)
LIGO and Virgo TODAY
Experimental Milestone: Kilometer scale interferometric GW detectors (LIGO and
Virgo) have achieved their predicted design goals.
Pre-dawn GW astronomy : Unprecedented sensitivity already allows
• Upper Limits on GW from a variety of Astrophysical sources.
• Improve on Spin down of Crab, Vela pulsars..Less than 2% available energy in Crab
emitted as GW
• Experimentally surpass Big Bang nucleosynthesis bound on Stochastic GW..
Advanced LIGO
Era of Advanced LIGO detectors: 2015
10x sensitivity
10x reach
 1000 volume
>> 1000X event rate
(reach beyond
nearest super-
clusters)
A Day of Advanced
LIGO Observation >>
A year of Initial LIGO
Mean Expected Annual Coalescence Event Rates
Detector
Generation
Initial LIGO
(2002 -2006)
Advanced LIGO
(10X sensitivity)
(2014+ - …)
NS-NS
NS-BH
BH-BH
0.02
0.0006
0.0009
10.
20.0
40
In a 95% confidence interval, rates uncertain by 3 orders of magnitude
NS-NS (0.4 - 400); NS-BH (0.2 - 300) ; BH-BH (2 - 4000) yr^-1
Based on Extrapolations from observed Binary Pulsars, Stellar birth rate
estimates, Population Synthesis models. Rates quoted below are mean of the distribution.
Need for Long baseline global
Network:
IndIGO opportunities and benefits
From the GWIC Strategic Roadmap for GW
Science with thirty year horizon (2007)
• “… the first priority for ground-based
gravitational wave detector development is to
expand the network, adding further detectors with
appropriately chosen intercontinental baselines
and orientations to maximize the ability to extract
source information. ….Possibilities for a detector in
India (IndIGO) are being studied..”
•Invitation to Present IndIGO case for GWIC Membership
on July 10 at GWIC meeting at Cardiff
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GW Astronomy with Intl. Network of GW Observatories
1. Detection confidence 2. Duty cycle 3. Source direction 4. Polarization info.
GEO: 0.6km
LIGO-LHO: 2km+ 4km
VIRGO: 3km
LCGT 3 km
TAMA/CLIO
LIGO-LLO: 4km
LIGO-Australia?
LIGO-India ?
LIGO-India: … the opportunity
Science Gain from Strategic Geographical Relocation:
Source localization error
Courtesy:
S. Fairhurst
LIGO-India plan
1+1 LIGO USA+ Virgo+ LIGO-India
Original Plan
2 +1 LIGO USA+ Virgo
LIGO-Aus plan
1+1 LIGO USA+ Virgo+ LIGO-Aus
Gravitational wave legacy in India
Internationally recognized Indian contribution to the global effort
for detecting GW on two significant fronts over two decades
• Seminal contributions to source modeling at RRI [Bala Iyer] and
to GW data analysis at IUCAA [Sanjeev Dhurandhar]
• RRI: Indo-French collaboration for two decades to compute high accuracy
waveforms for in-spiraling compact binaries from which the GW templates
used in LIGO and Virgo are constructed.
• IUCAA: Designing efficient data analysis algorithms involving advanced
mathematical concepts.. Notable contributions include the search for binary
in-spirals, hierarchical methods, coherent search with a network of detectors
and the radiometric search for stochastic gravitational waves.
• IUCAA has collaborated with most international GW
detector groups and has been a member of the LIGO
Scientific Collaboration (LSC) for a decade.
• At IUCAA, Tarun Souradeep with expertise in CMB data and
Planck has worked to create a bridge between CMB and GW
data analysis challenges.
Indian Gravitational wave strengths
• Very good students and post-docs produced from this.
* Leaders in GW research abroad [Sathyaprakash, Bose, Mohanty] (3) *
*New faculty at premier Indian institutions (6) [Gopakumar, Archana Pai,
Rajesh Nayak, Anand Sengupta, K.G. Arun, Sanjit Mitra, P. Ajith?]
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Gopakumar (Jena  TIFR) and Arun (Virgo  CMI) : PN modeling, dynamics of CB, Ap and
cosmological implications of parameter estimation
Rajesh Nayak (UTB  IISER K) , Archana Pai (AEI  IISER T), Anand Sengupta (LIGO, Caltech Delhi),
Sanjit Mitra (JPL  IUCAA ): Extensive experience on single and multi-detector detection, hierarchical
techniques, noise characterization schemes, veto techniques for GW transients, bursts, continuous and
stochastic sources, radiometric methods, …
P. Ajith (Caltech, LIGO/TAPIR  ? ) ……
Sukanta Bose (Faculty UW, USA  ?)
Strong Indian presence in GW Astronomy with Global detector network
 broad international collaboration is the norm
 relatively easy to get people back.
•
Close interactions with Rana Adhikari (Caltech), B.S. Sathyaprakash (Cardiff),
Sukanta Bose ( WU, Pullman), Soumya Mohanty (UTB), Badri Krishnan ( AEI) …
• Very supportive International community reflected in International
Advisory committee of IndIGO – Chair Abhay Ashtekar
High precision and Large experiment in India
• TIFR [C.S. Unnikrishnan] : High precision experiments and tests
– Test gravitation using most sensitive torsional balances and optical sensors.
– Techniques related to precision laser spectroscopy, electronic locking, stabilization.
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•
Groups at BARC and RRCAT : involved in LHC
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•
G.Rajalakshmi (TIFR, 3m prototype); Suresh Doravari (Caltech, 40m)
providing a variety of components and subsystems like precision magnet positioning stand jacks,
superconducting correcting magnets, quench heater protection supplies and skilled manpower
support for magnetic tests and measurement and help in commissioning LHC subsystems.
RRCAT
[S.K. Shukla on INDUS] - UHV experience.
[Sendhil Raja] - Optical system design, laser based instrumentation, optical metrology,
Large aperture optics, diffractive optics, micro-optic system design.
[A.S. Raja Rao] (ex RRCAT) - UHV Consultant
•
IPR
[S.B. Bhatt on Aditya and Ajai Kumar] - UHV experience.
•
IITM [Anil Prabhakar] and IITK [Pradeep Kumar] (EE depts)
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Photonics, Fiber optics and communications
Characterization and testing of optical components and instruments for use in India..
Observatoire de la Cote d'Azur [Rijuparna Chakraborty] ..Adaptive Optics..
–
Under consideration for postdoc in LIGO or Virgo….
Multi-Institutional,
Multi-disciplinary Consortium
(2009)
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3.
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5.
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9.
CMI, Chennai
Delhi University
IISER Kolkata
IISER Trivandrum
IIT Madras (EE)
IIT Kanpur (EE)
IUCAA
RRCAT
TIFR
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•
•
•
RRI
IPR, Bhatt
Jamia Milia Islamia
Tezpur Univ
The IndIGO Consortium
IndIGO Council
1.
2.
3.
4.
Bala Iyer
Sanjeev Dhurandhar
C. S. Unnikrishnan
Tarun Souradeep
( Chair)
(Science)
(Experiment)
(Spokesperson)
Data Analysis & Theory
Instrumentation & Experiment
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2.
3.
4.
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6.
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16.
C. S. Unnikrishnan TIFR, Mumbai
G Rajalakshmi
TIFR, Mumbai
P.K. Gupta
RRCAT, Indore
Sendhil Raja
RRCAT, Indore
S.K. Shukla
RRCAT, Indore
Raja Rao
ex RRCAT, Consultant
Anil Prabhakar,
EE, IIT M
Pradeep Kumar,
EE, IIT K
Ajai Kumar
IPR, Bhatt
S.K. Bhatt
IPR, Bhatt
Ranjan Gupta
IUCAA, Pune
Bhal Chandra Joshi NCRA, Pune
Rijuparna Chakraborty, Cote d’Azur, Grasse
Rana Adhikari
Caltech, USA
Suresh Doravari
Caltech, USA
Biplab Bhawal
(ex LIGO)
RRI, Bangalore
IUCAA, Pune
TIFR, Mumbai
IUCAA, Pune
1.
2.
3.
4.
5.
6.
7.
8.
9.
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12.
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15.
16.
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20.
Sanjeev Dhurandhar
Bala Iyer
Tarun Souradeep
Anand Sengupta
Archana Pai
Sanjit Mitra
K G Arun
Rajesh Nayak
A. Gopakumar
T R Seshadri
Patrick Dasgupta
Sanjay Jhingan
L. Sriramkumar,
Bhim P. Sarma
Sanjay Sahay
P Ajith
Sukanta Bose,
B. S. Sathyaprakash
Soumya Mohanty
Badri Krishnan
IUCAA
RRI
IUCAA
Delhi University
IISER, Thiruvananthapuram
JPL , IUCAA
Chennai Math. Inst., Chennai
IISER, Kolkata
TIFR, Mumbai
Delhi University
Delhi University
Jamila Milia Islamia, Delhi
Phys., IIT M
Tezpur Univ .
BITS, Goa
Caltech , USA
Wash. U., USA
Cardiff University, UK
UTB, Brownsville , USA
Max Planck AEI, Germany
IndIGO: the goals & roles
•
Provide a common umbrella to initiate and expand GW related experimental activity and
training new manpower
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3m prototype detector in TIFR (funded) - Unnikrishnan
Laser expt. RRCAT, IIT M, IIT K - Sendhil Raja, Anil Prabhakar, Pradeep Kumar
Ultra High Vacuum & controls at RRCAT, IPR, BARC, ISRO, …. Shukla, Raja Rao, Bhatt,
UG summer internship at National & International GW labs & observatories.
Postgraduate IndIGO schools, specialized courses,…
Consolidated IndIGO membership of LIGO Scientific Collaboration in Advanced LIGO.
Proposal to create a Tier-2 data centre for LIGO Scientific Collaboration in IUCAA
IUSSTF Indo-US joint Centre at IUCAA with Caltech (funded)
Major experimental science initiative in GW astronomy

Earlier Plan: Partner in LIGO-Australia (a diminishing possibility)
–
–
–

Advanced LIGO hardware for 1 detector to be shipped to Australia at the Gingin site, near Perth. NSF approval
Australia and International partners find funds (equiv to half the detector cost ~$140M and 10 year running cost ~$60M)
within a year.
Indian partnership at 15% of Australian cost with full data rights.
Today: LIGO-India (Letter from LIGO Labs)
–
–
–
–
Advanced LIGO hardware for 1 detector to be shipped to India.
India provides suitable site and infrastructure to house the GW observatory
Two 4km arm length ultra high vacuum tubes in L configuration
Indian cost ~ Rs 1000Cr
The Science & technology benefit of LIGO-India is
transformational
LIGO-India: Why is it a good idea?
… for the World
• Strategic geographical relocation for GW astronomy
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–
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Increased event rates (x4) by coherent analysis
Improved duty cycle
Detection confidence
Improved Sky Coverage
Improved Location of Sources required for multi-messenger astronomy
Determine the two polarizations of GW
• Potentially large science community in the future
– Indian demographics: youth dominated – need challenges
– excellent UG education system already produces large number of trained
in India find frontline research opportunity at home.
• Large data analysis trained manpower and facilities exist (and
being created).
LIGO-India: Why is it a good idea? …for India
– Provides an exciting challenge at an International
forefront of experimental science. Can tap and
siphon back the extremely good UG students
trained in India. (a cause for `brain drain’).
– 1st yr summer intern 2010  MIT for PhD
– Indian experimental scientist  Postdoc at LIGO training for Adv.
LIGO subsystem
• Indian experimental expertise related to GW
observatories will thrive and attain high levels due
to LIGO-India.
• Symbiotic interplay of Engineering and Science
disciplines for a challenging endeavour involving
unforgiving technology
• Jump start direct participation in GW Observations
& Astronomy
Rewards and Spinoffs
Detection of GW is the epitome of breakthrough science!!!
• LIGO-India  India could become a partner in
international science of Nobel Prize significance
• GW detection is an instrument technology intensive field pushing
frontiers simultaneously in a number of fields like lasers and
photonics. Impact allied areas and smart industries.
• The imperative need to work closely with industry and other end
users will lead to spinoffs as GW scientists further develop optical
sensor technology.
• Presence of LIGO-India will lead to pushing technologies and
greater innovation in the future.
• Increase number of research groups performing at world class
levels and produce skilled researchers.
• Increase international collaborations in Indian research &
establishing Science Leadership in the Asia-Pacific region.
… rewards and spinoffs
• LIGO-India will raise public/citizen profile of science since it
will be making ongoing discoveries fascinating the young.
GR, BH, EU and Einstein have a special attraction and a pioneering facility in India
participating in important discoveries will provide science & technology role models
with high visibility and media interest. Einstein@home; Black Hole Hunter…
• LIGO has a strong outreach tradition and LIGO-India will
provide a platform to increase it and synergyesically benefit.
• Opportune time to a launch a promising field (GW astronomy)
with high end technological spinoffs, well before it has
obviously blossomed. Once in a generation opportunity to
host an unique, path defining, international Experiment in
India.
• A GREAT opportunity but a very sharp deadline of 31 Mar 2012.
If we cannot act quickly the possibility will close. Conditions laid
out in the Requirement Document of LIGO-Lab will need to be
ready for LIGO-Lab examination latest by Dec 2011 so that in
turn LIGO-Lab can make a case with NSF by Jan 2012.
Science Payoffs
New Astronomy, New Astrophysics, New Cosmology, New Physics
” A New Window ushers a New Era of Exploration in Physics & Astronomy”
– Testing Einstein’s GR in strong and time-varying fields
– Testing Black Hole phenomena
– Understanding nuclear matter by Neutron star EOS
– Neutron star coalescence events
– Understanding most energetic cosmic events ..Supernovae, Gamma-ray bursts,
LMXB’s, Magnetars
– New cosmology..SMBHB’s as standard sirens..EOS of Dark
Energy
– Phase transition related to fundamental unification of forces
– Multi-messenger astronomy
– The Unexpected !!!!!
Unique Technology Payoffs
• Lasers and optics..Purest laser light..Low phase noise, excellent
beam quality, high single frequency power
• Applications in precision metrology, medicine, micro-machining
• Coherent laser radar and strain sensors for earthquake prediction
and other precision metrology
• Surface accuracy of mirrors 100 times better than telescope
mirrors..Ultra-high reflective coatings : New technology for other fields
• Vibration Isolation and suspension..Applications for mineral prospecting
• Squeezing and challenging “quantum limits” in measurements.
• Largest Ultra-high vacuum system 10^-9 torr (1picomHg) in the
region. Such a UHV system will provide industry a challenge and
experience.
• Computation Challenges: Cloud computing, Grid computing, new
hardware and software tools for computational innovation.
•
Thank you !!!
END
Part I
Over to Tarun…
Gravitational wave Astronomy :
vit
Synergy with other major Astronomy projects
• SKA : Pulsars timing and GW background, GW from Pulsars ,…
( RADIO: Square Kilometer array)
• CMB : GW from inflation, cosmic phase transitions, dark energy ….
(Cosmic Microwave Background : WMAP, Planck, CMBPOl, QUaD,…)
• X-ray satellite (AstroSat) : Spacetime near Black Holes, NS, ….
• Gamma ray observatory: GRB triggers from GW
(FermiLAT, GLAST,….)
• Thirty Meter Telescope: Resolving multiple AGNs, optical follow-up, …
• INO: cross correlate neutrino signals from SN event
• LSST: Astro-transients with GW triggers, Cosmic distribution of dark
matter , Dark energy
•
•
GWIC Roadmap Document
23 July 2011
Dear Bala:
I am writing to invite you to attend the next meeting of the Gravitational
Wave International Committee (GWIC) to present the GWIC membership
application for IndIGO. This in-person meeting will give you the opportunity
to interact with the members of GWIC and to answer their questions about
the status and plans for IndIGO. Jim Hough (the GWIC Chair) and I have
reviewed your application and believe that you have made a strong case for
membership……
Invitation to Present IndIGO case for GWIC
Membership on July 10 at GWIC meeting at Cardiff
IndIGO 3m Prototype Detector
Funded by TIFR Mumbai on compus (2010)
PI: C. S. Unnikrishnan (Cost ~ INR 2.5 crore)
Vibration isolation
schematic
Laser table
Sensing &
Control
180 cm
All mirros and beamsplitters
are suspended as in the diagram on right
Power recycling
Detector
Vacuum
tanks
F-P cavity
3.2 meters
0.8 m
Mirror
60 cm
LIGO-India: … the opportunity
Strategic Geographical relocation: science gain
Polarization info
Homogeneity of Sky coverage
Courtesy: S.Kilmenko & G. Vedovato
LIGO-India: … the opportunity
Strategic Geographical relocation: science gain
Sky coverage
: Synthesized
Network
beam
(antenna power)
Courtesy: B. Schutz
IndIGO Advisory Structure
Committees:
International Advisory Committee
Abhay Ashtekar (Penn SU)[ Chair]
Rana Adhikari (LIGO, Caltech, USA)
David Blair (ACIGA &UWA, Australia)
Adalberto Giazotto (Virgo, Italy)
P.D. Gupta (Director, RRCAT, India)
James Hough (GEO ; Glasgow, UK)[GWIC Chair]
Kazuaki Kuroda (LCGT, Japan)
Harald Lueck (GEO, Germany)
Nary Man (Virgo, France)
Jay Marx (LIGO, Director, USA)
David McClelland (ACIGA&ANU, Australia)
Jesper Munch (Chair, ACIGA, Australia)
B.S. Sathyaprakash (GEO, Cardiff Univ, UK)
Bernard F. Schutz (GEO, Director AEI, Germany)
Jean-Yves Vinet (Virgo, France)
Stan Whitcomb (LIGO, Caltech, USA)
National Steering Committee:
Kailash Rustagi (IIT, Mumbai) [Chair]
Bala Iyer (RRI) [Coordinator]
Sanjeev Dhurandhar (IUCAA) [Co-Coordinator]
D.D. Bhawalkar (Quantalase, Indore)[Advisor]
P.K. Kaw (IPR)
Ajit Kembhavi (IUCAA)
P.D. Gupta (RRCAT)
J.V. Narlikar (IUCAA)
G. Srinivasan
Program Management Committee:
C S Unnikrishnan (TIFR, Mumbai), [Chair]
Bala R Iyer (RRI, Bangalore), [Coordinator]
Sanjeev Dhurandhar (IUCAA, Pune) [Co-cordinator]
Tarun Souradeep (IUCAA, Pune)
Bhal Chandra Joshi (NCRA, Pune)
P Sreekumar (ISAC, Bangalore)
P K Gupta (RRCAT, Indore)
S K Shukla (RRCAT, Indore)
Sendhil Raja (RRCAT, Indore)]
Using GWs to Learn about the Source: an Example
Over two decades,
RRI involved in
computation of
inspiral waveforms
for compact
binaries & their
implications and
IUCAA in its Data
Analysis Aspects.
Can determine
• Distance from the earth r
• Masses of the two bodies
• Orbital eccentricity e and orbital inclination i
Strategic Geographical relocation: science gain
Network
HHLV
HILV
AHLV
Mean horizon
distance
1.74
1.57
1.69
Detection
Volume
8.98
8.77
8.93
41.00%
54.00%
44.00%
Triple
Detection
Rate(80%)
4.86
5.95
6.06
Triple
Detection
Rate(95%)
7.81
8.13
8.28
47.30%
79.00%
53.50%
0.66
2.02
3.01
Volume Filling
factor
Sky Coverage:
81%
Directional
Precision
Space Time as a fabric
Special Relativity (SR) replaced Absolute space and Absolute Time by flat 4dimensional space-time (the normal three dimensions of space, plus a fourth
dimension of time).
In 1916, Albert Einstein published his famous Theory of General Relativity, his
theory of gravitation consistent with SR, where gravity manifests as a curved
4-diml space-time
Theory describes how space-time is affected by mass and also how
energy, momentum and stresses affects space-time.
Matter tells space-time how to curve, and
Space-time tells matter how to move.
Space Time as a fabric
Earth follows a “straight path” in the curved
space-time caused by sun’s mass !!!
What happens when
matter is in motion?
Detecting GW with Laser Interferometer
B
A
Path A
Path B
Difference in distance of Path A & B  Interference of laser
light at the detector (Photodiode)
Indo-Aus.Meeting, Delhi, Feb
2011
Concluding remarks
• A century after Einstein’s prediction, we are on the threshold of a new
era of GW astronomy following GW detection. Involved four decades of
very innovative and Herculean struggle at the edge of science & technology
• First generation detectors like Initial LIGO and Virgo have achieved design
sensitivity  Experimental field is mature
Broken new ground in optical sensitivity, pushed technology and proved technique.
• Second generation detectors are starting installation and expected
to expand the “Science reach” by factor of 1000
• Cooperative science model: A worldwide network is starting to come on line and
the ground work has been laid for operation as a integrated system.
• Low project risk : A compelling Science case with shared science risk, a proven
design for India’s share of task (other part : opportunity w/o responsibility)
• National mega-science initiative: Need strong multi-institutional support
to bring together capable scientists & technologist in India
• An unique once-in-a-generation opportunity for India. India could
play a key role in Intl. Science by hosting LIGO-India.
… Concluding remarks
• A GREAT opportunity but a very sharp deadline of 31 Mar 2012. If we cannot act
quickly the possibility will close. Conditions laid out in the Request Doc of LIGOLab will need to be ready for LIGO-Lab examination latest by Dec 2011 so that in
turn LIGO-Lab can make a case with NSF by Jan 2012.
• Of all the large scientific projects out there, this one is pushing the
greatest number of technologies the hardest.
“Every single technology they’re touching they’re pushing, and there’s a lot
of different technologies they’re touching.”
(Beverly Berger, National Science Foundation Program director for gravitational physics. )
• One is left speculating if by the centenary of General
Relativity in 2015, the first discovery of Gravitational
waves would be from a Binary Black Hole system, and
Chandrasekhar would be doubly right about
Astronomy being the natural home of general relativity.
Initial LIGO Sensitivity Goal
• Strain sensitivity
<3x10-23 1/Hz1/2
at 200 Hz
l
Sensor Noise
» Photon Shot Noise
» Residual Gas
l
Displacement Noise
» Seismic motion
» Thermal Noise
» Radiation Pressure
47
Advanced LIGO
•Take advantage of new technologies and on-going R&D
>> Active anti-seismic system operating to lower frequencies:
(Stanford, LIGO)
>> Lower thermal noise suspensions and optics :
(GEO )
>> Higher laser power 10 W  180 W
(Hannover group, Germany)
>> More sensitive and more flexible optical configuration:
Signal recycling
• Design: 1999 – 2010 : 10 years of high end R & D internationally.
• Construction: Start 2008; Installation 2011; Completion 2015
A Century of Waiting
• Almost 100 years since Einstein predicted GW but no
direct experimental confirmation (a la Hertz for
Maxwell EM theory)
• Two Fundamental Difference between GR and EM
- Weakness of Gravitation relative to EM (10^-39)
-Spin two nature of Gravitation vs Spin one of EM that forbids dipole
radiation in GR
• Low efficiency for conversion of mechanical energy
to GW & Feeble effects of GW on any Detector
• GW Hertz experiment ruled out. Only astrophysical systems
involving huge masses and accelerating very strongly are
potential detectable sources of GW signals.
GW  Astronomy link
Astrophysical systems are sources of copious GW emission:
•GW emission efficiency (10% of mass for BH mergers) >>
EM radiation via Nuclear fusion (0.05% of mass)
Energy/mass emitted in GW from binary >> EM radiation in the lifetime
• Universe is buzzing with GW signals from cores of astrophysical events
Bursts (SN, GRB), mergers, accretion, stellar cannibalism ,…
• Extremely Weak interaction, hence, has been difficult to detect directly
But also implies GW carry unscreened & uncontaminated signals
Scientific Payoffs
Advanced GW network sensitivity needed to observe
GW signals at monthly or even weekly rates.
• Direct detection of GW probes strong field regime of gravitation
 Information about systems in which strong-field and time dependent gravitation
dominates, an untested regime including non-linear self-interactions
• GW detectors will uncover NEW aspects of the physics
 Sources at extreme physical conditions (eg., super nuclear density physics), relativistic
motions, extreme high density, temperature and magnetic fields.
• GW signals propagate un-attenuated
weak but clean signal from cores of astrophysical event where EM signal is screened by
ionized matter.
• Wide range of frequencies  Sensitivity over a range of astrophysical scales
To capitalize one needs a global array of GW antennas separated by
continental distances to pinpoint sources in the sky and extract all the
source information encoded in the GW signals
LIGO-India: … the opportunity
Strategic Geographical relocation: science gain
Sky coverage: ‘reach’ /sensitivity in different directions
Courtesy: B. Schutz
Principle behind Detection of GW
Detecting GW with Laser Interferometer
LIGO Optical Configuration
Power Recycled
Michelson
Interferometer
end test mass
Light bounces back and
forth along arms about
100 times
with Fabry-Perot Arm
Cavities
Light is “recycled”
about 50 times
input test mass
Laser
signal
beam splitter
Difference in distance of Paths  Interference of laser
light at the detector (Photodiode)
Courtesy: Stan Whitcomb
LIGO-India from LIGO
Dear Prof. Kasturirangan,
1 June 2011
In its road-map with a thirty year horizon, the Gravitational Wave International Committee (a
working unit of the International Union of Pure and Applied Physics, IUPAP) has identified the
expansion of the global network of gravitational wave interferometer observatories as a high
priority for maximizing the scientific potential of gravitational wave observations. We are writing
to you to put forward a concept proposal on behalf of LIGO Laboratory (USA) and the IndIGO
Consortium, for a Joint Partnership venture to set up an Advanced gravitational wave detector
at a suitable Indian site. In what follows this project is referred to as LIGO-India. The key idea
is to utilize the high technology instrument components already fabricated for one of the three
Advanced LIGO interferometers in an infrastructure provided by India that matches that of the
US Advanced LIGO observatories.
LIGO-India could be operational early in the lifetime of the advanced versions of gravitational wave
observatories now being installed the US (LIGO) and in Europe (Virgo and GEO) and would be of
great value not only to the gravitational wave community, but to broader physics and astronomy
research by launching an era of gravitational wave astronomy, including, the fundamental first direct
detection of gravitational waves. As the southernmost member observatory of the global array of
gravitational wave detectors, India would be unique among nations leading the scientific exploration
of this new window on the universe. The present proposal promises to achieve this at a fraction of
the total cost of independently establishing a fully-equipped and advanced observatory. It also
offers technology that was developed over two decades of highly challenging global R&D effort that
preceded the success of Initial LIGO gravitational wave detectors and the design of their advanced
version.
Binary Pulsars..NS-NS Binary
Pulsar
companion
High quality observational data that GW exist….