Mega Science Project India Will Soon Be Joining a Global Network of Gravitational Wave Observatories

Y. B ALA MURALI KRISHNA

Article Gravitational Wave Feature Observatory Mega Science Project India will soon be joining a global network of Gravitational Wave Observatories.

(GWO)” in collaboration with the United involved sanction of Rs.1260 crores to be States of America as part of a global spent over the next 15 years (2012-2027). VEN as top particle physicists the network. The prestigious project, mooted by world over recently celebrated the The proposal for the $290 million the Consortium of Indian Initiative in Ediscovery of the Higgs boson at dollar facility is pending approval of the Gravitational Wave Observations, Geneva’s CERN facility, India is geared to Government of India. The Indian scientists codenamed IndIGO, aims at construction add a new dimension to 21st century are confident that the Union Cabinet will and subsequent fifteen year operation of astrophysics by setting up a state-of-the- soon clear the ‘mega-science project’ that an advanced interferometric gravitational art “Gravitational Wave Observatory wave detector in India, called LIGO-India, in collaboration with USA’s LIGO What are Gravitational Waves? Laboratory. We often hear of X-rays, Radio waves, Alpha-rays, Gamma-rays, Micro-waves, “We are confident that India joins the Ultra-violet rays and Light-rays from different sources including the sky. All US-led global network of GWOs to further of them, in the language of science, are known as electro-magnetic waves, promote astronomy of the 21st century. emitted by electric charges in motion that have several applications in day- India could play a pivotal role as a partner to-day life, medicine, electronics and even telecommunications including of the global network as we are on the television and radio networks. threshold of a new era of gravitational wave Another type of waves, known as “gravitational waves” (GWs) akin to the astrophysics,” says Dr. Stan Whitcomb, chief electro-magnetic waves, have been detected from the Universe. The GWs are scientist of the LIGO Lab. emitted by gravitating bodies in motion, such as two ‘black holes’ spiralling He was interacting with the author after towards each other in a binary orbit in the cosmos. visiting India recently as part of a five- Gravitational Waves are extremely difficult to detect, and although they member high-level US delegation to find were predicted about one hundred years ago, till today they have not been out whether India is keen to take seen in experiments, physicists say. advantage of the global network. There is irrefutable indirect evidence that they do exist – this evidence Other members of the US’s LIGO group comes from the Nobel Prize winning discovery that the compact binary orbit delegation included Dr. Dave Reitze (LIGO of a pair of stars is shrinking due to the emission of gravitational waves, Director), Dr. Jay Marx (LIGO ex-Director), precisely as predicted by General Theory of Relativity. Dr. David Shoemaker (Advanced LIGO The experimental discovery of gravitational waves will open an Project Leader) and Dr. Fred Raab (Head, extraordinary new window in astronomy, what is often known as gravitational LIGO Hanford Observatory). wave astronomy. Just as astronomers have been studying the Universe for “We visited IPR (Ahmedabad), RRCAT centuries using electromagnetic waves, they will in the future be able to (Indore) and IUCAA (Pune). At each study it with gravity waves. location, we met with a number of IndIGO Great experiments are currently in progress worldwide, using colleagues for discussions about the LIGO ‘Gravitational Wave Detectors (GWD)’, to find gravitational waves. technical requirements, and visited a

SCIENCE REPORTER, NOVEMBER 2012 44 Feature Article

Dr. Bala Iyer, Chairman, IndIGO Council with US’s LIGO-Lab Chief Scientist Dr. Stan Whitcomb (right) number of laboratories to see the Indian ready by 2017, is under construction in an holes, tight constraints on physics at nuclear capabilities in the relevant areas,” he said. underground Kemijoki mine in Japan as densities, insight into the mechanism of Asked about the site selection for the part of the network. short gamma-ray bursts, highly accurate mega-science project in India, he said, measurements of the Hubble flow out to the delegation reviewed some general z ~ 0.2, tests of strong-field relativity, information concerning the Indian Significance of GWO measurements of the speed of geological formations, and discussed the Prof. Bernard F. Schutz from the Max Planck gravitational waves, constraints on extra steps that would be needed to assess and Institute for Gravitational Physics, Albert scalar gravitational fields, and tests of the validate any proposed site. Einstein Institute, Potsdam, Germany, who cosmic censorship hypothesis,” Prof. Schutz There are two detectors in the USA had earlier interacted with Indian claims. under LIGO Laboratory while the third one astrophysicists and cosmologists in Goa Further, sensitivity improvements, and GEO is in Hannover (Germany) now under avers that study of the Gravitational Waves then the construction of third-generation upgrade with pioneering advanced is the astronomy of the 21st century. detectors like the Einstein Telescope, offer optical technologies. An advanced LIGO “Advanced ground-based detectors much more than this. The opening of the version of the VIRGO with advanced will almost certainly make the first low-frequency window with a space- seismic isolation system is also operational detections of gravitational waves within the based detector like LISA or eLISA will bring near Pisa in France with US collaboration next few years. With a worldwide network all our galaxy’s compact binary systems since May 2007. of five sensitive detectors, we will be able under scrutiny and will reveal how the A $100-million Large Cryogenic to count on spectacular science returns: massive black hole population of the Gravitational Telescope (CGWT), to be mass functions for neutron stars and black universe got started and grew. The ultra-low frequency window explored by pulsar timing can give further

Completing the Global Network information about the supermassive black ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ hole population. These are the scientific outcomes we can predict and what we can’t predict will be guaranteed to be GEO Virgo LIGO even more interesting! LCGT Planned detectors are very close to IndIGO on the Move co-planar-- Meanwhile, chairman of the IndIGO not optimal for all-sky coverage Consortium Council Dr. Bala Iyer says the consortium is going ahead with identifying suitable seismically free sites for the Large increase to science capability proposed GWO. from a southern node in the network “Various sites would be studied for various parameters before shortlisting them LIGO-India even as we are anxiously awaiting the clearance of the project by the LIGO-G110127201 ICGC, Goa Government of India,” he said. “The An artistic view of the global network of GWOs indications so far are positive.” 45 SCIENCE REPORTER, NOVEMBER 2012 Feature Article

For the LIGO-India project, the US and its international partners (UK, Germany and Australia) will contribute complete design and hardware of the detector worth $140M (Rs 650 Crores). Consortium is going ahead with identifying suitable seismically free sites Inside view of LIGO for the proposed GWO.

The project would go a long way in facilitating national and international is considered to be an essential element providing job opportunities for young Indian collaboration. in the global network of detectors. astrophysicists and cosmologists besides “The task of constructing this very paving way for high-end research with sophisticated detector at the limits of IndIGO: Status international collaborators. Some Indian present day technology is facilitated by Interestingly, the IndIGO Consortium has scientists have already been undergoing the amazing opportunity offered by the become a member of the Gravitational training at the US LIGO Laboratory. LIGO Laboratory and its international Wave International Committee (GWIC) and partners to provide the complete design of the LIGO Scientific Collaboration (LSC). Dimensions of LIGO-INDIA and all the key components required to LSC membership gives the IndIGO scientists The proposed Indian detector is a 4-km build the detector as part of the access to detector data of LIGO-USA and arm-length Michelson Interferometer with collaboration,” Dr. Tarun says. the opportunity to be part of the potential Fabry-Perot enhancement arms, and aims Indian scientists will build the detector first detection of GW. to detect fractional changes in the arm- as also the entire infrastructure including The US National Science Foundation length smaller than 10-23 Hz-1/2, says the ultra-high vacuum vessels and tubes (Advanced LIGO’s main sponsor) has IndIGO spokesman Dr. Tarun Souradeep. required to house the interferometer at a already given approval to study the The minimum size requirement for the suitable, gravitationally and seismically feasibility for LIGO-India. At the same time, detector is a L-shaped site of arms 4 km quiet site in India. IndIGO and the LIGO the foundation board is expected soon to and width 150 m. This is about 300 acres. Laboratory will work together in realizing give formal approval for the collaboration. The area should be seismically quiet and the Indian node (LIGO-India) of the The science case for LIGO-India is free of anthropogenic noise but close international gravitational wave detector compelling, observes the NSF. enough to reasonable infrastructure for network in India. The IndIGO consortium submitted its These advanced detectors, he said, proposal 2011 end to the nodal agencies will be 10 times more sensitive than the first – Department of Atomic Energy and generation initial detectors reaching that Department of Science and Technology The Laser Interferometer Gravitational Wave level of sensitivity when the first detection Observatory (LIGO) of gravitational waves from astrophysical events involving neutron stars or black holes Installing task requires real are expected. The proposal to build and operate the Indian detector is timed to time quality control by be in this exciting decade of the first experienced engineers and detection and observations with gravitational waves. physicists, including vacuum Operating as part of the international leak checking, residual gas network of gravitational wave detectors, LIGO-India will be a valuable frontline analysis and baking of the instrument for GW astronomy. LIGO-India sealed system. SCIENCE REPORTER, NOVEMBER 2012 46 Feature Article the nations leading the scientific exploration of this new window to the universe. This project is a timely opportunity to enter the field of Gravitational Wave Detection and Astronomy without the gestation period required for component development and at a time when the detector sensitivity has reached the threshold for gravitational wave detection. The advanced interferometer detector located and operated in India will be transformational and rejuvenating for Indian astronomy and gravity research, bringing together the best engineering and physics groups, fostering very importantly the research-industry partnership for advanced scientific instrument building and initiating the much needed development of expertise and human resource in many fields relevant to the next The LIGO control panel generation technology, physics and computation, scientists claim. The challenges of making measurements to detect GW requires the most sophisticated technologies in lasers, – which, in turn, forwarded it to the Planning gravitational waves is of great importance optics, vibration isolation, electronics, high Commission of India for approval of the to fundamental physics and would also speed and high volume computing, data mega-science project. serve to open a new window for astronomy handling and network communications, The IndIGO Consortium Institutions to study astrophysical phenomena and engineering. include Chennai Mathematical Institute, inaccessible to electromagnetic waves, IISER-Kolkata, IISER-Pune, IISER- such as the growth of black holes, final Thiruvananthapuram, IIT-Madras, IIT-Kanpur phase of in-spiraling and merging binary Benefits of LIGO-India IPR, IUCAA-Pune, RRCAT-Indore and neutron stars asymmetric supernova The LIGO-India project will be highly multi- University of Delhi. explosions and the stochastic gravitational disciplinary and will bring together According to the proposal wave background or the murmurs of the scientists and engineers from different document, the major funding in the XII Plan big-bang. fields. The technologies for these detectors is Rs. 650 Crores for the construction of the The Gravitational Wave International are at the limits of current capabilities and civil infrastructure and installation of the Committee (GWIC) has identified the would push the current technologies to detector. During the XIII 5-year Plan (2017- expansion of the global network of new levels, motivating new R&D in these 22) the expected expenditure is Rs. 380 gravitational wave interferometers as a fields. Crores, out of which Rs 280 Crores is for high priority for maximizing the scientific Spin-offs to other science, completing the construction and potential of gravitational wave engineering and industrial applications will installation of the detector and the observations in the coming three decades. provide unprecedented commercial remaining Rs 100 Crores for continuous Among the first questions that must be opportunities for Indian industries and operation and maintenance. answered about each gravitational wave businesses in collaboration with research The XIV Plan will see mature observed is where it originates. institutions and universities. gravitational wave astronomy with the The international GW detector These have the potential to seed LIGO-India detector. Projected operation network answers this question by technological spin-offs in several areas cost for continuous operation and comparing the signals at widely separated that include ultra-stable and high-power maintenance during this period (2022-27) detectors. This will enable gravitational lasers, high-tech optics, sensors and is Rs. 230 Crores. Thus, the total projected wave sources to be studied using the tools vibration isolation platforms, multi-channel expenditure for 15 years spanning three of multi-messenger astronomy such as control systems, large volume data plan periods from 2012 to 2027 is Rs. 1260 optical telescopes, the Square Kilometer storage, retrieval, computing and fast Crores. Array (SKA) radio telescope, or x-ray network communications and quantum detectors. The addition of LIGO-India to technologies for communication. Global Network the international network offers a very LIGO-India will be transformational for Predicted by Einstein’s General Theory of significant improvement in establishing the Indian physics, technology and astronomy Relativity (GTR) almost a century ago, sky location of gravitational wave sources. and will drive accelerated growth in these gravitational waves are yet to be directly The development of this critical areas over decades. The partnership with detected. Apart from putting GTR on a element of a global array of gravitational LIGO moves the gravitational wave sound footing, the detection of wave detectors will place India among detector project to a state of readiness 47 SCIENCE REPORTER, NOVEMBER 2012 Feature Article

VIRGO Gravitational Wave Observatory, Italy capability in the latest developments in large vacuum system engineering, welding techniques and technology. The vacuum system is by far the largest and most critical single component. Without an excellent vacuum system the interferometer cannot work, and this system also forms the visual envelope and backbone of the instrument. The LIGO vacuum systems are amongst the largest in the world, with a pumped volume of 10000 m3 (10 Mega- liters), evacuated to an ultra high vacuum 14 of 10-9 Torr. Building the vacuum system will include manufacturing the beam tubes, the tanks and all the essential vacuum components and pumps as well as the subsequent assembly, baking, leak Large Cryogenic Gravitational-Wave Telescope checking and testing of the completed system. The large beam tubes will be manufactured on site to avoid complicated and expensive transportation. A total of about 1000 tons of specially processed 304L stainless steel is required, delivered in 3 mm thick, 0.75 m wide coils. These will be formed into a helix and spiral welded into tubes, 1.2 m in diameter. Each 20 m length will be fitted with stiffening rings on the outside and optical baffles inside. The total weld length for the whole system is about 50 km, and it must be completely free of any leaks. The 20 m tube length from the mill must be fitted with expansion bellows and then installed on site. Sections will be joined by butt- welding with ports at 250 m spacing for residual gas analysis (leak checking). Large flanges each 2 km, to accommodate Illustration of the $100-million Large Cryogenic Gravitational Telescope (CGWT), to be ready by 2017, large 1 m gate valves, are required to under construction in an underground Kemijoki mine in Japan as part of the GWO network isolate sections for bake-out and for that would normally take decades to power CW laser, core optics, mode installation of the tanks. achieve. cleaning cavities, thermal compensation In addition, the large optics tanks, Though a collaborative project with system; Vibration isolation system vacuum pumps, gate valves and much peripheral vacuum system components an international partner, unlike other similar consisting of three-stage isolation; a and leak checking equipment must be collaborative projects, the LIGO-India hydraulic external pre-isolator, a four detector will be installed in India and the stage passive isolation system with a procured and installed. The task will require major part of the project money will be monolithic fused silica suspension for the real time quality control by experienced spent in India with several components mirrors and beam splitters; Control engineers and physicists, including (e.g., vacuum envelopes) sourced from Systems and Electronics; Data analysis vacuum leak checking, residual gas Indian industries. algorithms and protocols, as used in the analysis and baking of the sealed system. For the LIGO-India project, the US and LIGO detectors; Installation tooling and Dr Y. Bala Muralikrishna is a Hyderabad-based its international partners (UK, Germany and fixturing. science writer, media consultant and journalism Australia) will contribute complete design To house and operate this detector educator, formerly Special Correspondent, United and hardware of the detector worth requires a facility meeting stringent and News of India (UNI). Address: Flat-103, Anand $140M (Rs 650 Crores). specialized requirements. The actual Residency, Behind Donald Church, Attapur- The hardware includes the Detector construction will in itself be a substantial Hyderguda (RR Dist), Hyderabad-500048; Email: (Laser Interferometer) consisting of a high engineering project, building Indian [email protected] SCIENCE REPORTER, NOVEMBER 2012 48