An Indian ad venture in gravitational wave astronomy

1. An Indian adventure in gravitational wave astronomy Tarun Souradeep, IUCAA, Pune Spokesperson, IndIGO Consortium (Indian Initiative in Gravitational-wave Observations) IISER, Pune Feb 4, 2012 www.gw-indigo.org

2. Space Time as a fabric Special Relativity (SR) replaced Absolute space and Absolute Time by flat 4-dimensional 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.

3. Space Time as a fabric Earth follows a “straight path” in the curved space-time caused by sun’s mass !!!

4. Einstein’s Theory of Gravitation experimental tests Mercury’s orbit perihelion shifts forward • Mercury's elliptical path around the Sun shifts slightly with each orbit such that its closest point to the Sun (or "perihelion") shifts forward with each pass. • Astronomers had been aware for two centuries of a small flaw in the orbit, as predicted by Newton's laws. • Einstein's predictions exactly matched the observation.

5. Einstein’s Theory of Gravitation Matter bends light: Gravitational lens First observational confirmation of Einstein’s theory The position of a distant star on the sky shifts due to the gravity of sun

6. Gravitational lens

7. Interesting Gravitational lens ! Einstein Cross Einstein Ring A nearer galaxy lenses a distant one that happens to be exactly along the same line of sight !! Four distinct images of gravitationally lensed distant quasar i!!

8. Grandest Gravitational lens ! Distant galaxies beyond a cluster lens into arcs ….

9. Beauty & Precision Einstein’s General theory of relativity is the most beautiful, as well as, successful theory of modern physics. It has matched all experimental tests of Gravitation remarkably well. Era of precision tests : GP-B,….

10. What happens when matter is in motion?

11. 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 (i.e., mass-less) , are transverse and have two states of polarization. • The major qualitatively unique prediction beyond Newton’s gravity • Begs direct verification !!!

12. A Century long Wait • Einstein’s Gravitation (1916-2011): • Beauty : symmetry in fundamental physics –mother of gauge theories • & precision : matches all experimental tests till date to high precision Gravitational Waves -- travelling space-time ripples are a fundamental prediction • Existence of GW inferred beyond doubt (Nobel Prize 1993) • Feeble effect of GW on a Detector  strong sources 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 96%universe does not emit Electromagnetic signal!

13. Indirect evidence for Gravity waves Binary pulsar systems emit gravitational waves Nobel prize in 1993 !!! Hulse and Taylor 14yr slowdown of PSR1913+16 Pulsar companion

14. Astrophysical Sources for Terrestrial GW Detectors • Compact binary Coalescence: “chirps” • NS-NS, NS-BH, BH-BH • 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 • Cosmological distribution of Primordial black holes Courtesy;: Stan Whitcomb

15. 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

17. Neutron star-BH merger

18. Theoretical developments in classical GR

19. Principle behind direct Detection of GW

20. Path A Path B Detecting GW with Laser Interferometer B A Difference in distance of Path A & B Interference of laser light at the detector (Photodiode)

21. Challenge of Direct Detection Gravitational wave is measured in terms of strain,h (change in length/original length) Gravitational waves are very weak! Expected amplitude of GW signals Measure changes of one part in thousand-billion-billion!

22. Power Recycled end test mass with Fabry-Perot Arm Cavities Light bounces back and forth along arms about 100 times Light is “recycled” about 50 times beam splitter signal Detecting GW with Laser Interferometer LIGO Optical Configuration Michelson Interferometer input test mass Laser Difference in distance of Paths Interference of laser light at the detector (Photodiode) Courtesy: Stan Whitcomb

23. Terrestrial GW observatories GEO-600 Germany 600m

24. LIGO Laser Interferometer Gravitational-Wave Observatory LIGO Hanford Washington USA 4 kms LIGO Livingston Louisiana, USA 4 kms

25. Why a GW Observatory in space ? • Terrestrial GW observatories are limited to GW frequencies above 10 Hz due to seismic noise. • ( 10 Hz– 2000 Hz.) • Interesting sources abundant at sub-Hertz frequencies (milli-Hz to Hz range) are accessible. • Easier to attain higher sensitivity with longer baselines.

26. GW OBSERVATORY IN SPACE !! LISA : Laser Interferometer Space Antenna A NASA, ESA joint proposal for space based GW Observatory ( expected launch 2011).

27. LISA : Laser Interferometer Space Antenna A NASA, ESA joint proposal for space based GW Observatory ( launch 2011). Frequency range: 10– 4 Hz - 1 Hz A configuration of three `freely falling’ spacecrafts in earth-like orbit linked by optical laser beams working as an interferometer in space

28. The Orbit of LISA The spacecraft are freely falling in the Sun’s field .

30. GW Source for LISA

32. Initial LIGO Sensitivity Goal • Strain sensitivity <3x10-23 1/Hz1/2at 200 Hz • Sensor Noise • Photon Shot Noise • Residual Gas • Displacement Noise • Seismic motion • Thermal Noise • Radiation Pressure

33. Era of Advanced GW detectors: 2015 • 10x sensitivity • 10x dist reach • 1000 volume • >> 1000X event rate • (reach beyond • nearest super-clusters) • A Day of Advanced LIGO Observation >> • A year of Initial LIGO • observation

34. GEO: 0.6km VIRGO: 3km LIGO-LHO: 2km+ 4km future: LCGT 3 km TAMA/CLIO LIGO-LLO: 4km Global Network of GW Observatories improves… 1. Detection confidence 2. Duty cycle 3. Source direction 4. Polarization info. Time delays in milliseconds India provides almost largest possible baselines. (Antipodal baseline 42ms) LIGO-India ?

35. LIGO-India: … the opportunity Science Gain from Strategic Geographical Relocation Source localization error Courtesy: S. Fairhurst Launch of Gravitational wave Astronomy

36. Gravitational wave Astronomy : vit • Fundamental physics • Astronomy & Astrophysics • Cosmology GWIC Roadmap Document

37. 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

38. LIGO-India:a good idea for GW community ! • Geographical relocation Strategic for GW astronomy • Increased event rates (x2-4) by coherent analysis • Improved duty cycle • Improved Detection confidence • Improved Sky Coverage • Improved Source Location required for multi-messenger astronomy • Improved Determination of the two GW polarizations • Potentially large Indian science user community in the future • Indian demographics: youth dominated – need challenges • Improved UG education system will produce a larger number of students with aspirations looking for frontline research opportunity at home. • Substantial data analysis trained faculty exists in India and Large Data Analysis Center Facilities are being planned under the next five year plan for consolidated IndIGO participation in LSC for Advanced LIGO

39. LIGO-India: … the opportunity Strategic Geographical relocation - the science gain Sky coverage: ‘reach’ /sensitivity in different directions Courtesy: Bernard Schutz

40. LIGO-India: … the opportunity Strategic Geographical relocation: science gain Polarization info Homogeneity of Sky coverage Courtesy: S.Kilmenko & G. Vedovato

41. Strategic Geographical relocation: science gain Courtesy: Bernard Schutz

42. LIGO-India:Attractive Indian megaproject • On Indian Soil with International Cooperation (no competition) • Shared science risks and credits with the International community. • AdvLIGO setup & initial setup risks primarily rests with USA. • AdvLIGO-USA precedes LIGO-India by > 2 years. • Vacuum 10 yr of operation in initial LIGO  2/3 vacuum enclosure + 1/3 detector assembly split (US ‘costing’ : manpower and h/ware costs) • Indian expters can contribute to AdvLIGO-USA : opportunity without primary responsibility • US hardware contribution funded & ready • AdvLIGO largest NSF project funded in USA • LIGO-India needs NSF approval, but not additional funds from USA • Expenditure almost completely in Indian labs & Industry • Very significant Industrial capability upgrade in India. • Well defined training plan  Large number of highly trained HRD • Host a major data analysis facility for the entire LIGO network

43. Schematic Optical Design of Advanced LIGO detectors Reflects International cooperation Basic nature of GW Astronomy LASER AEI, Hannover Germany Suspension GEO, UK

44. Highly Multi-disciplinary Astro++ Schematic of Advanced LIGOdetectors “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. ) Large scale Ultra high Vacuum to be fabricated in India 10 mega -litres at nano-torr!!!

45. Multi-Institutional, Multi-disciplinary Consortium Nodal Institutions • CMI, Chennai • Delhi University • IISER, Kolkata • IISER, TVM • IISER, Pune • IIT Madras (EE) • IIT Kanpur (EE) • IUCAA, Pune • RRCAT, Indore • IPR, Ahmedabad Members from • TIFR Mumbai • IISc, Bangalore • RRI, Bangalore • …

46. IndIGO Consortium – a brief history • Dec. 2007 : ICGC2007 @IUCAA: RanaAdhikari’s visit & discussions • 2009: • Australia-India S&T collaboration (Iyer & Blair) Establishing Australia-India collaboration in GW Astronomy • IndIGO Consortium: IUCAA Reunion meeting (Aug 9, 2009) • GW Astronomy Roadmap for India; • 2009-2011: • Meetings at Kochi, Pune, Shanghai, Perth, Delhi to Define, Reorient and Respond to the Global (GWIC) strategies for setting up the International GW Network. • Bring together scattered Indian Experimental Expertise; Individuals & Institutions • March 2011: IndIGO-I Proposal: Participation in LIGO-Australia • May 2011+: LIGO-India.. Note: • IndIGO was admitted to GWIC in July 2011 : Intl. recognition of the growing community in India. • IndIGO has been accepted into the LIGO Science Collab. (LSC) : pan-Indian 7 institutes: 15 members: Theory, DA + EXPERIMENTERS ): Sept. 2011

47. IndIGO Consortium Data Analysis & Theory T R Seshadri Delhi University Patrick DasguptaDelhi University Sanjay JhinganJamilaMilia L. Sriramkumar, IIT M Bhim P. SarmaTezpurUniv . Sanjay SahayBITS, Goa P AjithCaltech Sukanta Bose, Wash. U. B. S. SathyaprakashCardiff University SoumyaMohantyUTB, Brownsville Badri Krishnan Max Planck AEI SatyanarayanMohapatraUM, Amherst SanjeevDhurandharIUCAA BalaIyerRRI Tarun Souradeep IUCAA AnandSenguptaDelhi Univ. ArchanaPaiIISER,-TVM SanjitMitraJPL ,IUCAA K G ArunCMI Rajesh NayakIISER-K GopakumarTIFR

48. Instrumentation & Experiment C. S. Unnikrishnan TIFR G RajalakshmiTIFR P.K. Gupta RRCAT Sendhil Raja RRCAT S.K. Shukla RRCAT Raja Rao RRCAT exx Anil Prabhakar, IIT M Shanti Bhattacharya IIT M Pradeep Kumar, IIT K Ajai Kumar IPR S.K. Bhatt IPR VasantNatarajanIISc. UmakantRapolIISER Pune Shiva PatilIISER Pune Joy MitraIISER Tvm S. GhoshIISER Kol SupriyoMitraIISER Kol RanjanGupta IUCAA Bhal Chandra Joshi NCRA RijuparnaChakrabortyCote d’Azur RanaAdhikari Caltech Suresh Doravari Caltech S. Sunil U. W. Aus. Rahul Kumar U. of Glasgow BiplabBhawalLIGO ex K. VenkatU. Washington B. BhadurU. of Illinois

49. LIGO-India: unique once-in-a-generation opportunity LIGO labs LIGO-India ?

50. Advanced LIGO Laser • Unique globally. Well beyond current Indian capability. Would require years of focused R &D effort. Both power and frequency stability ratings. • AdvLIGO laser has spurred RRCAT to envisage planning development of similar laser capability in the next 5 year plans. IIT M group also interested. • Multiple applications of narrow line width laser : Freq time stand, precision metrology, Quantum key distribution, high sensitivity seismic sensors (geo sc.), coherence LIDAR (atm sc.), …. • Designed and contributed by Albert Einstein Institute, Germany • Much higher power (to beat down photon shot noise) • 10W  180W (narrow sub kHz line width) • Better stability • 10ximprovement in intensity (nano ppm) and frequency stability (mHz) Courtesy: Stan Whitcomb