LISA: Probing the Universe with Gravitational Waves. Tom Prince Caltech/JPL. Laser Interferometer Space Antenna LISA

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1 : Probing the Universe with Gravitational Waves Tom Caltech/JPL Laser Interferometer Space Antenna

2 Gravitational Wave Astronomy is Being Born LIGO, VIRGO, GEO, TAMA 4000m, 3000m, 2000m, 600m, 300m interferometers built to detect gravitational waves from compact objects

3 DECIGO

4 Massive Black Hole Coalescence Rotating NS SN Proto-NS Unresolved Galactic Binaries Resolved Galactic Binaries NS-NS and BH-BH Coalescence Extreme Mass Ratio Inspiral Advanced LIGO Extended Systems Compact Systems

5 What is DECIGO? Deci-hertz Interferometer Gravitational Wave Observatory (Kawamura, et al., CQG 23 (2006) S125-S131) Bridges the gap between and terrestrial detectors Low confusion noise Extremely high sensitivity Strain [Hz -1/2 ] have moved Above band Confusion Noise DECIGO will move into TD band Terrestrial detectors (e.g. LCGT) (Slide from Kawamura et al.) Frequency [Hz]

6 Many Strong Signals at Low Frequencies signals record a richly populated universe of strong sources Massive Black Hole Binary (BHB) inspiral and merger (~hundreds) Ultra-compact binaries (~thousands) Capture of stellar-mass Black Holes by massive BHs in normal galactic nuclei (~hundreds) Cosmic backgrounds, superstring bursts,?

7 Why are Gravitational Waves (GW) Excellent Probes of Physics & Astrophysics? GW are not attenuated Universe transparent since about sec GW sources are standard candles Luminosity distance measurements with 1% accuracy GW sources are clean and simple Black Holes have mass and spin and radiate coherently GW sources are strong High signal-to-noise allows precision measurements

8 Massive Black Hole Systems: Massive BH Mergers & Extreme Mass Ratio Mergers (EMRIs)

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10 sources have very large signals Merger signals have high SNR even in a single wave cycle Simulated data stream at merger event, two 10 5 M BH at z=5 (including simulated noise) Strain Time (seconds)

11 sources have very large signals Merger signals have high SNR even in a single wave cycle Simulated data stream at merger event, two 10 5 M BH at z=15 including simulated noise Strain Time (seconds) (Baker et al. 2006)

12 : Precision Measurements of Simple Systems High SNR waveforms carry precision information about the emitting systems High-precision black hole properties from measurements: Massive black hole mergers: Masses, spins to <0.1%, distances to 1% or less (z=1; an order of magnitude worse at z=20) Extreme mass ratio inspirals: Spins to 0.01%, distances to 1% (z<1) Masses,spins, and numbers as a function of redshift: How did black holes (BHs) initially form and what were their masses? How did accretion spin-up the BHs? How do the spins evolve over time? What happened to BHs as the initial galaxies merged to make modern galaxies.

13 BH Mergers: Nodes on Merger Trees Supermassive BH evolution includes mergers of many (10 s) of smaller BHs will detect the mergers of moderate mass BH s (10 4 M M ) can detect BH mergers out to z=20 Mass, spin, distance well-measured Di Matteo et al (2007) simulation Merger tree evolution of most massive BH at z=1 Recent result: spectroscopic evidence for quasar with 2650 km/s velocity relative to host (Komossa et al, arxiv: ). See also recent papers on kicks.

14 Capture of Compact Objects by Massive Black Holes will observe 10 s to 100 s of stellar-mass BH captures (EMRIs) can detect captures out to Gigaparsec distances Unique information on masses and spins of massive BHs in centers of normal galaxies Unique information on compact object populations in galactic nuclei Supporting evidence for such events from our own Galactic Center and observations of stellar disruption in distant galaxies

15 How well does General Relativity describe real black holes? Waveforms of Extreme Mass Ratio Inspirals (EMRIs) test the unique Kerr black hole solutions of GR ~10 5 orbits Rich waveforms test: No-hair Theorem of General Relativity to ~1% accuracy Response of dynamical tide on horizon to ~0.1%

16 Massive BH Science with DECIGO Formation of Supermassive BH Strain [Hz -1/2 ] Radiation pressure noise BH binary (1000 M z=1) Shot noise Coalescence 1 unit Intermediate Mass and Seed Black Holes + EMRIs & IMRIs Frequency [Hz] (Slide adapted from Kawamura et al.)

17 Measuring Absolute Distances & Electromagnetic Counterparts

18 Absolute Distances from Black Hole Binaries Waveforms of black hole binaries give precise, gravitationally calibrated distances to high redshift Absolute luminosity distances can be derived directly from amplitude orbital frequency chirp time Distance " c 1 frequency 2 # t chirp # amplitude 1. Distances accurate to 0.1% to ~10% per event 2. Absolute, physical calibration using only gravitational physics

19 Absolute Distances: Hubble Constant and Dark Energy H 0 potentially measured to <1%, Dark Energy parameters to <10% ~10 s of events expected to z~3; 100 s to z~20 Cosmological distance requires redshift (either host identification or statistical ID) Noise from weak lensing will limit precision Could yield comparable precision to weak lensing, baryon acoustic oscillations, clusters, and supernovae techniques depending on number of sources Absolute & Independent measurement

20 Will We See Electromagnetic Signals from BH mergers? Not guaranteed, but if detected yields exciting scientific return Host galaxy identification provides unique information on galaxy-bh co-evolution Host galaxy identification allows precision determination of distance-redshift relation will provide few-degree error boxes and time of merger months before event Error boxes shrink to degree or subdegree size as signal-to-noise increases and merger approaches The first detections of massive Black Hole mergers will mobilize global astronomical resources and be an astronomical event of enormous excitement. These are the most energetic events in the universe since the Big Bang.

21 Ultra-Compact Binaries

22 Exploring a new Galaxy of compact binary stars will measure orbital motions and 3D positions throughout our Galaxy of binary stars at the extreme endpoints of their evolution ~10 known binaries are guaranteed verification sources ~10,000 more may be individually detected (but see new SDSS results) Extreme degenerate stars (mainly white dwarfs, some NS, BH) Precursors of Type Ia SNe, millisecond pulsars, exotic novae

23 Resolving 19,000 Individual Compact Binaries with Used JPL/MT catalog (thanks to Jeff Crowder) of ~19,000 sources

24 Decigo could see >100,000 NS & BH binaries! Strain [Hz -1/2 ] Radiation pressure noise BH binary (1000 M z=1) 5 years 3 months NS binary (z=1) Shot noise Coalescence 1 unit (Slide adapted from Kawamura et al.) Pre-cursors of Groundbased GW & possible EM detections Acceleration of Universe Dark energy Coalescence Frequency [Hz]

25 The Very Early Universe

26 Gravitational Waves are not Attenuated Big Bang Plus Seconds Inflation WMAP Big Bang Plus 300,000 Years Gravitational Waves First Galaxies Big Big Bang Plus Billion Years Now

27 Gravitational Waves from the Early Universe will probe length and energy scales 15 orders of magnitude shorter and more energetic than CMB observations Universe became transparent to gravitational waves at very early times (~ sec after the big bang) Gravitational waves provide about our only chance to directly observe the early Universe The cosmic microwave background (CMB) probes much later times (300,000 years after the big bang), although inflationary GW may have left a polarization imprint on the CMB Possibilities for relic gravitational wave emission: Non-standard inflation, phase transitions, cosmic strings? sensitivity: Ω GW ~ Compare to slow-roll prediction in range Ω GW ~

28 What has science missed so far? With a new way of observing all forms of mass-energy in the universe, may discover entirely new phenomena, photons (EM) see different slices of cosmic history

29 Possible backgrounds from exotic new physics data could yield evidence for entirely new physical phenomena Log( Ω GW ) may be sensitive to: Terascale first-order phase transitions Gravitational wave backgrounds and bursts from cosmic superstring loops Log (frequency)

30 Early Universe Science with DECIGO Strain [Hz -1/2 ] Verification of inflation Radiation pressure noise BH binary (1000 M z=1) Inflation 5 years 3 months NS binary (z=1) Shot noise Correlation (3 years) Frequency [Hz] Coalescence 1 unit Coalescence (Slide adapted from Kawamura et al.) Early Universe: phase transitions & superstrings

31 Summary rated very highly scientifically in all major reviews Very broad physics and astrophysics reach Black hole/galaxy evolution - spins, masses, distances End points of stellar evolution - complete census of ultra-compact binaries in the Galaxy Masses, spins of BHs at z<1 (extreme mass ratio inspirals) Conditions in vicinity of BHs in normal galactic nuclei (extreme mass ratio inspirals) Precision cosmography (possible dark energy, H 0 measurement) Precision tests of General Relativity New physics discovery potential (cosmic strings, early universe phase transitions) The unexpected (this is a new window on the Universe!) ready to finish formulation and proceed to implementation Gravitational wave astronomy has huge potential for 2020 and beyond

32 will sense the remote Universe in an entirely new way, and will explore new things that can be explored in no other way Status highly ranked in all major NRC reviews: 2000 Decadal Review, 2003 Quarks to Cosmos, 2005 Mid-Course Decadal Update, 2007 Beyond Einstein Review Pathfinder: 2010 launch :