LISA mission design. Guido Mueller. APS April Meeting, Jan 30th, 2017, Washington DC

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1 LISA mission design Guido Mueller University of Florida APS April Meeting, Jan 30th, 2017, Washington DC 1

2 L3 from ESA s perspective 2013: Selection of L3 Science Theme by ESA The Gravitational Universe Goals of L3: Measure GWs between 100µHz - 100mHz MBHBs out to z ~ EMRIs out to 6 Gyr (z ~ 1) 2

3 LISA Proposal LISA proposal submitted Fr. 13th, 2017 Core Team: 82 scientists from Europe and the US Lead: Karsten Danzmann Consortium: > 300 members Supported by > 1300 scientists Might not be the only L3 proposal 3

4 Mission design 3 identical S/C Mission concept for L3: LISA 3 arms/6 links 2.5 Gm baseline Heliocentric Orbits 18o Earth trailing Free falling test masses LPF-like GRS Laser interferometry Lifetime 4 yrs Extendable to 10yrs 4

5 Mission design overview LISA Technology: developed over 20+ years Key systems: GRS with Test mass Drag-free control system with µn-thrusters Optical bench Laser frequency stabilized phase modulated Telescope Phase Meter Back link Hasn t really changed since 20 years 5

6 Mission design <- 2.5 Gm -> Each arm Each IFO Two one way measurements TM to OB -> Local IFO OB to OB -> Far (Science) IFO Backlink -> Reference IFO Beat note between two lasers MHz frequency range Phasemeter input Reference: local USO 6

7 Interferometry Goal: 10pm/ Hz sensitivity over 2.5Gm Environment: ±5m/s relative motions, ±5MHz Doppler shifts SC 3 Breathing constellation ±1deg Method: Heterodyne interferometry Signals: Phases in laser beat signals OB 31 OB 32 Time delay interferometry Clock synchronization Ranging τ 13 τ 31 τ 23 τ 32 OB 13 τ 12 OB 23 SC 1 τ SC 2 21 OB 21 OB 12 7

8 Interferometry Demonstrated already for LISA 8 yrs ago Frequency [Hz] 8

9 Quiet Test Masses LISA Pathfinder: GRS Low noise performance Capacitive sensing and actuation UV-Discharging Test mass release µn-thrusters Gas (ESA/Gaia-type) Colloidal (JPL/NASA) Local IFO Optical Bench Master laser 9

10 Quiet Test Masses LISA Pathfinder published from proposal Source: LISA proposal 10

11 Mission design LISA Technology: developed over 20+ years mature industrial designs need to be rescaled 11

12 Science to strain sensitivity Requirements: Acceleration noise S 1/2 a apple ms 2 p Hz s mHz f s 1+ 4 f 8mHz Displacement noise S 1/2 x apple m p Hz s1+ 2mHz f 4 Frequency range: Requirement: Goal: 100µHz apple f apple 0.1Hz 20µHz apple f apple 1Hz 12

13 Mission design Technology readiness: Very ready for a mission 17 years before launch Open issues (my view): In-field guiding vs. OATM Backlink Phase fidelity of fiber amplifier Stray light Alignment and focal stability of telescope System engineering & Industrialization Source: LISA proposal 13

14 Scientific objectives of LISA 1. Formation and evolution of compact binaries in MW 2. Origin, growth and merger history of massive black holes across cosmic ages 3. Dynamics or dense nuclear clusters using EMRIs 4. Astrophysics of stellar origin black holes 5. Fundamental nature of gravity and black holes 6. Expansion of the Universe 7. Stochastic GW background and implications for early Universe and TeV physics 8. GW bursts and unforeseen sources 14

15 Scientific objectives of LISA 1. Galactic binaries: Formation and evolution by measuring period, mass and spatial distribution Distinguish between ~5000 individual binaries with f > 3mHz, d < 15kpc Measure confusion noise between 0.5 to 3 mhz Enable joint EM and GW observations of ~10 verification binaries study dynamics of system identify ~ 500 EM counterparts Source: The gravitational wave white paper 15

16 Scientific objectives of LISA 2. Massive Black Holes power active nuclei at large z Seed BHs: ~10 3 to few 10 5 M at z 15 at cosmic dawn MBH growths in early quasars ~10 4 to 10 6 M at z 9 determine masses to ~5% Center of today s galaxies Mass/Spin meas. of ~10 5 to 10 6 M at z 3 Provide sky localization for 10 6 z 2 ~100deg 2 one day prior to merger ~1deg 2 after merger Search for IMBH (600 to 10 4 z 1 Search for IMBH/MBH z 3 Source: LISA proposal Mass ratios 100 to

17 Scientific objectives of LISA 3. Extreme Mass Ratio Inspirals 10 to 60 M BHs into 10 5 to 10 6 M BHs out to z 4 months to year long inspiral 10 3 to 10 5 close orbits ultra-precise binary parameters reveals structure of spacetime around large BH study immediate environment of Milky Way like center BHs Source: The gravitational wave white paper 17

18 Scientific objectives of LISA 4. Stellar Origin Black holes Discover 10 to 30 solar mass black hole binaries months/years before merger forecast LIGO signal within 1min predict sky localization ~1deg 2 SOBH formation channels Number and parameters of SOBH binaries out to z

19 Scientific objectives of LISA 5. Fundamental nature of gravity and black holes Requires golden binaries MBHBs with SNR > 100 Detect several ring down modes EMRIs with high spin SNR > 50 search for deviations from Kerr GWs beyond GR Dipole radiation Graviton mass Constrain mass of axion-like particles Source: The gravitational wave white paper 19

20 Scientific objectives of LISA 6. Cosmology and new signals Expansion of universe Hubble 0.02 Localize GW sirens ~ 1deg 2 Stellar origin z 0.2 z 1.5 z 6 (~ 10deg 2 ) and EM counterparts 7. Stochastic background SOBH origin Source: The gravitational wave white paper Big bang origin 8. Unexpected signals GWs from cosmic strings 20

21 Science case to protect strain sensitivity Source: LISA proposal 21

22 ESA s next steps and schedule : Initial negotiations betw. ESA/NASA/Nationals ?: Technology development of critical technologies : Industrial Phase A studies in Europe (two in parallel) 22

23 L3 from ESA s perspective What is next in the US? Identify US payload contribution Input to US Decadal Survey Science White Papers from community (You!) Science Goals/Open Questions How can LISA address them? What will LISA not be able to address? WPs for a mission beyond LISA should not hurt Advertise LISA and LISA Science Sign up to GWSIG to stay informed 23

24 Gravitational Waves: Soon detected in Space 24