LISA Status Report Alberto Vecchio GWDAW8 UWM, 17 th 20 th - - PowerPoint PPT Presentation

LISA Status Report

Alberto Vecchio

GWDAW8 UWM, 17th – 20th December 2003

Outline

• LISA

– Status of the project – LISA Pathfinder: SMART-2

• Data analysis challenges

– Band “cleaning” – Extreme mass ratio binary systems – Foregrounds detection

• The long term future: Big Bang Observer

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

LISA: the instrument

5 106 km

Test Masses Telescopes Spacecrafts

• 3 pairs of “free falling” test

masses: 3x10-15 ms-2 Hz-1/2 @ 0.1 mHz

• 3 “test-mass follower”

shielding spacecraft

• 2 semi-independent 5x106 km

Michelson Interferometers with Laser Transponders: 40 pm Hz-1/2

• Goal: GW observations at 0.1

mHz – 0.1 Hz

21

• 3

Strain sensitivity 3 10 Hz @ 10 Hz

−

≈ ×

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Multiple observables

One can synthesise different observables 6 independent beams

Symmetrized-Sagnac allows noise calibration

(Tinto et al, 2000)

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

LISA: the orbit

• Vast majority of LISA

sources are long lived

• Amplitude and phase

modulations introduced by the instrument motion allow reconstruction of source position

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Observational window

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Advanced resonant Acceleration noise Optical path noise Arm length

Testing quality of free fall

10-12 10-13 10-14 10-15 LISA Pathfinder (SMART-2)

F

N S Hz ⎛ ⎞ ⎜ ⎟ ⎝ ⎠

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

LISA Torsion pendulum

(surface disturbances)

(Carbone et al, 2003)

Sources

1<z<30 Galactic and z<1 D ~ 1 Gpc t ~ 10-10 sec

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Guaranteed detection

(Nelemans et al, 2001; Nelemans, 2003) 19 know n galactic binaries 19 know n galactic binaries “Calibration sources” “Calibration sources”

Actually many more:

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Data analysis challenges

• Cleaning of the observational band
• Observations of in-spirals from extreme

mass ratio binary systems

• Noise “calibration”: unambiguous

detection of astrophysical foregrounds

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Band cleaning

• Important to make

resolved sources as visible as possible

• First go at the problem:

gCLEAN (Cornish and Larson, 2003)

– Works for isolated sources – Not quite for

• verlapping sources

(Nelemans et al, 2001)

Stochastic foreground

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

WD extra-galactic foreground

(Farmer and Phinney, 03)

Is NS-NS foreground an issue? (PSR J 0737-3039)

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Extreme mass ratio binaries

• “Dream signal” for a theorist: point

particle – WD, NS, low mass BH - in completely generic (eccentric, non- equatorial, spins) orbit around a Kerr black hole

– Number of cycles in a yr ~ a few 105

• General Relativity:

– Map of the black hole spacetime (Ryan, 1996) – Test “no-hair theorem”

• Astrophysics:

– Dynamics in galaxy cores – MBH’s demographics and properties – Mass distribution, isotropy, dispersion of “swarms”

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

LISA and EMR binaries

(Finn and Thorne, 2000; Barak and Cutler, 2003)

• Event rate is good

if we assume nearly optimal filtering: SNR ~ 30 for 1 yr

• f coherent

integration

• Signals fight

against confusion noise and each

• thers

D = 1 Gpc

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

The challenge

• Waveform computation

– In principle the theoretical problem is very well posed: perturbation theory (“point” particle around massive black hole:Teukolsky formalism) – Prescription for rigorous radiation reaction available (Mino et al, 1997; Quinn and Wald, 1997) – Emphasis is on implementation: we need waveforms

• Data analysis

– Check SNR loss – Estimate number of filters – Design effective/efficient search strategy

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

EMR in-spirals

The approach:

• Generate incorrect

(“kludge”) waveforms that capture the key behaviour

• f the signal (Glampedakis,

Hughes, Kennefick, 2002; Hughes, 2001,02; Barak and Cutler, 2003)

• Use kludge waveforms to

gain insight into the problem What have we learned:

• Naive calculation gives

~1020-30 filters: no way

• However one can:

– Exploit correlations among templates – Use a sub-optimal hierarchical approach

• Preliminary results are

actually very encouraging (T. Creighton&Gair and Barak&Cutler)

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

LISA and foregrounds

• Detection of (isotropic) stochastic

signals depends on LISA multiple readouts

– Several ways of recombining the readouts, e.g. “symmetrized-Sagnac”

(Tinto et al, 00)

– Michelson+Sagnac: detection of the isotropic component with one instrument

• Substantial progress in

understanding multiple readouts (Caltech/JPL and Pune/Nice groups)

(Hogan and Bender, 2001)

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Big Bang Observer (~2025)

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report

Conclusions

• LISA in on track for launch in 2012
• Encouraging progress on all the key

data analysis issues

• … but still a lot of work to do

GWDAW8 – UWM, 17th – 20th December 2003 A Vecchio – LISA: Status report