1. Gravitational Wave Detection of Astrophysical Sources Barry C
Gravitational Wave Detection of Astrophysical Sources Barry C. Barish Caltech Neutrino Telescope Venice 24-Feb-05
Crab Pulsar
LIGO-xxx

2. gravitational radiation
Einstein’s Theory of Gravitation
a necessary consequence of Special Relativity with its finite speed for information transfer
gravitational waves come from the acceleration of masses and propagate away from their sources as a space-time warpage at the speed of light
gravitational radiation
binary inspiral of
compact objects
24-Feb-05
Venice Neutrino Telescope

3. Einstein’s Theory of Gravitation
gravitational waves
Using Minkowski metric, the information about space-time curvature is contained in the metric as an added term, hmn. In the weak field limit, the equation can be described with linear equations. If the choice of gauge is the transverse traceless gauge the formulation becomes a familiar wave equation
The strain hmn takes the form of a plane wave propagating at the speed of light (c).
Since gravity is spin 2, the waves have two components, but rotated by 450 instead of 900 from each other.
24-Feb-05
Venice Neutrino Telescope

4. Detection of Gravitational Waves
Gravitational Wave Astrophysical Source
Terrestrial detectors
Virgo, LIGO, TAMA, GEO
AIGO
Detectors in space
LISA
24-Feb-05
Venice Neutrino Telescope

5. Gravitational Waves in Space
LISA
Three spacecraft, each with a Y-shaped payload, form an equilateral triangle with sides 5 million km in length.
24-Feb-05
Venice Neutrino Telescope

6. Venice Neutrino Telescope
LISA
The diagram shows the sensitivity bands for LISA and LIGO
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Venice Neutrino Telescope

7. Venice Neutrino Telescope
Detecting a passing wave ….
Free masses
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Venice Neutrino Telescope

8. Venice Neutrino Telescope
Detecting a passing wave ….
Interferometer
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Venice Neutrino Telescope

9. Interferometer Concept
Laser used to measure relative lengths of two orthogonal arms
Arms in LIGO are 4km
Measure difference in length to one part in 1021 or meters
…causing the interference pattern to change at the photodiode
As a wave passes, the arm lengths change in different ways….
Suspended
Masses
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Venice Neutrino Telescope

10. Simultaneous Detection
3002 km
(L/c = 10 ms)
Hanford
Observatory
MIT
Caltech
Livingston
Observatory
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Venice Neutrino Telescope

11. LIGO Livingston Observatory
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Venice Neutrino Telescope

12. LIGO Hanford Observatory
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Venice Neutrino Telescope

13. LIGO Goals and Priorities
Interferometer performance
Integrate commissioning and data taking
Obtain one year of integrated data at h = by 2008
Physics results from LIGO I
Initial upper limit results by early 2003
First search to begin in 2005
Reach LIGO I goals by 2008
Advanced LIGO
Advanced LIGO approved at NSF / NSB (Nov 04) for ($185M)
Included in the Bush Administration’s budget plan released Feb 05 for 2008 start
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Venice Neutrino Telescope

14. Venice Neutrino Telescope
Lock Acquisition
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Venice Neutrino Telescope

15. What Limits LIGO Sensitivity?
Seismic noise limits low frequencies
Thermal Noise limits middle frequencies
Quantum nature of light (Shot Noise) limits high frequencies
Technical issues - alignment, electronics, acoustics, etc limit us before we reach these design goals
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Venice Neutrino Telescope

16. Venice Neutrino Telescope
Evolution of LIGO Sensitivity
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Venice Neutrino Telescope

17. From electronic logbook
Detecting Earthquakes
From electronic logbook
2-Jan-02
An earthquake occurred, starting at UTC 17:38.
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Venice Neutrino Telescope

18. Detect the Earth Tide from the Sun and Moon
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Venice Neutrino Telescope

19. Venice Neutrino Telescope
Science Runs
A Measure of
Progress
Virgo Cluster
Andromeda
Milky Way
NN Binary
Inspiral Range
E8 ~ 5 kpc
S1 ~ 100 kpc
S2 ~ 0.9Mpc
S3 ~ 3 Mpc
Design ~ 14 Mpc
24-Feb-05
Venice Neutrino Telescope

20. Astrophysical Sources
Compact binary inspiral: “chirps”
NS-NS waveforms are well described
BH-BH need better waveforms
search technique: matched templates
Supernovae / GRBs: “bursts”
burst signals in coincidence with signals in electromagnetic radiation
prompt alarm (~ one hour) with neutrino detectors
Pulsars in our galaxy: “periodic”
search for observed neutron stars (frequency, doppler shift)
all sky search (computing challenge)
r-modes
Cosmological Signals “stochastic background”
24-Feb-05
Venice Neutrino Telescope

21. Detection of Periodic Sources
Pulsars in our galaxy: “periodic”
search for observed neutron stars
all sky search (computing challenge)
r-modes
Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes.
Amplitude modulation due to the detector’s antenna pattern.
24-Feb-05
Venice Neutrino Telescope

22. Venice Neutrino Telescope
Two Search Methods
Frequency domain
Best suited for large parameter space searches
Maximum likelihood detection method + Frequentist approach
Time domain
Best suited to target known objects, even if phase evolution is complicated
Bayesian approach
Early science runs --- use both pipelines for the same search for cross-checking and validation
24-Feb-05
Venice Neutrino Telescope

23. Directed Pulsar Limits on StrainJ S2
J1910 – 5959D:
h0 = 1.7 x 10-24
Crab pulsar
h95 1
PDF
strain
Marginalized Bayesian PDF for h
Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties
Blue dots: field pulsars for which spin-downs are known
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Venice Neutrino Telescope

24. Directed Pulsar Search
28 Radio Sources
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Venice Neutrino Telescope

25. NO gravitational waves
Upper limit on pulsar ellipticity
moment of inertia tensor
gravitational ellipticity of pulsar
NEW RESULT
28 known pulsars
NO gravitational waves
e < 10-5 – 10-6
(no mountains > 10 cm R . .
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Venice Neutrino Telescope

26. Blue dots: field pulsars for which spin-downs are known
Ellipticity Limits
Best upper-limits:
J1910 – 5959D: h0 < 1.7 x 10-24
J2124 – 3358:  < 4.5 x 10-6
How far are S2 results from spin-down limit? Crab: ~ 30X
EM spin-down upper-limits
LIGO upper-limits from hmax J S1 S2
Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties
Blue dots: field pulsars for which spin-downs are known
24-Feb-05
Venice Neutrino Telescope

27. Detection of Periodic Sources
Signature of gravitational wave Pulsars
Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes.
Amplitude modulation due to the detector’s antenna pattern.
ALL SKY SEARCH
enormous computing challenge
24-Feb-05
Venice Neutrino Telescope

28. Venice Neutrino Telescope
A maximum-sensitivity all-sky search for pulsars in LIGO data requires more computer resources than exist on the planet.
The world’s largest supercomputer is arguably
A $599 computer from Radio Shack is a very powerful computational engine.
Currently runs on a half-million machines at any given time.
With help from the developers, LIGO scientists have created a distributed public all-sky pulsar search.
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Venice Neutrino Telescope

29. Venice Neutrino Telescope
Versions are available for Windows, Mac, Linux.
How does work?
Downloads a 12 MB ‘snippet’ of data from servers
Searches the sky in a narrow range of frequencies
Uploads interesting candidates for further follow-up
Screensaver shows where you are currently searching in the sky
We invite all of you to join and help us find gravitational waves.
24-Feb-05
Venice Neutrino Telescope

30. Einstein@Home Usage Test Version had about 7K Users
5x LIGO computing capacity
OFFICIAL RELEASE on 20-Feb
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Venice Neutrino Telescope

31. Venice Neutrino Telescope
Users
I'm from Germany and was interested in the mysteries of the universe since I was a little boy. I read lots of magazines about astrophysics and astronomy. When I heard about the project it was no question for me to participate.
My job is to make original-sized design models of new Mercedes-Benz cars, especially the interieur. When I don't work I often play keyboards and percussions and sing some backing vocals in my cover-rock-band "Gilga-Mesh"
24-Feb-05
Venice Neutrino Telescope

32. Venice Neutrino Telescope
Users
Hi, my name's John Slattery. I'm a 62 year old English teacher, originally from Boston, MA, currently living in Santa Fe, New Mexico where I'm tutoring, and teaching ESL.
My hobbies: fitness, camping, hiking, reading, writing, surfing the Net
I'm so very new at this; I'm not even sure what's going on. But it seemed, from the little I could understand, to be a worthwhile project.
24-Feb-05
Venice Neutrino Telescope

33. Venice Neutrino Telescope
Users
24-Feb-05
Venice Neutrino Telescope

34. LIGO Pulsar Search using personal computers
LIGO Pulsar Search using personal computers
BRUCE ALLEN
Project Leader
Univ of Wisconsin
Milwaukee
LIGO, UWM, AEI, APS
24-Feb-05
Venice Neutrino Telescope