1. Searches for CW signals
M.Alessandra Papa for the CW group
LSC meeting, Oct 2007, AEI

2. LIGO has completed its 5th science run (S5)
2002
2003
2004
2005
2006
2007
S1 S2 S3 S4 S5
Duty factors:
(so far)
H1 59 % 74 % 69 % 80 % 73 %
H2 73 % 58 % 63 % 81 % 77 %
L1 43 % 37 % 22 % 74 % 62 %

3. Goal: 1 year of 2-site coincident live-time
5th Science Run of LIGO
Science Run 5: Nov 05 to Oct 07
Goal: 1 year of 2-site coincident live-time

4. The CW group * ~ 20 active members
* “teams” work on specific searches or software
* not single integrated software
* every type of search has been cross-checked with 2 independent codes
* overlap yes, but a lot of complementarity and fine tuning for different scopes
* lots of communication and exchange between “teams”
* most mature software not only utilized by developers
* designated an official liason between the group and the
community of astronomers, B. Owen

5. What are we doing ? * Analysis development:
- to extend depth of deep wide parameters space searches
- to enhance sensitivity of the fast scans of data
- to extend capabilities beyond isolated objects
* Perform searches:
- utilize existing software to search in interesting parameter space regions (optimization problem to determine parameter of search and then set up search, i.e. grid, thresholds, coincidence windows )

6. Searches now underway
Searches for signals from known pulsars, isolated and in binary systems (S3/S4 paper accepted for publ. In PRD, Crab paper in prep, with also f-fdot search, all S5 for all pulsars at end of S5 underway)
Blind searches for signals from isolated pulsars (S4 data “fast-scans” accpted in PRD, final results S4, S5 hierarchical search running, S5a fast scan underway)
Targeted searches for signals from known (or suspected) non-pulsating isolated objects (S5 CasA search underway)

7. Upper limits: on what ?
On h0: the intrinsic amplitude at the detector.
ℎ 𝑡 = ℎ + 𝑡 𝐹 + 𝑡,𝑝𝑜𝑠,𝑝𝑜𝑙 + ℎ 𝑥 𝑡 𝐹 𝑥 𝑡,𝑝𝑜𝑠,𝑝𝑜𝑙
Signal at the detector:
ℎ + =0.5 ℎ cos 2 𝑖 cosF 𝑇
ℎ 𝑥 = 2h 0 cos𝑖sinF 𝑇
We do not directly measure h0 we infer it from
detection efficiency studies.
But it is nicely connected to interesting properties of the source.
ℎ 0 = 16 𝜋 2 𝐺 𝑐 4 ε𝐼 𝑓 2 𝑑

8. Searches for signals from known pulsars
* timing data from astronomers, assuming:
* EM and GW phases locked
* fGW=2fem
* spin-down inferred upper limits exist but...
* for objects in globular clusters these should be taken with grain of salt
* moment of inertia is not known precisely
* so:
* first direct limits
* starting to probe new grounds
* Plan to increase targets X 2

9. Known pulsars, preliminary S5
Joint 95% upper limits from first ~13 months
of S5 using H1, H2 and L1 (97 pulsars)
Lowest h0 upper limit:
PSR J (ngw = Hz, r = 2.2 kpc) h0_min = 3.4x10-26
If all rotational kinetic
energy were carried away
by Gws, their
ℎ 0 = 5𝐺 2c 3 𝐼 𝑓 𝑑 2 𝑓
Pitkin for the LSC, APS07

10. Known pulsars, preliminary S5
ℎ 0 = 16 𝜋 2 𝐺 𝑐 4 ε𝐼 𝑓 2 𝑑
known
fiducial value
Lowest ellipticity upper limit:
PSR J (ngw = 405.6Hz, r = 0.25 kpc)  = 7.3x10-8
If all rotational kinetic
energy were carried away
by Gws, their
ℎ 0 = 5𝐺 2c 3 𝐼 𝑓 𝑑 2 𝑓
Pitkin for the LSC, APS07

11. Known pulsars, preliminary S5
Due to pulsar glitches the Crab pulsar result uses data up to the glitch on 23 Aug 2006, and the PSRJ result uses only three months of data between two glitches on 5th May and 4th Aug 2006
If all rotational kinetic
energy were carried away
by Gws, then
ℎ 0 = 5𝐺 2c 3 𝐼 𝑓 𝑑 2 𝑓
Pitkin for the LSC, APS07

12. Crab pulsar preliminary result
at fiducial I = 1038kg m2
espin-down = 7.3x10-4
eS5 first year = 2.6 x10-4
h0 spin-down = 1.4x10-24
h0 S5 first year = 5 x10-25
Would like to discuss (the significance of) this result – Matthew Pitkin's presentation.

13. Crab
More reasonable upper limit for e
Exclusion region goes as low as e =9x10-5 for I = 3 X 1038 (kg m2)
Reasonable range for I

14. Blind searches for signals from isolated objects
monochromatic signal with spin-down
* search method works well if phase coherence is maintained over coherent search time baseline
* 2 types of searches, both hierarchical:
- long time-baseline initial coherent search (≈day)
- short time-baseline initial coherent search (≈hour)
Deep, comput. Intensive
Robust, wide param space, fast scans

15. Blind searches for signals from isolated objects
* various types of building blocks:
- Fstat coherent search
- Virgo coherent search
- Powerflux semi-coherent
- Stack-slide semi-coherent
- Hough semi-coherent (2 flavours)
* specifically, the 2 hierarchical searches use:
- Multi-IFO Fstat + Hough/Stack-slide
- Powerflux/Hough, for Virgo + coincidences + coherent follow-ups

16. H1 (best sky) upper limit [worst case orientation]
S5 Powerflux results
H1 (best sky) upper limit [worst case orientation]
10-24
Freq (Hz)
200
600
1200
10-23
10-21
h095%

17. The Big Picture (!)

18. Expressing the reach of search from UL values.
Contour plots of distance at which one of the fast-scan S4
searches could detect a source with a given f and fdot.
These are NOT
typical S5 numbers.
Deepest searches
are expected to reach
at 1kpc for e=10-5 at ~ 220Hz.

19. Starting targeted searches towards non-pulsating objects
At the age of CasA, at 150 Hz, fdot=0.25*f/tau gives fdot = 3e-9 which corresponds at epsilon greater than 1e hardly promising....

20. Targeted searches towards non-pulsating objects
Assuming spin-down due to GW emission:
ℎ 𝐼𝑈𝐿 =2.3𝑋 10 −24 1𝑘𝑝𝑐 𝐷 𝐼 𝑘𝑔 𝑚 kyr t
t: age, D distance, I moment of inertia
f-fdot searches for point-sources (from Chandra observations):
CasA : hIUL= 1.2 X (t = 325 yr, D=3.4 kpc)
VelaJn: hIUL= 5.7 X (t = 680 yr, D=480 pc)
SN1987A : 3.2 X (t = 20 yr, D=50 kpc)
At the age of CasA, at 150 Hz, fdot=0.25*f/tau gives fdot = 3e-9 which corresponds at epsilon greater than 1e hardly promising....
K. Wette

21. Actively planned: Semi-targeted searches, towards:
* Galactic Center (8kpc) : could ``see'' objects formed in last 100 yrs
* Globular clusters (2 kpc): could ``see'' objects formed in last 1000 yrs . Less likely.
* what parameters (spin-down, area in sky)?
* anything else ?

22. What about pulsars in binaries? any wisdom to offer ?
Assuming GWs balance torque from accretion:
ℎ 𝐼𝑈𝐿 =5𝑋 10 − 𝐻𝑧 n 𝐹 𝑥 10 −8 𝑒𝑟𝑔 𝑐𝑚 −2 𝑠 −1
* The ones we now about:
- LMXBs (85 known), unknown spin freq, higher accretion rates
- AMXPs (7 known), known spin freq
Hierarchical search under construction using a method similar to what used in radio-astronomy (C. Messenger)
* Blind (or targeted) searches ? First steps towards search (E. Goetz and Nikhef group), radiometer approach (Mitra,Krishnan)

23. We'd like to discuss * Crab result and search: - its significance
- the assumptions that went into analysis
- what happens if we relax them and widen search
- are we using all astrophysical information ?
* Blind searches for isolated objects:
- any suggestion ?
* Targeted searches for isolated objects:
- indirect upper limit, its significance (more in Owen's talk)
- suggestions ?
* Objects in binary systems:
- hopeless ?