S4 Pulsar Search Results from PowerFlux Vladimir Dergachev, Keith Riles (University of Michigan) LSC Meeting, Hanford August 14-17 2005 DCC: G050344-00-Z

Reminder of PowerFlux approach PowerFlux computes the flux of linearly and circularly polarized CW radiation incident on the Earth from any direction and in-band frequency, with one spin-down parameter allowed, and with explicit correction for antenna pattern and noise weighting (neighboring bins used for noise estimation)  Allows frequentist upper limit for each sky location separately  Monte Carlo injections unnecessary for deriving limits (needed only for validation of procedure) One circular and four linear polarization projections are computed for each set of (RA, dec, f0, df0/dt). The number of sky points scales quadratically with f0

“All-sky” upper limits on linear polarization based on highest of four linear-projection upper limits over “good” sky regions, with conservative correction for polarization mismatch.  Corresponds to worst-case pulsar orientation ( = π/2) All-sky upper limits on circular polarization based on highest circular-projection over good sky regions  Corresponds to best-case pulsar orientation ( = 0) Limits dominated by least sensitive region of sky or by non-Gaussian detector artifacts (e.g., wandering lines) But high detection SNR is examined separately, allowing detection sensitivity better than indicated by worst strain limit

Where do things stand? March LSC meeting: Presented preliminary S3 H1 & very preliminary S4 H1/L1 linear-polarization upper limits over the 200-700 Hz band with no spindown June LSC meeting: Presented preliminary S4 H1 and L1 linear- and circular-polarization upper limits for 140-240 Hz and 50 spindown values: [–5,+5] x 10-8 Hz/s (aggressive “deep spindown search” in relatively clean band for coincident H1-L1 detection  no plausible candidates found) Today: Prelim S4 limits (no-spindown) for H1 (50-1500 Hz) H2 (50-700 Hz) L1 (50-700 Hz) Prelim S4 H1 limits (50-800 Hz) for 11 spindown values [-1,0] x 10-8 Hz/s (partial results from ongoing 50-1000 Hz production run)

Where do things stand? Review process: PowerFlux method & code review began January 13 Review of core code & critical scripts completed July 19 (minor bugs and documentation errors found and fixed – many thanks to Peter Shawhan and other reviewers) Production analysis: Launched ongoing 11-spindown production analysis jobs on July 23: Search range: 50-1000 Hz for H1, H2, L1 (4 jobs / Hz ) x (950 Hz) x (3 IFO’s) = 11 kjobs Completed so far: ~3 kjobs (H1 up to 800 Hz) Wall-clock time per job (<1 hour at 50 Hz to 40+ Hours at 800 Hz) (see figure)

LSC meeting approaches (busy cluster) Time scales with number of sky points: α (frequency)2 (11 spindowns / job)

Zero-spindown 95% CL limits – H1 (50-1500 Hz) Linear amplitude (=0.5*h0worst-pulsar-orient.) “Good sky bands” (discussed later) Color coding Cyan – 60 Hz harmonic BLUE – Non-Gaussian Diamond – Wand. Line Green – Upper Limit Red point – Candidate (SNR > 7)

Why SNR > 7 ? SNR of highest upper limit over good sky bands (sample) The crud

? SNR Ceiling for plot Violins Calib / SB’s Injected Pulsars SNR = 107 92 754 93 Injected Pulsars SNR Ceiling for plot Calib / SB’s Violins ?

Comparing linear to circular polarization limits Linear amplitude (=0.5*h0worst-pulsar) Circular amplitude (h0best-pulsar) Typical: h0worst-pulsar ~ 4 x h0best-pulsar

Other IFO’s: H2 & L1 (50-700 Hz) – no spindown H2 L1 Linear amplitude (=0.5*h0worst-pulsar) H2 L1

Now for the 11-spindown run: –10-8 Hz/s < df0/dt < 0 Linear amplitude limits (good sky, all spindowns)

Maximum SNR over “good” sky – all spindowns Most are usual suspects, but many are worse than for zero spindown WHY?

“Bad” means Doppler shift for zero-spindown source is fairly stationary Sky bands during S4 Empirical: safe to use: |cos(Θband-axis)| < 0.5 DEC GOOD BAD GOOD BAD GOOD Average direction of Sun [= band axis] RA

Greatest net frequency stationarity (detector frame) for But “good” sky can become “bad” for pulsar with spindown  Doppler non-stationarity compensated by opposite spindown For negative df0/dt (positive spindown), region toward sun can become “bad” for frequency-dependent spindown range Greatest net frequency stationarity (detector frame) for df0/dt ~ – (a/c) f0 cos(Θband-axis) (with a = Earth acceleration) Numerically, df0/dt ~ – (2×10-9 Hz/s) [f0 / 100 Hz] × cos(Θband-axis)  Some part of the sky is bad for | df0/dt | < (2×10-9 Hz/s) [f0 / 100 Hz]

Bad for 0.5 < cos(Θ) < 1.0 (half of good band for df0/dt = 0) pdf

pdf Restricting to sky bands 0 & 8 gives cleaner map [|cos(θband-axis)| > 0.94]

Zooming in to a low-frequency 200-Hz band… Injected pulsars Deep-spindown region Crud

Zooming in to a higher-frequency 200-Hz band… Detchar studies ? Injected pulsars (both binary) Calib / SB’s Violins (but will check for L1 coincidence!)

Conclusions Hope to complete production run soon: Apply loose coincidence requirements among IFO’s to follow up on candidates – using machinery from deep-spindown search Attempt at detection (not for upper limits) But need to decide how to handle good sky vs bad sky in quoting upper limits – may restrict limits to (large) sky regions that are dependent on f0 and df0/dt Publication plans: Incorporate single-IFO limits into S4 incoherent search paper Hope to include corresponding limits from Hough / StackSlide for methods comparisons, in addition to results

End Notes for Pulsar Face-to-Face Meeting Some recent validation studies H1-L1 coincidence – zero-spindown

Some recent S4 validation studies (based on power injections)

Some recent S4 validation studies (cont.) Different from before: |cos(θband-axis)| < 0.3

Some recent S4 validation studies (cont.) Black: df0/dt < 1.E-10 Hz/s Red: df0/dt < 5.E-10 Hz/s

L1-H1 Coincidence check – Zero-spindown Look for loose coincidence of outliers (blue/red points, red diamonds): |Δf0| < 10 mHz, |ΔRA| < 0.5 rad, |Δdec| < 0.5 rad Survivors: Pulsars 2, 8 & 11