LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 1

Status of inspiral search reviews

Alan Weinstein(LIGO Laboratory / Caltech)

For the LSC Internal review committee:

Vicky Kalogera, Bill Kells, Alan Weinstein, John Whelan, Laura Cadonati, Duncan Brown

LIGO LSC Meeting

June 3, 2006

LIGO- G060260-00-Z

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 2

Review Process

• Roughly ~weekly review telecons since the March meeting.

• Reviews greatly facilitated by well-organized, detailed elog pages assembled by analysis principle authors.

• Also facilitated by the commonality amongst all searches currently under review (pipeline, data handling procedures, bookkeeping for observation time, vetoes, etc).

• All the code is in lal, lalapps, pylal, etc…, in CVS, tagged.

• Code review for features unique to the BBH search (BCV templates, template bank generation, coincidence code…)

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 3

Analyses under review

• Binary Neutron Stars (BNS, 1-3 Msun): S3 and S4 • Both boxes opened, no detections, background and efficiencies reviewed

• Binary MACHOs (AKA PBHs, 0.35-1 Msun): S3 and S4• Both boxes opened, no detections, background and efficiencies reviewed

• Binary Black Holes (BBH, 3-40 Msun): S3 and S4• S3 box opened, no detections, background and efficiencies reviewed

• S4 box to be opened soon

Upper Limits and Systematic Errors:

• In all cases, work is in progress to fold in measured efficiencies with source model (spatial distribution, component mass distribution) to extract astrophysical upper limit (events/y/L10 )

• Evaluation of systematic errors (MC stats, calibration, waveform modeling, source population modeling) in progress.

• Review of upper limits and systematics have begun, converging quickly.

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 4

Coming up before August meeting

• Complete the review of S4 BBH analysis (box opening soon)

• Review astrophysical upper limit calculations

• Results paper for S3/S4 BNS/MACHO/BBH

• Longer papers on methods, astrophysical source models

By August, these six analyses, reviews, mature paper draft should be complete – at least, this reviewer hopes so!

•Then on to (not necessarily in this order):

• S5 BNS

• S3 Spinning BBH

• Detection confidence follow-ups

• Coherent follow-up

• Ringdown search

• GRB/Inspiral coincidence

• Parameter estimation: Time-domain-templates, MCMC

• …

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 5

Elements of the Search that have been reviewed

• Data segment selection, Data quality flags, vetoes

• Template waveforms

• Template bank generation, bank size vs time

• Sensitivity: Inspiral horizon distance (AKA range, = 2.26*sensemon)

• Hierarchical pipeline

• Parameter estimation for coincidence window tuning

• Coincidence cuts in time, m1/m2, psi0/psi3…

• chisq, rsq, alphaf cuts.

• H1/H2 amplitude consistency cut

• DQ flags, vetoes applied at various stages of the pipeline

•Time slides for accidental background estimation

• Injections, missed injections, efficiency vs effective distance(s)

• Zero lag candidates

• Follow-up of loudest events (trigger parameters, Qscans, etc)

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 6

double-and-triple-coincidence times

•Various double-and-triple-coincidence cases / data sets:• H1H2, H1L1, or H2L1 double coincidence in 2-IFO livetime

• H1H2, H1L1, or H2L1 double coincidence in 3-IFO livetime

• H1H2L1 triple coincidence in 3-IFO livetime

• Only consider times when H1 and H2 are both in-lock (but not necessarily both in science mode). Also require amplitude consistency between H1/H2. Some of these combinations are not relevant in some cases.

• Need to keep track of livetime, vetoes, background time slides, etc for all the relevant cases.

• Independent scripts, going from segments lists through all stages of the DAG. The bookkeeping is nontrivial, especially given the complexity of the Condor DAG.

• These timing checks are now reviewed. Automated, routine, and common to all inspiral group searches.

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 7

Detection statistic

• SNR is not the best way to distinguish signal from background;use “effective SNR”, taking into account chisq test of signal consistency, constructed to give a rough sense of the ~ average SNR of the coincident trigger.

•

• Need to combine signal / background discriminators from 2 or more coincident detectors as a single measure of coincident trigger strength: “Combined SNR”.

• This helps, to give guidance on where an analysis needs improvement.

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 8

Background estimation via time slides

• Anomalies are seen in many cases.

• Expected, for H1/H2.

• In other cases, could just be (extreme?) statistical fluctuations.

• Continued worry about this method of background estimation (especially for H1/H2, obviously).

• No better ideas or checks have emerged.

• For now, analyze the (considerable amount of) data; use for upper limits, look carefully at the (small number) of potential detection candidates.

S4 BNS, H1H2

S4 BNS, H2L1

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 9

Efficiency vs Livetime

• Rate ~ 1 / (T * NL10s)

• T = livetime (AKA observation time).

• NL10s ~ Int(efficiency * source distribution)

• Selection of science segments (including ~ long duration data quality flags) determines livetime.

• Shorter duration data quality flags, as well as cuts, event vetoes, etc, produce inefficiency. Eg, SNR threshold cut produces falloff of efficiency vs effective distance.

• Because of cuts and signal consistency vetoes, efficiency < 100% for short effective distance.

• Some “intermediate duration” DQ flags cause inefficiency to be 10% or more even for nearby sources.

• Would prefer to see this counted as loss of livetime.

• Issue only for presentation; upper limit calculation shouldn’t depend on how this is reported.

• Work in progress / review.

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 10

Astrophysical upper limit

•To determine number of sources (in MWEG or L10), convolute efficiency with source model

•Convolution is in 3-dim space: deff

LHO , deffLLO , Mch

•Reduced to 2D: dch

LHO , dchLLO

•Makes it easier to convolute with different source models

•Not easily generalized to more detector sites, more important parameters (spin), etc.. Works for now.

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 11

Follow-up of loudest triggers

LSC Meeting, June 3, 2006 LIGO-G060260-00-Z 12

Summary

• Hope to wrap up S3/S4 BNS/MACHO/BBH analyses and review by August meeting.

• Move on to new analyses and features ASAP• spinning BBH

• ringdowns

• S5 analyses

• detection candidate followup

• coherent analysis

• parameter estimation

• Inspiral/Merger/Ringdown

• tests of GR

• etc…