IDEA: A methodology paper about issues on source reconstruction

First comments

Reading the old version, these are some comments:

• Check the earth coordinates of KAGRA and LIGO/India
  Last paper should be Phys. Rew. D 90, 024053 (2014)
• Check if the sensitivity curves have changed
  The same paper gives the same curves we are already using (as it seems comparing the figures)
• Remind the contributions of main effects on source estimation:
  Triangulation -> Paper puts comparison with 3ifo Wen&Chen formula -> Put results from Feirhust paper?
  Antenna pattern -> Puts results using a small earth radius?
• Analysis probably should be re-done with an appropriate cWB svn version and configuration parameters: establish which
• Decide which waveform to use

Past articles/Presentation/Poster

• Stephen Fairhurst 2009 New J. Phys. 11 123006
• L Wen et al 2008 J. Phys.: Conf. Ser. 122 012038
• Stephen Fairhurst 2011 Class. Quantum Grav. 28 105021
• Klimenko et al, Phys. Rev. D 83, 102001
• Amaldi poster (DCC ligo)

State of the art

Reed paper presents results for 2015HL and 2016HLV, link at DCC. This paper should presents results from 3-fold network to 5-fold network, adding analysis using Invariant Topology detectors.

Last results on source reconstruction are in this wiki page. In particular:

1. The comparison of un-modeled search (row 22) with respect to a previous version link shows little difference, some better, other worse, but not so important. Improvements with respect to 1G still remains.
2. Some not understood aspects remains, in particular on P search (row 21). This search performs a circular constraint adding a transformation on the pixel composing the cluster. In particular this transformation make a projection of the pixels likelihood according to the mean values of all composing the cluster. For an example see the link under the title "G & MASK". It is not still clear why the circular polarization waveform has worse results while linear polarization ones are better.

Results

I made some simulations of SG for various Q for LHV network. Results report median value of erA[0] over each single sky pixel (Healpix=4) and construct Lars Histogram.

Results show a dependency on frequency according to the sensitivity curve as in the figure:

L1H1V1	Median of erA[0]	90 Percentile of erA[0]
Triangulation Error from Fairhust paper
SGQ100 SGQ45 SGQ30 SGQ15 SGQ9 SGQ6 SGQ3
Q behaviour
Linear Sine Gaussian, changing of Q
SGQ100 SGQ45 SGQ30 SGQ15 SGQ9  SGQ6 SGQ3 
Q behaviour
SGQ9 ​Sample rate and Sky grid limitations
SGQ9  SGQ9_upTDF SGQ9_Healpix8 SGQ9_Healpix_upTDF Benchmark (h) SGQ9 : 0.19 upDTF: 0.26 Healpix: 0.32 Healpix_upTDF: 0.38
Linear Sine Gaussian, Search R, S, P
SGQ100 R SGQ100_S SGQ100_P SGQ9_R SGQ9_S SGQ9_P SGQ3_R SGQ3_S SGQ3_P SGCQ3_WNB
Elliptical waveform SGEQ9 Search R
e=1.0 (C) e=0.6 e=0.4 e=0.3 e=0.2 e=0.1 e=0.0 (L)
ellipticity behaviour
Elliptical waveforms SGEQ9 SEARCH P
e=1.0 (C) e=0.8 e=0.6 e=0.4 e=0.3 e=0.2 e=0.1 e=0.0 (L)

Comments and other proposal

According to the results, the following comes out:

• For lower frequency (up to 500 Hz) the curves seems following the behaviour of 1/f^2, like in Wen&Chen formula
• For upper frequency, the results are probably related to algorithm approximation, this is quite confirmed by test with upTDF=8 (instead of 4) for SGQ9
• For higher Q, performances worse, because it enters the group error, other than phase error. It would be nice to identify the correlation between the two effects

Next proposal:

Consider a methodological paper where studying in details the results explaining the possible causes, like explained in the previous bullets. Some starting point:

• Network: 3-fold and 4-fold, no invariant detectors.
• Waveforms: Focus on SG, linear and elittical polization. Study the results on variation on polarization values. Could be interesting to see RingDown (nearer to astrophysical binaries?)
• Search: R and E (other polarization if there is space.)
• SNR: characterize at fixed network SNR. Consider a study of reduced waveforms varying SNR.

Notes from LVC meeting in Pasadena

Tentative title:
Low-latency localization of sources of transient Gravitational Waves with generic waveforms

Assume that a low-latency GW detection is triggering a low latency GW follow-up for estimation purposes

• A. Methodological investigation: understanding and comparing performances simulations vs network SNR
  LHV 32Hz-2kHz, ADE design spectral sensitivity, with Gaussian noise
  R and P(new) searches
  SG as a function of central frequency, Q (3-100), ellipticity
  Ring-down, WNB, …

• B. Performances on astrophysical source distributions
  Simulations with astrophysical motivated source populations (best if multimessenger prompt follow-up is motivated)
  NSBH, BBH uniform in volume
  NS excitations, galactic mode
  cosmic strings
  P(new) search LHV, LHV+Kagra ?

• C. Lesson learned for advanced detectors observations