Are We Closer to Finding Elusive Gravitational Waves with New Search Methods?

[wolram]

Null results so far for the elusive gravitational search, but were they expected to be found at this range?

arXiv:1402.4974 (cross-list from gr-qc) [pdf, ps, other]
Implementation of an F-statistic all-sky search for continuous gravitational waves in Virgo VSR1 data
J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, M. Andersen, R. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, L. Austin, B. E. Aylott, S. Babak, P. T. Baker, G. Ballardin, S. W. Ballmer, J. C. Barayoga, M. Barbet, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. C. Batch, J. Bauchrowitz, Th. S. Bauer, B. Behnke, M. Bejger, M. G. Beker, C. Belczynski, A. S. Bell, C. Bell, G. Bergmann, D. Bersanetti, A. Bertolini, J. Betzwieser, et al. (785 additional authors not shown)
Comments: 27 pages, 10 figures, submitted to CQG
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present an implementation of the $\mathcal{F}$-statistic to carry out the first search in data from the Virgo laser interferometric gravitational wave detector for periodic gravitational waves from a priori unknown, isolated rotating neutron stars. We searched a frequency $f_0$ range from 100 Hz to 1 kHz and the frequency dependent spindown $f_1$ range from $-1.6\,(f_0/100\,{\rm Hz}) \times 10^{-9}\,$ Hz/s to zero. A large part of this frequency - spindown space was unexplored by any of the all-sky searches published so far. Our method consisted of a coherent search over two-day periods using the $\mathcal{F}$-statistic, followed by a search for coincidences among the candidates from the two-day segments. We have introduced a number of novel techniques and algorithms that allow the use of the Fast Fourier Transform (FFT) algorithm in the coherent part of the search resulting in a fifty-fold speed-up in computation of the $\mathcal{F}$-statistic with respect to the algorithm used in the other pipelines. No significant gravitational wave signal was found. The sensitivity of the search was estimated by injecting signals into the data. In the most sensitive parts of the detector band more than 90% of signals would have been detected with dimensionless gravitational-wave amplitude greater than $5 \times 10^{-24}$.

 

[Chronos]

It looks like they used data from the original Virgo design, so it is unsurprising they came up empty this run. The sensitivity was not expected to be sufficient to detect more than 0.1 events per year. Advance Virgo, expected to come on line in 2017, will be much more sensitivity and yield much better detection probability. For further information, see http://hal.archives-ouvertes.fr/docs/00/28/06/10/PDF/in2p3-00280610.pdf

 

[ryan albery]

I'll read the paper Chronos suggests in the morning, but I wonder, how do they hold the temperature (energy/momentum) constant enough between the mirrors to get an interference pattern?

 

[mfb]

With a lot of cooling effort. I think constant is not the issue, just colder than the environment (and with some way to get rid of absorbed beam power).