Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
抄録
<jats:title>Abstract</jats:title> <jats:p>We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25–<jats:inline-formula> <jats:tex-math> <?CDATA $2000\,\mathrm{Hz}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and simulated signal injections. The most stringent upper limit was set at <jats:inline-formula> <jats:tex-math> <?CDATA $175\,\mathrm{Hz}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, with comparable limits set across the most sensitive frequency range from 100 to <jats:inline-formula> <jats:tex-math> <?CDATA $200\,\mathrm{Hz}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>. At this frequency, the 95% upper limit on the signal amplitude <jats:italic>h</jats:italic> <jats:sub>0</jats:sub> is <jats:inline-formula> <jats:tex-math> <?CDATA $2.3\times {10}^{-25}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> marginalized over the unknown inclination angle of the neutron star’s spin, and <jats:inline-formula> <jats:tex-math> <?CDATA $8.0\times {10}^{-26}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> assuming the best orientation (which results in circularly polarized gravitational waves). These limits are a factor of 3–4 stronger than those set by other analyses of the same data, and a factor of ∼7 stronger than the best upper limits set using data from Initial LIGO science runs. In the vicinity of <jats:inline-formula> <jats:tex-math> <?CDATA $100\,\mathrm{Hz}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjaa86f0ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>, the limits are a factor of between 1.2 and 3.5 above the predictions of the torque balance model, depending on the inclination angle; if the most likely inclination angle of 44° is assumed, they are within a factor of 1.7.</jats:p>
収録刊行物
-
- The Astrophysical Journal
-
The Astrophysical Journal 847 (1), 47-, 2017-09-20
American Astronomical Society