Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
A clearer picture of the continuous gravitational-wave sky
Early data release of an expanded atlas to enable new searches
November 12, 2024
Rapidly rotating, deformed neutron stars emit continuous gravitational waves. Observing this never-before-seen type of ripples in space-time will allow astrophysicists to study the “dark” population of Galactic neutron stars that we could not detect through electromagnetic surveys. Scientists from the permanent independent research group “Continuous Gravitational Waves” at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hannover have extened their previous work and analysed public LIGO data from O3a, the first half the third observing run. Their expanded atlas of the sky in continuous gravitational waves covers the entire sky and a much wider frequency range than their first version. Other scientists can immediately start using the new atlas to perform searches for continuous gravitational waves with small personal computers.
Paper abstract
We present the early release of the atlas of continuous gravitational waves covering frequencies from 20 Hz to 1500 Hz and spindowns from −5×10−10 to 5×10−10 Hz/s. Compared to the previous atlas release we have greatly expanded the parameter space, and we now also provide polarization-specific data – both for signal-to-noise ratios and for the upper limits. Continuous wave searches are computationally difficult and take a long time to complete. The atlas enables new searches to be performed using modest computing power. To allow new searches to start sooner, we are releasing this data early, before our followup stages have completed.
Summary of atlas data from the bins between 1220.2–1220.4 Hz. The top panels show the highest SNR (left) and upper limit values (right) across the frequency band, for each pixel of the sky map, using equatorial coordinates. The red lines denote the galactic plane. The black triangle shows the location of hardware injection. The blue band of smaller SNRs near the ecliptic equator is due to large correlations between waveforms of sources in that region. The blue regions in the upper limit plot are due to the lower-SNR values in the ecliptic plane, and also occur near the ecliptic poles that are favored by the antenna pattern of the detectors. The bottom panels show the same data as a function of frequency and with the maximum taken over the sky. We mark the frequency of the band where the hardware injection was performed.
Summary of atlas data from the bins between 1220.2–1220.4 Hz. The top panels show the highest SNR (left) and upper limit values (right) across the frequency band, for each pixel of the sky map, using equatorial coordinates. The red lines denote the galactic plane. The black triangle shows the location of hardware injection. The blue band of smaller SNRs near the ecliptic equator is due to large correlations between waveforms of sources in that region. The blue regions in the upper limit plot are due to the lower-SNR values in the ecliptic plane, and also occur near the ecliptic poles that are favored by the antenna pattern of the detectors. The bottom panels show the same data as a function of frequency and with the maximum taken over the sky. We mark the frequency of the band where the hardware injection was performed.
