Digging deeper with Einstein@Home
New searches for continuous gravitational waves from central compact objects in two young supernova remnants
The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hannover runs the distributed volunteer computing project Einstein@Home. Researchers on the project team used the combined computing power of tens of thousands of volunteers to analyse data from LIGO's second and third observing runs (O2 and O3) by comparing them with 1018 possible signals. They searched for continuous gravitational waves emitted by deformed rotating or oscillating neutron stars left behind in the Vela Jr. and G347.3-0.5 supernova remnants. Because the sky positions of their central compact objects are known a priori, the team’s more focused search could “dig deeper” and look for fainter signals that other searches might have missed. Among other things, the non-detection of gravitational waves in this study provides the strongest constraints yet on gravitational-wave emission from the neutron star in G347.3-0.5.
Publication
We perform a search for continuous nearly monochromatic gravitational waves from the central compact objects associated with the supernova remnants Vela Jr. and G347.3. Over 1018 different waveforms are considered, covering signal frequencies between 20-1300 Hz (20-400 Hz) for G347.3-0.5 (Vela Jr) and a very broad range of frequency derivatives. The data set used for this first search is from the second observing run of LIGO (O2). Thousands of volunteers donating compute cycles through the computing project Einstein@Home have made this endeavour possible. Following the Einstein@Home search, we perform multi-stage follow-ups of over 5 million waveforms. The threshold for selecting candidates from the Einstein@Home search is such that after the multi-stage follow-up, we do not expect any surviving candidate due to noise. The very last stage uses a different data-set, namely the LIGO O3 data. We find no significant signal candidate for either targets. Based on this null result, for G347.3-0.5, we set the most constraining upper limits to date on the amplitude of gravitational wave signals, corresponding to deformations below 10-6 in a large part of the search band. At the frequency of best strain sensitivity, near 161 Hz, we set 90% confidence upper limits on the gravitational wave intrinsic amplitude of h090%≈6.2×10-26. Over most of the frequency range our upper limits are a factor of 10 smaller than the indirect age-based upper limit. For Vela Jr., near 163 Hz, we set h090%≈6.4×10-26. Over most of the frequency range our upper limits are a factor of 15 smaller than the indirect age-based upper limit. The Vela Jr. upper limits presented here are slightly less constraining than the most recent upper limits of Abbot et al. (2022a) but they apply to a broader set of signals.
