All-sky search for periodic gravitational waves in the O1 LIGO data

Abstract

We report on an all-sky search for periodic gravitational waves in the frequency band 20-475 Hz and with a frequency time derivative in the range of ½−1.0; þ0.1 × 10 −8 Hz=s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our galaxy. This search uses the data from Advanced LIGO's first observational run, O1. No periodic gravitational wave signals were observed, and upper limits were placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude h 0 are ∼4 × 10 −25 near 170 Hz. For a circularly polarized source (most favorable orientation), the smallest upper limits obtained are ∼1.5 × 10 −25 . These upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest upper limits obtained for the strain amplitude are ∼2.5 × 10 −25 .

Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

“…2 In particular there was a change of a power supply source which could have caused the lines to disappear (log entry n. 32262) which has been used in also in Eq. (5) of [33]. The fit parameters are A 1 and A 2 , while x − x min = log 10 ( hinj hmin ) where h inj is the injected signal strain and h min is the value that satisfies D(x min ) = 0.…”

Identification and mitigation of narrow spectral artifacts that degrade searches for persistent gravitational waves in the first two observing runs of Advanced LIGO

“…The inverse noise weighting is meant to mimic the weightings used in many CW searches [33], which weight more heavily those time spans with better sensitivity. Comparing such spectral averages with arithmetic averages also allows rapid identification of nonstationary line artifacts.…”

“…Searches for CWs, such as recent all-sky searches for unknown isolated sources [33], typically use a list of known lines and combs to veto frequency bands prior to running the searches or, afterward, for vetoing outliers. We summarize here the procedure used to generate these lists.…”

Direct Constraints on the Ultralight Boson Mass from Searches of Continuous Gravitational Waves

“…the minimum detectable amplitude, goes as (T obs × T FFT ) −1/4 , where T obs is the total observation time. They have been applied to several LIGO and Virgo runs [see [27][28][29][30][31] for the most recent results to date]. For instance, the all-sky hierarchical pipeline based on the FrequencyHough transform [24] used T FFT = 8192, 4096, 2048, 1024 second for the frequency ranges (10−128) Hz, (128−512) Hz, (512−1024) Hz and (1024 − 2048) Hz respectively, to analyze LIGO O2 data, which covered about 9 months from November 2016 to August 2017 [31].…”