Upper Limits on the Stochastic Gravitational-Wave Background from Advanced LIGO’s First Observing Run

We consider an alternative to WIMP cold dark matter (CDM), ultralight bosonic dark matter (m 10 −22 eV/c 2 ) described by a complex scalar field (SFDM) with a global U (1) symmetry, for which the comoving particle number density, or charge density, is conserved after particle production during standard reheating. We allow for a repulsive self-interaction. In a ΛSFDM universe, SFDM starts relativistic, evolving from stiff (w = 1) to radiation-like (w = 1/3), before becoming nonrelativistic at late times (w = 0). Thus, before the familiar radiation-dominated era, there is an earlier era of stiff-SFDM-domination. During both the stiff-SFDM-dominated and radiation-dominated eras, the expansion rate is higher than in ΛCDM. SFDM particle mass m and quartic self-interaction coupling strength λ, are therefore constrained by cosmological observables, particularly N eff , the effective number of neutrino species during BBN, and zeq, the redshift of matter-radiation equality. Furthermore, since the stochastic gravitational wave background (SGWB) from inflation is amplified during the stiff-SFDM-dominated era, it can contribute a radiationlike component large enough to affect these observables, by further boosting the expansion rate after the stiff era ends. Remarkably, this same amplification makes detection of the SGWB possible at high frequencies by current laser interferometer experiments, e.g., aLIGO/Virgo and LISA. For SFDM particle parameters that satisfy these cosmological constraints, the amplified SGWB is detectable by LIGO for a broad range of reheat temperatures T reheat , for values of the tensor-to-scalar ratio r currently allowed by CMB polarization measurements. For a given r and λ/(mc 2 ) 2 , the marginally-allowed ΛSFDM model for each T reheat has the smallest m that satisfies the cosmological constraints, and maximizes the present SGWB energy density for that T reheat . This SGWB is then maximally detectable for values of T reheat for which modes that reenter the horizon when reheating ended have frequencies today that lie within the LIGO sensitive band. For example, for the family of marginally-allowed models with r = 0.01 and λ/(mc 2 ) 2 = 10 −18 eV −1 cm 3 , the maximally detectable ΛSFDM model has T reheat ≃ 2 × 10 4 GeV and m ≃ 1.6 × 10 −19 eV/c 2 , for which we predict an aLIGO O1 run detection with signal-to-noise ratio of ∼ 10. We show that the null detection of the SGWB recently reported by the aLIGO O1 run excludes the parameter range 8.75 × 10 3 T reheat (GeV) 1.7 × 10 5 for this illustrative family at 95% confidence, thereby demonstrating that GW detection experiments can already place a new kind of cosmological constraint on SFDM. A wider range of SFDM parameters and reheat temperatures should be accessible to aLIGO/Virgo O5, with the potential to detect this unique signature of the ΛSFDM model. For this same illustrative family, for example, a 3σ detection is predicted for 600 T reheat (GeV) 10 7 .

Section: Results: Present-day Sgwb Energy Density Spectrum and Itsmentioning

confidence: 99%

Bose-Einstein-condensed scalar field dark matter and the gravitational wave background from inflation: New cosmological constraints and its detectability by LIGO

Shapiro

Rindler-Daller

2017

“…These couplings were reduced following O1 via isolation of power supplies, and in some cases, reduction of periodic current draws in the timing system itself (blinking LEDs). A subset of these lines with common origins at the two observatories contaminated the O1 search for a stochastic background of gravitational waves, which relies upon cross correlation of H1 and L1 data, requiring excision of affected bands [30].…”

Section: Ligo Interferometers and The O1 Observing Runmentioning

confidence: 99%

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

Abbott¹,

Abbott²,

Abbott³

et al. 2017

Self Cite

178

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 .

“…To calculate the significance of the combined power of a set of discrete frequency bins f i representing a comb, we calculate the signal-to-noise ratio (SNR) from the crosscorrelation estimatorŶðf i Þ and the associated standard deviation σ Y ðf i Þ [38,39]. The optimal way to combine these statistics is using a weighted sum (as described in [39,40] for combining segments).…”

Section: Sub-threshold Combs In Coherence Datamentioning

confidence: 99%

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

Covas¹,

Effler²,

Goetz³

et al. 2018

Self Cite

137

157

Searches are under way in Advanced LIGO and Virgo data for persistent gravitational waves from continuous sources, e.g. rapidly rotating galactic neutron stars, and stochastic sources, e.g. relic gravitational waves from the Big Bang or superposition of distant astrophysical events such as mergers of black holes or neutron stars. These searches can be degraded by the presence of narrow spectral artifacts (lines) due to instrumental or environmental disturbances. We describe a variety of methods used for finding, identifying and mitigating these artifacts, illustrated with particular examples. Results are provided in the form of lists of line artifacts that can safely be treated as non-astrophysical. Such lists are used to improve the efficiencies and sensitivities of continuous and stochastic gravitational wave searches by allowing vetoes of false outliers and permitting data cleaning.