Prospects for stochastic background searches using Virgo and LSC interferometers

Fan

2011

ApJ

We revisit the possibility and detectability of a stochastic gravitational wave (GW) background produced by a cosmological population of newborn neutron stars (NSs) with r-mode instabilities. The NS formation rate is derived from both observational and simulated cosmic star formation rates (CSFRs). We show that the resultant GW background is insensitive to the choice of CSFR models, but depends strongly on the evolving behavior of CSFR at low redshifts. Nonlinear effects such as differential rotation, suggested to be an unavoidable feature which greatly influences the saturation amplitude of r-mode, are considered to account for GW emission from individual sources. Our results show that the dimensionless energy density Ω GW could have a peak amplitude of ≃ (1 − 3.5) × 10 −8 in the frequency range (200 − 1000) Hz, if the smallest amount of differential rotation corresponding to a saturation amplitude of order unity is assumed. However, such a high mode amplitude is unrealistic as it is known that the maximum value is much smaller and at most 10 −2 . A realistic estimate of Ω GW should be at least 4 orders of magnitude lower (∼ 10 −12 ), which leads to a pessimistic outlook for the detection of r-mode background. We consider different pairs of terrestrial interferometers (IFOs) and compare two approaches to combine multiple IFOs in order to evaluate the detectability of this GW background. Constraints on the total emitted GW energy associated with this mechanism to produce a detectable stochastic background (a SNR of 2.56 with 3-year cross correlation) are ∼ 10 −3 M ⊙ c 2 for two co-located advanced LIGO detectors, and 2×10 −5 M ⊙ c 2 for two Einstein Telescopes. These constraints may also be applicable to alternative GW emission mechanisms related to oscillations or instabilities in NSs depending on the frequency band where most GWs are emitted.

Section: Introductionmentioning

confidence: 99%

STOCHASTIC GRAVITATIONAL WAVE BACKGROUND FROM NEUTRON STARr-MODE INSTABILITY REVISITED

Fan

2011

ApJ

“…Additional searches of S4 LIGO data set limits on the strength of possible point-like backgrounds [115] and (by correlating LIGO Livingston data with data from the ALLEGRO bar detector) set a higher-frequency limit of Ω gw (915 Hz) < 1.02 [116]. Correlation measurements using LIGO and Virgo data are expected to improve the high-frequency measurement [117]. Further searches for anisotropic backgrounds are also being conducted.…”

Section: Search Resultsmentioning

confidence: 99%

Current status of gravitational wave observations

et al. 2010

The first generation of gravitational wave interferometric detectors have taken data at, or close to, their design sensitivity. This data has been searched for a broad range of gravitational wave signatures. An overview of gravitational wave search methods and results are presented. Searches for gravitational waves from unmodelled burst sources, compact binary coalescences, continuous wave sources and stochastic backgrounds are discussed

“…With more than two instruments, there are multiple baselines and multiple calibration uncertainties to marginalize over. For instance, the stochastic background search using initial LIGO and Virgo data [6,7] involved 4 different instruments I ∈ {H1, H2, L1, V1} and 5 different baselines α ∈ {H1L1, H1V1, H2L1, H2V1, L1V1}.…”

Section: Calibration Uncertainty With Multiple Baselinesmentioning

confidence: 99%

Treatment of calibration uncertainty in multi-baseline cross-correlation searches for gravitational waves

Robinson

Romano²,

Thrane

2014

J. Phys.: Conf. Ser.

Uncertainty in the calibration of gravitational-wave (GW) detector data leads to systematic errors which must be accounted for in setting limits on the strength of GW signals. When cross-correlation measurements are made using data from a pair of instruments, as in searches for a stochastic GW background, the calibration uncertainties of the individual instruments can be combined into an uncertainty associated with the pair. With the advent of multi-baseline GW observation (e.g., networks consisting of multiple detectors such as the LIGO observatories and Virgo), a more sophisticated treatment is called for. We describe how the correlations between calibration factors associated with different pairs can be taken into account by marginalizing over the uncertainty associated with each instrument.