We present a method for detection and reconstruction of the gravitational wave (GW) transients with the networks of advanced detectors. Originally designed to search for transients with the initial ...GW detectors, it uses significantly improved algorithms, which enhance both the low-latency searches with rapid localization of GW events for the electromagnetic follow-up and high confidence detection of a broad range of the transient GW sources. In this paper, we present the analytic framework of the method. Following a short description of the core analysis algorithms, we introduce a novel approach to the reconstruction of the GW polarization from a pattern of detector responses to a GW signal. This polarization pattern is a unique signature of an arbitrary GW signal that can be measured independently from the other source parameters. The polarization measurements enable rapid reconstruction of the GW waveforms, sky localization, and helps identification of the source origin.
In this paper, we investigate the morphology of the events from the GWTC-1 catalog of compact binary coalescences as reconstructed by a method based on coherent excess power: we use an open-source ...version of the coherent WaveBurst (cWB) analysis pipeline, which does not make use of waveform models. The coherent response of the LIGO-Virgo network of detectors is estimated by using loose bounds on the duration and bandwidth of the signal. This pipeline version reproduces the same results that are reported for cWB in recent publications by the LIGO and Virgo collaborations. In particular, the sky localization and waveform reconstruction are in a good agreement with those produced by methods which exploit the detailed theoretical knowledge of the expected waveform for compact binary coalescences. However, in some cases cWB also detects features in excess in well-localized regions of the time-frequency plane. Here we focus on such deviations and present the methods devised to assess their significance. Out of the 11 events reported in the GWTC-1, in two cases-GW151012 and GW151226-cWB detects an excess of coherent energy after the coalescence (Δt≃0.2 and ≃0.1 s, respectively) with p-values that call for further investigations (0.004 and 0.03, respectively), though they are not sufficient to exclude noise fluctuations. We discuss the morphological properties and plausible interpretations of these features. In case they are genuine, we anticipate that several more such outliers will be uncovered by our methodology in the ongoing advanced LIGO-Virgo observation run (O3).
Most compact binary systems are expected to circularize before the frequency of emitted gravitational waves (GWs) enters the sensitivity band of the ground based interferometric detectors. However, ...several mechanisms have been proposed for the formation of binary systems, which retain eccentricity throughout their lifetimes. Since no matched-filtering algorithm has been developed to extract continuous GW signals from compact binaries on orbits with low to moderate values of eccentricity, and available algorithms to detect binaries on quasicircular orbits are suboptimal to recover these events, in this paper we propose a search method for detection of gravitational waves produced from the coalescences of eccentric binary black holes (eBBH). We study the search sensitivity and the false alarm rates on a segment of data from the second joint science run of LIGO and Virgo detectors, and discuss the implications of the eccentric binary search for the advanced GW detectors.
By probing the population of binary black hole (BBH) mergers detected by LIGO-Virgo, we can infer properties about the underlying black hole formation channels. A mechanism known as pair-instability ...(PI) supernova is expected to prevent the formation of black holes from stellar collapse with mass greater than ∼ 40 – 65 M ⊙ and less than ∼ 120 M ⊙ . Any BBH merger detected by LIGO-Virgo with a component black hole in this so-called PI mass gap likely originated from an alternative formation channel. Here, we firmly establish GW190521 as an outlier to the stellar-mass BBH population if the PI mass gap begins at or below 65 M ⊙ . In addition, for a PI lower boundary of 40 – 50 M ⊙ , we find it unlikely that the remaining distribution of detected BBH events, excluding GW190521, is consistent with the stellar-mass BBH population.
Gravitational-wave astronomy is established with direct observation of gravitational wave from merging binary black holes and binary neutron stars during the first and second observing run of LIGO ...and Virgo detectors. The gravitational-wave transient searches mainly separate into two families: modeled and modeled-independent searches. The modeled searches are based on matched filtering techniques, and model-independent searches are based on the extraction of excess power from time-frequency representations. We have proposed a hybrid method, called wavegraph that mixes the two approaches. It uses astrophysical information at the extraction stage of model-independent search using a mathematical graph. In this work, we assess the performance of wavegraph clustering in real LIGO and Virgo noise (the sixth science run and the first observing run) and using the coherent WaveBurst transient search as a backbone. Further, we propose a new signal consistency test for this algorithm. This test uses the amplitude profile information to distinguish between the gravitational-wave transients from the noisy glitches. This test is able to remove a large fraction of loud glitches, which thus results in additional overall sensitivity in the context of searches for binary black-hole mergers in the low-mass range.
Transient gravitational-wave searches can be divided into two main families of approaches: modeled and unmodeled searches, based on matched filtering techniques and time-frequency excess power ...identification respectively. The former, mostly applied in the context of compact binary searches, relies on the precise knowledge of the expected gravitational-wave phase evolution. This information is not always available at the required accuracy for all plausible astrophysical scenarios, e.g., in the presence of orbital precession, or eccentricity. The other search approach imposes little priors on the targeted signal. We propose an intermediate route based on a modification of unmodeled search methods in which time-frequency pattern matching is constrained by astrophysical waveform models (but not requiring accurate prediction for the waveform phase evolution). The set of astrophysically motivated patterns is conveniently encapsulated in a graph, that encodes the time-frequency pixels and their co-occurrence. This allows the use of efficient graph-based optimization techniques to perform the pattern search in the data. We show in the example of black-hole binary searches that such an approach leads to an averaged increase in the distance reach (+7–8%) for this specific source over standard unmodeled searches.
•We analyzed the association between consumer behaviors and food acquisition patterns.•Buying fresh produce at supermarket is related to lower ultra-processed purchase.•Walking and use of fresh ...produce market are related to minimally-processed purchase.•The use of taxi to buy food is associated with ultra-processed pattern.•Perceived access to fresh produce influences household food acquisition patterns.
Objective: This cross-sectional study examined the association between local food environment and consumers' acquisition of ultra-processed food. Methods: Households were randomly selected from 36 census tracts in Santos City, Brazil. Mothers, of varying economic status, who had children ages 10 or younger (n = 538) were interviewed concerning: their household food acquisition of 31 groups of food and beverages, perceptions of local food environment, food sources destinations, means of transportation used, and socioeconomic status. Food acquisition patterns were classified based on the degree of industrial food processing. Logistic regression models were fitted to assess the association between consumer behaviors and acquisition patterns. Results: The large variety of fresh produce available in supermarkets was significantly related to lower odds of ultra-processed food purchases. After adjusting for sociodemographic characteristics, higher odds for minimally-processed food acquisition were associated with: frequent use of specialized markets to purchase fruits and vegetables (OR 1.89, 95% CI 1.01–2.34), the habit of walking to buy food (OR 1.58, 95% CI 1.08–2.30), and perceived availability of fresh produce in participants' neighborhood (OR 1.58, 95% CI 1.08–2.30). Acquisition of ultra-processed food was positively associated with the use of taxis as principal means of transportation to food sources (OR 2.35, 95% CI 1.08–5.13), and negatively associated with perceived availability of a variety of fruits and vegetables in the neighborhood (OR 0.57, 95% CI 0.37–0.88). Conclusion: The results suggest that interventions aiming to promote acquisition of less processed food in settings similar to Santos, may be most effective if they focus on increasing the number of specialized fresh food markets in local neighborhood areas, improve residents' awareness of these markets' availability, and provide appropriate transportation.
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