Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

The effects of selected corn-soybean tillage systems on rill cross-sectional geometry and soil erosion for two Illinois soils

The objectives of this study were to quantify rill cross sectional geometry under different tillage, crop and soil conditions and to relate variations in rill geometric properties to measured sediment discharge and to soil erosion and sediment transport predicted by various models. In the experimental phase of this study, simulated rainfall and additional run-on water were applied to plots that had been subjected to alternative corn-soybean tillage treatments in two soils in central Illinois. Before and after rainfall simulations, a pin type rill meter was used to record soil surface elevations. For each soil surface profile recorded, a series of water surface elevations were assumed, and a top width, wetted perimeter, hydraulic radius, and cross sectional area were calculated for each depression in the soil surface. Non-linear regression analyses were conducted to estimate mean rill top width, wetted perimeter and hydraulic radius as functions of rill cross sectional area for each tillage treatment and rainfall simulation run. Rill geometric properties as functions of cross sectional area appeared to vary across tillage treatments, soils and rainfall simulation runs. Rill geometric properties were also related to estimates of rill flow. A rill width equation was identified that accounted for 86% of the variation in rill width calculated from the rill meter measurements, but for tillage treatments with residue cover ranging from 15% to 54%, this equation tended to underpredict rill widths by 20% to 40%. Multiple linear regression analyses indicated that most of the variation in measured sediment discharge could be accounted for with a model that included runoff rate, but rill geometric properties also added statistically significant information to such a model. Calculations with the multiple linear regression models suggested that a 25% increase in rill width may be associated with a 25% to 50% decrease in sediment discharge while runoff rate remains constant. In the modeling phase of this study, various erosion models were calibrated to the field conditions, and different estimates of rill geometry were used to estimate sediment discharge. For one tillage treatment, sediment discharge estimated by the excess shear model varied by 36% on average as rill width varied by an average of 54%.U of I OnlyETDs are only available to UIUC Users without author permissio

Evaluation of Watershed Management Practices for Improving Stream Quality in the Illinois Watershed Program

ID: 8886; issued July 1, 2000 F-136-RINHS Technical Report prepared for Division of Fisheries, Illinois Department of Natural Resource

Evaluation of Watershed Management Practices for Improving Stream Quality in the Illinois Watershed Program

Annual Progress Report, Federal Aid Project F-136-RReport issued on: July 1999INHS Technical Report prepared for the IDNR Division of Fisherie

Relating Net Nitrogen Input in the Mississippi River Basin to Nitrate Flux in the Lower Mississippi River: A Comparison of Approaches

A quantitative understanding of the relationship between terrestrial N inputs and riverine N flux can help guide conservation, policy, and adaptive management efforts aimed at preserving or restoring water quality. The objective of this study was to compare recently published approaches for relating terrestrial N inputs to the Mississippi River basin (MRB) with measured nitrate flux in the lower Mississippi River. Nitrogen inputs to and outputs from the MRB (1951 to 1996) were estimated from state-level annual agricultural production statistics and NOy (inorganic oxides of N) deposition estimates for 20 states that comprise 90% of the MRB. A model with water yield and gross N inputs accounted for 85% of the variation in observed annual nitrate flux in the lower Mississippi River, from 1960 to 1998, but tended to underestimate high nitrate flux and overestimate low nitrate flux. A model that used water yield and net anthropogenic nitrogen inputs (NANI) accounted for 95% of the variation in riverine N flux. The NANI approach accounted for N harvested in crops and assumed that crop harvest in excess of the nutritional needs of the humans and livestock in the basin would be exported from the basin. The U.S. White House Committee on Natural Resources and Environment (CENR) developed a more comprehensive N budget that included estimates of ammonia volatilization, denitrification, and exchanges with soil organic matter. The residual N in the CENR budget was weakly and negatively correlated with observed riverine nitrate flux. The CENR estimates of soil N mineralization and immobilization suggested that there were large (2000 kg N ha-1) net losses of soil organic N between 1951 and 1996. When the CENR N budget was modified by assuming that soil organic N levels have been relatively constant after 1950, and ammonia volatilization losses are redeposited within the basin, the trend of residual N closely matched temporal variation in NANI and was positively correlated with riverine nitrate flux in the lower Mississippi River. Based on results from applying these three modeling approaches, we conclude that although the NANI approach does not address several processes that influence the N cycle, it appears to focus on the terms that can be estimated with reasonable certainty and that are correlated with riverine N flux

Estimated Historical and Current Nitrogen Balances for Illinois

The Midwest has large riverine exports of nitrogen (N), with the largest flux per unit area to the Mississippi River system coming from Iowa and Illinois. We used historic and current data to estimate N inputs, outputs, and transformations for Illinois where human activity (principally agriculture and associated landscape drainage) have had a dominant impact. Presently, ~800,000 Mg of N is added each year as fertilizer and another 420,000 Mg is biologically fixed, primarily by soybean (Glycine max L. Merr.). These annual inputs are greater than exports in grain, which results in surplus N throughout the landscape. Rivers within the state export approximately 50% of this surplus N, mostly as nitrate, and the remainder appears to be denitrified or temporarily incorporated into the soil organic matter pool. The magnitude of N losses for 1880, 1910, 1950, and 1990 are compared. Initial cultivation of the prairies released large quantities of N (~500,000 Mg N year�1), and resulted in riverine N transport during the late 19th century that appears to have been on the same order of magnitude as contemporary N losses. Riverine flux was estimated to have been at a minimum in about 1950, due to diminished net mineralization and low fertilizer inputs. Residual fertilizer N from corn (Zea mays L.), biological N fixed by soybean, short-circuiting of soil water through artificial drainage, and decreased cropping-system diversity appear to be the primary sources for current N export

Bio-Physical and Social Barriers Restrict Water Quality Improvements in the Mississippi River Basin

The Gulf of Mexico hypoxic zone that was measured in July of 2013 was 15 120 km2, the result of riverine losses of nitrate and total P from the Mississippi River Basin (MRB). Despite twelve years of an action plan calling for reducing the zone to a five-year running average of 5000 km2 by 2015, little progress has been made (ref 1, Figure 1). To meet the hypoxic zone target, the 2007 plan called for 45% reductions in total N and total P. (2) There is no evidence that nutrient loading to the Gulf has decreased during this period. Here we discuss the biophysical and social barriers that have limited measurable progress. We suggest that the most viable approach to developing the suite of practices needed to reduce nutrient losses from agricultural fields is a partnership of researchers working closely with farmers to develop realistic practices on real-world farms (where the constraints that influence management are present), to document the effectiveness, and to communicate the environmental and socioeconomic results regionally. To widely implement the resulting nutrient reduction practices will require substantial new funding if we are to continue using our current agronomic production systems in the MRB