Confusion Background Research Articles

Gravitational wave peeps from EMRIs and their implication for LISA signal confusion noise

Scattering events around the center of massive galaxies will occasionally toss a stellar-mass compact object into an orbit around the massive black hole (MBH) at the center, beginning an extreme mass ratio inspiral (EMRI). The early stages of such a highly eccentric orbit are not likely to produce detectable gravitational waves (GWs), as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This repeated burst of emission, firmly in the millihertz band, is the GW peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across the Universe, together they may produce an unresolvable background noise that could obscure sources otherwise detectable by the Laser Interferometer Space Antenna. Previous studies of the extreme mass ratio signal confusion background focused either on parabolic orbits near the MBH or events closer to merger. We seek to improve this characterization by implementing numerical kludge waveforms that can calculate highly eccentric orbits with relativistic effects. Our focus is on orbits at the point of capture that are farther away from the MBH. Here we present the waveforms and spectra of peeps generated from recent calculations of EMRIs/extreme mass ratio bursts capture parameters and discuss how these can be used to estimate the signal confusion noise generated by such events. We demonstrate the effects of changing the orbital parameters on the resulting spectra as well as showing direct comparisons to parabolic orbits and why the GW ‘peep’ needs to be studied further. The results of this study will be expanded upon in a further paper that aims to provide an update on the EMRI signal confusion noise problem.

최근 소개된 두 건의 고구려 유민 묘지명 자료

In 2022, two new epitaph materials for Koguryo refugees were introduced in China. These are The epitaph of Lee Inhoe and the epitaph of Mrs. Cheon. Lee Inhoe was a man of Liaoyang and his family was a powerful family from the Liaoxi and Liaodong areas.
 Lee Inhoe's ancestors directly participated in the Tang's control of Koguryo's old lands, and most likely participated in the Tang's invasion of Koguryo before that. However, it seems that a more cautious approach is needed to directly identify them as being from Koguryo.
 According to the epitaph of Mrs. Cheon, Mrs. Cheon is the daughter of Cheon Hyuneun and the great-granddaughter of Cheon Heonsung. However, the genealogy of the family differs from the existing data, raising questions. Unlike the existing data showing that Heonsung and Hyuneun were in a father-son relationship, in the epitaph of Mrs. Cheon, Heonsung and Hyuneun appear in a grand-grandson relationship. In addition, her grandfather, Dongje, is a person who has not been confirmed in any known materials related to the Cheon family. Unraveling the background of information confusion will be a future task.

Development of toxic shock syndrome as one of the causes of mortality in streptococcal infection

Toxic shock syndrome is a condition in which a state of shock with a drop in blood pressure to critical numbers and multiple organ failure develops against the background of exposure to endoand exotoxins produced by bacteria and viruses. Every third patient who enters the intensive care unit suffers from certain manifestations of toxic shock syndrome. This term was first introduced in 1978 by the English pediatrician Jim Todd, who observed hyperthermia, hypotension, occurrence of rashes against the background of confusion and severe asthenia in patients. Type B enterotoxin produced by Staphylococcus aureus was isolated from blood samples of one of the patients, which made it possible to suspect the infectious nature of this process. This pathological condition can be observed with the development of postpartum sepsis, presence of wounds and burn surfaces, including closed wounds, occur against the background of postoperative interventions, or complicate the course of allergic contact dermatitis. Mortality in toxic shock syndrome reaches 5-15%, and if Streptococcus pyogenes acts as the causative agent, the mortality rate can increase several times and reach 50-60%. The main reservoir of streptococcus in the human body is the pharynx, but at the same time it can be found on the surface of the skin, rectal mucosa and vagina. A considerable number of cases of the development of toxic shock syndrome occurs in women who have been using vaginal tampons during menstruation for a long time.

Management of Medication-Induced Psychiatric Disorders.

Management of Medication-Induced Psychiatric Disorders.

Probability distribution of astrophysical gravitational-wave background fluctuations

The coalescence of compact binary stars is expected to produce a stochastic background of gravitational waves (GW) observable with future GW detectors. Such backgrounds are usually characterized by their power spectrum as a function of frequency. Here, we present a method to calculate the full 1-point distribution of strain fluctuations. We focus on time series data, but our approach generalizes to the frequency domain. We illustrate how this probability distribution can be evaluated numerically. In addition, we derive accurate analytical asymptotic expressions for the large strain tail, which demonstrate that it is dominated by the nearest source. As an application, we calculate the distribution of strain fluctuations for the astrophysical GW background produced by binary mergers of compact stars in the Universe, and the distribution of the observed confusion background obtained upon subtracting bright, resolved sources from the signal. We quantify the extent to which they deviate from a Gaussian distribution. Our approach could be useful for the spectral shape reconstruction of stochastic GW backgrounds.

Subtracting compact binary foreground sources to reveal primordial gravitational-wave backgrounds

Detection of primordial gravitational-wave backgrounds generated during the early universe phase transitions is a key science goal for future ground-based detectors. The rate of compact binary mergers is so large that their cosmological population produces a confusion background that could masquerade the detection of potential primordial stochastic backgrounds. In this paper we study the ability of current and future detectors to resolve the confusion background to reveal interesting primordial backgrounds. The current detector network of LIGO and Virgo and the upcoming KAGRA and LIGO-India will not be able to resolve the cosmological compact binary source population and its sensitivity to stochastic background will be limited by the confusion background of these sources. We find that a network of three (and five) third generation (3G) detectors of Cosmic Explorer and Einstein Telescope will resolve the confusion background produced by binary black holes leaving only about 0.013\% (respectively, 0.00075\%) unresolved; in contrast, as many as 25\% (respectively, 7.7\%) of binary neutron star sources remain unresolved. Consequently, the binary black hole population will likely not limit observation of primordial backgrounds but the binary neutron star population will limit the sensitivity of 3G detectors to $\Omega_{\rm GW} \sim 10^{-11}$ at 10 Hz (respectively, $\Omega_{\rm GW} \sim 3\times 10^{-12}$).

Joint search for isolated sources and an unresolved confusion background in pulsar timing array data

Supermassive black hole binaries are the most promising source of gravitational-waves in the frequency band accessible to pulsar timing arrays. Most of these binaries will be too distant to detect individually, but together they will form an approximately stochastic background that can be detected by measuring the correlation pattern induced between pairs of pulsars. A small number of nearby and especially massive systems may stand out from this background and be detected individually. Analyses have previously been developed to search for stochastic signals and isolated signals separately. Here we present BayesHopper, an algorithm capable of jointly searching for both signal components simultaneously using trans-dimensional Bayesian inference. Our implementation uses the reversible jump Markov chain Monte Carlo method for sampling the relevant parameter space with changing dimensionality. We have tested BayesHopper on various simulated datasets. We find that it gives results consistent with fixed-dimensional methods when tested on data with a stochastic background or data with a single binary. For the full problem of analyzing a dataset with both a background and multiple black hole binaries, we find two kinds of interactions between the binary and background components. First, the background effectively increases the noise level, thus making individual binary signals less significant. Second, weak binary signals can be absorbed by the background model due to the natural parsimony of Bayesian inference. Because of its flexible model structure, we anticipate that BayesHopper will outperform existing approaches when applied to realistic data sets produced from population synthesis models.

Multiple-component Decomposition from Millimeter Single-channel Data

Abstract We present an implementation of a blind source separation algorithm to remove foregrounds off millimeter surveys made by single-channel instruments. In order to make possible such a decomposition over single-wavelength data, we generate levels of artificial redundancy, then perform a blind decomposition, calibrate the resulting maps, and lastly measure physical information. We simulate the reduction pipeline using mock data: atmospheric fluctuations, extended astrophysical foregrounds, and point-like sources, but we apply the same methodology to the Aztronomical Thermal Emission Camera/ASTE survey of the Great Observatories Origins Deep Survey–South (GOODS-S). In both applications, our technique robustly decomposes redundant maps into their underlying components, reducing flux bias, improving signal-to-noise ratio, and minimizing information loss. In particular, GOODS-S is decomposed into four independent physical components: one of them is the already-known map of point sources, two are atmospheric and systematic foregrounds, and the fourth component is an extended emission that can be interpreted as the confusion background of faint sources.

Digging Deeper: Observing Primordial Gravitational Waves below the Binary-Black-Hole-Produced Stochastic Background.

The merger rate of black hole binaries inferred from the detections in the first Advanced LIGO science run implies that a stochastic background produced by a cosmological population of mergers will likely mask the primordial gravitational wave background. Here we demonstrate that the next generation of ground-based detectors, such as the Einstein Telescope and Cosmic Explorer, will be able to observe binary black hole mergers throughout the Universe with sufficient efficiency that the confusion background can potentially be subtracted to observe the primordial background at the level of Ω_{GW}≃10^{-13} after 5years of observation.

LIGO and the opening of a unique observational window on the universe

A unique window on the universe opened on September 14, 2015, with direct detection of gravitational waves by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors. This event culminated a half-century effort around the globe to develop terrestrial detectors of adequate sensitivity to achieve this goal. It also happened appropriately only a few months before the centennial of Einstein’s final paper introducing the general theory of relativity. This detection provided the surprising discovery of a coalescing pair of “heavy” black holes (more massive than ≃25 M๏) leading to the formation of a spinning ≃62 solar mass black hole. One more binary black-hole detection and a significant candidate event demonstrated that a population of such merging binaries is formed in nature with a broad mass spectrum. This unique observational sample has already provided concrete measurements on the coalescence rates and has allowed us to test the theory of general relativity in the strong-field regime. As this nascent field of gravitational-wave astrophysics is emerging we are looking forward to the detection of binary mergers involving neutron stars and their electromagnetic counterparts, as well as continuous-wave sources, supernovae, a stochastic confusion background of compact-object mergers, known sources detected in unexpected ways, and completely unknown sources.

When is a gravitational-wave signal stochastic?

We discuss the detection of gravitational-wave backgrounds in the context of Bayesian inference and suggest a practical definition of what it means for a signal to be considered stochastic---namely, that the Bayesian evidence favors a stochastic signal model over a deterministic signal model. A signal can further be classified as Gaussian-stochastic if a Gaussian signal model is favored. In our analysis we use Bayesian model selection to choose between several signal and noise models for simulated data consisting of uncorrelated Gaussian detector noise plus a superposition of sinusoidal signals from an astrophysical population of gravitational-wave sources. For simplicity, we consider co-located and co-aligned detectors with white detector noise, but the method can be extended to more realistic detector configurations and power spectra. The general trend we observe is that a deterministic model is favored for small source numbers, a non-Gaussian stochastic model is preferred for intermediate source numbers, and a Gaussian stochastic model is preferred for large source numbers. However, there is very large variation between individual signal realizations, leading to fuzzy boundaries between the three regimes. We find that a hybrid, trans-dimensional model comprised of a deterministic signal model for individual bright sources and a Gaussian-stochastic signal model for the remaining confusion background outperforms all other models in most instances.

Inclusion of carers when confused relatives are admitted to hospital.

It is well recognised that many older people have dementia but have never been investigated or received a formal diagnosis. If they are admitted to acute hospitals from their own homes or long-term care settings with confusion and little background information about their usual condition, it can be challenging for staff to determine if they have dementia, delirium, delirium superimposed on pre-existing dementia or confusion with a reversible cause such as vitamin deficiency. A careful history and information seeking from carers or family members about their loved one's pre-admission baseline can inform nursing and medical assessments and help nurses to provide high quality care.

Placebo treatments, informed consent and ‘the grip of a false picture’

It is widely supposed that the prescription of placebo treatments to patients for therapeutic purposes is ethically problematic on the grounds that the patient cannot give informed consent to the...

Noirse-Made-Earsy:

It has been said that “anybody who takes ‘Finnegans Wake’ as an ur-text will probably have a low signal to noise ratio.”1 Doubtless any meaningful signal that the reader of the Wake receives must be separated from a much larger background of confusion and dissonance. Another way of looking at it, however, is that noise is inseparable from the process of sense making. In this study I use such theoreticians of noise as Jacques Attali, Michel Serres, and Avital Ronell to show how noise in the Wake does not merely destroy, distort, or obscure meaningful patterns and structures but collaborates in their creation. The article is divided into three sections. First, I take two test cases from Ulysses and the Wake respectively, to show how noise is coded into meaning by both the waking and dreaming mind. Second, I examine the political dimensions of the imposition of meaning on noise and the subversions of meaning by noise in terms of the battle between generations (father against sons) and within generations (brother against brother). Finally, I place these themes in the context of the postmodernist

Mock data challenge for the Einstein Gravitational-Wave Telescope

Einstein Telescope (ET) is conceived to be a third generation gravitational-wave observatory. Its amplitude sensitivity would be a factor ten better than advanced LIGO and Virgo and it could also extend the low-frequency sensitivity down to 1--3 Hz, compared to the 10--20 Hz of advanced detectors. Such an observatory will have the potential to observe a variety of different GW sources, including compact binary systems at cosmological distances. ET's expected reach for binary neutron star (BNS) coalescences is out to redshift $z\simeq 2$ and the rate of detectable BNS coalescences could be as high as one every few tens or hundreds of seconds, each lasting up to several days. %in the sensitive frequency band of ET. With such a signal-rich environment, a key question in data analysis is whether overlapping signals can be discriminated. In this paper we simulate the GW signals from a cosmological population of BNS and ask the following questions: Does this population create a confusion background that limits ET's ability to detect foreground sources? How efficient are current algorithms in discriminating overlapping BNS signals? Is it possible to discern the presence of a population of signals in the data by cross-correlating data from different detectors in the ET observatory? We find that algorithms currently used to analyze LIGO and Virgo data are already powerful enough to detect the sources expected in ET, but new algorithms are required to fully exploit ET data.

Weak lensing effects in the measurement of the dark energy equation of state with LISA

The Laser Interferometer Space Antenna's (LISA's) observation of supermassive binary black holes (SMBBH) could provide a new tool for precision cosmography. Inclusion of subdominant signal harmonics in the inspiral signal allows for high-accuracy sky localization, dramatically improving the chances of finding the host galaxy and obtaining its redshift. A SMBBH merger can potentially have component masses from a wide range (${10}^{5}--{10}^{8}{M}_{\ensuremath{\bigodot}}$) over which parameter accuracies vary considerably. We perform an in-depth study in order to understand (i) what fraction of possible SMBBH mergers allow for sky localization, depending on the parameters of the source, and (ii) how accurately $w$ can be measured when the host galaxy can be identified. We also investigate how accuracies on all parameters improve when a knowledge of the sky position can be folded into the estimation of errors. We find that $w$ can be measured to within a few percent in most cases, if the only error in measuring the luminosity distance is due to LISA's instrumental noise and the confusion background from Galactic binaries. However, weak lensing-induced errors will severely degrade the accuracy with which $w$ can be obtained, emphasizing that methods to mitigate weak lensing effects would be required to take advantage of LISA's full potential.

Confusion background from compact binaries

Double neutron stars are one of the most promizing sources for terrestrial gravitational wave interferometers. For actual interferometers and their planned upgrades, the probability of having a signal present in the data is small, but as the sensitivity improves, the detection rate increases and the waveforms may start to overlap, creating a confusion background, ultimately limiting the capabilities of future detectors. The third generation Einstein Telescope, with an horizon of z > 1 and very low frequency "seismic wall" may be affected by such confusion noise. At a minimum, careful data analysis will be require to separate signals which will appear confused. This result should be borne in mind when designing highly advanced future instruments.

Gravitational wave backgrounds and the cosmic transition from Population III to Population II stars

Using the results of a numerical simulation which follows the evolution, metal enrichment and energy deposition of both Population III and Population II stars, we predict the redshift dependence of the formation rate of black hole remnants of Population III stars with masses 100- 500Msun and of neutron stars(black holes) remnants of Population II stars with masses 8-20Msun (20-40Msun). We describe the gravitational wave spectrum produced by Population III and Population II sources adopting the most appropriate signals available in the literature and we compute the stochastic backgrounds resulting from the cumulative emission of these sources throughout the history of the Universe. With the aim of assessing whether these backgrounds might act as foregrounds for signals generated in the Inflationary epoch, we compare their amplitudes with the sensitivity of currently planned and future ground/space-based interferometers.

Gravitational-wave confusion background from cosmological compact binaries: Implications for future terrestrial detectors

Increasing the sensitivity of a gravitational-wave (GW) detector improves our ability to measure the characteristics of detected sources. It also increases the number of weak signals that contribute to the data. Because GW detectors have nearly all-sky sensitivity, they can be subject to a confusion limit: Many sources which cannot be distinguished may be measured simultaneously, defining a stochastic noise floor to the sensitivity. For GW detectors operating at present and for their planned upgrades, the projected event rate is sufficiently low that we are far from the confusion-limited regime. However, some detectors currently under discussion may have large enough reach to binary inspiral that they enter the confusion-limited regime. In this paper, we examine the binary inspiral confusion limit for terrestrial detectors. We consider a broad range of inspiral rates in the literature, several planned advanced gravitational-wave detectors, and the highly advanced 'Einstein telescope' design. Though most advanced detectors will not be impacted by this limit, the Einstein telescope with a very low-frequency 'seismic wall' may be subject to confusion noise. At a minimum, careful data analysis will be require to separate signals which will appear confused. This result should be borne in mind when designing highly advanced futuremore » instruments.« less

La nueva filosofía de la naturaleza del hombre de Oliva Sabuco

In an open-minded discussion, free of commitments to one discipline or another, I try to tackle, explore and unfold the concept of ?sense?, without reducing it to mere ?linguistic enunciation? or ?semantic meaning?. I will argue that ?sense? comes into view only when posed against the background of confusion, disorientation or ambiguity. As well as describing its orienting function, its dialogic character and its relationship to "being", I will contend that ?sense? is both an act of opening, and of positioning with regard to the world and the real. If my argument is right, then ?sense? does not aim to limit an object (i.e., defining it); rather, it must try to reach beyond its horizons. ?Sense?, then, reveals itself as a search for intelligibility in action - in other words, as critical thought.