Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

On the progenitor of binary neutron star merger GW170817

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr

Constraints on cosmic strings using data from the first Advanced LIGO observing run

Cosmic strings are topological defects which can be formed in grand unified theory scale phase transitions in the early universe. They are also predicted to form in the context of string theory. The main mechanism for a network of Nambu-Goto cosmic strings to lose energy is through the production of loops and the subsequent emission of gravitational waves, thus offering an experimental signature for the existence of cosmic strings. Here we report on the analysis conducted to specifically search for gravitational-wave bursts from cosmic string loops in the data of Advanced LIGO 2015-2016 observing run (O1). No evidence of such signals was found in the data, and as a result we set upper limits on the cosmic string parameters for three recent loop distribution models. In this paper, we initially derive constraints on the string tension Gμ and the intercommutation probability, using not only the burst analysis performed on the O1 data set but also results from the previously published LIGO stochastic O1 analysis, pulsar timing arrays, cosmic microwave background and big-bang nucleosynthesis experiments. We show that these data sets are complementary in that they probe gravitational waves produced by cosmic string loops during very different epochs. Finally, we show that the data sets exclude large parts of the parameter space of the three loop distribution models we consider

Are food intolerances and allergies increasing in immigrant children coming from developing countries? (I.F. 2.849)

There are not available data concerning the occurrence, the clinical features and the environmental risk factors for food intolerances and allergies in immigrant children. The aim of the study was to evaluate rates, distribution, clinical features and environmental risk factors for food intolerances and allergies in immigrant children. Hospital records of 4130 patients with celiac disease (CD), cow milk protein intolerance (CMPI) and food allergies (FA) diagnosed in 24 Italian Centres from 1999 to 2001 were retrospectively reviewed, comparing immigrant patients with Italian ones. 78/4130 (1.9%) patients were immigrant: 36/ 1917 (1.9%) had CD, 24/1370 (1.75%) CMPI and 18/843 (2.1%) FA. They were evenly distributed across Italy and their native areas were: East Europe (23/78), Northern Africa (23/78), Southern Asia (14/78), Saharan and Sub-Saharan Africa (9/78), Southern America (4/78), Far East (3/7), Middle East (2/78). Despite differences in their origin, the clinical features of immigrant children were similar to the ones of Italian patients and among each ethnic group. The majority of them were born in Italy (57/78) or have been residing in Italy since several years (19/78). All of them had lost dietary habits of the native countries and had acquired those of the Italian childhood population. Food intolerances and allergies are present also in children coming from developing countries, and paediatricians will need to have a full awareness of them because the number of immigrant children in Italy is quickly increasing. The clinical features of food intolerances and allergies appear the same in each ethnic group, despite differences in races. Sharing of dietary habits with the Italian childhood population seems to be an important environmental risk factor

Prevalence and distribution of Inflammatory Bowel Diseases in a group of immigrant children. Is Inflammatory Bowel Diseases incidence increasing also in children coming from developing countries?

Aims. To evaluate rate and number of immigrant children affected by Inflammatory Bowel Diseases; to investigate their family conditions and compliance to therapy; to establish the interval between their arrival in Italy, the onset of the clinical features and time until diagnosis. Patients and Methods. Four immigrant children from a cohort of 134 patients participating in a three-year survey on Inflammatory Bowel Diseases, referred to 21 Italian centres. Their family history was investigated, including the reasons for coming to Italy and their countries of origin. Results. The 4 children studied represented about 3% of the whole patient population (134) with Inflammatory Bowel Diseases. Time until diagnosis in the 3 cases with Crohn's disease ranged from 12 to 18 months, whereas the one patient with Ulcerative Colitis was diagnosed immediately. Therapeutic compliance was satisfactory. Discussion. Although Inflammatory Bowel Diseases is not believed to occur in developing countries, it is found also in immigrants from those areas, and the exceptional presentation in these ethnic groups could be related to a different environmental impact rather than a different genetic susceptibility