Probing Ensemble Properties of Vortex-avalanche Pulsar Glitches with a Stochastic Gravitational-Wave Background Search

A stochastic gravitational-wave background (SGWB) is expected to be produced by the superposition of individually undetectable, unresolved gravitational-wave (GW) signals from cosmological and astrophysical sources. Such a signal can be searched with dedicated techniques using the data acquired by a network of ground-based GW detectors. In this work, we consider the astrophysical SGWB resulting from pulsar glitches, which are sudden increases in the rotational pulsar frequency, within our Galaxy. More specifically, we assume glitches to be associated with quantized, superfluid, vortex-avalanches in the pulsars, and we model the SGWB from the superposition of GW bursts emitted during the glitching phase. We perform a cross-correlation search for this SGWB-like signal employing the data from the first three observation runs of Advanced LIGO and Virgo. Not having found any evidence for a SGWB signal, we set upper limits on the dimensionless energy density parameter $\Omega_{\mathrm{gw}}(f)$ for two different power-law SGWBs, corresponding to two different glitch regimes. We obtain $\Omega_{\mathrm{gw}}(f)\leq 7.5 \times 10^{-10}$ at 25 Hz for a spectral index 5/2, and $\Omega_{\mathrm{gw}}(f)\leq 5.7 \times 10^{-17}$ at 25 Hz for a spectral index 17/2. We then use these results to set constraints on the average glitch duration and the average radial motion of the vortices during the glitches for the population of the glitching Galactic pulsars, as a function of the Galactic glitch rate.Comment: 16 pages, 3 figures, 1 tabl

Follow-up procedure for gravitational wave searches from isolated neutron stars using the time-domain F\mathcal{F}-statistic method

International audienceAmong promising sources of gravitational waves are long-lived nearly periodic signals produced by rotating, asymmetric neutron stars. Depending on the astrophysical scenario, the sources of asymmetry may have thermal, viscous, elastic and/or magnetic origin. In this work we introduce a follow-up procedure for an all-sky search for gravitational wave signals from rotating neutron stars. The procedure denoted as Followup implements matched-filtering -statistic method. We describe data analysis methods and algorithms used in the procedure. We present tests of the Followup for artificial signals added to white, Gaussian noise. The tests show a good agreement with the theoretical predictions. The Followup will become part of the Time-Domain -statistic pipeline that is routinely used for all-sky searches of LIGO and Virgo detector data

Advanced Virgo Status

The detection of a gravitational wave signal in September 2015 by LIGO interferometers, announced jointly by LIGO collaboration and Virgo collaboration in February 2016, opened a new era in Astrophysics and brought to the whole community a new way to look at - or "listen" to - the Universe. In this regard, the next big step was the joint observation with at least three detectors at the same time. This configuration provides a twofold benefit: it increases the signal-to-noise ratio of the events by means of triple coincidence and allows a narrower pinpointing of GW sources, and, in turn, the search for Electromagnetic counterparts to GW signals. Advanced Virgo (AdV) is the second generation of the gravitational-wave detector run by the Virgo collaboration. After a shut-down lasted 5 years for the upgrade, AdV has being commissioned to get back online and join the two advance LIGO (aLIGO) interferometers to realize the aforementioned scenario. We will describe the challenges and the status of the commissioning of AdV, and its current performances and perspectives. A few lines wil be also devoted to describe the latest achievements, occurred after the TAUP 2017 conference

Measuring neutron-star distances and properties with gravitational-wave parallax

Gravitational-wave astronomy allows us to study objects and events invisible to electromagnetic waves. So far, only signals triggered by coalescing binaries have been detected. However, as the interferometers' sensitivities improve over time, we expect to observe weaker signals in the future, e.g. emission of continuous gravitational waves from spinning, isolated neutron stars. Parallax is a well-known method, widely used in electromagnetic astronomical observations, to estimate the distance to a source. In this work, we consider the application of the parallax method to gravitational-wave searches and explore possible distance estimation errors. We show that detection of parallax in the signal from a spinning down source can constrain the neutron star moment of inertia. For instance, we found that the relative error of the moment of inertia estimation is smaller than $10\%$ for all sources closer than 300 pc, for the assumed birth frequency of 700 Hz, ellipticity $\geq 10^{-7}$ and for two years of observations by the Einstein Telescope, assuming spin down due purely to quadrupolar gravitational radiation

Impact of the COVID-19 Pandemic on Atopic Dermatitis Patients

Atopic dermatitis (AD) can have a significantly negative impact on quality of life (QoL). The impact of coronavirus disease 2019 (COVID-19) on the AD population is not yet well established. The study comprised 195 patients with diagnosed AD who were asked about their cognitive and preventive behaviors regarding COVID-19 and the accessibility of medical support, including online consultations. Moreover, the patients responded to the self-reported Dermatology Life Quality Index (DLQI) and Hospital Anxiety and Depression Scale (HADS). Most of the patients were worried about being infected with COVID-19. Most of the patients believed that people suffering from skin disease were more prone to be infected with COVID-19 compared with the general population. Most the patients negatively assessed the availability of dermatological treatment during the pandemic. Furthermore, 66.1% of the patients declared using telemedicine. Nearly 50% of patients were discontented with telemedicine, and 1/3 of the patients did not mind the use of telemedicine. AD during the COVID-19 pandemic was associated with a lower overall health rating and life satisfaction and impaired QoL related to mental health in a Polish population. These results provide original information that can be applied in dermatologic patient screenings to evaluate the state of depression and anxiety during the epidemic period

Detectability of continuous gravitational waves from isolated neutron stars in the Milky Way

Aims. We estimate the number of pulsars, detectable as continuous gravitational wave sources with the current and future gravitational-wave detectors, assuming a simple phenomenological model of evolving non-axisymmetry of the rotating neutron star. Methods. We employed a numerical model of the Galactic neutron star population, with the properties established by comparison with radio observations of isolated Galactic pulsars. We generated an arbitrarily large synthetic population of neutron stars and evolved their period, magnetic field, and position in space. We used a gravitational wave emission model based on exponentially decaying ellipticity (i.e. non-axisymmetry of the star) with no assumption of the origin of a given ellipticity. We calculated the expected signal in a given detector for a one-year observation, and assumed a detection criterion of the signal-to-noise ratio of 11.4, comparable to a targeted continous wave search. We analysed the detectable population separately in each detector: Advanced LIGO, Advanced Virgo, and the planned Einstein Telescope. In the calculation of the expected signal we neglect the frequency change of the signals due to the source’s spindown and the Earth’s motion with respect to the solar barycentre. Results. With conservative values for the neutron star evolution (a supernova rate of once per 100 years, initial ellipticity ϵ0 ≃ 10−5 with no decay of the ellipticity η = thub ≃ 104 Myr), the expected number of detected neutron stars is 0.15 (based on a simulation of 10 M stars) for the Advanced LIGO detector. A broader study of the parameter space (ϵ0, η) is presented. With the planned sensitivity for the Einstein Telescope, and assuming the same ellipiticity model, the expected detection number is 26.4 pulsars during a one-year observing run

Gravitational-wave searches in the era of Advanced LIGO and Virgo

The field of gravitational-wave astronomy has been opened up by gravitational-wave observations made with interferometric detectors. This review surveys the current state-of-the-art in gravitational-wave detectors and data analysis methods currently used by the Laser Interferometer Gravitational-Wave Observatory in the United States and the Virgo Observatory in Italy. These analysis methods will also be used in the recently completed KAGRA Observatory in Japan. Data analysis algorithms are developed to target one of four classes of gravitational waves. Short duration, transient sources include compact binary coalescences, and burst sources originating from poorly modelled or unanticipated sources. Long duration sources include sources which emit continuous signals of consistent frequency, and many unresolved sources forming a stochastic background. A description of potential sources and the search for gravitational waves from each of these classes are detailed