arXiv subjects

Rosario De Rosa

Publications and source records attributed to Rosario De Rosa.

At least 19 recordsLinked to original sources

arXiv2026

The impact of seasonality over the sensitivity of Einstein Telescope and the SNR of CBC signals at the Sardinia candidate site

This work presents the first investigation of the impact of seasonal variations in seismic noise on the low-frequency performance of the Einstein Telescope (ET) at the Sardinia candidate site, focusing on their effect on compact binary coalescence signals. Using seismic data collected between 2022 and 2025 from a deep borehole, we characterize the seasonal variability of the seismic noise and identify the months of July and December as representative best- and worst-case conditions. The measured seismic spectra are used to estimate the Newtonian noise contribution in the 2--10 Hz frequency range and to derive corresponding modifications to the ET design sensitivity. These sensitivity curves are then used in simulations of binary neutron star and intermediate-mass black hole signals in the triangular ET configuration to quantify the resulting changes in signal-to-noise ratio. We find that median seasonal conditions produce only minor changes in the expected SNR, with deviations from the design case typically below 2$\%$. Larger effects are found for the upper tail of the December noise distribution, where the average SNR loss reaches approximately 20--25$\%$. These results indicate that seasonal seismic variability at the Sardinia candidate site has a limited impact on the low-frequency performance of ET under typical conditions.

gr-qc↗

arXiv2026

Alternative neural-network follow-up for all-sky FrequencyHough in continuous gravitational-wave searches

Continuous gravitational waves are long-lived signals emitted by spinning neutron stars (NSs) or boson clouds around black holes. While the Milky Way is expected to host $\mathrm{O}(10^{8}-10^{9})$ NSs, only $\mathrm{O}(10^{3})$ are currently identified through electromagnetic observations. This large observational gap motivates searches based on alternative messengers. In particular, all-sky searches for continuous gravitational waves (GWs) offer a unique opportunity to detect NSs that are electromagnetically silent or otherwise undiscovered. By exploring a broad region of parameter space without any a priori source information, these searches can probe the vast hidden NS population of our Galaxy. In this work, we present a novel way to include a Neural Network (NN) classifier into an all-sky search strategy for isolated NSs. Starting from candidates produced by the FrequencyHough pipeline running on data from ground-based detectors such as LIGO and Virgo, the proposed method improves sensitivity without increasing computational cost and can be parallelized across multiple detectors to enhance detection probability and reduce false alarms. We analyze data from the third observing run (O3) --- April 1, 2019 to March 27, 2020 --- and focus on the frequency range [129, 229] Hz and spin-down interval [$-2.5\cdot10^{-9}, 1.0\cdot10^{-9}$] Hz/s. The model is trained on noise constructed to be statistically consistent with real O3 data and tested on real O3 data. Results show robust performance in distinguishing signal from noise, even at low strain, and successful identification of hardware injections outside the training spin-down range.

gr-qc↗

arXiv2026

Mechanical Long Baseline Differential Gradiometers as Low Frequency Gravitational Wave Detectors

We present a new differential mechanical gradiometer for the detection of low-frequency Gravitational Waves. The frequency range is 0.05 to 1 Hz, a frequency gap not covered either by future space-based detectors such as LISA or by ground-based observatories such as Einstein Telescope or Cosmic Explorer. The proposed detection principle is similar to antennas based on torsion pendulums but solves the problem of physical confinement of these antennas by operating vertically and by having a counterweight at one end of each bar and a mass suspended from a long wire at the other. With this configuration, we enlarge the gravitational force acting on the system \textit{without} changing the moment of inertia of the system, so that we move from a signal $Δθ$ of the order of $Δθ= h$, where h is the amplitude of the gravitational wave, to a signal of the order $Δθ= h\frac{L}{D}$, where D is the length of the arm and L is the length of the wire suspending the test mass. This configuration is a further evolution of the recent development of tiltmeters and balances with double suspended arms and interferometric read-out, where the main working principles are already tested. The expected sensitivity will be discussed with respect to the proposed parameters and the present technology.

gr-qc↗

arXiv2025

Investigating all-sky Frequency Hough performances for neutron stars

Between the estimated population of Neutron Stars (NSs) and the actual number present in the catalogs, there is a huge gap: O(10$^{8-9}$) vs O(10$^3$). Among the different search techniques for Continuous gravitational waves (CWs), the all-sky could help to reduce the discrepancy. We focus on the all-sky CW pipeline Frequency Hough (FH), which operates without prior knowledge of the source parameters ($f,\dot{f}, λ, β$). Here, we present a Machine Learning strategy, diverging from the standard follow-up(FU) of the FH pipeline. We study the performance with real interferometer data, until reaching $h$ value subthreshold for the standard FU procedure ($CR_{thr}=5$), with encouraging classification results.

gr-qc↗

arXiv2025

The impact of local noise recorded at the ET candidate sites on the signal to noise ratio of CBC gravitational wave signals for the ET triangle configuration

We present an evaluation of how site dependent noise can affect the signal to noise ratio (SNR) of compact binary coalescence (CBC) signals in the future 3rd generation gravitational wave (GW) detector Einstein Telescope (ET). The design of ET is currently pushing the scientific community to study its scientific potential with respect to known, and possibly unexpected, GW signals using its design sensitivity curves. However, local ambient noise may have an impact on the ET sensitivity at low frequency and therefore affect the SNR of CBC signals at low frequency. Therefore, we study the impact of ambient noise on the ET sensitivity curve at the two sites candidate to host ET - Sardinia, in Italy, and the Euregio Meuse-Rhine (EMR) at the Netherlands-Belgium border - and infer the impact on the ET sensitivity curve and how the SNR of CBC signals at low frequencies is affected. We find that Sardinia shows results which are on par, if not better, than the design case. On the other hand, ambient noise for the current EMR sensitivity curve in Terziet causes a higher degradation of the SNR performances.

gr-qc↗

arXiv2024

Adaptive algorithms for low-latency cancellation of seismic Newtonian-noise at the Virgo gravitational-wave detector

A system was recently implemented in the Virgo detector to cancel noise in its data produced by seismic waves directly coupling with the suspended test masses through gravitational interaction. The data from seismometers are being filtered to produce a coherent estimate of the associated gravitational noise also known as Newtonian noise. The first implementation of the system uses a time-invariant (static) Wiener filter, which is the optimal filter for Newtonian-noise cancellation assuming that the noise is stationary. However, time variations in the form of transients and slow changes in correlations between sensors are possible and while time-variant filters are expected to cope with these variations better than a static Wiener filter, the question is what the limitations are of time-variant noise cancellation. In this study, we present a framework to study the performance limitations of time-variant noise cancellation filters and carry out a proof-of-concept with adaptive filters on seismic data at the Virgo site. We demonstrate that the adaptive filters, at least those with superior architecture, indeed significantly outperform the static Wiener filter with the residual noise remaining above the statistical error bound.

gr-qc↗

arXiv2024

Correlated 0.01Hz-40Hz seismic and Newtonian noise and its impact on future gravitational-wave detectors

We report correlations in underground seismic measurements with horizontal separations of several hundreds of meters to a few kilometers in the frequency range 0.01Hz to 40Hz. These seismic correlations could threaten science goals of planned interferometric gravitational-wave detectors such as the Einstein Telescope as well as atom interferometers such as MIGA and ELGAR. We use seismic measurements from four different sites, i.e. the former Homestake mine (USA) as well as two candidate sites for the Einstein Telescope, Sos Enattos (IT) and Euregio Maas-Rhein (NL-BE-DE) and the site housing the MIGA detector, LSBB (FR). At all sites, we observe significant coherence for at least 50% of the time in the majority of the frequency region of interest. Based on the observed correlations in the seismic fields, we predict levels of correlated Newtonian noise from body waves. We project the effect of correlated Newtonian noise from body waves on the capabilities of the triangular design of the Einstein Telescope's to observe an isotropic gravitational-wave background (GWB) and find that, even in case of the most quiet site, its sensitivity will be affected up to $\sim$20Hz. The resolvable amplitude of a GWB signal with a negatively sloped power-law behaviour would be reduced by several orders of magnitude. However, the resolvability of a power-law signal with a slope of e.g. $α=0$ ($α=2/3$) would be more moderately affected by a factor $\sim$ 6-9 ($\sim$3-4) in case of a low noise environment. Furthermore, we bolster confidence in our results by showing that transient noise features have a limited impact on the presented results.

gr-qc↗

arXiv2023

Doppler orbital correction for the targeted search of known pulsars with the 5-vector method

Pulsars are promising targets for the first detection of continuous gravitational waves (CWs) by the LIGO-Virgo-KAGRA (LVK) Collaboration. Targeted searches leverage critical information derived from continued monitoring of pulsars related to the spin evolution, astrometry, and binary orbit. This information maximizes the probability to detect CW signals using full coherent methods. The 5-vector method is one of the three pipelines used by the LVK Collaboration for the targeted search of CWs from known pulsars. In this letter, we describe the first implementation and test of an heterodyne method to correct the orbital Doppler effect for pulsars in binary systems for the 5-vector targeted search.

gr-qc↗

arXiv2023

A weighted multidetector extension to the 5-vector method for the search of continuous gravitational wave signals

The 5-vector method is one of the main pipeline used by the LIGO-Virgo-KAGRA Collaboration for the analysis of continuous gravitational waves (CWs). This method is a matched filter in the frequency domain based on the splitting in five frequencies of the expected gravitational wave frequency due to the Earth sidereal motion. The data 5-vector is composed by five components, each defined as the Fourier transform of the data at one of the five frequencies where the signal power is split. When dealing with a scenario involving $n$ detectors, the standard multidetector extension combines the data 5-vector from each detector, resulting in a total of $5n$ components. In this letter, we introduce a novel multidetector extension that goes beyond the standard approach. It takes into consideration the varying noise levels and observation times associated with each detector, offering a more sophisticated and effective approach for CWs analysis.

gr-qc↗

arXiv2023

Search for gravitational wave signals from known pulsars in LIGO-Virgo O3 data using the 5n-vector ensemble method

The 5n-vector ensemble method is a multiple test for the targeted search of continuous gravitational waves from an ensemble of known pulsars. This method can improve the detection probability combining the results from individually undetectable pulsars if few signals are near the detection threshold. In this paper, we apply the 5n-vector ensemble method to the O3 data set from the LIGO and Virgo detectors considering an ensemble of 201 known pulsars. We find no evidence for a signal from the ensemble and set a 95% credible upper limit on the mean ellipticity assuming a common exponential distribution for the pulsars' ellipticities. Using two independent hierarchical Bayesian procedures, we find upper limits of $1.2 \times 10^{-9}$ and $2.5 \times 10^{-9}$ on the mean ellipticity for the 201 analyzed pulsars.

gr-qc↗

arXiv2023

Design and implementation of a seismic Newtonian-noise cancellation system for the Virgo gravitational-wave detector

Terrestrial gravity perturbations caused by seismic fields produce the so-called Newtonian noise in gravitational-wave detectors, which is predicted to limit their sensitivity in the upcoming observing runs. In the past, this noise was seen as an infrastructural limitation, i.e., something that cannot be overcome without major investments to improve a detector's infrastructure. However, it is possible to have at least an indirect estimate of this noise by using the data from a large number of seismometers deployed around a detector's suspended test masses. The noise estimate can be subtracted from the gravitational-wave data; a process called Newtonian-noise cancellation (NNC). In this article, we present the design and implementation of the first NNC system at the Virgo detector as part of its AdV+ upgrade. It uses data from 110 vertical geophones deployed inside the Virgo buildings in optimized array configurations. We use a separate tiltmeter channel to test the pipeline in a proof-of-principle. The system has been running with good performance over months.

gr-qc↗

arXiv2022

Quantum zero point electromagnetic energy difference between the superconducting and the normal phase in a HTc superconducting metal bulk sample

We provide a novel methodological approach to the estimate of the change of the Quantum Vacuum electromagnetic energy density in a High critical Temperature superconducting metal bulk sample, when it undergoes the transition in temperature, from the superconducting to the normal phase. The various contributions to the Casimir energy in the two phases are highlighted and compared. While the TM polarization of the vacuum mode allows for a macroscopic description of the superconducting transition, the changes in the TE vacuum mode induced by the superconductive correlations are introduced within a microscopic model, which does not explicitly take into account the anisotropic structure of the material.

cond-mat.supr-con↗

arXiv2022

External environmental noise influences on Virgo during O3

Sources of geophysical noise, such as wind, sea waves and earthquakes, can have an impact on gravitational wave interferometers causing sensitivity worsening and gaps in data taking. During the 1-year long O3 run (April 1st 2019 to March 27th 2020), the Virgo Collaboration collected a statistically significant dataset to study the response of the detector to a variety of environmental conditions. We used these data to correlate environmental parameters to global detector performance, such as observation range, duty cycle and control losses. Where possible, we identified weaknesses in the detector and we elaborated strategies to improve Virgo robustness against external disturbances for the next run O4, planned to start in summer 2022. In this article we present preliminary results of this study.

gr-qc↗

arXiv2022

A lower limit for Newtonian-noise models of the Einstein Telescope

The Einstein Telescope (ET) is a proposed third-generation gravitational-wave (GW) underground observatory. It will have greatly increased sensitivity compared to current GW detectors, and it is designed to extend the observation band down to a few Hz. At these frequencies, a major limitation of the ET sensitivity is predicted to be due to gravitational fluctuations produced by the environment, most importantly by the seismic field, which give rise to the so-called Newtonian noise (NN). Accurate models of ET NN are crucial to assess the compatibility of an ET candidate site with the ET sensitivity target also considering a possible reduction of NN by noise cancellation. With NN models becoming increasingly complex as they include details of geology and topography, it is crucial to have tools to make robust assessments of their accuracy. For this purpose, we derive a lower bound on seismic NN spectra, which is weakly dependent on geology and properties of the seismic field. As a first application, we use the lower limit to compare it with NN estimates recently calculated for the Sardinia and Euregio Meuse-Rhine (EMR) candidate sites. We find the utility of the method, which shows an inconsistency with the predictions for the EMR site, which indicates that ET NN models require further improvement.

gr-qc↗

arXiv2021

Characterization of the seismic field at Virgo and improved estimates of Newtonian-noise suppression by recesses

Fluctuations of gravitational forces cause so-called Newtonian noise (NN) in gravitational-wave (GW) detectors which is expected to limit their low-frequency sensitivity in upcoming observing runs. Seismic NN is produced by seismic waves passing near a detector's suspended test masses. It is predicted to be the strongest contribution to NN. Modeling this contribution accurately is a major challenge. Arrays of seismometers were deployed at the Virgo site to characterize the seismic field near the four test masses. In this paper, we present results of a spectral analysis of the array data from one of Virgo's end buildings to identify dominant modes of the seismic field. Some of the modes can be associated with known seismic sources. Analyzing the modes over a range of frequencies, we provide a dispersion curve of Rayleigh waves. We find that the Rayleigh speed in the NN frequency band 10 Hz - 20 Hz is very low ($\lesssim$100\,m/s), which has important consequences for Virgo's seismic NN. Using the new speed estimate, we find that the recess formed under the suspended test masses by a basement level at the end buildings leads to a 10 fold reduction of seismic NN.

astro-ph.IM↗

arXiv2019

Liquid actuated gravity experiments

We describe a new actuation technique for gravity experiments based on a liquid field mass. The Characterizing idea is to modulate the gravity force acting on a test mass by controlling the level of a liquid in a suitable container. This allows to obtain a periodical gravity force without moving parts (except the liquid level) close to the TM. We describe in detail the most relevant aspects of the liquid actuator and discuss how it can be used in gravity experiments. In particular we analyse an application to test the inverse square law in the mm to cm distance region.

physics.ins-det↗

arXiv2018

Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

Correlated magnetic noise from Schumann resonances threatens to contaminate the observation of a stochastic gravitational-wave background in interferometric detectors. In previous work, we reported on the first effort to eliminate global correlated noise from the Schumann resonances using Wiener filtering, demonstrating as much as a factor of two reduction in the coherence between magnetometers on different continents. In this work, we present results from dedicated magnetometer measurements at the Virgo and KAGRA sites, which are the first results for subtraction using data from gravitational-wave detector sites. We compare these measurements to a growing network of permanent magnetometer stations, including at the LIGO sites. We show how dedicated measurements can reduce coherence to a level consistent with uncorrelated noise. We also show the effect of mutual magnetometer attraction, arguing that magnetometers should be placed at least one meter from one another.

gr-qc↗

arXiv2016

Subtraction of correlated noise in global networks of gravitational-wave interferometers

The recent discovery of merging black holes suggests that a stochastic gravitational-wave background is within reach of the advanced detector network operating at design sensitivity. However, correlated magnetic noise from Schumann resonances threatens to contaminate observation of a stochastic background. In this paper, we report on the first effort to eliminate intercontinental correlated noise from Schumann resonances using Wiener filtering. Using magnetometers as proxies for gravitational-wave detectors, we demonstrate as much as a factor of two reduction in the coherence between magnetometers on different continents. While much work remains to be done, our results constitute a proof-of-principle and motivate follow-up studies with a dedicated array of magnetometers.

gr-qc↗