arXiv subjects

Gianluca Pagliaro

Publications and source records attributed to Gianluca Pagliaro.

3 recordsLinked to original sources

arXiv2026

Sco X-1 as a continuous gravitational waves source: modelling the secular evolution using MESA

We study the prospects for detecting continuous gravitational waves (GWs) from Sco X-1 and evaluate the most likely waveform and progenitor parameters. We model the spin of the neutron star by the accretion torque and the gravitational-wave torque, considering two mechanisms for generating the non-axisymmetry responsible for the latter: magnetic mountains and crustal breakage deformation. Both torques are intertwined with the binary evolution, which we trace from the formation of the NS in a binary system with a main-sequence companion. We do this with MESA, starting from a set of initial binary configurations. At current sensitivity, a magnetic ellipticity of $\varepsilon\gtrsim 10^{-6}$ is necessary for detection. The highest frequency at which we have detectable signals increases with the accretion efficiency $η$, and it can be as high as 360Hz. At 3G (Cosmic Explorer/Einstein telescope) sensitivity, less deformed Sco X-1 NSs, with ellipticities as small as $6\cdot 10^{-9}$, are detectable, but the waveform highly depends on the binary system: the highest frequency of detectable signals spans the very broad range 600-1700Hz, strongly depending on $η$ and mass of the progenitor donor star $M^d$. If $η\leq$30%, the crust does not break. For $η\in$[40%,60%] only progenitors with $M^d\geq[1.1,1.5]M_{\odot}$ present crustal breakage, while if $η\geq$70% all crusts break. In some systems, the crust breaks during their Sco X-1 phase. If Sco X-1 were one of those systems, it would be emitting a very loud GW signal sweeping from O(1000)Hz down to torque-balance frequencies in $\approx 150000[\varepsilon /10^{-5}]^{-2/5}$ years. We estimate the current detection probability for this signal to be under 1%; this probability increases substantially - to around 41% - with 3G detectors.

astro-ph.HE↗

arXiv2026

Continuous gravitational waves from Galactic neutron stars: demography, detectability and prospects

We study the prospects for detection of continuous gravitational signals from "normal" Galactic neutron stars, i.e. non-recycled ones. We use a synthetic population generated by evolving stellar remnants in time, according to several models. We consider the most recent constraints set by all-sky searches for continuous gravitational waves and use them for our detectability criteria. We discuss detection prospects for the current and the next generation of gravitational wave detectors. We find that neutron stars whose ellipticity is solely caused by magnetic deformations cannot produce any detectable signal, not even by 3rd-generation detectors. Currently detectable sources all have $B\lesssim10^{12}$ G and deformations not solely due to the magnetic field. For these in fact we find that the larger the magnetic field is, the larger is the ellipticity required for the signal to be detectable and this ellipticity is well above the value induced by the magnetic field. Third-generation detectors as the Einstein Telescope and Cosmic Explorer will be able to detect up to $\approx 250$ more sources than current detectors. We briefly treat the case of recycled neutron stars, with a simplified model. We find that continuous gravitational waves from these objects will likely remain elusive to detection by current detectors but should be detectable with the next generation of detectors.

gr-qc↗

arXiv2025

Searching for continuous gravitational waves from slowly spinning neutron stars with DECIGO, Big Bang Observer, Einstein Telescope and Cosmic Explorer

We consider stably rotating highly magnetised neutron stars and glitching pulsars. We discuss the prospects for detecting continuous gravitational waves from these sources below 20 Hz with next-generation ground-based facilities such as the Einstein Telescope and Cosmic Explorer and space-based observatories such as DECIGO and Big Bang Observer. We demonstrate that these constitute interesting science targets. We use a robust sensitivity estimation method for future searches based on demonstrated performance. We show that the spin-down upper limit on the gravitational wave amplitude of all highly magnetised pulsars and magnetars suitable for a years-long fully coherent search, exceeds the smallest gravitational wave amplitude estimated detectable with DECIGO and Big Bang Observer. We find that the hidden magnetar candidate PSR J1852+0040 can be detected by Cosmic Explorer if it is emitting at least at 20% of its spin-down luminosity. Finally, post-glitch transient continuous gravitational waves from magnetars are an interesting target for deci-Hz detectors, with all but one of the recorded glitches giving rise to a spin-down limit signal above the smallest detectable level.

astro-ph.HE↗