arXiv subjects

Serena Vinciguerra

Publications and source records attributed to Serena Vinciguerra.

25 records · Page 2Linked to original sources

arXiv2021

Multi-Messenger Astrophysics with THESEUS in the 2030s

Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact.

astro-ph.IM↗

arXiv2021

Wind mass-loss rates of stripped stars inferred from Cygnus X-1

Recent observations of the high-mass X-ray binary Cygnus X-1 have shown that both the companion star (41 solar masses) and the black hole (21 solar masses) are more massive than previously estimated. Furthermore, the black hole appears to be nearly maximally spinning. Here we present a possible formation channel for the Cygnus X-1 system that matches the observed system properties. In this formation channel, we find that the orbital parameters of Cygnus X-1, combined with the observed metallicity of the companion, imply a significant reduction in mass loss through winds relative to commonly used prescriptions for stripped stars.

astro-ph.SR↗

arXiv2020

Be X-ray binaries in the SMC as indicators of mass transfer efficiency

Be X-ray binaries (BeXRBs) consist of rapidly rotating Be stars with neutron star companions accreting from the circumstellar emission disk. We compare the observed population of BeXRBs in the Small Magellanic Cloud with simulated populations of BeXRB-like systems produced with the COMPAS population synthesis code. We focus on the apparently higher minimal mass of Be stars in BeXRBs than in the Be population at large. Assuming that BeXRBs experienced only dynamically stable mass transfer, their mass distribution suggests that at least 30% of the mass donated by the progenitor of the neutron star is typically accreted by the B-star companion. We expect these results to affect predictions for the population of double compact object mergers. A convolution of the simulated BeXRB population with the star formation history of the Small Magellanic Cloud shows that the excess of BeXRBs is most likely explained by this galaxy's burst of star formation around 20--40 Myr ago.

astro-ph.HE↗

arXiv2020

Common-Envelope Episodes that lead to Double Neutron Star formation

Close double neutron stars have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational-wave sources. They are believed to have experienced at least one common-envelope episode during their evolution prior to double neutron star formation. In the last decades there have been numerous efforts to understand the details of the common-envelope phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche-lobe overflow leading to these common-envelope episodes as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the common-envelope phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the Roche-lobe overflow: giant donors with fully-convective envelopes, cool donors with partially-convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of Roche-lobe overflow. This makes the study and understanding of eccentric mass-transferring systems relevant for double neutron star populations.

astro-ph.SR↗

arXiv2019

The effect of the metallicity-specific star formation history on double compact object mergers

We investigate the impact of uncertainty in the metallicity-specific star formation rate over cosmic time on predictions of the rates and masses of double compact object mergers observable through gravitational waves. We find that this uncertainty can change the predicted detectable merger rate by more than an order of magnitude, comparable to contributions from uncertain physical assumptions regarding binary evolution, such as mass transfer efficiency or supernova kicks. We statistically compare the results produced by the COMPAS population synthesis suite against a catalog of gravitational-wave detections from the first two Advanced LIGO and Virgo observing runs. We find that the rate and chirp mass of observed binary black hole mergers can be well matched under our default evolutionary model with a star formation metallicity spread of $0.39$ dex around a mean metallicity $\left $ that scales with redshift $z$ as $\left =0.035 \times 10^{-0.23 z}$, assuming a star formation rate of $0.01 \times (1+z)^{2.77} / (1+((1+z)/2.9)^{4.7}) \, \rm{M}_\odot$ Mpc$^{-3}$ yr$^{-1}$. Intriguingly, this default model predicts that 80\% of the approximately one binary black hole merger per day that will be detectable at design sensitivity will have formed through isolated binary evolution with only dynamically stable mass transfer, i.e., without experiencing a common-envelope event.

astro-ph.SR↗

arXiv2018

saprEMo: a simplified algorithm for predicting detections of electromagnetic transients in surveys

The multi-wavelength detection of GW170817 has inaugurated multi-messenger astronomy. The next step consists in interpreting observations coming from population of gravitational wave sources. We introduce saprEMo, a tool aimed at predicting the number of electromagnetic signals characterised by a specific light curve and spectrum, expected in a particular sky survey. By looking at past surveys, saprEMo allows us to constrain models of electromagnetic emission or event rates. Applying saprEMo to proposed astronomical missions/observing campaigns provides a perspective on their scientific impact and tests the effect of adopting different observational strategies. For our first case study, we adopt a model of spindown-powered X-ray emission predicted for a binary neutron star merger producing a long-lived neutron star. We apply saprEMo on data collected by XMM-Newton and Chandra and during $10^4$ s of observations with the mission concept THESEUS. We demonstrate that our emission model and binary neutron star merger rate imply the presence of some signals in the XMM-Newton catalogs. We also show that the new class of X-ray transients found by Bauer et al. in the Chandra Deep Field-South is marginally consistent with the expected rate. Finally, by studying the mission concept THESEUS, we demonstrate the substantial impact of a much larger field of view in searches of X-ray transients.

astro-ph.IM↗

arXiv2017

Accelerating gravitational wave parameter estimation with multi-band template interpolation

Parameter estimation on gravitational wave signals from compact binary coalescence (CBC) requires the evaluation of computationally intensive waveform models, typically the bottleneck in the analysis. This cost will increase further as low frequency sensitivity in later second and third generation detectors motivates the use of longer waveforms. We describe a method for accelerating parameter estimation by exploiting the chirping behaviour of the signals to sample the waveform sparsely for portions where the full frequency resolution is not required. We demonstrate that the method can reproduce the original results with a waveform mismatch of $\leq 5\times 10^{-7}$, but with a waveform generation cost up to $\sim 50$ times lower for computationally costly frequency-domain waveforms starting from below 8 Hz.

gr-qc↗