arXiv subjects

Andrzej Pisarski

Publications and source records attributed to Andrzej Pisarski.

4 recordsLinked to original sources

arXiv2023

Banks of templates for directed and all-sky narrow-band searches of continuous gravitational waves from spinning neutron stars with several spindowns

We construct efficient banks of templates suitable for searches of continuous gravitational waves from isolated spinning neutron stars. We assume that the search algorithm is based on the time-domain maximum-likelihood $\mathcal{F}$-statistic and we consider narrow-band searches with several spindown parameters included. Our template banks are suitable for both all-sky and directed searches and they enable the usage of the fast Fourier transform in the computation of the $\mathcal{F}$-statistic as well as, in the case of all-sky searches, efficient resampling of data to barycentric time.

gr-qc↗

arXiv2023

Search for Postmerger Gravitational Waves from Binary Neutron Star Mergers Using a Matched-filtering Statistic

In this paper, we present a new method to search for a short, a few tens of milliseconds long, postmerger gravitational-wave signal following the merger of two neutron stars. Such a signal could follow the event GW170817 observed by LIGO and Virgo detectors. Our method is based on a matched filtering statistic and an approximate template of the postmerger signal in the form of a damped sinusoid. We test and validate our method using postmerger numerical simulations from the CoRe database. We find no evidence of the short postmerger signal in the LIGO data following the GW170817 event and we obtain upper limits. For short postmerger signals investigated, our best upper limit on the root sum square of the gravitational-wave strain emitted from 1.15 kHz to 4 kHz is $h_{\text{rss}}^{50\%}=1.8\times 10^{-22}/\sqrt{\text{Hz}}$ at 50% detection efficiency. The distance corresponding to this best upper limit is 4.64 Mpc.

gr-qc↗

arXiv2015

Banks of templates for all-sky narrow-band searches of gravitational waves from spinning neutron stars

We construct efficient banks of templates suitable for all-sky narrow-band searches of almost monochromatic gravitational waves originating from spinning neutron stars in our Galaxy in data collected by interferometric detectors. We consider waves with one spindown parameter included and we assume that both the position of the gravitational-wave source in the sky and the wave's frequency together with spindown parameter are unknown. In the construction we employ simplified model of the signal with constant amplitude and phase which is a linear function of unknown parameters. Our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood $\mathcal{F}$-statistic for nodes of the grids defining the bank and fulfill an additional constraint needed to resample the data to barycentric time efficiently. All these template bank features were employed in the recent all-sky $\mathcal{F}$-statistic-based search for continuous gravitational waves in Virgo VSR1 data [J.Aasi et al., Classical Quantum Gravity 31, 165014 (2014)]. Here we improve that template bank by constructing templates suitable for larger range of search parameters and of smaller thicknesses for certain values of search parameters. One of our template banks has thickness 12% smaller than the thickness of the template bank used in the all-sky search of Virgo VSR1 data and only 4% larger than the thickness of 4-dimensional optimal lattice covering $A_4^\star$.

gr-qc↗

arXiv2010

Banks of templates for directed searches of gravitational waves from spinning neutron stars

We construct efficient banks of templates suitable for directed searches of almost monochromatic gravitational waves originating from spinning nuetron stars in our Galaxy in data being collected by currently operating interferometric detectors. We thus assume that the position of the gravitational-wave source in the sky is known, but we do not assume that the wave's frequency and its derivatives are a priori known. In the construction we employ simplified model of the signal with constant amplitude and phase which is a polynomial function of time. All our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood F-statistic for nodes of the grids defining the bank. We study and employ the dependence of the grid's construction on the choice of the position of the observational interval with respect to the origin of time axis. We also study the usage of the fast Fourier transform algorithms with non-standard frequency resolutions achieved by zero padding or folding the data. In the case of the gravitational-wave signal with one spindown parameter included we have found grids with covering thicknesses which are only 0.1%--16% larger than the thickness of the optimal two-dimensional hexagonal covering.

gr-qc↗