arXiv subjects

Cristiano Palomba

Publications and source records attributed to Cristiano Palomba.

41 records · Page 3Linked to original sources

arXiv2014

A method for narrow-band searches of continuous gravitational wave signals

Targeted searches of continuous waves from spinning neutron stars normally assume that the frequency of the gravitational wave signal is at a given known ratio with respect to the rotational frequency of the source, e.g. twice for an asymmetric neutron star rotating around a principal axis of inertia. In fact this assumption may well be invalid if, for instance, the gravitational wave signal is due to a solid core rotating at a slightly different rate with respect to the star crust. In this paper we present a method for {\it narrow-band} searches of continuous gravitational wave signals from known pulsars in the data of interferometric detectors. This method assumes source position is known to high accuracy, while a small frequency and spin-down range around the electromagnetic-inferred values is explored. Barycentric and spin-down corrections are done with an efficient time-domain procedure. Sensitivity and computational efficiency estimates are given and results of tests done using simulated data are also discussed.

astro-ph.IM↗

arXiv2012

Coherent search of continuous gravitational wave signals: extension of the 5-vectors method to a network of detectors

We describe the extension to multiple datasets of a coherent method for the search of continuous gravitational wave signals, based on the computation of 5-vectors. In particular, we show how to coherently combine different datasets belonging to the same detector or to different detectors. In the latter case the coherent combination is the way to have the maximum increase in signal-to-noise ratio. If the datasets belong to the same detector the advantage comes mainly from the properties of a quantity called {\it coherence} which is helpful (in both cases, in fact) in rejecting false candidates. The method has been tested searching for simulated signals injected in Gaussian noise and the results of the simulations are discussed.

astro-ph.IM↗

arXiv2004

The Hough transform search for continuous gravitational waves

This paper describes an incoherent method to search for continuous gravitational waves based on the Hough transform, a well known technique used for detecting patterns in digital images. We apply the Hough transform to detect patterns in the time-frequency plane of the data produced by an earth-based gravitational wave detector. Two different flavors of searches will be considered, depending on the type of input to the Hough transform: either Fourier transforms of the detector data or the output of a coherent matched-filtering type search. We present the technical details for implementing the Hough transform algorithm for both kinds of searches, their statistical properties, and their sensitivities.

gr-qc↗

arXiv2001

Detectability of Gravitational Radiation from Prompt and Delayed Star Collapse to a Black Hole

We consider the emission of gravitational waves in the two proposed models for the collapse of a massive star to a black hole: the prompt collapse, in which nearly all the star collapses to a black hole in a dynamical time scale, and the delayed collapse, in which a light black hole, or a neutron star, which subsequently accretes matter, forms due to the fall-back achieving, in the neutron star case, the critical mass for black hole formation. Recent simulations strongly support this last scenario. We show that, due to the slowness of fall-back, in the delayed collapse the main burst of gravitational radiation is emitted depending on the parameters, mass and angular momentum, of the initial, light, black hole. We estimate, under different assumptions, the detectability of the emitted gravitational waves showing that such kind of collapse is not particularly suited for detection by forthcoming interferometric detectors. Detectors with high sensitivity at frequencies greater than ~4-5 kHz would be well suited for this kind of sources. We calculate also the final mass distribution function of single black holes.

astro-ph↗

arXiv1999

Pulsars ellipticity revised

We derive new upper limits on the ellipticity of pulsars whose braking index has been measured, more tightening than those usually given, assuming that both a gravitational torque and an electromagnetic one act on them. We show that the measured braking indexes of pulsars are recovered in this model. We consider the electromagnetic torque both constant and varying with time. At the same time constraints on the pulsars initial period and on the amplitude of the gravitational waves emitted are obtained.

astro-ph↗