Publications (240)693.54 Total impact
 [Show abstract] [Hide abstract]
ABSTRACT: We present a method for detection and reconstruction of the gravitational wave (GW) transients with the networks of advanced detectors. Originally designed to search for the transients with the initial GW detectors, it uses significantly improved algorithms, which enable both the lowlatency searches with rapid localization of GW events for the electromagnetic followup and high confidence detection of a broad range of the transient GW sources. In the paper we present the analytic framework of the method. Following a short description of the core analysis algorithms, we introduce a novel approach to the reconstruction of the GW polarization from a pattern of detector responses to a GW signal. This polarization pattern is a unique signature of an arbitrary GW signal that can be measured independent from the other source parameters. The polarization measurements enable rapid reconstruction of the GW waveforms, sky localization and helps identification of the source origin.  [Show abstract] [Hide abstract]
ABSTRACT: In this paper we present the results of the first low frequency allsky search of continuous gravitational wave signals conducted on Virgo VSR2 and VSR4 data. The search covered the full sky, a frequency range between 20 Hz and 128 Hz with a range of spindown between $1.0 \times 10^{10}$ Hz/s and $+1.5 \times 10^{11}$ Hz/s, and was based on a hierarchical approach. The starting point was a set of short Fast Fourier Transforms (FFT), of length 8192 seconds, built from the calibrated strain data. Aggressive data cleaning, both in the time and frequency domains, has been done in order to remove, as much as possible, the effect of disturbances of instrumental origin. On each dataset a number of candidates has been selected, using the FrequencyHough transform in an incoherent step. Only coincident candidates among VSR2 and VSR4 have been examined in order to strongly reduce the false alarm probability, and the most significant candidates have been selected. The criteria we have used for candidate selection and for the coincidence step greatly reduce the harmful effect of large instrumental artifacts. Selected candidates have been subject to a followup by constructing a new set of longer FFTs followed by a further incoherent analysis. No evidence for continuous gravitational wave signals was found, therefore we have set a populationbased joint VSR2VSR4 90$\%$ confidence level upper limit on the dimensionless gravitational wave strain in the frequency range between 20 Hz and 128 Hz. This is the first allsky search for continuous gravitational waves conducted at frequencies below 50 Hz. We set upper limits in the range between about $10^{24}$ and $2\times 10^{23}$ at most frequencies. Our upper limits on signal strain show an improvement of up to a factor of $\sim$2 with respect to the results of previous allsky searches at frequencies below $80~\mathrm{Hz}$.  [Show abstract] [Hide abstract]
ABSTRACT: We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is $6.87^\circ$ in diameter and centered on $20^\textrm{h}10^\textrm{m}54.71^\textrm{s}+33^\circ33'25.29"$, and the other (B) is $7.45^\circ$ in diameter and centered on $8^\textrm{h}35^\textrm{m}20.61^\textrm{s}46^\circ49'25.151"$. We explored the frequency range of 501500 Hz and frequency derivative from $0$ to $5\times 10^{9}$ Hz/s. A multistage, loosely coherent search program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous followup parameters have winnowed initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational wave emitter, and 95% confidence level upper limits were placed on continuouswave strain amplitudes. Near $169$ Hz we achieve our lowest 95% CL upper limit on worstcase linearly polarized strain amplitude $h_0$ of $6.3\times 10^{25}$, while at the high end of our frequency range we achieve a worstcase upper limit of $3.4\times 10^{24}$ for all polarizations and sky locations.  [Show abstract] [Hide abstract]
ABSTRACT: The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for groundbased GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, corecollapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity.General Relativity and Gravitation 09/2015; 47(2). DOI:10.1007/s107140141796x · 1.77 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report the experimental observation of twomode squeezing in the oscillation quadratures of a thermal microoscillator. This effect is obtained by parametric modulation of the optical spring in a cavity optomechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing enhanced squeezing effect surpassing the stationary 3dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum optomechanical modes.  [Show abstract] [Hide abstract]
ABSTRACT: The study of the optomechanical coupling between the radiation pressure of a laser beam and a mechanical oscillator is an emerging field in quantum optics that is taking advantage of all the recent developments in microfabrication. The manipulation of the quantum state of light is within the reach of systems based on a FabryPerot cavity with a MicroOptoMechanicalSystem (MOMS) resonators used as endmirror. To approach the quantum regime, these micro devices must satisfy two basic requirements: low optical and mechanical losses. We have recently proposed a class of very low loss MOMS devices working in the 100 kHz frequency region, based on twoside MEMS processing bulkmicromachining. In this work we describe our latest process development, based on the used of pure aluminum as a masking layer for the optical coating during fabrication, that significantly improves the quality of the devices and the yield of the process, opening the way for their use in integrated systems for quantum optics. The devices show very high optical quality (finesse up to 105 can be achieved in optical cavity) and a mechanical quality factor over 106 at cryogenic temperatures.Microelectronic Engineering 09/2015; 145:138142. DOI:10.1016/j.mee.2015.03.036 · 1.20 Impact Factor 
Dataset: PhysRevA.86.051801 2012 ESerra
 [Show abstract] [Hide abstract]
ABSTRACT: We present an oscillating micromirror with mechanical quality factors Q up to 1.2×10^6 at cryogenic temperature and optical losses lower than 20 ppm. The device is specifically designed to ease the detection of ponderomotive squeezing (or, more generally, to produce a cavity quantum optomechanical system) at frequencies of about 100 kHz. The design allows one to keep under control both the structural loss in the optical coating and the mechanical energy leakage through the support. The comparison between devices with different shapes shows that the residual mechanical loss at 4.2 K is equally contributed by the intrinsic loss of the silicon substrate and of the coating, while at higher temperatures the dominant loss mechanism is thermoelasticity in the substrate. As the modal response of the device is tailored for its use in optical cavities, these features make the device very promising for quantumoptics experiments.Physical Review Applied 05/2015; 5(3):054009. DOI:10.1103/PhysRevApplied.3.054009 
Article: The Advanced Virgo detector
[Show abstract] [Hide abstract]
ABSTRACT: The Advanced Virgo interferometer is the upgraded version of the Virgo detector having the goal to extend by a factor 10 the observation horizon in the universe and consequently increase the detection rate by three orders of magnitude. Its installation is in progress and is expected to be completed in late 2015. In this proceeding we will present the scheme and the main challenging technical features of the detector and we will give an outline of the installation status and the foreseen time schedule which will bring Advanced Virgo to its full operation.Journal of Physics Conference Series 05/2015; 610(1):012014. DOI:10.1088/17426596/610/1/012014  [Show abstract] [Hide abstract]
ABSTRACT: We address the problem of noise regression in the output of gravitationalwave (GW) interferometers, using data from the physical environmental monitors (PEM). The objective of the regression analysis is to predict environmental noise in the gravitationalwave channel from the PEM measurements. One of the most promising regression method is based on the construction of WienerKolmogorov filters. Using this method, the seismic noise cancellation from the LIGO GW channel has already been performed. In the presented approach the WienerKolmogorov method has been extended, incorporating banks of Wiener filters in the timefrequency domain, multichannel analysis and regulation schemes, which greatly enhance the versatility of the regression analysis. Also we presents the first results on regression of the bicoherent noise in the LIGO data.Classical and Quantum Gravity 03/2015; 32(16). DOI:10.1088/02649381/32/16/165014 · 3.17 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We address the problem of the stability of a cavity optomechanical system based on an oscillator having at the same time low optical and mechanical losses. As we are interested in extending the use of optical squeezing as a tool for improving quantum limited displacement sensing at low frequency, we have developed a family of optomechanical devices designed to work at frequencies of about 100 kHz. The devices actually meet the initial design goals, but new requirements have emerged from the analysis of their behavior in optical cavities, due to the interaction between the cavity locking system and the low order normal modes of the devices.Annalen der Physik 01/2015; 527(12). DOI:10.1002/andp.201400093 · 3.05 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We describe directed searches for continuous gravitational waves in data from the sixth LIGO science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with nonpulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of ten. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.325.3 days using the matchedfiltering Fstatistic. We found no credible gravitationalwave signals. We set 95% confidence upper limits as strong (low) as $4\times10^{25}$ on intrinsic strain, $2\times10^{7}$ on fiducial ellipticity, and $4\times10^{5}$ on rmode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutronstar ellipticities and rmode amplitudes.The Astrophysical Journal 12/2014; 813(1). DOI:10.1088/0004637X/813/1/39 · 5.99 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present results of a search for continuouslyemitted gravitational radiation, directed at the brightest lowmass Xray binary, Scorpius X1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50550 Hz, and performs an incoherent sum of coherent $\mathcal{F}$statistic power distributed amongst frequencymodulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitationalwave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X1; and an anglerestricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3e24 and 8e25 are reported at 150 Hz for the standard and anglerestricted searches respectively. This proof of principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of ~1.4 for the standard, and 2.3 for the anglerestricted search at the sensitive region of the detector.Physical Review D 12/2014; 91(6). DOI:10.1103/PhysRevD.91.062008 · 4.64 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A minimal observable length is a common feature of theories that aim to merge quantum physics and gravity. Quantum mechanically, this concept is associated to a nonzero minimal uncertainty in position measurements, which is encoded in deformed commutation relations. In spite of increasing theoretical interest, the subject suffers from the complete lack of dedicated experiments and bounds to the deformation parameters are roughly extrapolated from indirect measurements. As recently proposed, lowenergy mechanical oscillators could allow to reveal the effect of a modified commutator. Here we analyze the free evolution of high quality factor micro and nanooscillators, spanning a wide range of masses around the Planck mass $m_{\mathrm{P}}$ (${\approx 22\,\mu\mathrm{g}}$), and compare it with a model of deformed dynamics. Previous limits to the parameters quantifying the commutator deformation are substantially lowered.Nature Communications 11/2014; 6. DOI:10.1038/ncomms8503 · 11.47 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitationalwave observatories and the partially completed IceCube highenergy neutrino detector, including periods of joint operation between 20072010. These include parts of the 20052007 run and the 20092010 run for LIGOVirgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitationalwave emission energy of $10^{2}$ M$_\odot$c$^2$ at $\sim 150$ Hz with $\sim 60$ ms duration, and highenergy neutrino emission of $10^{51}$ erg comparable to the isotropic gammaray energy of gammaray bursts, we limit the source rate below $1.6 \times 10^{2}$ Mpc$^{3}$yr$^{1}$. We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitationalwave detector era.Physical Review D 11/2014; 90:102002. DOI:10.1103/PhysRevD.90.102002 · 4.64 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In this paper we present the results of a coherent narrowband search for continuous gravitationalwave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95$\%$ confidence level upper limits have been computed both assuming polarization parameters are completely unknown and that they are known with some uncertainty, as derived from Xray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spindown limit, computed assuming that all the observed spindown is due to the emission of gravitational waves. For Crab the upper limits are about a factor of two below the spindown limit, and represent a significant improvement with respect to past analysis. This is the first time the spindown limit is significantly overcome in a narrowband search.Physical Review D 10/2014; 91(2). DOI:10.1103/PhysRevD.91.022004 · 4.64 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In 20092010, the Laser Interferometer Gravitationalwave Observa tory (LIGO) operated together with international partners Virgo and GEO600 as a network to search for gravitational waves of astrophysical origin. The sensitiv ity of these detectors was limited by a combination of noise sources inherent to the instrumental design and its environment, often localized in time or frequency, that couple into the gravitationalwave readout. Here we review the performance of the LIGO instruments during this epoch, the work done to characterize the de tectors and their data, and the effect that transient and continuous noise artefacts have on the sensitivity of LIGO to a variety of astrophysical sources.Classical and Quantum Gravity 10/2014; 32(11). DOI:10.1088/02649381/32/11/115012 · 3.17 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Searches for a stochastic gravitationalwave background (SGWB) using terrestrial detectors typically involve crosscorrelating data from pairs of detectors. The sensitivity of such crosscorrelation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitationalwave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO's fifth science run. At low frequencies, 40  460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitationalwave signal. However, at high frequencies, 4601000 Hz, these techniques are sufficient to set a $95\%$ confidence level (C.L.) upper limit on the gravitationalwave energy density of \Omega(f)<7.7 x 10^{4} (f/ 900 Hz)^3, which improves on the previous upper limit by a factor of $\sim 180$. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.Physical Review D 10/2014; 91(2). DOI:10.1103/PhysRevD.91.022003 · 4.64 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We summarise the parallel session C7 MultiMessenger Astronomy of GW Sources in the GR20 Amaldi 10 Conference. The talks in this session covered a wide range of topics in multimessenger astronomy.General Relativity and Gravitation 09/2014; 46(9). DOI:10.1007/s1071401417716 · 1.77 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We have recently shown that the very low mechanical energy achieved and measured in the main vibration mode of gravitational wave bar detectors can set an upper limit to possible modifications of the Heisenberg uncertainty principle that are expected as an effect of gravity. Here we give more details on the data analysis procedure that allows one to deduce the energy of the bar mode (i.e., the meaningful parameter for our purpose). Furthermore, we extend the analysis of our results, discussing their implication for physical models that face quantum gravity from different points of view, e.g., proposing modified commutation relations or exploring spacetime discreteness.New Journal of Physics 08/2014; 16(8):085012. DOI:10.1088/13672630/16/8/085012 · 3.56 Impact Factor
Publication Stats
3k  Citations  
693.54  Total Impact Points  
Top Journals
Institutions

19892015

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy


19872015

Università degli Studi di Trento
 Department of Physics
Trient, TrentinoAlto Adige, Italy


2012

Trent University
Питерборо, Ontario, Canada


2010

University of NiceSophia Antipolis
Nice, ProvenceAlpesCôte d'Azur, France 
University of Naples Federico II
 Department of Physical Sciences
Napoli, Campania, Italy


2008

University of Padova
Padua, Veneto, Italy


2000

Nottingham Trent University
Nottigham, England, United Kingdom
