Publications (210)504.01 Total impact
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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. · 4.06 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The Amaldi 10 Parallel Session C3 on Advanced Gravitational Wave detectors gave an overview of the status and several specific challenges and solutions relevant to the instruments planned for a middecade start of observation. Invited overview talks for the Virgo, LIGO, and KAGRA instruments were complemented by more detailed discussions in presentations and posters of some instrument features and designs.General Relativity and Gravitation 07/2014; 46. · 1.90 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 07/2014; · 1.51 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.07/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We present the results of a search for gravitational waves associated with 223 gammaray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 20052010 during LIGO's fifth and sixth science runs and Virgo's first, second and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a wellmodeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitationalwave search sensitivity as compared to corresponding alltime, allsky searches. We find no evidence of a gravitationalwave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitationalwave signals associated with the GRBs. For all IPNdetected GRBs, for which a sufficient duration of quality gravitationalwave data is available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitationalwave emission energy of $10^{2}M_{\odot}c^2$ at 150 Hz, and find a median of 13 Mpc. For the 27 shorthard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in firstgeneration LIGO and Virgo gravitationalwave detectors, and a resulting examination of prospects for the advanced gravitationalwave detectors.Physical Review Letters 06/2014; 113(1):011102. · 7.73 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the universe. We carry out a search for the stochastic background with the latest data from LIGO and Virgo. Consistent with predictions from most stochastic gravitationalwave background models, the data display no evidence of a stochastic gravitationalwave signal. Assuming a gravitationalwave spectrum of Omega_GW(f)=Omega_alpha*(f/f_ref)^alpha, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.51726 Hz. In the frequency band of 41.5169.25 Hz for a spectral index of alpha=0, we constrain the energy density of the stochastic background to be Omega_GW(f)<5.6x10^6. For the 6001000 Hz band, Omega_GW(f)<0.14*(f/900 Hz)^3, a factor of 2.5 lower than the best previously reported upper limits. We find Omega_GW(f)<1.8x10^4 using a spectral index of zero for 170600 Hz and Omega_GW(f)<1.0*(f/1300 Hz)^3 for 10001726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the detection of inflationary gravitational waves.06/2014; 
Article: First allsky search for continuous gravitational waves from unknown sources in binary systems
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ABSTRACT: We present the first results of an allsky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO Science Run and the second and third Virgo Science Runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ~2,254 h and a frequency and perioddependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range of projected semimajor axes of the orbit from ~0.6e3 ls to ~6,500 ls assuming the orbit of the binary is circular. While no plausible candidate gravitational wave events survive the pipeline, upper limits are set on the analyzed data. The most sensitive 95% confidence upper limit obtained on gravitational wave strain is 2.3e24 at 217 Hz, assuming the source waves are circularly polarized. Although this search has been optimized for circular binary orbits, the upper limits obtained remain valid for orbital eccentricities as large as 0.9. In addition, upper limits are placed on continuous gravitational wave emission from the lowmass xray binary Scorpius X1 between 20 Hz and 57.25 Hz.05/2014;  [Show abstract] [Hide abstract]
ABSTRACT: In this paper we report on a search for shortduration gravitational wave bursts in the frequency range 64 Hz1792 Hz associated with gammaray bursts (GRBs), using data from GEO600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyse GRB events with large sky localisation uncertainties such as the localisations provided by the Fermi Gammaray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not welllocalised, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of O(10) for GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localisation of GRBs detected by the GBM, if a highfrequency GW signal is observed in coincidence. We use the linear search grid method in a search for GWs associated with 129 GRBs observed satellitebased gammaray experiments between 2006 and 2011. The GRBs in our sample had not been previously analysed for GW counterparts. A fraction of our GRB events are analysed using data from GEO600 while the detector was using squeezedlight states to improve its sensitivity; this is the first search for GWs using data from a squeezedlight interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, assuming a fixed GW emission energy of $10^{2} M_{\odot}c^{2}$, with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events in the Advanced detector era.05/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We estimated the sensitivity of the upcoming advanced, groundbased gravitationalwave observatories (the upgraded LIGO and Virgo and the KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to detectors' simulated data and searched for the injected signals with the coherent WaveBurst algorithm. The tested binary's parameter space covers nonspinning IMBHBs with sourceframe total masses between 50 and 1050 $\text{M}_{\odot}$ and mass ratios between $1/6$ and 1$\,$. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and open a new, intriguing channel for probing the Universe over cosmological scales.04/2014; 

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ABSTRACT: This paper reports on an unmodeled, allsky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009  October 2010) and was sensitive to IMBHBs with a range up to $\sim 200$ Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescencerate density of nonspinning IMBHBs with total masses between 100 and $450 \ \mbox{M}_{\odot}$ and mass ratios between $0.25$ and $1\,$ were placed by combining this analysis with an analogous search performed on data from the first LIGOVirgo joint science run (November 2005  October 2007). The most stringent limit was set for systems consisting of two $88 \ \mbox{M}_{\odot}$ black holes and is equal to $0.12 \ \mbox{Mpc}^{3} \ \mbox{Myr}^{1}$ at the $90\%$ confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with nonspinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with antialigned spins decreases the visible volume by $\sim 20\%\,$.04/2014;  [Show abstract] [Hide abstract]
ABSTRACT: The interaction of the radiation pressure with micromechanical oscillators is earning a growing interest for its widerange applications and for fundamental research. In this contribution we describe the fabrication of a family of optomechanical devices specifically designed to ease the detection of ponderomotive squeezing and of entanglement between macroscopic objects and light. These phenomena are not easily observed, due to the overwhelming effects of classical noise sources of thermal origin with respect to the weak quantum fluctuations of the radiation pressure. A low thermal noise background is required, together with a weak interaction between the micromirror and this background (i.e. high mechanical quality factors). In the development of our optomechanical devices, we heve explored an approach focused on relatively thick silicon oscillators with high reflectivity coating. The relatively high mass is compensated by the capability to manage high power at low temperatures, owing to a favourable geometric factor (thicker connectors) and the excellent thermal conductivity of silicon crystals at cryogenic temperature. We have measured at cryogenic temperatures mechanical quality factors up to 105 in a microoscillator designed to reduce as much as possible the strain in the coating layer and the consequent energy dissipation. This design improves an approach applied in micromirror and microcantilevers, where the coated surface is reduced as much as possible to improve the quality factor. The deposition of the highly reflective coating layer has been carefully integrated in the micromachining process to preserve its low optical losses.Microsystem Technologies 04/2014; 20(45). · 0.83 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We estimated the sensitivity of the upcoming advanced, groundbased gravitationalwave observatories (the upgraded LIGO and Virgo and the KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to detectors' simulated data and searched for the injected signals with the coherent WaveBurst algorithm. The tested binary's parameter space covers nonspinning IMBHBs with sourceframe total masses between 50 and 1050 $\text{M}_{\odot}$ and mass ratios between $1/6$ and 1$\,$. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and open a new, intriguing channel for probing the Universe over cosmological scales.03/2014; 
Dataset: 13119

Dataset: 122

Dataset: 84 local APF20 617
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ABSTRACT: We report results from a search for gravitational waves produced by perturbed intermediate mass black holes (IMBH) in data collected by LIGO and Virgo between 2005 and 2010. The search was sensitive to astrophysical sources that produced damped sinusoid gravitational wave signals, also known as ringdowns, with frequency $50\le f_{0}/\mathrm{Hz} \le 2000$ and decay timescale $0.0001\lesssim \tau/\mathrm{s} \lesssim 0.1$ characteristic of those produced in mergers of IMBH pairs. No significant gravitational wave candidate was detected. We report upper limits on the astrophysical coalescence rates of IMBHs with total binary mass $50 \le M/\mathrm{M}_\odot \le 450$ and component mass ratios of either 1:1 or 4:1. For systems with total mass $100 \le M/\mathrm{M}_\odot \le 150$, we report a 90%confidence upper limit on the rate of binary IMBH mergers with nonspinning and equal mass components of $6.9\times10^{8}\,$Mpc$^{3}$yr$^{1}$. We also report a rate upper limit for ringdown waveforms from perturbed IMBHs, radiating 1% of their mass as gravitational waves in the fundamental, $\ell=m=2$, oscillation mode, that is nearly three orders of magnitude more stringent than previous results.03/2014; 
Article: Detection of weak stochastic force in a parametrically stabilized micro optomechanical system
Physical Review A 02/2014; 89:023848. · 3.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present an implementation of the $\mathcal{F}$statistic to carry out the first search in data from the Virgo laser interferometric gravitational wave detector for periodic gravitational waves from a priori unknown, isolated rotating neutron stars. We searched a frequency $f_0$ range from 100 Hz to 1 kHz and the frequency dependent spindown $f_1$ range from $1.6\,(f_0/100\,{\rm Hz}) \times 10^{9}\,$ Hz/s to zero. A large part of this frequency  spindown space was unexplored by any of the allsky searches published so far. Our method consisted of a coherent search over twoday periods using the $\mathcal{F}$statistic, followed by a search for coincidences among the candidates from the twoday segments. We have introduced a number of novel techniques and algorithms that allow the use of the Fast Fourier Transform (FFT) algorithm in the coherent part of the search resulting in a fiftyfold speedup in computation of the $\mathcal{F}$statistic with respect to the algorithm used in the other pipelines. No significant gravitational wave signal was found. The sensitivity of the search was estimated by injecting signals into the data. In the most sensitive parts of the detector band more than 90% of signals would have been detected with dimensionless gravitationalwave amplitude greater than $5 \times 10^{24}$.02/2014;
Publication Stats
700  Citations  
504.01  Total Impact Points  
Top Journals
Institutions

1989–2014

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy


1987–2014

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


2011

California Institute of Technology
Pasadena, California, United States


2008

Fondazione Bruno Kessler
Trient, TrentinoAlto Adige, Italy


2005

The University of Tokyo
 Institute for Cosmic Ray Research
Tokyo, Tokyoto, Japan


2001

JustusLiebigUniversität Gießen
Gieben, Hesse, Germany


1996

Universita degli studi di Ferrara
 Department of Physics and Earth Sciences
Ferrara, EmiliaRomagna, Italy
