44 research outputs found
Prospects for detecting and localizing short-duration transient gravitational waves from glitching neutron stars without electromagnetic counterparts
Neutron stars are known to show accelerated spin-up of their rotational
frequency called a glitch. Highly magnetized rotating neutron stars (pulsars)
are frequently observed by radio telescopes (and in other frequencies), where
the glitch is observed as irregular arrival times of pulses which are otherwise
very regular. A glitch in an isolated neutron star can excite the fundamental
(f)-mode oscillations which can lead to gravitational wave generation.
Electromagnetic observations of pulsars (and hence pulsar glitches) require the
pulsar to be oriented so that the jet is pointed toward the detector, but this
is not a requirement for gravitational wave emission which is more isotropic
and not jetlike. Hence, gravitational wave observations have the potential to
uncover nearby neutron stars where the jet is not pointed towards the Earth. In
this work, we study the prospects of finding glitching neutron stars using a
generic all-sky search for short-duration gravitational wave transients. The
analysis covers the high-frequency range from kHz of LIGO-Virgo detectors
for signals up to a few seconds. We set upper limits for the third observing
run of the LIGO-Virgo detectors and present the prospects for upcoming
observing runs of LIGO, Virgo, KAGRA, and LIGO India. We find the detectable
glitch size will be around Hz for the fifth observing run for pulsars
with spin frequencies and distances comparable to the Vela pulsar. We also
present the prospects of localizing the direction in the sky of these sources
with gravitational waves alone, which can facilitate electromagnetic follow-up.
We find that for the five detector configuration, the localization capability
for a glitch size of Hz is around at
confidence for of events with distance and spin frequency as
that of Vela
coherent WaveBurst, a pipeline for unmodeled gravitational-wave data analysis
coherent WaveBurst (cWB) is a highly configurable pipeline designed to detect a broad range of gravitational-wave (GW) transients in the data of the worldwide network of GW detectors. The algorithmic core of cWB is a time\u2013frequency analysis with the Wilson\u2013Daubechies\u2013Meyer wavelets aimed at the identification of GW events without prior knowledge of the signal waveform. cWB has been in active development since 2003 and it has been used to analyze all scientific data collected by the LIGO-Virgo detectors ever since. On September 14, 2015, the cWB low-latency search detected the first gravitational-wave event, GW150914, a merger of two black holes. In 2019, a public open-source version of cWB has been released with GPLv3 license
Search for gravitational-wave bursts in the third Advanced LIGO-Virgo run with coherent WaveBurst enhanced by Machine Learning
This paper presents a search for generic short-duration gravitational-wave
(GW) transients (or GW bursts) in the data from the third observing run of
Advanced LIGO and Advanced Virgo. We use coherent WaveBurst (cWB) pipeline
enhanced with a decision-tree classification algorithm for more efficient
separation of GW signals from noise transients. The machine-learning (ML)
algorithm is trained on a representative set of noise events and a set of
simulated stochastic signals that are not correlated with any known signal
model. This training procedure preserves the model-independent nature of the
search. We demonstrate that the ML-enhanced cWB pipeline can detect GW signals
at a larger distance than previous model-independent searches. The sensitivity
improvements are achieved across the broad spectrum of simulated signals, with
the goal of testing the robustness of this model-agnostic search. At a
false-alarm rate of one event per century, the detectable signal amplitudes are
reduced up to almost an order of magnitude, most notably for the single-cycle
signal morphologies. This ML-enhanced pipeline also improves the detection
efficiency of compact binary mergers in a wide range of masses, from stellar
mass to intermediate-mass black holes, both with circular and elliptical
orbits. After excluding previously detected compact binaries, no new
gravitational-wave signals are observed for the two-fold Hanford-Livingston and
the three-fold Hanford-Livingston-Virgo detector networks. With the improved
sensitivity of the all-sky search, we obtain the most stringent constraints on
the isotropic emission of gravitational-wave energy from short-duration burst
sources.Comment: 15 pages, 7 figure
Investigation on Planck scale physics by the AURIGA gravitational bar detector
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
coherent WaveBurst, a pipeline for unmodeled gravitational-wave data analysis
coherent WaveBurst (cWB) is a highly configurable pipeline designed to detect a broad range of gravitational-wave (GW) transients in the data of the worldwide network of GW detectors. The algorithmic core of cWB is a timeâfrequency analysis with the WilsonâDaubechiesâMeyer wavelets aimed at the identification of GW events without prior knowledge of the signal waveform. cWB has been in active development since 2003 and it has been used to analyze all scientific data collected by the LIGO-Virgo detectors ever since. On September 14, 2015, the cWB low-latency search detected the first gravitational-wave event, GW150914, a merger of two black holes. In 2019, a public open-source version of cWB has been released with GPLv3 license
Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)
This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands
All-sky search for long-duration gravitational wave transients with initial LIGO
We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10â500Â s in a frequency band of 40â1000Â Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4Ă10â5 and 9.4Ă10â4ââMpcâ3âyrâ1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves
A 15 ÎŒK noise temperature SQUID amplifier for ultracryogenic gravitational wave detectors
Electrochemically driven luminescence in organometallic and inorganic systems
This chapter analyses the literature appeared within the decade that follows the publication of M. Richter\ue2\u80\u99s exhaustive chapter dedicated to metal chelates in the comprehensive ECL monograph edited by A. J. Bard in 2004. In this chapter, we have attempted to cover, although somehow selectively, the published work on the application of metal chelates in ECL, organizing the material, similarly to Richter\ue2\u80\u99s choice, according to the main metal. Perhaps not surprisingly, among the metal chelate systems, Ru(bpy)32+ (bpy = 2,2'-bipyridine) has still been, over the last decade, the main star in the ECL sky as previously, in view in particular of its outstanding role in bioanalytical research and commercial applications. Nonetheless, the importance of other coordination and organometallic systems, especially those based on iridium, has grown in the recent research literature because of their photophysical and electrochemical properties that may offer great advantages in the technical development of ECL. A variety of reviews pertaining to particular aspects of metal chelates application in ECL, in particular for (bio)analytical purposes but also covering many other aspects of this fascinating area, are available to which the reader is directed for further information