80 research outputs found
Swift follow-up observations of candidate gravitational-wave transient events
We present the first multi-wavelength follow-up observations of two candidate
gravitational-wave (GW) transient events recorded by LIGO and Virgo in their
2009-2010 science run. The events were selected with low latency by the network
of GW detectors and their candidate sky locations were observed by the Swift
observatory. Image transient detection was used to analyze the collected
electromagnetic data, which were found to be consistent with background.
Off-line analysis of the GW data alone has also established that the selected
GW events show no evidence of an astrophysical origin; one of them is
consistent with background and the other one was a test, part of a "blind
injection challenge". With this work we demonstrate the feasibility of rapid
follow-ups of GW transients and establish the sensitivity improvement joint
electromagnetic and GW observations could bring. This is a first step toward an
electromagnetic follow-up program in the regime of routine detections with the
advanced GW instruments expected within this decade. In that regime
multi-wavelength observations will play a significant role in completing the
astrophysical identification of GW sources. We present the methods and results
from this first combined analysis and discuss its implications in terms of
sensitivity for the present and future instruments.Comment: Submitted for publication 2012 May 25, accepted 2012 October 25,
published 2012 November 21, in ApJS, 203, 28 (
http://stacks.iop.org/0067-0049/203/28 ); 14 pages, 3 figures, 6 tables;
LIGO-P1100038; Science summary at
http://www.ligo.org/science/Publication-S6LVSwift/index.php ; Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p110003
Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts
We outline the scientific motivation behind a search for gravitational waves
associated with short gamma ray bursts detected by the InterPlanetary Network
(IPN) during LIGO's fifth science run and Virgo's first science run. The IPN
localisation of short gamma ray bursts is limited to extended error boxes of
different shapes and sizes and a search on these error boxes poses a series of
challenges for data analysis. We will discuss these challenges and outline the
methods to optimise the search over these error boxes.Comment: Methods paper; Proceedings for Eduardo Amaldi 9 Conference on
Gravitational Waves, July 2011, Cardiff, U
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data
This paper presents results of an all-sky searches for periodic gravitational
waves in the frequency range [50, 1190] Hz and with frequency derivative ranges
of [-2 x 10^-9, 1.1 x 10^-10] Hz/s for the fifth LIGO science run (S5). The
novelty of the search lies in the use of a non-coherent technique based on the
Hough-transform to combine the information from coherent searches on timescales
of about one day. Because these searches are very computationally intensive,
they have been deployed on the Einstein@Home distributed computing project
infrastructure. The search presented here is about a factor 3 more sensitive
than the previous Einstein@Home search in early S5 LIGO data. The
post-processing has left us with eight surviving candidates. We show that
deeper follow-up studies rule each of them out. Hence, since no statistically
significant gravitational wave signals have been detected, we report upper
limits on the intrinsic gravitational wave amplitude h0. For example, in the
0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h0
greater than 7.6 x 10^-25 with a 90% confidence level.Comment: 29 pages, 14 figures, 6 tables. Science summary page at
http://www.ligo.org/science/Publication-FullS5EatH/index.php ; Public access
area to figures and tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120002
The characterization of Virgo data and its impact on gravitational-wave searches
Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and
GEO gravitational-wave (GW) detectors. These data have been searched for GWs
emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating
neutron stars or from a stochastic background in the frequency band of the
detectors. The sensitivity of GW searches is limited by noise produced by the
detector or its environment. It is therefore crucial to characterize the
various noise sources in a GW detector. This paper reviews the Virgo detector
noise sources, noise propagation, and conversion mechanisms which were
identified in the three first Virgo observing runs. In many cases, these
investigations allowed us to mitigate noise sources in the detector, or to
selectively flag noise events and discard them from the data. We present
examples from the joint LIGO-GEO-Virgo GW searches to show how well noise
transients and narrow spectral lines have been identified and excluded from the
Virgo data. We also discuss how detector characterization can improve the
astrophysical reach of gravitational-wave searches.Comment: 50 pages, 12 figures, 5 table
Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network
Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a "blind injection" where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1 M⊙-25 M⊙ and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors. © 2013 American Physical Society.J. Aasi ... J. Munch ... D. J. Ottaway ... P. J. Veitch ... et al. (LIGO-Virgo Scientific Collaboration
A research agenda for geographies of everyday intergenerational encounter
This paper calls for a research agenda that attends to the geographies of everyday intergenerational encounter that occur informally in communities. Using the theoretical framing of social infrastructure and encounter, it argues that we need to better understand the potential of the everyday, mundane, and often fleeting social interactions we have in the everyday shared spaces of our neighbourhoods, and that it is these interactions that can have the biggest impact on intergenerational relations. This argument is made in response to a lack of research on “naturally occurring” intergenerational encounters when compared to a more well-established body of research on intentional intergenerational practice and design. To demonstrate the value of attending to encounters of the everyday, the paper draws on a body of research within social and cultural geography on intercultural encounters that points to the value of “everyday civics” in contributing to community cohesion in the context of cultural diversity
- …