26 research outputs found
A First Comparison Between LIGO and Virgo Inspiral Search Pipelines
This article reports on a project that is the first step the LIGO Scientific
Collaboration and the Virgo Collaboration have taken to prepare for the mutual
search for inspiral signals. The project involved comparing the analysis
pipelines of the two collaborations on data sets prepared by both sides,
containing simulated noise and injected events. The ability of the pipelines to
detect the injected events was checked, and a first comparison of how the
parameters of the events were recovered has been completed.Comment: GWDAW-9 proceeding
Effects of Data Quality Vetoes on a Search for Compact Binary Coalescences in Advanced LIGO's First Observing Run
The first observing run of Advanced LIGO spanned 4 months, from September 12,
2015 to January 19, 2016, during which gravitational waves were directly
detected from two binary black hole systems, namely GW150914 and GW151226.
Confident detection of gravitational waves requires an understanding of
instrumental transients and artifacts that can reduce the sensitivity of a
search. Studies of the quality of the detector data yield insights into the
cause of instrumental artifacts and data quality vetoes specific to a search
are produced to mitigate the effects of problematic data. In this paper, the
systematic removal of noisy data from analysis time is shown to improve the
sensitivity of searches for compact binary coalescences. The output of the
PyCBC pipeline, which is a python-based code package used to search for
gravitational wave signals from compact binary coalescences, is used as a
metric for improvement. GW150914 was a loud enough signal that removing noisy
data did not improve its significance. However, the removal of data with excess
noise decreased the false alarm rate of GW151226 by more than two orders of
magnitude, from 1 in 770 years to less than 1 in 186000 years.Comment: 27 pages, 13 figures, published versio
Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914
On 14 September 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal
Book review: Malavika Karlekar, Memories of Belonging: Images from the Colony and Beyond
The intimate city: violence, gender, and ordinary life in Delhi slums
In this paper I argue for an expansion of the horizons of urban geography through a notion of the intimate city. I focus on the slum as a space where a violence of an exclusionary city is woven into its intimate material and social conditions, but where this violence is also domesticated and rendered as part of the everyday. I illustrate through three stories of intimate lives of slum women that everyday life in the slum requires the production of a) an urban subject who shows agency not by resisting but by living with intimate violence b) an urban subjectivity involved in acquiring knowledge of one’s bodily terrain in order to limit this violence and c) a urban citizenship that argues for a ‘right to intimacy’ as a way to claim a right to the city. This paper calls for a recasting of the public/private divides in urban geography in order to understand how violence circulates through and contravenes the boundaries of public/private, city/slum, tradition/modernity