2 research outputs found
Follow-up analyses to the O3 LIGO-Virgo-KAGRA lensing searches
Along their path from source to observer, gravitational waves may be
gravitationally lensed by massive objects. This results in distortions of the
observed signal which can be used to extract new information about fundamental
physics, astrophysics, and cosmology. Searches for these distortions amongst
the observed signals from the current detector network have already been
carried out, though there have as yet been no confident detections. However,
predictions of the observation rate of lensing suggest detection in the future
is a realistic possibility. Therefore, preparations need to be made to
thoroughly investigate the candidate lensed signals. In this work, we present
some of the follow-up analyses and strategies that could be applied to assess
the significance of such events and ascertain what information may be extracted
about the lens-source system from such candidate signals by applying them to a
number of O3 candidate events, even if these signals did not yield a high
significance for any of the lensing hypotheses. For strongly-lensed candidates,
we verify their significance using a background of simulated unlensed events
and statistics computed from lensing catalogs. We also look for potential
electromagnetic counterparts. In addition, we analyse in detail a candidate for
a strongly-lensed sub-threshold counterpart that is identified by a new method.
For microlensing candidates, we perform model selection using a number of lens
models to investigate our ability to determine the mass density profile of the
lens and constrain the lens parameters. We also look for millilensing
signatures in one of the lensed candidates. Applying these additional analyses
does not lead to any additional evidence for lensing in the candidates that
have been examined. However, it does provide important insight into potential
avenues to deal with high-significance candidates in future observations.Comment: 34 pages, 27 figure
Characterizing Gravitational Wave Detector Networks: From A to Cosmic Explorer
Gravitational-wave observations by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) and Virgo have provided us a new tool to
explore the universe on all scales from nuclear physics to the cosmos and have
the massive potential to further impact fundamental physics, astrophysics, and
cosmology for decades to come. In this paper we have studied the science
capabilities of a network of LIGO detectors when they reach their best possible
sensitivity, called A#, and a new generation of observatories that are factor
of 10 to 100 times more sensitive (depending on the frequency), in particular a
pair of L-shaped Cosmic Explorer observatories (one 40 km and one 20 km arm
length) in the US and the triangular Einstein Telescope with 10 km arms in
Europe. We use a set of science metrics derived from the top priorities of
several funding agencies to characterize the science capabilities of different
networks. The presence of one or two A# observatories in a network containing
two or one next generation observatories, respectively, will provide good
localization capabilities for facilitating multimessenger astronomy and
precision measurement of the Hubble parameter. A network of two Cosmic Explorer
observatories and the Einstein Telescope is critical for accomplishing all the
identified science metrics including the nuclear equation of state,
cosmological parameters, growth of black holes through cosmic history, and make
new discoveries such as the presence of dark matter within or around neutron
stars and black holes, continuous gravitational waves from rotating neutron
stars, transient signals from supernovae, and the production of stellar-mass
black holes in the early universe. For most metrics the triple network of next
generation terrestrial observatories are a factor 100 better than what can be
accomplished by a network of three A# observatories.Comment: 45 pages, 20 figure