64 research outputs found
Searching for gravitational wave burst in PTA data with piecewise linear functions
Transient gravitational waves (aka gravitational wave bursts) within the
nanohertz frequency band could be generated by a variety of astrophysical
phenomena such as the encounter of supermassive black holes, the kinks or cusps
in cosmic strings, or other as-yet-unknown physical processes. Radio-pulses
emitted from millisecond pulsars could be perturbed by passing gravitational
waves, hence the correlation of the perturbations in a pulsar timing array can
be used to detect and characterize burst signals with a duration of
years. We propose a fully Bayesian framework for the
analysis of the pulsar timing array data, where the burst waveform is
generically modeled by piecewise straight lines, and the waveform parameters in
the likelihood can be integrated out analytically. As a result, with merely
three parameters (in addition to those describing the pulsars' intrinsic and
background noise), one is able to efficiently search for the existence and the
sky location of {a burst signal}. If a signal is present, the posterior of the
waveform can be found without further Bayesian inference. We demonstrate this
model by analyzing simulated data sets containing a stochastic gravitational
wave background {and a burst signal generated by the parabolic encounter of two
supermassive black holes.Comment: 13 pages, 10 figure
Supermassive Black-hole Demographics & Environments With Pulsar Timing Arrays
Precision timing of large arrays (>50) of millisecond pulsars will detect the
nanohertz gravitational-wave emission from supermassive binary black holes
within the next ~3-7 years. We review the scientific opportunities of these
detections, the requirements for success, and the synergies with
electromagnetic instruments operating in the 2020s.Comment: Submitted to the Astro2020 Decadal Survey. One of 5 core white-papers
authored by members of the NANOGrav Collaboration. 9 pages, 2 figure
Implementation of an efficient Bayesian search for gravitational wave bursts with memory in pulsar timing array data
The standard Bayesian technique for searching pulsar timing data for
gravitational wave (GW) bursts with memory (BWMs) using Markov Chain Monte
Carlo (MCMC) sampling is very computationally expensive to perform. In this
paper, we explain the implementation of an efficient Bayesian technique for
searching for BWMs. This technique makes use of the fact that the signal model
for Earth-term BWMs (BWMs passing over the Earth) is fully factorizable. We
estimate that this implementation reduces the computational complexity by a
factor of 100. We also demonstrate that this technique gives upper limits
consistent with published results using the standard Bayesian technique, and
may be used to perform all of the same analyses that standard MCMC techniques
can perform.Comment: 19 pages, 3 figures, 1 table. Submitted to Astrophysical Journa
Supermassive Black-hole Demographics & Environments With Pulsar Timing Arrays
Precision timing of large arrays (>50) of millisecond pulsars will detect the nanohertz gravitational-wave emission from supermassive binary black holes within the next ~3-7 years. We review the scientific opportunities of these detections, the requirements for success, and the synergies with electromagnetic instruments operating in the 2020s
Recommended from our members
Techno–ecological synergies of solar energy for global sustainability
The strategic engineering of solar energy technologies—from individual rooftop modules to large solar energy power plants—can confer significant synergistic outcomes across industrial and ecological boundaries. Here, we propose techno–ecological synergy (TES), a framework for engineering mutually beneficial relationships between technological and ecological systems, as an approach to augment the sustainability of solar energy across a diverse suite of recipient environments, including land, food, water, and built-up systems. We provide a conceptual model and framework to describe 16 TESs of solar energy and characterize 20 potential techno–ecological synergistic outcomes of their use. For each solar energy TES, we also introduce metrics and illustrative assessments to demonstrate techno–ecological potential across multiple dimensions. The numerous applications of TES to solar energy technologies are unique among energy systems and represent a powerful frontier in sustainable engineering to minimize unintended consequences on nature associated with a rapid energy transition
- …