Pulsar Timing Arrays: a tool for astrophysics and cosmology
Chiara Mingarelli
Caltech
Pulsar Timing Arrays (PTAs) are currently the only way to search for
gravitational radiation in the nanohertz band. Sources of interest include
gravitational wave (GW) backgrounds generated by supermassive black hole
binaries (SMBHBs) and processes in the early universe such as relic GWs
and cosmic strings. Limits on the GW background continue to improve,
and searches of increasing sensitivity are ongoing. Here I will discuss
recent limits on the stochastic GW background, how we can characterize
the stochastic GW background from SMBHBs on any angular scale to search
for anisotropy, and how environmental interactions with SMBHBs affect
the GW strain spectrum, and thus become observable. I then discuss how
PTAs can place limits on the amplitude of the relic GW background and
may eventually be a valuable tool for cosmology by providing independent
constraints on the scalar-to-tensor ratio "r", and the spectral index
of the tensor fluctuation spectrum "n_t". Finally, I present recent
European PTA limits on cosmic string tension, which are a factor of 1.5
more constraining than the Planck (2014) results.
Date: | Tuesday, 21 April 2015 |
Time: | 13:30 |
Where: | McGill University |
| McGill Space Institute (3550 University), Conference Room |
Contact: | Robert Rutledge |
|