Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observational Black Hole Spectroscopy: A time-domain multimode analysis
  of GW150914   The detection of the least damped quasi-normal mode from the remnant of the
gravitational wave event GW150914 realised the long sought possibility to
observationally study the properties of quasi-stationary black hole spacetimes
through gravitational waves. Past literature has extensively explored this
possibility and the emerging field has been named "black hole spectroscopy". In
this study, we present results regarding the ringdown spectrum of GW150914,
obtained by application of Bayesian inference to identify and characterise the
ringdown modes. We employ a pure time-domain analysis method which infers from
the data the time of transition between the non-linear and quasi-linear regime
of the post-merger emission in concert with all other parameters characterising
the source. We find that the data provides no evidence for the presence of more
than one quasi-normal mode. However, from the central frequency and damping
time posteriors alone, no unambiguous identification of a single mode is
possible. More in-depth analysis adopting a ringdown model based on results in
perturbation theory over the Kerr metric, confirms that the data do not provide
enough evidence to discriminate among an $l=2$ and the $l=3$ subset of modes.
Our work provides the first comprehensive agnostic framework to observationally
investigate astrophysical black holes' ringdown spectra.

24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin