Characterising filaments in the SDSS volume from the galaxy distribution
  Detecting the large-scale structure of the Universe based on the galaxy
distribution and characterising its components is of fundamental importance in
astrophysics but is also a difficult task to achieve. Wide-area spectroscopic
redshift surveys are required to accurately measure galaxy positions in space
that also need to cover large areas of the sky. It is also difficult to create
algorithms that can extract cosmic web structures (e.g. filaments). Moreover,
these detections will be affected by systematic uncertainties that stem from
the characteristics of the survey used (e.g. its completeness and coverage) and
from the unique properties of the specific method adopted to detect the cosmic
web (i.e. the assumptions it relies on and the free parameters it may employ).
For these reasons, the creation of new catalogues of cosmic web features on
wide sky areas is important, as this allows users to have at their disposal a
well-understood sample of structures whose systematic uncertainties have been
thoroughly investigated. In this paper we present the filament catalogues
created using the discrete persistent structure extractor (DisPerSE) tool in
the Sloan Digital Sky Survey (SDSS), and we fully characterise them in terms of
their dependence on the choice of parameters pertaining to the algorithm, and
with respect to several systematic issues that may arise in the skeleton as a
result of the properties of the galaxy distribution (such as Finger-of-God
redshift distortions and defects of the density field that are due to the
boundaries of the survey).
