The latticework structure known as the cosmic web provides a valuable insight
into the assembly history of large-scale structures. Despite the variety of
methods to identify the cosmic web structures, they mostly rely on the
assumption that galaxies are embedded in a Euclidean geometric space. Here we
present a novel cosmic web identifier called SCONCE (Spherical and CONic Cosmic
wEb finder) that inherently considers the 2D (RA,DEC) spherical or the 3D
(RA,DEC,z) conic geometry. The proposed algorithms in SCONCE generalize the
well-known subspace constrained mean shift (SCMS) method and primarily address
the predominant filament detection problem. They are intrinsic to the
spherical/conic geometry and invariant to data rotations. We further test the
efficacy of our method with an artificial cross-shaped filament example and
apply it to the SDSS galaxy catalogue, revealing that the 2D spherical version
of our algorithms is robust even in regions of high declination. Finally, using
N-body simulations from Illustris, we show that the 3D conic version of our
algorithms is more robust in detecting filaments than the standard SCMS method
under the redshift distortions caused by the peculiar velocities of halos. Our
cosmic web finder is packaged in python as SCONCE-SCMS and has been made
publicly available.Comment: 20 pages, 9 figures, 2 table