SDSS-IV Cosmic Web Catalog

This repository contains the cosmic web catalog data released in the paper "Cosmic Web Catalog on SDSS-IV Data with SCONCE" (preparing).

The catalog is constructed on the SDSS-IV galaxies and quasars (QSO) using our proposed Directional Subspace Constrained Mean Shift (DirSCMS) algorithm. We release both the cosmic filaments and local modes (i.e., local maxima of the estimated galaxy/QSO density field, which serves as candidates of galaxy clusters) within 325 thin redshift slices, each of which spans 20Mpc under the Planck15 cosmology. The entire catalog covers the redshift range from \(z=0\) to \(z=3\).

    1. "Cosmic_filaments_2D_DirSCMS_new1": The file contains some discrete realizations of the estimated cosmic filaments in some particular redshift slices. The meaning of each column in the file is described as follows:

RA -- right ascension.

DEC -- declination.

z_low -- lower limit of the redshift slice.

z_high -- upper limit of the redshift slice.

comov_dist_low -- lower limit of the comoving distance in the redshift slice under the Planck15 cosmology.

comov_dist_high -- upper limit of the comoving distance in the redshift slice under the Planck15 cosmology.

bw -- smoothing bandwidth parameter for the DirSCMS algorithm in the redshift slice.

unc_meas -- uncertainty measure of the filamentary point by the nonparametric bootstrap techinque.

density -- (proportional) estimated galaxy/QSO density value at the filamentary point.

grad_Dir1 -- (Riemannian) gradient of the estimated density field (first direction).

grad_Dir2 -- (Riemannian) gradient of the estimated density field (second direction).

grad_Dir3 -- (Riemannian) gradient of the estimated density field (third direction).

knot_label -- indicator of whether the filamentary point is a knot (i.e., the intersection of several filaments) or not.

    2. "Cosmic_local_modes_2D_DirMS_unique1": The file contains some discrete realizations of the estimated local modes in some particular redshift slices. The columns are subsumed by the ones in the cosmic filament file and has been described above.

Additional notes: We provide both the "csv" and "fits" format for each of the above file.

Please cite the paper when using the data in this repository.

► Pure catalog data:

[1] Cosmic Web Catalog on SDSS-IV Data with SCONCE. (In preparation)

►Methodology:

[1] Yikun Zhang, Rafael S. de Souza, and Yen-Chi Chen (2022). SCONCE: A Cosmic Web Finder for Spherical and Conic Geometries. arXiv preprint arXiv:2207.07001

[2] Yikun Zhang and Yen-Chi Chen (2022) Linear Convergence of the Subspace Constrained Mean Shift Algorithm: From Euclidean to Directional Data. Information and Inference: A Journal of the IMA, iaac005, https://doi.org/10.1093/imaiai/iaac005

[3] Yikun Zhang and Yen-Chi Chen (2021) Kernel Smoothing, Mean Shift, and Their Learning Theory with Directional Data. Journal of Machine Learning Research 22(154): 1-92.