Datasets:

juliensimon
/

cosmic-void-catalog

license: cc-by-4.0
pretty_name: Cosmic Void Catalog
language:
  - en
description: >-
  Catalog of 1,228 cosmic voids from SDSS, with positions, redshifts, radii, and
  density contrasts. Cosmic voids are vast underdense regions in the large-scale
  structure of the universe.
task_categories:
  - tabular-classification
tags:
  - space
  - cosmic-void
  - large-scale-structure
  - cosmology
  - sdss
  - astronomy
  - dark-energy
  - open-data
  - tabular-data
  - parquet
size_categories:
  - 1K<n<10K
configs:
  - config_name: default
    data_files:
      - split: train
        path: data/cosmic_voids.parquet
    default: true

Cosmic Void Catalog

Part of the Astronomy Datasets and Galaxies & Cosmology collections on Hugging Face.

Catalog of 1,228 cosmic voids identified in the Sloan Digital Sky Survey (SDSS), sourced from VizieR CDS Strasbourg.

Dataset description

Cosmic voids are vast underdense regions in the large-scale structure of the universe, typically 20-50 Mpc in radius. They occupy the majority of the volume of the universe and are bounded by filaments, walls, and clusters that form the cosmic web. Voids are among the cleanest cosmological laboratories available because their interiors are dominated by dark energy rather than by the complex nonlinear gravitational dynamics that govern overdense regions.

Void properties are powerful probes of fundamental physics. The void size function (abundance as a function of radius) is sensitive to the matter density parameter, sigma_8, and the dark energy equation of state. The Alcock-Paczynski test applied to stacked void shapes constrains the expansion history of the universe. Void lensing profiles measure the matter content of underdense regions and test modified gravity theories, since voids amplify the differences between general relativity and alternative theories such as f(R) gravity. The integrated Sachs-Wolfe (ISW) effect -- the late-time blueshift of CMB photons traversing growing voids -- provides independent evidence for dark energy.

This catalog enables studies of void demographics, spatial distribution, and correlations with other large-scale structure tracers. Cross-matching with galaxy surveys reveals how galaxy properties (color, morphology, star formation rate) depend on large-scale environment, testing the hypothesis that void galaxies evolve differently from their counterparts in denser regions.

Schema

Column	Type	Description
`sample`	string	Sample
`id`	int	Id
`ra_deg`	float	Right ascension J2000 (degrees)
`dec_deg`	float	Declination J2000 (degrees)
`redshift`	float	Void center redshift
`ngal`	int	Ngal
`v`	float	V
`radius_eff_mpc`	float	Effective void radius (Mpc)
`nmin`	float	Nmin
`delmin`	float	Delmin
`r`	float	R
`prob`	float	Prob
`dbound`	float	Dbound

Quick stats

1,228 cosmic voids
Median effective radius: 54.1 Mpc
Largest void radius: 452.7 Mpc
Median redshift: 0.480
Redshift range: 0.214 to 0.672

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/cosmic-void-catalog", split="train")
df = ds.to_pandas()

# Void size distribution
import matplotlib.pyplot as plt
if "radius_eff_mpc" in df.columns:
    df["radius_eff_mpc"].dropna().hist(bins=30, edgecolor="black")
    plt.xlabel("Effective Radius (Mpc)")
    plt.ylabel("Count")
    plt.title("Cosmic Void Size Distribution")

# Redshift distribution
if "redshift" in df.columns:
    df["redshift"].dropna().hist(bins=30, edgecolor="black")
    plt.xlabel("Redshift")
    plt.ylabel("Count")
    plt.title("Void Redshift Distribution")

# Sky distribution
plt.figure(figsize=(12, 6))
plt.scatter(df["ra_deg"], df["dec_deg"], s=df.get("radius_eff_mpc", 5)**2 / 50,
            alpha=0.5, c=df.get("redshift"), cmap="viridis")
plt.colorbar(label="Redshift")
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("Cosmic Void Sky Distribution")

Data source

Cosmic void catalog from the Sloan Digital Sky Survey (SDSS), accessed via VizieR, CDS Strasbourg.

Primary source: Pan D.C., Vogeley M.S., Hoyle F., Choi Y.-Y., Park C., 2012, MNRAS, 421, 926.

Update schedule

Semi-annual (January and July 1st at 07:30 UTC) via GitHub Actions.

Related datasets

desi-dr1-redshifts -- DESI DR1 galaxy redshifts
galaxy-clusters -- Planck SZ galaxy clusters
pantheon-plus-sne-ia -- Pantheon+ Type Ia supernovae
planck-sz2-clusters -- Planck SZ2 cluster catalog

Pipeline

Source code: juliensimon/space-datasets

Support

If you find this dataset useful, please give it a ❤️ on the dataset page and share feedback in the Community tab! Also consider giving a ⭐️ to the space-datasets repo.

Citation

@dataset{cosmic_void_catalog,
  author = {Simon, Julien},
  title = {Cosmic Void Catalog},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/cosmic-void-catalog},
  note = {Based on SDSS void catalogs via VizieR CDS Strasbourg}
}

License

CC-BY-4.0