juliensimon/galaxy-clusters

Planck PSZ2 Galaxy Cluster Catalog

Credit: NASA/ESA/STScI

Part of a dataset collection on Hugging Face.

Dataset description

Galaxy clusters detected by the Planck satellite via the Sunyaev-Zeldovich effect, with mass, redshift, and signal-to-noise measurements sourced from NASA HEASARC.

Galaxy clusters are the largest gravitationally bound structures in the universe. The Planck satellite detected them through the thermal Sunyaev-Zeldovich effect: hot intracluster gas distorts the cosmic microwave background spectrum. The PSZ2 catalog is the second and final Planck SZ source catalog, based on the full mission data.

Galaxy clusters occupy a unique position in cosmology: they sit at the intersection of structure formation theory and observational cosmology. As the most massive virialized objects in the universe, their abundance as a function of mass and redshift is exquisitely sensitive to the matter density parameter, the amplitude of density fluctuations (sigma_8), and the dark energy equation of state. Counting clusters at different epochs therefore provides independent constraints on cosmological parameters complementary to those from the CMB power spectrum, baryon acoustic oscillations, and Type Ia supernovae.

The thermal Sunyaev-Zeldovich effect exploited by Planck arises when CMB photons inverse-Compton scatter off the hot electrons in the intracluster medium, which can reach temperatures of 10^7 to 10^8 K. This produces a characteristic spectral distortion that is independent of redshift, making SZ surveys uniquely capable of detecting massive clusters at any distance. The integrated SZ signal (Y_5R500) is tightly correlated with total cluster mass, providing a nearly mass-limited sample essential for cluster cosmology.

This dataset is suitable for tabular regression tasks.

Schema

Column	Type	Description	Sample	Null %
name	str	Planck cluster designation in the format 'PSZ2 GXXX.X+/-XX.X' (Galactic longitude and latitude encoded in the name)	PSZ2 G000.04+45.13	0.0%
ra	float64	ICRS J2000.0 right ascension of the cluster center in degrees (0-360)	229.190512	0.0%
dec	float64	ICRS J2000.0 declination of the cluster center in degrees (-90 to +90)	-1.017222	0.0%
lii	float64	Galactic longitude of the cluster center in degrees (0-360)	0.04053948	0.0%
bii	float64	Galactic latitude of the cluster center in degrees (-90 to +90)	45.13517508	0.0%
redshift	float64	Cluster spectroscopic or photometric redshift; null for ~30% of Planck clusters lacking optical confirmation	0.1198	33.8%
redshift_source_name	str	Survey or reference providing the redshift (e.g., 'SDSS', 'ACT', 'SPT'); null if redshift is null	RXC J1516.5-0056	43.6%
mass_sz	float64	SZ-derived cluster mass M_SZ in units of 10^14 solar masses; Planck clusters range ~1-15; null if Y_5R500 is unavailable	3.962411	33.8%
mass_sz_pos_err	float64	Upper (positive) 1-sigma uncertainty on mass_sz in units of 10^14 solar masses; null if mass_sz is null	0.39329	33.8%
mass_sz_neg_err	float64	Lower (negative) 1-sigma uncertainty on mass_sz in units of 10^14 solar masses; null if mass_sz is null	0.370242	33.8%
y5r500	float64	Integrated Compton y-parameter measured within 5*R_500 in arcmin^2; dimensionless measure of total ICM thermal energy; low-scatter mass proxy; typical range 1e-4 to 1e-2 arcmin^2	0.005481591	0.0%
y5r500_error	float64	1-sigma uncertainty on Y_5R500 in arcmin^2; null if y5r500 is null	0.0018995	0.0%
snr	float64	Planck detection signal-to-noise ratio; catalog threshold SNR > 4.5; most massive clusters can reach SNR > 50	6.75319	0.0%
det_pipeline_codes	int64	Bitmask or code string indicating which of the three detection pipelines confirmed this cluster: MMF1, MMF3, PwS (PowellSnakes)	111	0.0%

Quick stats

• 1,653 galaxy clusters from the Planck PSZ2 catalog
• 1,094 with measured redshift (median z = 0.224, max z = 0.972)
• Median detection SNR: 5.6
• Median SZ mass: 4.74 x 10^14 M_sun

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/galaxy-clusters", split="train")
df = ds.to_pandas()

from datasets import load_dataset

ds = load_dataset("juliensimon/galaxy-clusters", split="train")
df = ds.to_pandas()

# Redshift distribution
z = df["redshift"].dropna()
print(f"{len(z):,} clusters with redshift, median z = {z.median():.3f}")

# Most massive clusters
top = df.nlargest(10, "mass_sz")[["name", "redshift", "mass_sz", "snr"]]
print(top)

# Sky map in Galactic coordinates
import matplotlib.pyplot as plt
plt.scatter(df["lii"], df["bii"], c=df["snr"], s=3, cmap="viridis")
plt.colorbar(label="SNR")
plt.xlabel("Galactic longitude (deg)")
plt.ylabel("Galactic latitude (deg)")
plt.title("Planck PSZ2 Galaxy Clusters")
plt.show()

Data source

https://heasarc.gsfc.nasa.gov/W3Browse/all/plancksz2.html

Related datasets

• juliensimon/planck-sz2-clusters

• juliensimon/desi-dr1-redshifts

• juliensimon/pantheon-plus-sne-ia

• juliensimon/gaia-qso

• juliensimon/black-holes

• juliensimon/cosmic-voids

• juliensimon/cosmicflows

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About the author

Created by Julien Simon — AI Operating Partner at Fortino Capital. Part of the Space Datasets collection.

Citation

@dataset{galaxy_clusters,
  title = {Planck PSZ2 Galaxy Cluster Catalog},
  author = {juliensimon},
  year = {2026},
  url = {https://huggingface.co/datasets/juliensimon/galaxy-clusters},
  publisher = {Hugging Face}
}

License

CC-BY-4.0