Data for, 'A Splashback-like Feature of Central Galaxies in Galaxy Clusters'

This data set, combined with the code in Github (https://github.com/yyzhang/BCG_splashback_2026), can be used to re-produce figures in the paper "A Splashback-like Feature of Central Galaxies in Galaxy Clusters" (arXiv:2509.22780).

The `data/` folder contains eight subdirectories of input files used by the scripts in the Github repo.

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Observational data (related to DES Y3 RedMaPPer)

These are the primary observational profiles used in Figures 1, 2, and 3.

rdmp6422_y6coadd_masked/

Holds the DES Y3 RedMaPPer cluster catalog and associated quality masks.

- **`y3_gold_2.2.1_wide_sofcol_run2_redmapper_v6.4.22+2_lgt20_vl02_catalog.fit`** (15 MB, FITS): The full RedMaPPer cluster catalog for DES Y3 Gold, richness λ > 20. Used by `make_SPLdetect_indCL.py` to load individual cluster properties (redshift, richness, RA/Dec).

- **`..._foreground_dis0.200000.txt`**: Per-cluster foreground contamination flag. Two columns: cluster index and a binary flag. Clusters flagged as contaminated within a 0.2-degree exclusion radius are excluded from the stacking analysis.

- **`..._y6a1zauto_5sigmadepth22.3_dis0.150000.txt`**: Per-cluster imaging depth quality flag derived from DES Y6 co-add 5σ depth maps. Two columns: cluster index and a binary flag. Clusters below the 22.3 mag depth threshold within 0.15 degrees are excluded.

- **`z020_030_01/`**: Directory containing ~1166 subdirectories (`object_N/`), one per cluster in the redshift bin z = 0.2–0.3. Each subdirectory holds raw per-cluster surface brightness profiles in three bands:
  - `profile_1_i.txt`, `profile_1_r.txt`, `profile_1_z.txt`: columns are radial bin center (kpc) and surface brightness; `nan` indicates no data at that radius.

redmapper_y3a2_6422v2_y6im/

Stacked and jackknife-resampled surface brightness profiles for the RedMaPPer cluster sample, split by redshift and richness. There are 12 subdirectories covering three redshift bins (z = 0.2–0.3, 0.3–0.4, 0.4–0.5) and four richness bins (λ = 20–30, 30–45, 45–60, 60+), e.g. `jacknife_profiles_foregroundflag_z020_030_y6coadd_rich20_30_zauto015/`.

Each subdirectory contains:
- **`jacknife_profile_{r,i,z}.fits`** (3 files): The full stacked surface brightness profile in the r, i, z photometric bands.
- **`jacknife_index_{0..39}_{r,i,z}.txt`** (120 files): Jackknife leave-one-out samples (index of the clusters in the sample) for each of the 40 jackknife spatial regions, in each band. Used by `plot_toolkit.py` to estimate the covariance and error bars on the stacked profiles.

rand_y3a2_6422v2/

Background (random-point) surface brightness profiles, structured identically to `redmapper_y3a2_6422v2_y6im/` but without a richness split. Three subdirectories cover the three redshift bins. Each contains `jacknife_profile_{r,i,z}.fits` and 40 × 3 jackknife index files. These random profiles are subtracted from the cluster profiles to remove the sky background and systematic gradients.

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Simulation data (derived from IllustrisTNG simulations)

TNG50-1_cluster/

Dark matter particle data for a single massive TNG50-1 cluster at z = 0 (snapshot 99). Contains 10 million randomly drawn DM particles.

| File | Contents |
|---|---|
| `dm_x_randraw.txt` | x-position of each particle (simulation units, kpc/h) |
| `dm_y_randraw.txt` | y-position |
| `dm_z_randraw.txt` | z-position |
| `dm_vx_randraw.txt` | x-velocity |
| `dm_vy_randraw.txt` | y-velocity |
| `dm_vz_randraw.txt` | z-velocity |
| `dm_norm_randraw.txt` | subhalo bound flag per particle (0 or 1) |

Each file has one value per line (10 million lines). Used by `plot_tng50-1_z0.py` (Figure 5) to produce spatial maps and phase-space diagrams.

TNG50-1_3D/

Three-dimensional stellar density profiles for the TNG50-1 cluster sample at snapshot 99 (z = 0). Contains 21 halos (one per row in the profile files, 50 log-spaced radial bins per halo, ranging from 0.005 to 1 R₂₀₀ₘ).

| File | Contents |
|---|---|
| `halos_proprties_snap99.txt` | Halo catalogue: M₂₀₀ₘ, R₂₀₀ₘ, GroupPos (x,y,z), GroupCM (x,y,z) — 1 header line + 21 rows |
| `haloprofile3D_Stellarsnapshot99.txt` | Total stellar density profile for each halo (21 × 50 values) |
| `haloprofile3D_Diffuse_Stellarsnapshot99.txt` | Diffuse/ICL stellar density profile for each halo (21 × 50 values) |
| `radii3D_Stellarsnapshot99.txt` | Radial bin centres in units of R₂₀₀ₘ for each halo (21 × 50 values) |

Used by `plot_tng50-1_z0.py` (Figure 5) for the 3D stellar profile panels.

TNG50-1_Projected/

Projected (2D line-of-sight integrated) stellar surface density profiles for the TNG50-1 cluster, at snapshot 99. Same four-file layout as `TNG50-1_3D/` but with `haloprofile2D` and `radii2D` naming. Contains 3 halos with 49 radial bins each. Used by `plot_tng50-1_z0.py` (Figure 5) for the 2D projected profile panels.

TNG300-1_Projected/

Projected stellar surface density profiles for all massive halos (M₂₀₀ₘ > 10¹⁴ M☉/h) in TNG300-1 at snapshot 99 (z = 0). Same four-file layout (`haloprofile3D_*`, `radii3D_*`) as the TNG50-1 directories. Contains 670 halos with 49 radial bins each.

| File | Contents |
|---|---|
| `halos_proprties_snap99.txt` | Halo catalogue for 670 TNG300-1 halos (M₂₀₀ₘ, R₂₀₀ₘ, GroupPos, GroupCM) |
| `haloprofile3D_Stellarsnapshot99.txt` | Total projected stellar density for each halo (note that this is the projected profile not 3D)|
| `haloprofile3D_Diffuse_Stellarsnapshot99.txt` | Diffuse/ICL projected stellar density for each halo (note that this is the projected profile not 3D) |
| `radii3D_Stellarsnapshot99.txt` | Radial bin centres in units of R₂₀₀ₘ for each halo (note that this is the projected profile not 3D)|

Used by `plot_TNG300splashback_panel_projected.py` (Figure 8).

history_tracking/

Time-series orbital data for dark matter particles tracked backwards from z = 0, used by `plot_history_all.py` and `plot_history_panel.py`. Particles are grouped into four initial-distance bins: `dist30` (< 30 kpc), `dist100` (< 100 kpc), `dist300` (< 300 kpc), and `dist20_500` (20–500 kpc from cluster centre at z = 0).

For each distance bin `{X}`, the following files are present:

| File | Contents |
|---|---|
| `dm_bth_randraw_dist{X}part_dmx.txt` | x-position of each tracked particle at each snapshot (rows = snapshots, columns = particles); `-99999` flags particles not present at that snapshot |
| `dm_bth_randraw_dist{X}part_dmy.txt` | y-position |
| `dm_bth_randraw_dist{X}part_dmz.txt` | z-position |
| `dm_bth_randraw_dist{X}part_dm_vx.txt` | x-velocity |
| `dm_bth_randraw_dist{X}part_dm_vy.txt` | y-velocity |
| `dm_bth_randraw_dist{X}part_dm_vz.txt` | z-velocity |
| `dm_bth_randraw_dist{X}snap_info.txt` | Per-snapshot metadata: scale factor, snapshot number, cluster centre position (x,y,z) and velocity (vx,vy,vz) |
| `dm_bth_randraw_dist{X}_wid.txtpart_dm_dist_vfull.txt` | Normalised radial distance (r/Rsubhalo) to the nearest subhalo for each particle at each snapshot; `-99` flags absent particles |

Two global snapshot info files:
- **`snap_info_vfull.txt`**: Scale factor, snapshot number, and cluster centre position/velocity at each snapshot from z ≈ 1 to z = 0.
- **`snap_info_vfulldist20_500.txt`**: Same, for the `dist20_500` sample.